EXPLANATORY NOTE

Sangamo Therapeutics, Inc. (the “Company”) is filing this revised definitive proxy statement solely to correct inadvertent clerical errors contained in footnote (2) to the table titled “Security Ownership of Certain Beneficial Owners and Management” beginning on page 47 of the original definitive proxy statement filed with the Securities and Exchange Commission earlier on April 24, 2018. No other changes have been made to the original proxy statement. The Company will distribute and make available to its stockholders this revised definitive proxy statement in lieu of the original definitive proxy statement.

SANGAMO THERAPEUTICS, INC.

NOTICE OF ANNUAL MEETING OF STOCKHOLDERS

To Be Held June 11, 2018

To the Stockholders of Sangamo Therapeutics, Inc.:

NOTICE IS HEREBY GIVEN that the 2018 Annual Meeting of Stockholders of Sangamo Therapeutics, Inc., a Delaware corporation (the “Company,” “Sangamo” or “we”), will be held on Monday, June 11, 2018, at 9:00 a.m. Pacific Time at 501 Canal Boulevard, Richmond, California 94804, for the following purposes, as more fully described in the proxy statement accompanying this Notice:

In accordance with rules established by the Securities and Exchange Commission, we are providing you access to our proxy materials over the Internet. Accordingly, we plan to mail a Notice of Internet Availability of Proxy Materials (the “Notice”), to our stockholders on or about May 1, 2018. The Notice will describe how to access and review our proxy materials, including our proxy statement and annual report on Form 10-K. The Notice as well as the printed copy of proxy cards will also describe how you may submit your proxy on the Internet or by telephone. If you received a Notice by mail and would like to receive a printed copy of our proxy materials, you should follow the instructions for requesting such materials included in the Notice. As a courtesy, we will also mail our registered stockholders a printed copy of all proxy materials.

Only stockholders of record at the close of business on April 17, 2018, are entitled to notice of and to vote at the annual meeting. Our stock transfer books will remain open between the record date and the date of the annual meeting. A list of stockholders entitled to vote at the annual meeting will be available for inspection at our executive offices. All stockholders are cordially invited to attend the annual meeting in person. To attend the annual meeting you will need a form of photo identification. If your shares are held in street name, you will also need to bring proof of your ownership of our common stock, such as your most recent brokerage statement. Whether or not you plan to attend the annual meeting, please vote as soon as possible.

Richmond, California

April 24, 2018

Important Notice Regarding the Availability of Proxy Materials

For the Stockholder Meeting to be Held on June 11, 2018

at 9:00 a.m. Pacific Time at 501 Canal Boulevard, Richmond, California 94804

The Proxy Statement, Proxy Card and Annual Report on Form 10-K for 2017 are available at:

www.envisionreports.com/SGMO

YOUR VOTE IS VERY IMPORTANT

SANGAMO THERAPEUTICS, INC.

501 Canal Boulevard

Richmond, California 94804

PROXY STATEMENT

FOR THE ANNUAL MEETING OF STOCKHOLDERS

To Be Held On June 11, 2018

QUESTIONS AND ANSWERS ABOUT THESE PROXY MATERIALS AND VOTING

Why did I receive a notice regarding the availability of proxy materials on the Internet?

Pursuant to rules adopted by the Securities and Exchange Commission (the “SEC”), we have elected to provide access to our proxy materials over the Internet. Accordingly, we have sent you a Notice of Internet Availability of Proxy Materials (the “Notice”) because the Board of Directors (the “Board of Directors” or the “Board”) of Sangamo Therapeutics, Inc. (sometimes referred to as the “Company,” “Sangamo” or in the first person) is soliciting your proxy to vote at the 2018 Annual Meeting of Stockholders (the “Annual Meeting”), including at any adjournments or postponements of such meeting. All stockholders will have the ability to access the proxy materials on the website referred to in the Notice or request to receive a printed set of the proxy materials. Instructions on how to access the proxy materials over the Internet or to request a printed copy may be found in the Notice.

We intend to mail the Notice on or about April 26, 2018 to all stockholders of record entitled to vote at the Annual Meeting.

Will I receive any other proxy materials by mail?

We may send you a proxy card, along with a second Notice, on or after May 6, 2018. We also intend to mail a full set of proxy materials to our stockholders of record on or about April 26, 2018.

How do I attend the Annual Meeting?

The meeting will be held on Monday, June 11 at 9:00 a.m. Pacific Time at 501 Canal Boulevard, Richmond, California 94804. Directions to the Annual Meeting may be found at www.sangamo.com/about/contact. Information on how to vote in person at the Annual Meeting is discussed below.

Who can vote at the Annual Meeting?

Only stockholders of record at the close of business on April 17, 2018 will be entitled to vote at the Annual Meeting. On this record date, there were 87,145,700 shares of common stock outstanding and entitled to vote.

Stockholder of Record: Shares Registered in Your Name

If on April 17, 2018 your shares were registered directly in your name with our transfer agent, then you are a stockholder of record. As a stockholder of record, you may vote in person at the meeting or vote by proxy. Whether or not you plan to attend the meeting, we urge you to vote your shares electronically over the Internet or by telephone, or by completing and returning a printed proxy card that you may request or that we may elect to deliver at a later time, to ensure your vote is counted.

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Beneficial Owner: Shares Registered in the Name of a Broker or Bank

If on April 17, 2018 your shares were held, not in your name, but rather in an account at a brokerage firm, bank or other similar organization, then you are the beneficial owner of shares held in “street name” and the Notice is being forwarded to you by that organization. The organization holding your account is considered to be the stockholder of record for purposes of voting at the Annual Meeting. As a beneficial owner, you have the right to direct your broker, bank or other agent regarding how to vote the shares in your account. You are also invited to attend the Annual Meeting. However, because you are not the stockholder of record, you may not vote your shares in person at the meeting unless you request and obtain a valid proxy from your broker, bank or other agent.

What am I voting on?

There are five matters scheduled for a vote:

What if another matter is properly brought before the meeting?

The Board knows of no other matters that will be presented for consideration at the Annual Meeting. If any other matters are properly brought before the meeting, it is the intention of the persons named in the accompanying proxy to vote on those matters in accordance with their best judgment.

How do I vote?

For each of the other matters to be voted on at the Annual Meeting, including each nominee for director, you may vote “For” or “Against” or abstain from voting.

The procedures for voting are fairly simple:

Stockholder of Record: Shares Registered in Your Name

If you are a stockholder of record, you may vote in person at the Annual Meeting, vote by proxy over the telephone, vote by proxy through the Internet or vote by proxy using a proxy card that you may request or that we may elect to deliver at a later time. Whether or not you plan to attend the meeting, we urge you to vote by proxy to ensure your vote is counted. You may still attend the meeting and vote in person even if you have already voted by proxy.

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Beneficial Owner: Shares Registered in the Name of Broker or Bank

If you are a beneficial owner of shares registered in the name of your broker, bank or other agent, you should have received a Notice containing voting instructions from that organization rather than from us. Simply follow the voting instructions in the Notice to ensure that your vote is counted. Alternatively, you may vote by telephone or over the Internet as instructed by your broker or bank. To vote in person at the Annual Meeting, you must obtain a valid proxy from your broker, bank or other agent. Follow the instructions from your broker, bank or other agent included with these proxy materials, or contact that organization to request a proxy form.

How many votes do I have?

On each matter to be voted upon, you have one vote for each share of common stock you owned as of April 17, 2018.

If I am a stockholder of record and I do not vote, or if I return a proxy card or otherwise vote without giving specific voting instructions, what happens?

If you are a stockholder of record and do not vote through the Internet, by telephone, by completing a proxy card that may be delivered to you or in person at the Annual Meeting, your shares will not be voted.

If you return a signed and dated proxy card or otherwise vote without marking voting selections, your shares will be voted, “For” each of the proposals, including for each nominee for director. If any other matter is properly presented at the meeting, your proxyholder (one of the individuals named on your proxy card) will vote your shares using his or her best judgment.

If I am a beneficial owner of shares held in street name and I do not provide my broker or bank with voting instructions, what happens?

If you are a beneficial owner of shares held in street name and you do not instruct your broker, bank or other agent how to vote your shares, your broker, bank or other agent may still be able to vote your shares in its discretion. In this regard, under the rules of the New York Stock Exchange (“NYSE”), brokers, banks and other securities intermediaries that are subject to NYSE rules may use their discretion to vote your “uninstructed” shares with respect to matters considered to be “routine” under NYSE rules, but not with respect to “non-routine” matters. In this regard, we believe that Proposals Nos. 1, 2, 3 and 4 are considered to be “non-routine” under NYSE rules meaning that your broker may not vote your shares on those proposals in the absence of your voting instructions. However, Proposal No. 5 is considered a “routine” matter under NYSE rules, meaning that if you do not return voting instructions to your broker by its deadline, your shares may be voted by your broker in its discretion on Proposal No. 5.

If you are a beneficial owner of shares held in street name, to ensure your shares are voted in the way you would prefer, you must provide voting instructions to your broker, bank or other agent by the deadline provided in the materials you receive from your broker, bank or other agent.

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Who is paying for this proxy solicitation?

We will pay for the entire cost of soliciting proxies. In addition to these proxy materials, our directors and employees may also solicit proxies in person, by telephone, or by other means of communication. Directors and employees will not be paid any additional compensation for soliciting proxies. We may also reimburse brokerage firms, banks and other agents for the cost of forwarding proxy materials to beneficial owners.

What does it mean if I receive more than one Notice?

If you receive more than one Notice, your shares may be registered in more than one name or in different accounts. Please follow the voting instructions on the Notices to ensure that all of your shares are voted.

Can I change my vote after submitting my proxy?

Stockholder of Record: Shares Registered in Your Name

Yes. You can revoke your proxy at any time before the final vote at the meeting. If you are the record holder of your shares, you may revoke your proxy in any one of the following ways:

Your most current proxy card or telephone or Internet proxy is the one that is counted.

Beneficial Owner: Shares Registered in the Name of Broker or Bank

If your shares are held by your broker, bank or other agent, you should follow the instructions provided by your broker, bank or other agent.

How are votes counted?

Votes will be counted by the inspector of election appointed for the meeting, who will separately count votes “For” and “Against,” abstentions and, if applicable, broker non-votes.

What are “broker non-votes?”

As discussed above, when a beneficial owner of shares held in street name does not give voting instructions to his or her broker, bank or other securities intermediary holding his or her shares as to how to vote on matters deemed to be “non-routine” under NYSE rules, the broker, bank or other such agent cannot vote the shares. These un-voted shares are counted as “broker non-votes.” Proposals Nos. 1, 2, 3 and 4 are considered to be “non-routine” under NYSE rules and we therefore expect broker non-votes to exist in connection with those proposals.

As a reminder, if you are a beneficial owner of shares held in street name, to ensure your shares are voted in the way you would prefer, you must provide voting instructions to your broker, bank or other agent by the deadline provided in the materials you receive from your broker, bank or other agent.

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How many votes are needed to approve each proposal? How are abstentions and broker non-votes treated?

The following table summarizes the minimum vote needed to approve each proposal and the effect of abstentions and broker non-votes.

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What is the quorum requirement?

A quorum of stockholders is necessary to hold a valid meeting. A quorum will be present if stockholders holding at least a majority of the outstanding shares entitled to vote are present at the meeting in person or represented by proxy. On the record date, there were 87,145,700 shares outstanding and entitled to vote.

Your shares will be counted towards the quorum only if you submit a valid proxy (or one is submitted on your behalf by your broker, bank or other nominee) or if you vote in person at the meeting. Abstentions and broker non-votes will be counted towards the quorum requirement. If there is no quorum, the Chair of the Board may adjourn the meeting to another date without a stockholder vote.

How can I find out the results of the voting at the Annual Meeting?

Preliminary voting results will be announced at the Annual Meeting. In addition, final voting results will be published in a current report on Form 8-K that we expect to file within four business days after the Annual Meeting. If final voting results are not available to us in time to file a Form 8-K within four business days after the meeting, we intend to file a Form 8-K to publish preliminary results and, within four business days after the final results are known to us, file an additional Form 8-K to publish the final results.

When are stockholder proposals and director nominations due for next year’s Annual Meeting?

To be considered for inclusion in next year’s proxy materials, your proposal must be submitted in writing by December 27, 2018, to our Secretary at 501 Canal Boulevard, Richmond, California 94804, and you must comply with all applicable requirements of Rule 14a-8 promulgated under the Securities Exchange Act of 1934, as amended (the “Exchange Act”).

Pursuant to our Bylaws, if you wish to bring a proposal before the stockholders or nominate a director at the 2019 Annual Meeting of stockholders, but you are not requesting that your proposal or nomination be included in next year’s proxy materials, you must notify our Secretary, in writing, not later than the close of business on March 13, 2019 nor earlier than the close of business on February 11, 2019. However, if our 2019 Annual Meeting of stockholders is not held between May 12, 2019 and July 11, 2019, to be timely, notice by the stockholder must be received not later than the 10th day following the day on which the first public announcement of the date of the 2019 Annual Meeting is made or the notice of the meeting is mailed, whichever first occurs. You are also advised to review our Bylaws, which contain additional requirements about advance notice of stockholder proposals and director nominations.

The chair of the Annual Meeting may determine, if the facts warrant, that a matter has not been properly brought before the meeting and, therefore, may not be considered at the meeting. In addition, the proxy solicited by the Board for the 2019 Annual Meeting of Stockholders will confer discretionary voting authority with respect to any proposal (i) presented by a stockholder at that meeting for which we have not been provided with timely notice and (ii) made in accordance with our Bylaws, if (x) the 2019 proxy statement briefly describes the matter and how management’s proxy holders intend to vote on it, and (y) the stockholder does not comply with the requirements of Rule 14a-4(c)(2) promulgated under the Exchange Act.

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PROPOSAL NO. 1:

ELECTION OF DIRECTORS

General

Our Board consists of eight directors and one vacancy due to the resignation of William R. Ringo effective as of January 1, 2018. There are eight nominees for director this year. Each director to be elected and qualified will hold serve until the next annual meeting of stockholders or until a successor for such director is duly elected and qualified, or until the death, resignation or removal of such director. The nominees for election have agreed to serve if elected, and management has no reason to believe that such nominees will be unavailable to serve. In the event the nominees are unable or decline to serve as directors at the time of the annual meeting, the proxies will be voted for any nominee who may be designated by the present Board of Directors to fill the vacancy. Proxies may not be voted for a greater number of persons than the number of nominees named. Unless otherwise instructed, the proxy holders will vote the proxies received by them FOR the nominees named below.

Each of the eight nominees other than Roger Jeffs, Ph.D., and Joseph Zakrzewski, has been previously elected by the stockholders. Dr. Jeffs’ and Mr. Zakrzewski’s candidacies were recommended to the Nominating and Corporate Governance Committee by the Chief Executive Officer and another member of the Nominating and Corporate Governance Committee. While the Nominating and Corporate Governance Committee and the Board chose to nominate Alexander D. Macrae, our Chief Executive Officer, for election to the Board for the reasons set forth in his biography below, Dr. Macrae’s employment agreement also provides that the Board shall nominate Dr. Macrae for election as a member of the Board at each annual meeting of stockholders occurring while Dr. Macrae’s employment agreement is in effect.

Each of the eight nominees set forth in this Proxy Statement will be elected by the majority of the votes cast with respect to such nominee. If an incumbent director does not receive the required majority vote, the director shall promptly tender his or her resignation to the Board. Within 90 days after the annual meeting, the Nominating and Corporate Governance Committee of the Board will make a recommendation to the Board of Directors as to whether to accept or reject the resignation. The Board will act by taking into account such committee’s recommendation. If the Board does not accept the resignation, the Board is required to publicly disclose its decision and the rationale behind the decision.

The following includes a brief biography of each nominee for director, including their respective ages as of April 24, 2018. Each biography includes information regarding the specific experience, qualifications, attributes or skills that led the Nominating and Corporate Governance Committee and the Board to determine that the applicable nominee should serve as a member of the Board as of the date of this proxy statement.

Nominees

Alexander D. Macrae, M.B., Ch.B., Ph.D., age 55 has served as our President and Chief Executive Officer and as a member of our Board of Directors since June 2016. He has twenty years of experience in the pharmaceutical industry most recently serving as the Global Medical Officer of Takeda Pharmaceuticals, from 2012 to March 2016, where he established and led the Global Medical Office, which encompasses medical affairs, regulatory affairs, pharmacovigilance, outcomes research and epidemiology, quantitative sciences and knowledge and informatics. From 2001 to 2012, Dr. Macrae held roles of increasing responsibility at GlaxoSmithKline, including Senior Vice President, Emerging Markets Research and Development (“R&D”), from 2009 to 2012. In that position, he provided expertise and resources to create a first-of-its-kind group to expand GSK’s global reach by providing R&D strategies, clinical development and regulatory resources to enter emerging markets and Asia-Pacific. From 2007 to 2008, he was Vice President, Business Development. In that position, he was responsible for scientific assessment and business development project leadership for the neurology, psychiatry, cardiovascular and metabolic therapeutic areas. Earlier in his career, he worked for SmithKline Beecham, where he was responsible for clinical development in the therapeutic areas of neurology

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and gastroenterology. Dr. Macrae received his B.Sc. in pharmacology and his M.B., Ch.B. with honors from Glasgow University. He is a member of the Royal College of Physicians. Dr. Macrae also earned his Ph.D. in molecular genomics at King’s College, Cambridge. The Nominating and Corporate Governance Committee and the Board believe that Dr. Macrae’s day-to-day leadership and intimate knowledge of our business and operations, as well as our relationships with partners, collaborators and investors, provide the Board with an in-depth understanding of the Company.

Robert F. Carey, age 59, has served as a member of our Board of Directors since June 2016. Mr. Carey has been executive vice president, chief business officer for Horizon Pharma plc, a biopharmaceutical company, since March 2014. Prior to that, he served as managing director and head of the healthcare investment banking group at JMP Securities LLC, a full-service investment bank from March 2003 to March 2014. Prior to JMP, Mr. Carey was a managing director in the healthcare groups at Dresdner Kleinwort Wasserstein and Vector Securities International, Inc. He has also held roles at Shearson Lehman Hutton and Ernst & Whinney. Mr. Carey has served on the board of directors of Argos Therapeutics, Inc., a life science company, since September 2015. Mr. Carey received his B.S. in accounting from the University of Notre Dame. The Nominating and Corporate Governance Committee and the Board believe that Mr. Carey’s extensive experience and knowledge in the healthcare investment banking industry, particularly with financings, global expansion and other strategic transactions by life-science companies, as well as his role in business development for a public biopharmaceutical company, will provide the Board with valuable insight and contribution.

Stephen G. Dilly, M.B.B.S., Ph.D., age 58, has served as a member of our Board of Directors since March 2010. Since May 2014, Dr. Dilly has served as Chief Executive Officer and a member of the board of directors of Aimmune Therapeutics, Inc. (formerly Allergen Research Corporation), a biotechnology company developing treatments for food allergies. From January 2012 to December 2012, he was Chief Executive Officer of PhotoThera, Inc., a medical device company. From 2006 to December 2011, he served as President and Chief Executive Officer and a member of the board of directors of APT Pharmaceuticals, Inc., a drug development company. From 2007 to 2009, he served as a member of the board of directors of Avigen, Inc., a biopharmaceutical company that merged with MediciNova, Inc. in December 2009. From 2003 to 2006, he served as Chief Medical Officer and Senior Vice President of Development of Chiron BioPharma, a biotechnology company that was later acquired by Novartis International AG. From 1998 to 2003, he held various management positions at Genentech, Inc., including Vice President of Development Sciences from 2002 to 2003 and Vice President of Medical Affairs from 1998 to 2001. From 1988 to 1998, Dr. Dilly held various management positions in drug development with SmithKline Beecham in the U.K. During his career, Dr. Dilly has been closely associated with the development and launch of marketed drugs for many therapeutic areas, including Kytril, Paxil, Kredex, Requip, TNKase, Xolair, Avastin, Raptiva, Tarceva, Lucentis and Cubicin. In 1982 Dr. Dilly received an M.B.B.S., the equivalent of an M.D. in the United States, from the University of London in the U.K. and a Ph.D. in cardiac physiology from University of London in 1988. Dr. Dilly brings medical expertise and significant drug development experience to our Board. The Nominating and Corporate Governance Committee and the Board believe that Dr. Dilly’s extensive experience in all stages of drug development, from project prioritization through clinical trial design and data analysis to product launch, provides the Board with valuable insight into this process as the Company continues to advance and develop our pipeline of novel genomic and cell therapy assets.

Roger Jeffs, Ph.D., age 56, has served as a member of our Board of Directors since June 2017. Prior to his retirement in 2016, Dr. Jeffs served as President and co-Chief Executive Officer of United Therapeutics Corp., where he worked for 18 years, joining the company in its start-up phase in 1998 as Director, Research, Development and Medical and serving as President and Chief Operating Officer from 2001 to 2014. He has over 25 years of experience in the biopharmaceutical industry in R&D, clinical development, regulatory and medical affairs. While at United Therapeutics, Dr. Jeffs led the clinical development, regulatory approval and commercialization of six rare disease products and managed the commercial effort that led to a greater than 20% compound annual growth rate (CAGR) and $1.5 billion annual revenue run rate. Prior to joining United Therapeutics, he held positions in clinical development at Amgen, Inc. and Burroughs Wellcome Co. Dr. Jeffs currently also serves as a

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member of the board of directors of Albireo Pharma, Inc., Axsome Therapeutics, Inc., Axovant Sciences Ltd. and Dova Pharmaceuticals, Inc. He received a B.A. in Chemistry from Duke University and his Ph.D. in Pharmacology from the University of North Carolina School of Medicine. The Nominating and Corporate Governance Committee and the Board believe that Dr. Jeffs’ extensive experience at a publicly traded biotechnology company commercializing rare diseases provides the Board with important qualifications and skills as the Company moves towards the possible commercialization of its novel genomic and cell therapy assets.

Steven J. Mento, Ph.D., age 66, has served as a member of our Board of Directors since May 2005. Since July 2005, Dr. Mento has served as President and Chief Executive Officer of Conatus Pharmaceuticals Inc., a biotechnology company engaged in the development of human therapy for liver disease. From 1997 to 2005, he was President and Chief Executive Officer of Idun Pharmaceuticals. From 1992 to 1997, Dr. Mento was an executive officer at Viagene, Inc. In January of 1992 he joined Viagene, Inc. as Vice President of Research and Development, where he was responsible for directing the company’s transition from basic research through initiation of the first company sponsored Phase I and Phase II clinical trials in the emerging field of gene therapy. In October of 1995, Chiron Corporation acquired Viagene, Inc., and renamed the company Chiron Viagene, Inc. Prior to that, from 1982 to 1992, Dr. Mento held various positions at American Cyanamid Company, the last one being the Director of Viral Vaccine Research and Development at Lederle-Praxis Biologicals, a business unit of American Cyanamid Company. Dr. Mento currently serves on the boards of BIOCOM, the BIOCOM Institute and the Biotechnology Industry Organization (BIO), as well as a member of the BIO ECS Governing Body, the BIO Health Section Governing Body, the Donald P. Shiley BioScience Center at SDSU Scientific Advisory Board and Cal State San Marcos Advisory Council. Dr. Mento received a B.A., M.S., and a Ph.D. in microbiology from Rutgers University. He completed his post-doctoral fellowship in somatic cell genetics at the University of Toronto. The Nominating and Corporate Governance Committee and the Board believe that Dr. Mento’s scientific technical background and extensive operational experience in the early stages of the development of biologic drugs provide the Board with expertise in the management and development of our novel genomic and cell therapy assets.

H. Stewart Parker, age 62, has been a member of our Board of Directors since June 2014. Ms. Parker has over 30 years of experience in the biotechnology industry. Prior to focusing on boards and consulting, she served as the Chief Executive Officer of The Infectious Disease Research Institute (IDRI), a not-for-profit global health Research institute from March 2011 to December 2013. In 1992 Ms. Parker founded Targeted Genetics Corporation, a publicly traded Seattle-based biopharmaceutical company formed to develop gene-based treatments for acquired and inherited diseases that became a world leader in AAV gene therapy. She held the position of President and Chief Executive Officer and was a member of its board of directors from the company’s inception until November 2008. Prior to founding Targeted Genetics, Ms. Parker served in various capacities at Immunex from August 1981 through December 1991, most recently as Vice President, Corporate Development. From February 1991 to January 1993, Ms. Parker served as President and a Director of Receptech Corporation, a company formed by Immunex in 1989 to accelerate the development of soluble cytokine receptor products. She has served on the board of directors and the executive committee of BIO, the primary trade organization for the biotechnology industry. She currently serves as a member of the board of directors for several for-profit companies including C3J Therapeutics (formerly C3 Jian Inc), Achieve Life Sciences, Inc., StrideBio Inc. and Nexgenia and on the advisory boards of the University of Washington Foundation and College of Arts & Sciences. Ms. Parker received her B.A. and M.B.A. from the University of Washington. The Nominating and Corporate Governance Committee and the Board believe that Ms. Parker’s senior executive experience in AAV gene therapy and biotechnology drug development provides valuable operational, commercial assessment and management skills to the Board.

Saira Ramasastry, age 42, has served as a member of our Board of Directors since June 2012. Since April 2009, she has served as Managing Partner of Life Sciences Advisory, LLC, a company that she founded to provide strategic advice, business development solutions and innovative financing strategies for the life science industry. From August 1999 to March 2009, Ms. Ramasastry was an investment banker with Merrill Lynch & Co., Inc. where she helped establish the biotechnology practice and was responsible for origination of mergers

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and acquisitions (“M&A”), strategic and capital markets transactions. Prior to joining Merrill Lynch she served as a financial analyst in the M&A group at Wasserstein Perella & Co., an investment banking firm, from July 1997 to September 1998. Ms. Ramasastry currently serves on the Industry Advisory Board of the Michael J. Fox Foundation for Parkinson’s Research, the board of directors of Pain Therapeutics, Inc., and lead business advisor for the European Prevention of Alzheimer’s Dementia consortium. Ms. Ramasastry received her B.A. in economics with honors and distinction and an M.S. in management science and engineering from Stanford University, as well as an M. Phil. in management studies from the University of Cambridge where she is a guest lecturer for the Bioscience Enterprise Programme and serves on the Cambridge Judge Business School Advisory Council. Ms. Ramasastry is also a Health Innovator Fellow of the Aspen Institute and a member of the Aspen Global Leadership Network. The Nominating and Corporate Governance Committee and the Board believe that Ms. Ramasastry’s extensive experience in global healthcare investment banking and strategic advisory consulting provides valuable financial, commercial assessment and business development skills to the Board and her thorough understanding of our technology and programs provides the Board with valuable insight in the development of our novel genomic and cell therapy assets.

Joseph S. Zakrzewski, age 55, has served as a member of our Board of Directors since June 2017. Mr. Zakrzewski has over 25 years of experience in the biopharmaceutical industry with senior leadership experience in R&D, supply chain and manufacturing operations, business development and commercialization. Prior to focusing on serving on boards and investments, from 2010 through 2013, he was Chairman and Chief Executive Officer of Amarin Corporation PLC (formerly Amarin Pharmaceuticals, Inc.), where he led the development and commercialization of the company’s first product, Vascepa. Mr. Zakrzewski previously served as a Venture Partner with Orbimed Advisors LLC, a venture capital firm, and as Chairman, President and CEO of Xcellerex, Inc., a privately held company focused on the commercialization of its proprietary manufacturing technology for biotherapeutics and vaccines. Earlier, he served as COO of Reliant Pharmaceuticals, Inc. before its acquisition by GlaxoSmithKline in 2007 and held various executive positions at Eli Lilly & Company in the areas of R&D, manufacturing, finance and business development. Mr. Zakrzewski currently serves as a member of the board of directors of various public and private companies, including Acceleron Pharma, Inc., Amarin, Insulet Corporation and Onxeo SA where he serves as Chairman. Mr. Zakrzewski received a B.S. in Chemical Engineering and an M.S. in Biochemical Engineering from Drexel University, and an M.B.A. in Finance from Indiana University. The Nominating and Corporate Governance Committee and the Board believe that Mr. Zakrzewski’s significant experience as a Chief Executive Officer and leading a variety of functional areas including supply and manufacturing operations provides the Board with an important set of skills to assist in the oversight of the development of our novel genomic and cell therapy assets.

Board Independence

The Board of Directors has determined that William R. Ringo was, and each of its current and nominated directors is, independent under applicable listing standard of Nasdaq Stock Market LLC (“Nasdaq”), except for Dr. Macrae, who is our Chief Executive Officer. There are no family relationships between any of our directors and any of our executive officers.

Board Committees and Meetings

The Board of Directors held 10 meetings during 2017. The Board of Directors has an Audit Committee, a Compensation Committee, and a Nominating and Corporate Governance Committee. Each director attended or participated in 75% or more of the aggregate of (i) the total number of meetings of the Board of Directors and (ii) the total number of meetings held by all committees of the Board on which such director served during 2017, in each case held during the period for which each respective director was serving as a director.

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Audit Committee

The Audit Committee consists of three directors: Mr. Carey, Ms. Ramasastry, and Mr. Zakrzewski. Mr. Zakrzewski was appointed to serve on the Audit Committee in September 2017. Mr. Carey serves as the Chairman of this committee. Mr. Ringo served on the Audit Committee for all of 2017. His resignation from the Board, including all of its committees, was effective January 1, 2018. Our Board of Directors has determined that Mr. Ringo was, and each member of the Audit Committee is, independent under the applicable listing standard of Nasdaq and SEC rules. The Board of Directors has determined that Mr. Carey is an “audit committee financial expert” as defined under SEC rules and has the requisite financial sophistication in accordance with the applicable Nasdaq listing standards. The Audit Committee held five meetings during 2017.

The Audit Committee assists the Board of Directors in its oversight of the integrity of our financial statements, the risk management and our internal controls and our compliance with legal and regulatory requirements. The Audit Committee interacts directly with, and evaluates the performance of, the independent registered public accounting firm, including determining whether to engage or dismiss the independent registered public accounting firm and to monitor the independent registered public accounting firm’s qualifications and independence. The Audit Committee also pre-approves all audit services and permissible non-audit services provided by the independent registered public accounting firm. The Audit Committee Report is included herein on page 82. The Audit Committee has a written charter, which is available on our website at www.sangamo.com.

Compensation Committee

The Compensation Committee consists of three directors: Dr. Mento, Ms. Parker and Dr. Jeffs, each of whom is independent under applicable Nasdaq and SEC rules. Mr. Ringo served on the Compensation Committee for all of 2017 and was independent under applicable Nasdaq and SEC rules. His resignation from the Board, including all of its committees, was effective January 1, 2018. Dr. Mento serves as the Chairman of this committee. In September 2017, Dr. Jeffs was appointed to serve on the Compensation Committee.

The Compensation Committee’s responsibilities include (i) adopting, administering and reviewing compensation plans and programs for our executive officers, including incentive and equity plans and programs; (ii) approving compensation arrangements for our executive officers; (iii) evaluating the performance of our executive officers; (iv) adjusting compensation arrangements as appropriate based upon performance; (v) reviewing, considering and approving compensation programs applicable to non-employee members of the Board of Directors; (vi) reviewing and monitoring management development and succession plans and activities and (vii) administering, concurrently with the Board of Directors, the Sangamo Therapeutics Inc. 401(k) Profit Sharing Plan and Trust, originally effective on January 1, 1998, and as most recently amended and restated as of June 24, 2015 (the “401(k) Plan”).

The Compensation Committee may delegate any responsibility or authority of the Compensation Committee under its charter to one or more members of the Compensation Committee, as appropriate and as consistent with applicable laws and rules. Further, the Compensation Committee may delegate to one or more employees or one or more other members of the Board, the authority to grant awards of equity securities pursuant to our equity incentive plans, in each case to any persons who are not executive officers or key employees in accordance with such guidelines as may be established by the Compensation Committee. The Compensation Committee may also form and delegate authority to a committee composed solely of our employees to serve as an administrative and/or investment committee, with fiduciary responsibilities under the Employee Retirement Income Security Act of 1974 (“ERISA”), with respect to one or more of our plans that are subject to ERISA. The Compensation Committee may also form and delegate authority to a subcommittee composed solely of at least two members of the Compensation Committee who are “non-employee directors” under Rule 16b-3 to grant awards of equity securities and to take such other actions as may be necessary or appropriate to qualify transactions in our equity securities under the Rule 16b-3 exemptions.

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The Compensation Committee is authorized to engage, oversee and terminate independent compensation consultants and other professionals to assist in the design, formulation, analysis and implementation of compensation programs for our executive officers and other key employees. The Compensation Committee retained the services of Radford, an Aon Hewitt Company (“Radford”), in order to (i) assess compensation levels and mix of elements for our executive officers and vice presidents for 2017, (ii) review the peer group criteria and to recommend specific companies, (iii) assess the compensation of the non-employee directors and (iv) advise the committee on executive compensation and governance trends based on peer group trends and market practices.

The Compensation Committee held five meetings during 2017. The Compensation Committee has a written charter, which is available on our website at www.sangamo.com. For information regarding our processes and procedures for the consideration and determination of executive and director compensation, please see “Executive Compensation—Compensation Discussion and Analysis” and “—Director Compensation,” respectively.

Compensation Committee Interlocks and Insider Participation

During 2017, Dr. Mento, Ms. Parker, Dr. Jeffs, and William R. Ringo, who resigned from the Board and all committees thereof effective January 1, 2018, served on the Compensation Committee. None of our Compensation Committee members has been an officer or employee of Sangamo at any time. None of our executive officers serves on the board of directors or compensation committee of any entity that has one or more executive officers serving as a member of our Board or our Compensation Committee.

Nominating and Corporate Governance Committee

The Nominating and Corporate Governance Committee consists of three directors: Dr. Dilly, Ms. Parker and Dr. Jeffs, each of whom is independent under applicable Nasdaq listing standards. Mr. Ringo served on the Nominating and Corporate Governance for all of 2017. His resignation from the Board, including all of its committees, was effective January 1, 2018. As of March 2018, Dr. Jeffs chairs the Nominating and Corporate Governance Committee. The Nominating and Corporate Governance Committee considers and periodically reports on matters relating to the size, identification, selection and qualification of the Board of Directors and candidates nominated for the Board of Directors and its committees, and develops and recommends governance principles and policies applicable to the Company.

The Nominating and Corporate Governance Committee held one meeting and acted once by unanimous written consent in lieu of a meeting during 2017. The Nominating and Corporate Governance Committee has a written charter, which is available on our website at www.sangamo.com. The Nominating and Corporate Governance Committee considers properly submitted stockholder recommendations for candidates for membership on the Board of Directors as described below under “—Identification and Evaluation of Nominees for Directors.” In evaluating such recommendations, the Nominating and Corporate Governance Committee seeks to achieve a balance of knowledge, experience and capability on the Board of Directors and to address the membership criteria set forth below under “—Director Qualifications.”

Director Qualifications

The Nominating and Corporate Governance Committee will use a variety of criteria to evaluate the qualifications and skills necessary for members of our Board of Directors. The Nominating and Corporate Governance Committee may assess character, judgment, business acumen and scientific expertise, and familiarity with issues affecting the biotechnology and pharmaceutical industries. Other qualifications will be determined on a case-by-case basis, depending on whether the Nominating and Corporate Governance Committee desires to fill a vacant seat or increase the size of the Board to add new directors. In addition, the Nominating and Corporate Governance Committee may also evaluate whether a potential director nominee’s

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skills are complementary to existing Board members’ skills or meet the Board’s need for operations, management, commercial, financial or other expertise. While the Nominating and Corporate Governance Committee does not prescribe specific diversity standards, as a matter of practice, the committee considers diversity in the context of the Board as a whole and takes into account the personal characteristics and experiences of current and prospective directors that reflect a broad range of perspectives in the Board’s decision-making process.

Identification and Evaluation of Nominees for Directors

The Nominating and Corporate Governance Committee utilizes a variety of methods for identifying and evaluating nominees for director. The Nominating and Corporate Governance Committee assesses the appropriate size of the Board of Directors, and whether any vacancies on the Board of Directors are expected due to retirement or otherwise. In the event that vacancies are anticipated, or otherwise arise, the Nominating and Corporate Governance Committee considers various potential candidates for director. Candidates may come to the attention of the Nominating and Corporate Governance Committee through current members of the Board of Directors or senior management, executive recruiting firms, stockholders or other persons. With respect to the appointment of Dr. Jeffs and Mr. Zakrzewski, the Nominating and Corporate Governance Committee paid a fee to a third-party executive recruiting firm to assist with the identification and vetting potential candidates for the Board. These candidates are evaluated at regular or special meetings of the Nominating and Corporate Governance Committee, and may be considered at any point during the year. The Nominating and Corporate Governance Committee considers properly submitted stockholder recommendations for candidates for the Board of Directors. Stockholder nominees will receive the same consideration that nominees of the Board receive. Any stockholder recommendations proposed for consideration by the Nominating and Corporate Governance Committee must provide all information requested by the Nominating and Corporate Governance Committee relating to such recommendation, including the candidate’s name and qualifications for membership on the Board of Directors and should be addressed to Investor Relations at the following address:

Investor Relations Department

Sangamo Therapeutics, Inc.

501 Canal Boulevard

Richmond, CA 94804

In evaluating such recommendations, the Nominating and Corporate Governance Committee applies the qualifications standards discussed above and seeks to achieve a balance of knowledge, experience and capability on the Board of Directors.

Leadership Structure of the Board

Under our Bylaws, the Board is not required to appoint our Chief Executive Officer as the Chair of the Board, and the Board does not have a policy on whether or not the roles of Chief Executive Officer and Chair of the Board should be separate. Currently two individuals serve these two positions. Ms. Parker currently serves as the Chair of the Board. Ms. Parker has extensive knowledge and experience in the life science industry and an in-depth understanding of our business strategies and day-to-day operations, which makes her well suited to set the agenda and lead the discussions at Board meetings as the Chair. The Chair is responsible for chairing Board meetings and meetings of stockholders, setting the agenda for Board meetings and providing information to the Board members in advance of meetings and between meetings. In addition, our Chief Executive Officer, Dr. Macrae, also serves as a director on our Board. The Board believes that Dr. Macrae’s membership as a director provides the Board with an in-depth understanding of our business operations because of his extensive experiences and knowledge of the day-today management of all aspects of our operations. This will also facilitate communications between the Board and management by ensuring a regular flow of information, thereby enhancing the Board’s ability to make informed decisions on critical issues facing our company.

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Of the eight directors on the Board following the annual meeting, seven directors are independent under applicable Nasdaq corporate governance rules. The Board believes that this establishes a strong independent board that provides effective oversight of the Company. Moreover, in addition to feedback provided during the course of Board meetings, the independent directors conduct regular executive sessions without the presence of Dr. Macrae or any other members of management. We believe that our leadership structure of the Board is appropriate given the nature and size our businesses, because it provides both effective independent oversight and expertise in the complexity and management of our operations as a life sciences company.

Oversight of Risk Management by the Board

Our Board of Directors is generally responsible for the oversight of corporate risk in its review and deliberations relating to our activities and has determined that our principal source of risk falls into two categories: (1) financial and (2) product development and testing. The Audit Committee oversees management of risks associated with our financial and accounting systems, public financial reporting, investment strategies and policy, and certain other matters delegated to the Audit Committee, including risks associated with our information technology systems (including cybersecurity risks). Our Board of Directors regularly reviews information regarding our cash position, liquidity and operations, as well as the risks associated with each. The Board regularly reviews plans, results and potential risks related to our lead therapeutic development programs and other preclinical programs as well as financial and strategic risk related to our operations.

In addition, the Nominating and Corporate Governance Committee monitors the effectiveness of our corporate policies and manages risks associated with the independence of the Board of Directors and potential conflicts of interest. Our Compensation Committee oversees risk management as it relates to our compensation plans, policies and practices for all employees, including executives, particularly whether our compensation programs may create incentives for our employees to take excessive or inappropriate risks that could have a material adverse effect on the Company. While each committee is responsible for evaluating certain risks and overseeing the management of such risks, the entire Board of Directors is regularly informed through committee reports about such risks.

Annual Meeting Attendance

Although we do not have a formal policy regarding attendance by members of the Board of Directors at our annual meetings of stockholders, directors are encouraged to attend annual meetings of our stockholders. Six directors attended the 2017 annual meeting of stockholders.

Communications with the Board of Directors

Although we do not have a formal policy regarding communications with the Board of Directors, stockholders may communicate with the Board of Directors, including the non-management directors, by sending a letter to the Sangamo Board of Directors, c/o Investor Relations, 501 Canal Boulevard, Richmond, California 94804. Stockholders who would like their submission directed to a particular member of the Board of Directors may so specify.

Code of Business Conduct and Ethics

The Board of Directors has adopted a Code of Business Conduct and Ethics, which is applicable to all employees and directors of the Company. A copy of our Code of Business Conduct and Ethics is available on our website at www.sangamo.com in the Investors & Media Section under Corporate Governance. In the event that we make any amendments to or grant any waivers of, a provision of the Code of Business Conduct and Ethics that applies to the principal executive officer, principal financial officer, or principal accounting officer that requires disclosure under applicable SEC rules, we intend to disclose such amendment or waiver and the reasons therefore, on our website at www.sangamo.com, in the Investors & Media section.

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Director Compensation

The following table sets forth certain information regarding the compensation of each non-employee director for service as a member of the Board of Directors during 2017.

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Processes and Procedures for Determining Director Compensation.

The charter of the Compensation Committee provides the Compensation Committee with the responsibility for reviewing, considering and approving compensation programs applicable to non-employee directors. It is the practice of the Compensation Committee to seek input from outside compensation consultants, including Radford, our Compensation Committee’s compensation consultant, as it deems appropriate.

Director Annual Retainer and Meeting Fees

Each non-employee member of the Board of Directors receives an annual cash retainer of $40,000. To the extent the Board of Directors meets more than 10 times in any year, each non-employee member of the Board of Directors will receive, for each meeting in excess of 10, a per meeting fee of $1,000 if attended in person and $500 if attended by video or telephone conference. The Chairman of the Board of Directors receives an additional annual cash retainer of $35,000. In addition, the non-employee members of the Board of Directors serving as the Chairman of the Audit Committee, the Chairman of the Compensation Committee and the Chairman of the Nominating and Corporate Governance Committee receive an additional annual cash retainer of $20,000, $15,000 and $10,000, respectively. Each non-employee member of the Board of Directors serving as a member of the Audit Committee, the Compensation Committee and the Nominating and Corporate Governance Committee, other than the Chairman, receives an additional annual cash retainer of $10,000, $7,500 and $5,000, respectively. All retainer fees are subject to pro-ration for directors who join or leave the Board of Directors or the respective committee or begin or cease to serve Chairman of the Board or the respective committee, during the year.

The Automatic Grant Program under the 2013 Plan specifically provides the Compensation Committee with the ability to implement a program whereby directors are given the option to elect to convert their cash board retainer fees into restricted stock unit (“RSU”) grants. The Compensation Committee has not implemented such a deferral program.

Equity Incentives Granted Under 2013 Stock Incentive Plan

Under the Automatic Grant Program in effect under the 2013 Plan, on the date of each annual stockholders meeting, each continuing non-employee member of the Board of Directors who served as a director for the previous six months automatically receives an option to purchase 10,000 shares of our common stock. Each option granted under the Automatic Grant Program will have an exercise price per share equal to the fair market value per share of our common stock on the option grant date and will have a maximum term of 10 years, subject to earlier termination following the optionee’s cessation of Board service. Each option is immediately exercisable for all the option shares, but any shares purchased under the option will be subject to repurchase by the Company, at the exercise price paid per share, upon the optionee’s cessation of Board service prior to vesting in those shares. The shares subject to each automatic option grant will vest in successive equal monthly installments upon completion of each month of Board service over a one-year period. However, the shares subject to each automatic option grant will immediately vest upon (i) the optionee’s death or permanent disability while serving as a member of the Board of Directors, (ii) an acquisition of the Company by merger or asset sale, (iii) the successful completion of a tender offer for more than 50% of our outstanding voting stock or (iv) a change in the majority of the Board of Directors effected through one or more proxy contests for Board of Directors membership. The Automatic Grant Program under the 2018 Plan that is the subject of Proposal No. 3 provides for a similar program for continuing non-employee members of the Board of Directors who served as a director for the previous six months, although the amount, type and vesting terms of the awards to be automatically granted are modified. Accordingly, if Proposal No. 3 is approved by the stockholders, our non-employee members of the Board of Directors will continue to receive automatic equity award grants on the date of each annual stockholders meeting. Additionally, if Proposal No. 3 is approved by the stockholders, newly appointed or elected non-employee members of the Board will receive equity grants automatically upon their initial appointment or election. See “—Proposed New Automatic Grant Program Under 2018 Equity Incentive Plan” below for more information.

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The Compensation Committee awarded Dr. Jeffs and Mr. Zakrzewski an initial option to purchase 30,000 shares of our common stock on June 27, 2017, with an exercise price per share equal to the closing price per share of our common stock on that date. The option will vest in 36 successive equal monthly installments over the 36-month period measured from the grant date, subject to Dr. Jeffs’ and Mr. Zakrzewski’s continued service as a member of the Board on each monthly vesting date. The remaining terms of their options are similar to the terms of the annual grants under the Automatic Grant Program.

The Automatic Grant Program in effect under the 2013 Plan provides the Compensation Committee with discretion to grant, in lieu of the option grant that would otherwise be awarded under such program, a number of shares of restricted stock or RSUs to the non-employee directors with a fair market value substantially equal to the grant date fair value of the option that would otherwise be awarded. The Automatic Grant Program under the 2018 Plan that is the subject of Proposal No. 3 does not retain this feature and instead provides for automatic grants of a specified number of options and RSUs.

Pursuant to the Automatic Grant Program in effect under the 2013 Plan, on the date of the 2017 annual meeting of stockholders, Mr. Carey, Dr. Dilly, Dr. Mento, Ms. Parker, Ms. Ramasastry and Mr. Ringo each received an option to purchase 10,000 shares of common stock with an exercise price per share of $7.20.

Proposed New Automatic Grant Program Under 2018 Equity Incentive Plan

If Proposal No. 3 is approved at the Annual Meeting as of such date the Automatic Grant Program under the 2013 Plan will be replaced by a new Automatic Grant Program under the 2018 Plan. Under the automatic grant program of the 2018 Plan, on the date of each annual stockholders meeting commencing with the Annual Meeting, each individual serving as a non-employee Board member at that time, who has served on our Board for at least six months, and who will continue serving as a non-employee Board member immediately after such stockholders meeting will automatically be granted a nonqualified stock option (“NSO”) to purchase 15,000 shares of common stock and a RSU in respect of 2,500 shares of common stock under the 2018 Plan. The shares subject to each annual 15,000 share automatic NSO grant made to a continuing Board member will vest in 12 successive equal monthly installments upon such director’s completion of each month of Board service over the12-month period measured from the grant date. The shares subject to each 2,500 share automatic RSU grant will fully vest on the earlier of (x) the first anniversary of the date of grant or (y) the day prior to the next annual stockholders meeting, subject to the director’s continued service on the Board through the applicable vesting date.

Under the automatic grant program of the 2018 Plan, each non-employee Board member who is initially appointed or elected to the Board on or after the Annual Meeting will automatically be granted a NSO to purchase 30,000 shares of common stock and a RSU award in respect of 5,000 shares of common stock under the 2018 Plan. The shares subject to each initial 30,000 share automatic NSO grant made to a newly appointed Board member will vest in 36 successive equal monthly installments upon such director’s completion of each month of Board service over the 36-month period measured from the grant date. The shares subject to each 5,000 share automatic RSU grant will vest with respect to 1/3^rd of the shares in three equal annual installments over the three-year period measured from the date of grant.

Each automatic NSO grant will have an exercise price per share equal to the fair market value per share of our common stock on the grant date and will have a term of 10 years, subject to earlier termination following the optionee’s cessation of Board service. Each NSO option grant will be immediately exercisable for all of the option shares; however, we may repurchase, at the lower of the exercise price paid per share or the fair market value per share, any shares purchased under the NSO that are not vested at the time of the optionee’s cessation of Board service. The shares subject to each automatic NSO grant and each automatic RSU grant will immediately vest in full upon the director’s death or disability or upon the occurrence of a change of control or hostile takeover (as such terms are defined in Proposal No. 3 below) in each subject to the director’s continued Board service through such date.

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If Proposal No. 3 is approved at the Annual Meeting the options to purchase 105,000 shares of our common stock and RSU awards in respect of 17,500 shares of our common stock will be automatically granted to our non-employee directors as a group on such date under the 2018 Plan. If Proposal No. 3 is not approved at the Annual Meeting, the 2013 Plan will remain in effect so that options to purchase 70,000 shares of our common stock will be automatically granted to our non-employee directors as a group on such date under the 2013 Plan.

Recommendation of the Board of Directors

The Board of Directors recommends that the stockholders vote FOR the election of the nominees listed above.

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PROPOSAL NO. 2:

ADVISORY VOTE ON EXECUTIVE COMPENSATION

General

Under Section 14A(a)(1) of the Exchange Act, our stockholders are entitled to vote to approve, on a non-binding advisory basis, the compensation of our named executive officers as disclosed in this Proxy Statement in accordance with SEC rules (commonly referred to as a “say-on-pay” vote).

This vote is not intended to address any specific item of compensation, but rather the overall compensation of our named executive officers and the philosophy, policies and practices described in this Proxy Statement. Based on the voting results from the 2017 annual meeting of stockholders, our stockholders voted for, and we have adopted an annual advisory vote on the compensation of the named executive officers in our proxy materials, which will remain in effect until the next required vote on the frequency of stockholder votes on the compensation of named executive officers. Although the vote is non-binding, the Board of Directors and the Compensation Committee of the Board value the opinions of our stockholders and will consider the outcome of the vote when making future compensation decisions affecting our executive officers.

We encourage stockholders to read closely the “Executive Compensation” section of this Proxy Statement, beginning with the Compensation Discussion and Analysis (“CD&A”) on page 50, which describes in detail our executive compensation programs, policies and practices with respect to the compensation of our named executive officers in the year ended December 31, 2017.

Our overarching compensation goal is to create a positive relationship between our compensation program and our corporate performance.

We design our executive compensation program to implement our core objectives of attracting and retaining highly qualified executives with extensive industry or scientific experience, rewarding executives for success in meeting our annual clinical development and other research and operational goals, aligning the interests of our executives with those of our stockholders and recognizing executives’ individual performance and, for executives other than our Chief Executive Officer, achievement of their individual goals and those of the functional organizations that they manage.

The Compensation Committee established the 2017 compensation program and the associated Company goals in accordance with the foregoing goals and philosophy. During 2017, we continued the important work of laying the foundation for the Company as a sustainable, fully integrated company that develops, manufacturers and commercializes novel genomic therapies on our own and, where appropriate, in collaboration with industry partners. We now have six active clinical programs, with additional preclinical assets advancing toward an investigational new drug, or IND, application. The highlights of our business successes in 2017 are summarized under the heading “2017 and Early 2018 Performance Highlights” in the CD&A. The Board of Directors believes our executive compensation program uses appropriate structures and sound pay practices that are effective in achieving our core objectives.

Resolution

The Board is asking our stockholders to indicate their support for the compensation of our named executive officers, as described in this Proxy Statement, by casting a non-binding advisory vote “FOR” the following resolution:

“Resolved that the Company’s stockholders hereby approve, on an advisory basis, the compensation of the Company’s named executive officers as disclosed in this Proxy Statement pursuant to the

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compensation disclosure rules of the SEC, including the Compensation Discussion and Analysis, the various compensation tables and the accompanying narrative discussion and any related material included in this Proxy Statement.”

Advisory approval of this Proposal No. 2 requires votes “FOR” from holders of a majority of the stock having voting power present in person or represented by proxy at the Annual Meeting.

Recommendation of the Board of Directors

The Board of Directors recommends an advisory vote FOR the resolution to approve, on an advisory basis, the compensation of the named executive officers as disclosed in this Proxy Statement pursuant to the compensation disclosure rules of the SEC.

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PROPOSAL NO. 3:

2018 EQUITY INCENTIVE PLAN

Our Compensation Committee approved the Sangamo Therapeutics, Inc. 2018 Equity Incentive Plan, or the 2018 Plan, on April 23, 2018, subject to approval by our stockholders. The 2018 Plan is intended to be the successor to the Amended and Restated 2013 Stock Incentive Plan, or the 2013 Plan. Currently, we maintain the 2013 Plan to grant equity awards to provide long-term incentives to our employees, non-employee directors and consultants. In light of changes in 2017 to federal tax laws and other changes that have occurred since the 2013 Plan was originally adopted, our Compensation Committee decided to adopt and seek approval for the 2018 Plan to update our equity plan provisions to align with current tax and regulatory rules and market practices. In addition, the 2018 Plan will include a new reserve of 8,800,000 shares of common stock (in addition to the shares of common stock that are, or would become, available under our 2013 Plan) to ensure that we can continue to grant equity awards to attract and retain high quality employees, non-employee directors and consultants. Additionally, the 2018 Plan includes an automatic grant program for our non-employee directors.

If this Proposal No. 3 is approved by our stockholders, the 2018 Plan will become effective as of the date of the Annual Meeting and no additional equity awards will be granted under the 2013 Plan. However, all outstanding equity awards granted under the 2013 Plan will continue to be subject to the terms and conditions as set forth in the agreements evidencing such awards and the terms of the 2013 Plan. Stockholder approval of this Proposal No. 3 will also constitute pre-approval of each award granted under the 2018 Plan pursuant to the provisions of the automatic grant program for our non-employee directors as described below in this Proposal No. 3. In the event that our stockholders do not approve this Proposal No. 3, the 2018 Plan will not become effective and the 2013 Plan will continue to be effective in accordance with its terms.

Why You Should Vote to Approve the 2018 Plan

Equity Awards Are an Important Part of Our Compensation Philosophy

Our Board believes that the issuance of equity awards is a key element underlying our ability to attract, retain and motivate key personnel, non-employee directors and consultants because of the strong competition for highly trained and experienced individuals among biotechnology and pharmaceutical companies, especially in the greater San Francisco Bay area. Therefore, the Board believes that the 2018 Plan is in the best interests of our business and our stockholders and recommends a vote in favor of this Proposal No. 3.

Approval of the 2018 Plan by our stockholders will allow us to continue to grant equity awards at levels we determine to be appropriate. The 2018 Plan will also allow us to utilize equity awards as long-term incentives to secure and retain the services of our employees, non-employee directors and consultants, consistent with our compensation philosophy and common compensation practice for our industry in the greater San Francisco Bay Area. To date, equity incentives have been a key aspect of our program to attract and retain key employees, non-employee directors and consultants. We believe the use of equity awards strongly aligns the interests of our employees with those of our stockholders by placing a considerable proportion of our employees’ total compensation “at risk” because it is contingent on the appreciation in value of our common stock. In addition, we believe equity awards encourages employee ownership of our common stock and promotes retention through the reward of long-term Company performance.

We Carefully Manage the Use of Equity Awards and the Size of our Share Reserve is Reasonable

Our compensation philosophy reflects broad-based eligibility for equity incentive awards, and we generally grant equity awards to all of our employees and non-employee directors. However, we recognize that equity awards dilute existing stockholders, and, therefore, we are mindful to responsibly manage the growth of our equity compensation program. We are committed to effectively monitoring our equity compensation share reserve,

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including our “burn rate,” to ensure that we maximize stockholders’ value by granting the appropriate number of equity awards necessary to attract, reward, and retain employees, non-employee directors and consultants. The tables below show certain historical overhang and burn rate percentages.

Determination of Number of Shares to Request for the 2018 Plan

In its determination to approve the 2018 Plan, our Compensation Committee reviewed an analysis prepared by Radford, its compensation consultant, which included an analysis of our historic and estimated prospective share usage needs and the potential costs of the 2018 Plan. Specifically, our Compensation Committee considered:

Historic Use of Equity and Outstanding Awards

Overhang

The following table provides certain additional information regarding use of equity.

* Reflects the number of shares available under the Purchase Plan as of the record date. No other shares are available for grant under any other equity incentive plan.

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Burn Rate

The following table provides detailed information regarding the activity related to our 2013 Plan for fiscal year 2017.

Requested Shares

Subject to adjustment for certain changes in our capitalization, if this Proposal No. 3 is approved by our stockholders, the aggregate number of shares of our common stock that may be issued under the 2018 Plan will not exceed the sum of (i) the number of unallocated shares remaining available for the grant of new awards under the 2013 Plan as of the effective date of the 2018 Plan (which is equal to 1,618,588 shares as of April 17, 2018), (ii) 8,800,000 new shares, and (iii) certain shares subject to outstanding awards granted under the 2013 Plan and 2004 Stock Incentive Plan, which together are the Prior Plans, that may become available for grant under the 2018 Plan as such shares become available from time to time (as further described below under “—Description of the 2018 Plan—Shares Available for Stock Awards”).

If the 2018 Plan and the new share reserve of 8,800,000 shares is approved by our stockholders, we expect to have approximately 10,418,588 shares available for grant after our Annual Meeting (based on shares available as of April 17, 2018). We believe the adoption of the 2018 Plan and new share reserve of 8,800,000 shares is necessary for us to remain competitive in the greater San Francisco Bay Area marketplace and support our equity grant practices to align the interests of our employees and non-employee directors with our stockholders. We anticipate the available pool of shares in the 2018 Plan will be sufficient for our equity awards for approximately the next two years after considering our present average share usage rate, and that such pool of shares is necessary to provide a predictable amount of available equity awards for attracting, retaining, and motivating employees, non-employee directors and consultants.

Note Regarding Forward-Looking Statements

We do not as a matter of course make public forecasts as to our utilization of equity awards due to the unpredictability of the underlying assumptions and estimates. The inclusion of the information set forth above should not be regarded as an indication or prediction of actual future outcomes, and the statements should not be relied upon as such. Neither we nor any other person makes any representation to any of our stockholders regarding actual outcomes compared to the information contained in the forward-looking statements set forth above. Although presented with some numerical specificity, these statements are not fact and reflect numerous assumptions and estimates as to future events made by our management that our management believed were reasonable at the time this filing was prepared and other factors such as industry performance and general business, economic, regulatory, market and financial conditions, as well as factors specific to our business, all of which are difficult to predict and many of which are beyond the control of our management. The forecasts are forward-looking statements within the meaning of Section 27A of the Securities Act and Section 21A of the Exchange Act. These statements involve risks and uncertainties that could cause actual outcomes to differ materially from those in the forward-looking statements, including our ability to attract and retain talent, achievement of performance metrics, if any, with respect to certain equity awards, the extent of option exercise activity, forfeiture rates, and other factors described in this Proxy Statement.

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Key Features of the 2018 Plan

The 2018 Plan includes many of the same provisions from the 2013 Plan that are designed to protect our stockholders’ interests and to reflect corporate governance best practices. The following are features added to the 2018 Plan that will further moderate the number of shares available for new grants of equity awards and reflect best practices:

The following are such provisions in the 2018 Plan that are continuing unchanged from the 2013 Plan:

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Description of the 2018 Plan

The material features of the 2018 Plan are described below. The following description of the 2018 Plan is a summary only and is qualified in its entirety by reference to the complete text of the 2018 Plan. Stockholders are urged to read the actual text of the 2018 Plan in its entirety, which is attached to this proxy statement as Appendix A.

Purpose

The 2018 Plan is designed to secure and retain the services of our employees, non-employee directors and consultants, provide incentives for our employees, non-employee directors and consultants to exert maximum efforts for the success of our company and our affiliates, and provide a means by which our employees, non-employee directors and consultants may be given an opportunity to benefit from increases in the value of our common stock. The 2018 Plan also designed to align employees’ interests with stockholder interests.

Successor to 2013 Plan

The 2018 Plan is intended to be the successor to the 2013 Plan. If the 2018 Plan is approved by our stockholders, no additional stock awards will be granted under the 2013 Plan. If the 2018 Plan is not approved by our stockholders, the 2018 Plan will not become effective and the 2013 Plan will continue to be effective in accordance with its terms.

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Types of Stock Awards

The terms of the 2018 Plan provide for the grant of incentive stock options, nonstatutory stock options, stock appreciation rights, restricted stock awards, restricted stock unit awards, other stock awards, and performance stock awards that may be settled in cash, stock, or other property.

Shares Available for Stock Awards

Subject to adjustment for certain changes in our capitalization, the aggregate number of shares of our common stock that may be issued under the 2018 Plan, will not exceed the sum of (i) the number of unallocated shares remaining available for the grant of new stock awards under the 2013 Plan as of the effective date of the 2018 Plan (which is equal to 1,618,588 shares as of April 17, 2018), (ii) 8,800,000 new shares, and (iii) any Returning Shares (as defined below) from the 2018 Plan or the Prior Plans, as such shares become available from time to time. The number of shares of our common stock available for issuance under the 2018 Plan will be reduced by one share for each share of common stock issued pursuant to an Appreciation Award and 1.33 shares for each share of common stock issued pursuant to a Full Value Award.

“Returning Shares” are shares subject to outstanding stock awards granted under the Prior Plans or granted under the 2018 Plan and that in each case from and after the effective date of the 2018 Plan: (i) are not issued because the stock award expires or otherwise terminates without all of the shares covered by the stock award having been issued or is settled in cash, or (ii) are forfeited back to or repurchased by us because of the failure to meet a contingency or condition required for the vesting of such shares. For each Returning Share subject to a Full Value Award granted under the 2018 Plan, or Returning Share subject to Full Value Award granted under the Prior Plans, the number of shares of common stock available for issuance under the 2018 Plan will increase by 1.33 shares.

Any shares of common stock reacquired or withheld (or not issued) by us to satisfy the exercise or purchase price of a stock award granted under the Plan or a Prior Plan will no longer be available for issuance under the 2018 Plan, including any shares subject to such stock award that are not delivered to a participant because the stock award is exercised through a reduction of shares subject to the stock award. In addition, any shares reacquired or withheld (or not issued) by us to satisfy a tax withholding obligation in connection with a stock award granted under the 2018 Plan or a Prior Plan and any shares repurchased by us on the open market with the proceeds of the exercise or purchase price of a stock award granted under the 2018 Plan or a Prior Plan will not be available for issuance under the 2018 Plan.

Eligibility

All of our approximately 192 employees, seven non-employee directors and approximately 10 consultants as of April 17, 2018 are eligible to participate in the 2018 Plan and may receive all types of awards other than incentive stock options. Incentive stock options may be granted under the 2018 Plan only to our employees, including our executive officers. However, participation in the automatic grant program is limited to the seven non-employee directors (see “—Automatic Grant Program for Non-Employee Directors” below).

Administration

Our Compensation Committee administers the 2018 Plan (except the non-discretionary grant program, which is automatic) and may delegate authority to administer the 2018 Plan to a subcommittee of non-employee directors. Our Compensation Committee may, at any time, revest in itself some or all of the power delegated to such a committee. The Compensation Committee and any other committee of non-employee directors to whom the Compensation Committee may delegate authority to administer the 2018 Plan are each considered to be a Plan Administrator for purposes of this Proposal No. 3. Subject to the terms of the 2018 Plan, the Plan Administrator may determine the recipients, the types of stock awards to be granted, the number of shares of our common stock subject to or the cash value of stock awards, and the terms and conditions of stock awards granted

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under the 2018 Plan, including the period of their exercisability and vesting, subject to the minimum vesting requirements. The Plan Administrator also has the authority to provide for accelerated exercisability and vesting of stock awards. Subject to the limitations set forth below, the Plan Administrator also determines the fair market value applicable to a stock award and the exercise or strike price of stock options and stock appreciation rights granted under the 2018 Plan.

The Plan Administrator may also delegate to one or more executive officers the authority to designate employees who are not executive officers to be recipients of certain stock awards and the number of shares of our common stock subject to such stock awards. Under any such delegation, the Plan Administrator will specify the total number of shares of our common stock that may be subject to the stock awards granted by such executive officer. The executive officer may not grant a stock award to himself or herself.

Repricing; Cancellation and Re-Grant of Stock Options or Stock Appreciation Rights

Under the 2018 Plan, the Plan Administrator does not have the authority to reprice any outstanding stock option or stock appreciation right by reducing the exercise or strike price of the stock option or stock appreciation right or to cancel any outstanding stock option or stock appreciation right that has an exercise or strike price greater than the then-current fair market value of our common stock in exchange for cash or other stock awards without obtaining the approval of our stockholders. Such approval must be obtained within 12 months prior to such an event.

Stock Options

Stock options may be granted under the 2018 Plan pursuant to stock option agreements. The 2018 Plan permits the grant of stock options that are intended to qualify as incentive stock options, or ISOs, and nonstatutory stock options, or NSOs.

The exercise price of a stock option granted under the 2018 Plan may not be less than 100% of the fair market value of the common stock subject to the stock option on the date of grant and, in some cases (see “—Limitations on Incentive Stock Options” below), may not be less than 110% of such fair market value.

The term of stock options granted under the 2018 Plan may not exceed ten years and, in some cases (see “—Limitations on Incentive Stock Options” below), may not exceed five years. Except as otherwise provided in a participant’s stock option agreement or other written agreement with us, if a participant’s service relationship with us (referred to in this Proposal No. 3 as “continuous service”) terminates (other than for cause or the participant’s death or disability), the participant may exercise any vested stock options for up to three months following the participant’s termination of continuous service. Except as otherwise provided in a participant’s stock option agreement or other written agreement with us, if a participant’s continuous service terminates due to the participant’s disability, the participant may exercise any vested stock options for up to 12 months following the participant’s termination due to the participant’s disability. Except as otherwise provided in a participant’s stock option agreement or other written agreement with us, if a participant’s continuous service terminates due to the participant’s death (or the participant dies within a specified period, if any, following termination of continuous service), the participant’s beneficiary may exercise any vested stock options for up to 18 months following the participant’s termination due to the participant’s death. Except as explicitly provided otherwise in a participant’s stock option agreement or other written agreement with us or one of our affiliates, if a participant’s continuous service is terminated for cause (as defined in the 2018 Plan), all stock options held by the participant will terminate upon the participant’s termination of continuous service and the participant will be prohibited from exercising any stock option from and after such termination date. Except as otherwise provided in a participant’s stock option agreement or other written agreement with us or one of our affiliates, the term of a stock option may be extended if the exercise of the stock option following the participant’s termination of continuous service (other than for cause or the participant’s death or disability) would be prohibited by applicable securities laws or if the sale of any common stock received upon exercise of the stock option following the participant’s termination of continuous service (other than for cause) would violate our insider trading policy. In no event, however, may a stock option be exercised after its original expiration date.

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Acceptable forms of consideration for the purchase of our common stock pursuant to the exercise of a stock option under the 2018 Plan will be determined by the Plan Administrator and may include payment: (i) by cash, check, bank draft or money order payable to us; (ii) pursuant to a program developed under Regulation T as promulgated by the Federal Reserve Board; (iii) by delivery to us of shares of our common stock (either by actual delivery or attestation); (iv) by a net exercise arrangement (for NSOs only); or (v) in other legal consideration approved by the Plan Administrator.

Stock options granted under the 2018 Plan may become exercisable in cumulative increments, or “vest,” as determined by the Plan Administrator at the rate specified in the stock option agreement. Shares covered by different stock options granted under the 2018 Plan may be subject to different vesting schedules as the Plan Administrator may determine.

The Plan Administrator may impose limitations on the transferability of stock options granted under the 2018 Plan in its discretion. Generally, a participant may not transfer a stock option granted under the 2018 Plan other than by will or the laws of descent and distribution or, subject to approval by the Plan Administrator, pursuant to a domestic relations order or an official marital settlement agreement. However, the Plan Administrator may permit transfer of a stock option in a manner that is not prohibited by applicable tax and securities laws. In addition, subject to approval by the Plan Administrator, a participant may designate a beneficiary who may exercise the stock option following the participant’s death. Options may not be transferred to a third party financial institution for value.

Limitations on Incentive Stock Options

In accordance with current federal tax laws, the aggregate fair market value, determined at the time of grant, of shares of our common stock with respect to ISOs that are exercisable for the first time by a participant during any calendar year under all of our stock plans may not exceed $100,000. The stock options or portions of stock options that exceed this limit or otherwise fail to qualify as ISOs are treated as NSOs. No ISO may be granted to any person who, at the time of grant, owns or is deemed to own stock possessing more than 10% of our total combined voting power unless the following conditions are satisfied:

Subject to adjustment for certain changes in our capitalization, the aggregate maximum number of shares of our common stock that may be issued pursuant to the exercise of ISOs under the 2018 Plan is 17,600,000 shares.

Stock Appreciation Rights

Stock appreciation rights may be granted under the 2018 Plan pursuant to stock appreciation right agreements. Each stock appreciation right is denominated in common stock share equivalents. The strike price of each stock appreciation right will be determined by the Plan Administrator, but will in no event be less than 100% of the fair market value of the common stock subject to the stock appreciation right on the date of grant. The Plan Administrator may also impose restrictions or conditions upon the vesting of stock appreciation rights that it deems appropriate. The appreciation distribution payable upon exercise of a stock appreciation right may be paid in shares of our common stock, in cash, in a combination of cash and stock, or in any other form of consideration determined by the Plan Administrator and set forth in the stock appreciation right agreement. Stock appreciation rights will be subject to the same conditions upon termination of continuous service and restrictions on transfer as stock options under the 2018 Plan.

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Restricted Stock Awards

Restricted stock awards may be granted under the 2018 Plan pursuant to restricted stock award agreements. A restricted stock award may be granted in consideration for cash, check, bank draft or money order payable to us, the participant’s services performed for us, or any other form of legal consideration acceptable to the Plan Administrator. Shares of our common stock acquired under a restricted stock award may be subject to forfeiture to or repurchase by us in accordance with a vesting schedule to be determined by the Plan Administrator. Rights to acquire shares of our common stock under a restricted stock award may be transferred only upon such terms and conditions as are set forth in the restricted stock award agreement. A restricted stock award agreement may provide that any dividends paid on restricted stock will be subject to the same vesting conditions as apply to the shares subject to the restricted stock award. Upon a participant’s termination of continuous service for any reason, any shares subject to restricted stock awards held by the participant that have not vested as of such termination date may be forfeited to or repurchased by us.

Restricted Stock Unit Awards

Restricted stock unit awards may be granted under the 2018 Plan pursuant to restricted stock unit award agreements. Payment of any purchase price may be made in any form of legal consideration acceptable to the Plan Administrator. A restricted stock unit award may be settled by the delivery of shares of our common stock, in cash, in a combination of cash and stock, or in any other form of consideration determined by the Plan Administrator and set forth in the restricted stock unit award agreement. Restricted stock unit awards may be subject to vesting in accordance with a vesting schedule to be determined by the Plan Administrator. Dividend equivalents may be credited in respect of shares of our common stock covered by a restricted stock unit award, provided that any additional shares credited by reason of such dividend equivalents will be subject to all of the same terms and conditions of the underlying restricted stock unit award. Except as otherwise provided in a participant’s restricted stock unit award agreement or other written agreement with us, restricted stock units that have not vested will be forfeited upon the participant’s termination of continuous service for any reason.

Performance Awards

The 2018 Plan allows us to grant performance stock awards. A performance stock award is a stock award that is payable (including that may be granted, may vest, or may be exercised) contingent upon the attainment of pre-determined performance goals during a performance period. A performance stock award may require the completion of a specified period of continuous service. The length of any performance period, the performance goals to be achieved during the performance period, and the measure of whether and to what degree such performance goals have been attained will be determined by the Plan Administrator in its discretion. In addition, to the extent permitted by applicable law and the applicable stock award agreement, the Plan Administrator may determine that cash may be used in payment of performance stock awards.

Performance goals under the 2018 Plan will be based on any one or more of the following performance criteria: (i) earnings (including earnings per share and net earnings); (ii) earnings before interest, taxes and depreciation; (iii) earnings before interest, taxes, depreciation and amortization; (iv) earnings before interest, taxes, depreciation, amortization and legal settlements; (v) earnings before interest, taxes, depreciation, amortization, legal settlements and other income (expense); (vi) earnings before interest, taxes, depreciation, amortization, legal settlements, other income (expense) and stock-based compensation; (vii) earnings before interest, taxes, depreciation, amortization, legal settlements, other income (expense), stock-based compensation and changes in deferred revenue; (viii) total stockholder return; (ix) return on equity or average stockholder’s equity; (x) return on assets, investment, or capital employed; (xi) stock price; (xii) profit (including gross profit) and/or margin (including gross margin); (xiii) income (before or after taxes); (xiv) operating income; (xv) operating income after taxes; (xvi) pre-tax profit; (xvii) operating cash flow; (xviii) sales or revenue targets; (xix) increases in revenue or product revenue; (xx) expenses and cost reduction goals; (xxi) improvement in or attainment of working capital levels; (xxii) economic value added (or an equivalent metric); (xxiii) market share;

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(xxiv) cash flow; (xxv) cash flow per share; (xxvi) share price performance; (xxvii) debt reduction; (xxviii) implementation or completion of projects or processes; (xxix) employee retention; (xxx) stockholders’ equity; (xxxi) capital expenditures; (xxxii) debt levels; (xxxiii) operating profit or net operating profit; (xxxiv) workforce diversity; (xxxv) growth of net income or operating income; (xxxvi) billings; (xxxvii) bookings; and (xxxviii) other measures of performance selected by the Plan Administrator.

Performance goals may be based on a company-wide basis, with respect to one or more business units, divisions, affiliates or business segments, and in either absolute terms or relative to the performance of one or more comparable companies or the performance of one or more relevant indices. The Plan Administrator may, in its sole discretion, provide that one or more objectively determinable adjustments shall be made to one or more of the performance goals. Such adjustments may include one or more of the following: (i) items related to a change in accounting principle; (ii) items relating to financing activities; (iii) expenses for restructuring or productivity initiatives; (iv) other non-operating items; (v) items related to acquisitions; (vi) items attributable to the business operations of any entity acquired by us during the performance period; (vii) items related to the disposal of a business or segment of a business; (viii) items related to discontinued operations that do not qualify as a segment of a business under applicable accounting standards; (ix) items attributable to any stock dividend, stock split, combination or exchange of stock occurring during the Performance Period; (x) any other items of significant income or expense which are determined to be appropriate adjustments; (xi) items relating to unusual or extraordinary corporate transactions, events or developments, (xii) items related to amortization of acquired intangible assets; (xiii) items that are outside the scope of our core, on-going business activities; (xiv) items related to acquired in-process research and development; (xv) items relating to changes in tax laws; (xvi) items relating to major licensing or partnership arrangements; (xvii) items relating to asset impairment charges; (xviii) items relating to gains or losses for litigation, arbitration and contractual settlements; (xix) items relating to any other unusual or nonrecurring events or changes in applicable laws, accounting principles or business conditions; or (xx) any other items selected by the Plan Administrator.

In addition, the Plan Administrator retains the discretion to reduce or eliminate the compensation or economic benefit due upon the attainment of any performance goals and to define the manner of calculating the performance criteria it selects to use for a performance period.

Automatic Grant Program for Non-Employee Directors

Under the automatic grant program, on the date of each annual stockholders meeting, each individual serving as a non-employee Board member at that time, who has served on our Board for at least six months, and who will continue serving as a non-employee Board member immediately after such stockholders meeting will automatically be granted a NSO purchase 15,000 shares of common stock and restricted stock unit award in respect of 2,500 shares of common stock. The shares subject to each annual 15,000 share automatic NSO grant made to a continuing Board member will vest in 12 successive equal monthly installments upon such director’s completion of each month of Board service over the 12-month period measured from the grant date. The shares subject to each 2,500 share automatic restricted stock unit grant will fully vest on the earlier of (x) the first anniversary of the date of grant or (y) the day prior to the next annual stockholders meeting, subject to the director’s continued service on the Board through the applicable vesting date.

Under the automatic grant program, each non-employee Board member who is initially appointed or elected to the Board on or after the 2018 annual stockholders meeting will automatically be granted a NSO to purchase 30,000 shares of common stock and restricted stock unit award in respect of 5,000 shares of common stock. The shares subject to each initial 30,000 share automatic NSO grant made to a newly appointed Board member will vest in 36 successive equal monthly installments upon such director’s completion of each month of Board service over the 36-month period measured from the grant date. The shares subject to each 5,000 share automatic restricted stock unit grant will vest with respect to 1/3^rd of the shares in three equal annual installments over the three year period measured from the date of grant.

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Each automatic NSO grant will have an exercise price per share equal to the fair market value per share of our common stock on the grant date and will have a term of 10 years, subject to earlier termination following the optionee’s cessation of Board service. Each NSO option grant will be immediately exercisable for all of the option shares; however, we may repurchase, at the lower of the exercise price paid per share or the fair market value per share, any shares purchased under the NSO that are not vested at the time of the optionee’s cessation of Board service.

The shares subject to each automatic NSO grant and each automatic restricted stock unit grant will immediately vest in full upon the director’s death or disability or upon the occurrence of a change of control or hostile takeover (as defined below) in each subject to the director’s continued Board service through such date.

Other Stock Awards

Other forms of stock awards valued in whole or in part by reference to, or otherwise based on, our common stock may be granted either alone or in addition to other stock awards under the 2018 Plan. Subject to the terms of the 2018 Plan, the Plan Administrator will have sole and complete authority to determine the persons to whom and the time or times at which such other stock awards will be granted, the number of shares of our common stock to be granted and all other terms and conditions of such other stock awards.

Clawback Policy

Awards granted under the 2018 Plan will be subject to recoupment in accordance with any clawback provisions in a participant’s employment agreement or other agreement with us or any clawback policy that we are required to adopt pursuant to the listing standards of any national securities exchange or association on which our securities are listed or as is otherwise required by the Dodd-Frank Wall Street Reform and Consumer Protection Act or other applicable law. In addition, the Plan Administrator may impose other clawback, recovery or recoupment provisions in a stock award agreement as the Plan Administrator determines necessary or appropriate, including a reacquisition right in respect of previously acquired shares of our common stock or other cash or property upon the occurrence of cause.

Changes to Capital Structure

In the event of certain capitalization adjustments, the Plan Administrator will appropriately adjust: (i) the class(es) and maximum number of securities subject to the 2018 Plan; (ii) the class(es) and maximum number of securities that may be issued pursuant to the exercise of ISOs; (iii) the class(es) and number of securities to be granted under the automatic grant program, and (iv) the class(es) and number of securities and price per share of stock subject to outstanding stock awards.

Change in Control or Hostile Takeover

In the event of a change in control (as defined in the 2018 Plan and described below) outstanding stock awards shall be assumed, continued or substituted for similar stock awards by the surviving or acquiring corporation. If any surviving or acquiring corporation fails to assume, continue or substitute such stock awards, the vesting of stock awards held by participants who are our employee or non-employee directors and whose continuous service has not terminated will be accelerated in full to a date prior to the change in control as determined by our Board. All stock awards not assumed, continued or substituted for similar stock awards by the surviving or acquiring corporation will terminate upon the change in control. In addition, our Board may also provide, in its sole discretion, that the holder of a stock award that will terminate upon the occurrence of a change in control will receive a payment, if any, equal to the excess of (1) the value of the property the participant would have received upon exercise of the stock award over (2) the exercise price otherwise payable in connection with the stock award.

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For purposes of the 2018 Plan, a change in control generally will be deemed to occur if (1) we are acquired pursuant to a merger, consolidation or other reorganization approved by our stockholders, (2) a stockholder approved sale of all or substantially all our assets, or (3) there occurs any transaction or series of related transactions pursuant to which any person or group of related persons becomes directly or indirectly the beneficial owner of securities possessing (or convertible into or exercisable for securities possessing) more than fifty percent of the total combined voting power of our securities outstanding immediately after the consummation of such transaction or series of related transactions, whether such transaction involves a direct issuance from us or the acquisition of outstanding securities held by one or more of our stockholders.

Under the 2018 Plan, a stock award may be subject to additional acceleration of vesting and exercisability upon or after a change in control or hostile takeover (as defined in the 2018 Plan and described below, as may be provided in the participant’s stock award agreement, in any other written agreement with us, but in the absence of such provision, no such acceleration will occur. The awards granted to our non-employee directors under our Automatic Grant Program will automatically immediately fully accelerate vesting upon a change in control or hostile takeover subject to the director’s continued services on the Board through such date. The acceleration of vesting of a stock award in the event of a change in control or hostile takeover event under the 2018 Plan may be viewed as an anti-takeover provision, which may have the effect of discouraging a proposal to acquire or otherwise obtain control of us.

For purposes of the 2018 Plan, a hostile takeover will be deemed to occur if (1) there is a change in the majority of our Board as a result of one or more contested elections for Board membership, or (2) securities possessing more than 50% of the total combined voting power of our outstanding securities are acquired pursuant to a hostile tender offer.

Plan Amendments and Termination

The Plan Administrator will have the authority to amend or terminate the 2018 Plan at any time. However, except as otherwise provided in the 2018 Plan or a stock award agreement, no amendment or termination of the 2018 Plan may materially impair a participant’s rights under his or her outstanding stock awards without the participant’s consent. We will obtain stockholder approval of any amendment to the 2018 Plan as required by applicable law and listing requirements. No incentive stock options may be granted under the 2018 Plan after the tenth anniversary of the date the 2018 Plan became effective, which is the date of the Annual Meeting.

U.S. Federal Income Tax Consequences

The following is a summary of the principal United States federal income tax consequences to participants and us with respect to participation in the 2018 Plan. This summary is not intended to be exhaustive and does not discuss the income tax laws of any local, state or foreign jurisdiction in which a participant may reside. The information is based upon current federal income tax rules and therefore is subject to change when those rules change. Because the tax consequences to any participant may depend on his or her particular situation, each participant should consult the participant’s tax adviser regarding the federal, state, local and other tax consequences of the grant or exercise of a stock award or the disposition of stock acquired the 2018 Plan. The 2018 Plan is not qualified under the provisions of Section 401(a) of the Internal Revenue Code of 1986, as amended, (the “Code”) and is not subject to any of the provisions of the Employee Retirement Income Security Act of 1974. Our ability to realize the benefit of any tax deductions described below depends on our generation of taxable income as well as the requirement of reasonableness and the satisfaction of our tax reporting obligations.

Nonstatutory Stock Options

Generally, there is no taxation upon the grant of an NSO if the stock option is granted with an exercise price equal to the fair market value of the underlying stock on the grant date. Upon exercise, a participant will

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recognize ordinary income equal to the excess, if any, of the fair market value of the underlying stock on the date of exercise of the stock option over the exercise price. If the participant is employed by us or one of our affiliates, that income will be subject to withholding taxes. The participant’s tax basis in those shares will be equal to his or her fair market value on the date of exercise of the stock option, and the participant’s capital gain holding period for those shares will begin on that date.

Subject to the requirement of reasonableness, the provisions of Section 162(m) of the Code, and the satisfaction of a tax reporting obligation, we will generally be entitled to a tax deduction equal to the taxable ordinary income realized by the participant.

Incentive Stock Options

The 2018 Plan provides for the grant of stock options that are intended to qualify as “incentive stock options,” as defined in Section 422 of the Code. Under the Code, a participant generally is not subject to ordinary income tax upon the grant or exercise of an ISO. If the participant holds a share received upon exercise of an ISO for more than two years from the date the stock option was granted and more than one year from the date the stock option was exercised, which is referred to as the required holding period, the difference, if any, between the amount realized on a sale or other taxable disposition of that share and the participant’s tax basis in that share will be long-term capital gain or loss.

If, however, a participant disposes of a share acquired upon exercise of an ISO before the end of the required holding period, which is referred to as a disqualifying disposition, the participant generally will recognize ordinary income in the year of the disqualifying disposition equal to the excess, if any, of the fair market value of the share on the date of exercise of the stock option over the exercise price. However, if the sales proceeds are less than the fair market value of the share on the date of exercise of the stock option, the amount of ordinary income recognized by the participant will not exceed the gain, if any, realized on the sale. If the amount realized on a disqualifying disposition exceeds the fair market value of the share on the date of exercise of the stock option, that excess will be short-term or long-term capital gain, depending on whether the holding period for the share exceeds one year.

For purposes of the alternative minimum tax, the amount by which the fair market value of a share of stock acquired upon exercise of an ISO exceeds the exercise price of the stock option generally will be an adjustment included in the participant’s alternative minimum taxable income for the year in which the stock option is exercised. If, however, there is a disqualifying disposition of the share in the year in which the stock option is exercised, there will be no adjustment for alternative minimum tax purposes with respect to that share. In computing alternative minimum taxable income, the tax basis of a share acquired upon exercise of an ISO is increased by the amount of the adjustment taken into account with respect to that share for alternative minimum tax purposes in the year the stock option is exercised.

We are not allowed a tax deduction with respect to the grant or exercise of an ISO or the disposition of a share acquired upon exercise of an ISO after the required holding period. If there is a disqualifying disposition of a share, however, we will generally be entitled to a tax deduction equal to the taxable ordinary income realized by the participant, subject to the requirement of reasonableness, the provisions of Section 162(m) of the Code, and provided that either the employee includes that amount in income or we timely satisfy our reporting requirements with respect to that amount.

Restricted Stock Awards

Generally, the recipient of a restricted stock award will recognize ordinary income at the time the stock is received equal to the excess, if any, of the fair market value of the stock received over any amount paid by the recipient in exchange for the stock. If, however, the stock is not vested when it is received (for example, if the employee is required to work for a period of time in order to have the right to sell the stock), the recipient

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generally will not recognize income until the stock becomes vested, at which time the recipient will recognize ordinary income equal to the excess, if any, of the fair market value of the stock on the date it becomes vested over any amount paid by the recipient in exchange for the stock. A recipient may, however, file an election with the Internal Revenue Service, within 30 days following his or her receipt of the restricted stock award, to recognize ordinary income, as of the date the recipient receives the restricted stock award, equal to the excess, if any, of the fair market value of the stock on the date the restricted stock award is granted over any amount paid by the recipient for the stock.

The recipient’s basis for the determination of gain or loss upon the subsequent disposition of shares acquired from a restricted stock award will be the amount paid for such shares plus any ordinary income recognized either when the stock is received or when the stock becomes vested.

Subject to the requirement of reasonableness, the provisions of Section 162(m) of the Code, and the satisfaction of a tax reporting obligation, we will generally be entitled to a tax deduction equal to the taxable ordinary income realized by the recipient of the restricted stock award.

Restricted Stock Unit Awards

Generally, the recipient of a restricted stock unit award structured to comply with the requirements of Section 409A of the Code or an exception to Section 409A of the Code will recognize ordinary income at the time the stock is delivered equal to the excess, if any, of the fair market value of the stock received over any amount paid by the recipient in exchange for the stock. To comply with the requirements of Section 409A of the Code, the stock subject to a restricted stock unit award may generally only be delivered upon one of the following events: a fixed calendar date (or dates), separation from service, death, disability or a change in control. If delivery occurs on another date, unless the restricted stock unit award otherwise complies with or qualifies for an exception to the requirements of Section 409A of the Code (including delivery upon achievement of a performance goal), in addition to the tax treatment described above, the recipient will owe an additional 20% federal tax and interest on any taxes owed.

The recipient’s basis for the determination of gain or loss upon the subsequent disposition of shares acquired from a restricted stock unit award will be the amount paid for such shares plus any ordinary income recognized when the stock is delivered.

Subject to the requirement of reasonableness, the provisions of Section 162(m) of the Code, and the satisfaction of a tax reporting obligation, we will generally be entitled to a tax deduction equal to the taxable ordinary income realized by the recipient of the restricted stock unit award.

Stock Appreciation Rights

Generally, if a stock appreciation right is granted with an exercise price equal to the fair market value of the underlying stock on the grant date, the recipient will recognize ordinary income equal to the fair market value of the stock or cash received upon such exercise. Subject to the requirement of reasonableness, the provisions of Section 162(m) of the Code, and the satisfaction of a tax reporting obligation, we will generally be entitled to a tax deduction equal to the taxable ordinary income realized by the recipient of the stock appreciation right.

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New Plan Benefits

The following table sets forth certain information regarding future benefits under the 2018 Plan.

(1) As described above in this Proposal No. 3 future benefits under the 2018 Plan are generally discretionary for our employees, including executive officers, and consultants, and therefore are not currently determinable.

(2) Mr. Wolff retired from his position as Executive Vice President and Chief Financial Officer effective as of February 28, 2017 and is not eligible to receive future benefits under the 2018 Plan.

(3) As described above in this Proposal No. 3 under “—Automatic Grant Program for Non-Employee Directors” on the date of each annual stockholders meeting, commencing with the Annual Meeting, each individual serving as a non-employee Board member at that time, who has served on our Board for at least six months and will continue to serve on our Board immediately following such annual stockholders meeting will automatically be granted a NSO to purchase 15,000 shares of common stock and restricted stock units in respect of 2,500 shares of our common stock. Additionally, each non-employee Board member who is initially appointed or elected to the Board on or after the Annual Meeting will automatically be granted a NSO to purchase 30,000 shares of common stock and restricted stock unit award in respect of 5,000 shares of common stock. If this Proposal No. 3 is approved at the Annual Meeting options to purchase 105,000 shares of our common stock and restricted stock units with respect to 17,500 shares of our common stock will be automatically granted to our non-employee directors as a group on the date of the Annual Meeting.

Approval of this Proposal No. 3 requires votes “FOR” from holders of a majority of the stock having voting power present in person or represented by proxy at the Annual Meeting.

Recommendation of the Board of Directors

The Board of Directors recommends that the stockholders vote FOR the adoption of the Sangamo Therapeutics, Inc. 2018 Equity Incentive Plan.

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PROPOSAL NO. 4:

2010 EMPLOYEE STOCK PURCHASE PLAN AMENDMENT

Our Compensation Committee approved an amendment to our 2010 Employee Stock Purchase Plan, or the Purchase Plan, on April 23, 2018, subject to approval by our stockholders, to increase the number of shares of our common stock reserved for issuance under the Purchase Plan by 2,500,000 shares. In the event that our stockholders do not approve this Proposal No. 4, the amendment will not be effected so that the share increase will not be implemented and the Purchase Plan will continue to be effective in accordance with its existing terms.

Why You Should Vote to Approve the Amendment of the Purchase Plan

The Purchase Plan is an Important Part of Our Employee Compensation Program

Our Board believes that equity compensation is a key element underlying our ability to attract, retain and motivate our employees because of the strong competition for highly trained and experienced employees among biotechnology and pharmaceutical companies, especially in the greater San Francisco Bay area. Additionally, the Board believes the Purchase Plan encourages our employees to acquire an ownership interest in our Company and thereby encourages them to remain in our employ and more closely aligns their interests with those of the stockholders. Approval of amendment to the Purchase Plan will allow us to continue to offer the Purchase Plan to our employees at levels we determine to be appropriate. Therefore, the Board believes that the amendment to the Purchase Plan is in the best interests of us and our stockholders and recommends a vote in favor of this Proposal No. 4.

The Size of the Purchase Plan Share Reserve is Reasonable

As of April 17, 2018 only 835,674 shares of common stock remained available under the Purchase Plan. In its determination to approve the increase to the share reserve of the Purchase Plan our Compensation Committee reviewed the remaining available share reserve and an analysis of our historic and estimated prospective share usage needs. Our Compensation Committee also considered that the Purchase Plan is an important element in our market competitiveness. Based on our historic participation rates, we anticipate that if this Proposal No. 4 is approved the share reserve of the Purchase Plan will last for approximately two years.

Description of the Purchase Plan

The material features of the Purchase Plan as would be effective if the requested share increase set forth in this Proposal No. 4 is approved are described below. The following description of the Purchase Plan is a summary only and is qualified in its entirety by reference to the complete text of the Purchase Plan. Stockholders are urged to read the actual text of the Purchase Plan in its entirety, which is attached to this proxy statement as Appendix B.

Administration

The Purchase Plan is administered by our Compensation Committee, referred to as the ESPP Administrator in this Proposal No. 4. As ESPP Administrator, the Compensation Committee has full authority to adopt administrative rules and procedures and to interpret the provisions of the Purchase Plan.

Shares Subject to the Purchase Plan

As of April 17, 2018, an aggregate of 1,264, 326 shares of our common stock had been purchased under the Purchase Plan and 835,674 shares of common stock remained available for future purchase under the Purchase Plan. Upon approval of this Proposal No. 4 an additional 2,500,000 shares will become available for future purchases under the Purchase Plan beginning with the next offering period that commences on or after the

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Annual Meeting. If purchase rights granted under the Purchase Plan expire, lapse or otherwise terminate without being exercised, the shares of our common stock not purchased under such unexercised and expired rights again become available for issuance under the Purchase Plan. The shares issuable under the Purchase Plan may be made available from authorized but unissued shares of our common stock or from shares of common stock repurchased by us, including shares repurchased on the open market.

Should any change be made to our outstanding common stock by reason of any stock split, stock dividend, recapitalization, combination of shares, exchange of shares, spin-off transaction or other change affecting the outstanding common stock as a class without our receipt of consideration or should the value of the outstanding shares of our common stock be substantially reduced as a result of a spin-off transaction or an extraordinary dividend or distribution, then equitable adjustments will be made by the ESPP Administrator to (i) the maximum number and/or class of securities issuable under the Purchase Plan, (ii) the maximum number and/or class of securities purchasable per participant during any offering period and on any one purchase date during that offering period, (iii) the maximum number and/or class of securities purchasable in total by all participants on any one purchase date and (iv) the number and/or class of securities and the price per share in effect under each outstanding purchase right. The adjustments will be made in such manner as the ESPP Administrator deems appropriate and such adjustments shall be final, binding and conclusive.

Offering Periods and Purchase Rights

The Purchase Plan allows our eligible employees and those of our participating subsidiaries (whether now existing or subsequently acquired or established) to purchase shares of common stock at a discounted price at designated intervals through their accumulated payroll deductions or other permitted contributions.

Shares of our common stock will be offered for purchase under the Amended Purchase Plan through a series of offering periods. Unless otherwise specified by the ESPP Administrator prior to the start of the applicable offering period: (i) each offering period has a duration of 24 months, and (ii) offering periods commence on the first business day of May and the first business day of November each year, so that offerings run concurrently. Unless otherwise determined by the ESPP Administrator, the next offering period under the Purchase Plan is scheduled to commence on November 1, 2018.

The terms and conditions of each offering period may vary, and two or more offering periods may run concurrently under the Purchase Plan, each with its own terms and conditions. In addition, special offering periods may be established with respect to entities that are acquired by us or under such other circumstances as the ESPP Administrator deems appropriate. However, the participants in each separate offering period will have equal rights and privileges under that offering in accordance with the requirements of the federal tax laws and regulations applicable to employee stock purchase plans.

Unless otherwise specified by the ESPP Administrator prior to the start of the applicable offering period, each offering period will be comprised of four successive purchase intervals. Purchase intervals will run from the first business day in May to the last business day in October each year and from the first business day in November each year to the last business day in April in the following year, unless the ESPP Administrator specifies different purchase intervals prior to the start of the applicable offering period.

Should the fair market value per share of our common stock on any purchase date within an offering period be less than the fair market value per share of our common stock on the start date of that offering period, then the individuals participating in that offering period will, immediately after the purchase of our common stock on their behalf on such purchase date, be transferred from that offering period and automatically enrolled in the new offering period commencing on the next business day following such purchase date, provided the fair market value per share on the start date of that new offering period is lower than the fair market value per share of our common stock on the start date of the offering period in which they were currently enrolled.

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Eligibility and Participation

Any individual who is employed on a basis under which he or she is regularly expected to work for more than twenty hours per week for more than five months per calendar year in the employ of any participating parent or subsidiary corporation (whether any such corporation is now in existence or is subsequently established at any time during the term of the Purchase Plan) will be eligible to participate in any offering period implemented under the Purchase Plan. However, for one or more distinct separate offering periods, the ESPP Administrator may waive either or both of the twenty hour or five month service requirements. To participate in a particular offering period, an eligible employee must complete and file the requisite enrollment forms on or before the start date of that offering period.

As of April 17, 2018, 192 employees, including five executive officers, were eligible to participate in the Purchase Plan.

Payroll Deductions and Stock Purchases

For each offering period, the ESPP Administrator may allow contributions to the Purchase Plan to be effected in the form of periodic payroll deductions or one or more other permissible forms specified by the ESPP Administrator prior to the start date of the applicable offering period. However, all contributions, whether in the form of payroll deductions or other mode, must be based solely on either the participant’s cash earnings or base salary, as determined by the ESPP Administrator prior to the start of the offering period and may not exceed 15% of base salary or cash earnings, unless the ESPP Administrator authorizes a different maximum percentage prior to the start date of the applicable offering period.

The accumulated contributions will automatically be applied to the acquisition of common stock at six-month intervals. Accordingly, on each such purchase date (the last business day in April and October each year, unless the ESPP Administrator specifies other purchase date prior to the start of the applicable offering period), each participant’s payroll deductions or other permitted form of contribution accumulated for the purchase interval ending on that purchase date will automatically be applied to the purchase of whole shares of common stock at the purchase price in effect for the participant for that purchase date.

Purchase Price

The purchase price of the common stock acquired on each semi-annual purchase date will be fixed by the ESPP Administrator at the start of each offering period and will not be less than 85% of the lower of (i) the fair market value per share of our common stock on the start date of the offering period or (ii) the fair market value on the purchase date.

The fair market value per share of our common stock on any particular date under the Purchase Plan will be deemed to be equal to the closing price per share on such date on the national stock exchange serving as the primary market for our common stock at that time. On April 17, 2018, the fair market value of our common stock determined on such basis was $19.52 per share, the closing price per share on that date on the Nasdaq Global Market.

Special Limitations

The Purchase Plan imposes certain limitations upon a participant’s rights to acquire common stock, including the following limitations:

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The ESPP Administrator will have the discretionary authority to increase or decrease the per participant and total participant purchase limitations as of the start date of any new offering period under the Purchase Plan, with the new limits to be in effect for that offering period and each subsequent offering period. As indicated above, the applicable limitations will be adjusted for any stock split, stock dividend, stock reclassification or similar transaction affecting the number of shares of our outstanding common stock without our receipt of consideration.

Termination of Purchase Rights

The participant may withdraw from the Purchase Plan at any time up to the next scheduled purchase date, and his or her accumulated payroll deductions or other permitted contributions for the purchase interval in which that purchase date occurs will, at the participant’s election, either be applied to the purchase of shares on the next scheduled purchase date or be refunded immediately.

The participant’s purchase right will immediately terminate upon his or her cessation of employment or loss of eligible employee status. Any payroll deductions or other permitted contributions which the participant may have made for the purchase interval in which such cessation of employment or loss of eligibility occurs will be refunded and will not be applied to the purchase of common stock.

Stockholder Rights

No participant will have any stockholder rights with respect to the shares covered by his or her purchase rights until the shares are actually purchased on the participant’s behalf and the participant has become a holder of record of the purchased shares. No adjustment will be made for dividends, distributions or other rights for which the record date is prior to the date of such purchase.

Assignability

No purchase rights will be assignable or transferable by the participant, and the purchase rights will be exercisable only by the participant.

Change in Control

Should we be acquired by merger, or should there occur a sale of substantially all of our assets or of securities possessing more than 50% of the total combined voting power of our outstanding securities, then all outstanding purchase rights will automatically be exercised immediately prior to the effective date of such transaction. The purchase price will not be less than 85% of the lower of (i) the fair market value per share of common stock on the start date of the offering period in which such transaction occurs or (ii) the fair market value per share of common stock immediately prior to such transaction. The actual percentage purchase price will be equal to the percentage purchase price previously set by the ESPP Administrator for the offering period in which the transaction occurs.

The limitation on the maximum number of shares purchasable by each participant (but not the limitation on all participants in the aggregate) on any one purchase date will be applicable to any purchase date attributable to such transaction.

Share Pro-Ration

Should the total number of shares of common stock to be purchased pursuant to outstanding purchase rights on any particular date exceed the number of shares then available for issuance under the Purchase Plan, then the

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ESPP Administrator will make a pro-rata allocation of the available shares on a uniform and nondiscriminatory basis, and the payroll deductions or other permitted contributions of each participant, to the extent in excess of the aggregate purchase price payable for the common stock pro-rated to such individual, will be refunded.

Duration, Amendment and Termination

The Purchase Plan was originally adopted by our Board of Directors on March 31, 2010 and by our stockholders on June 2, 2010. The Purchase Plan will terminate upon the earliest to occur of (i) the last business day in April 2020, (ii) the date on which all shares available for issuance thereunder are sold pursuant to exercised purchase rights or (iii) the date on which all purchase rights are exercised in connection with a change in control or ownership.

The ESPP Administrator may alter or amend the Purchase Plan at any time to become effective as of the start date of the next offering period thereafter. In addition, the ESPP Administrator may suspend or terminate the Purchase Plan at any time to become effective immediately following the close of any purchase interval.

In no event may our Board of Directors effect any of the following amendments or revisions to the Purchase Plan without the approval of the stockholders: (i) increase the number of shares of our common stock issuable under the Purchase Plan, except for permissible adjustments in the event of certain changes in our capitalization or (ii) modify the eligibility requirements for participation in the Purchase Plan.

Purchase Plan Benefits

The following table sets forth, as to the individuals and groups indicated, the number of shares of our common stock purchased under the Purchase Plan from its original effective date through April 17, 2018 and the weighted average purchase price paid per share. As described above, only our employees are eligible to purchase shares of our common stock under the Purchase Plan.

(1) Mr. Wolff retired from his position as Executive Vice President and Chief Financial Officer effective as of February 28, 2017.

(2) Reflects the number of our employees who have previously purchased shares under the Purchase Plan.

New Benefits

Participation in the Purchase Plan is voluntary and each eligible employee will make his or her own decision regarding whether and to what extent to participate in the Purchase Plan. It is, therefore, not possible to determine the benefits or amounts that will be received in the future by individual employees or groups of employees under the Purchase Plan.

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Federal Income Tax Consequences

The following is a summary of the principal United States federal income taxation consequences to participants and us with respect to participation in the Purchase Plan. This summary is not intended to be exhaustive and does not discuss the income tax laws of any local, state or foreign jurisdiction in which a participant may reside. The information is based upon current federal income tax rules and therefore is subject to change when those rules change. The Purchase Plan is not qualified under the provisions of Section 401(a) of the Code and is not subject to any of the provisions of the Employee Retirement Income Security Act of 1974, as amended.

The Purchase Plan is intended to be an “employee stock purchase plan” within the meaning of Section 423 of the Code. Under a plan which so qualifies, no taxable income will be recognized by a participant, and no deductions will be allowable to us, upon either the grant or the exercise of the purchase rights. Taxable income will not be recognized by the participant until there is a sale or other disposition of the shares acquired under the Purchase Plan or in the event the participant should die while still owning the purchased shares.

If the participant sells or otherwise disposes of the purchased shares within two years after the start date of the offering period in which such shares were acquired or within one year after the purchase date of those shares, then the participant will recognize ordinary income in the year of sale or disposition equal to the amount by which the fair market value of the shares on the purchase date exceeded the purchase price paid for those shares, and we will be entitled to an income tax deduction, for the taxable year in which such sale or disposition occurs, equal in amount to such excess.

If the participant sells or disposes of the purchased shares more than two years after the start date of the offering period in which the shares were acquired and more than one year after the purchase date of those shares, then the participant will recognize ordinary income in the year of sale or disposition equal to the lesser of (i) the amount by which the fair market value of the shares on the sale or disposition date exceeded the purchase price paid for those shares or (ii) 15% of the fair market value of the shares on the start date of that offering period, and any additional gain upon the disposition will be taxed as a long-term capital gain. We will not be entitled to an income tax deduction with respect to such sale or disposition.

If the participant still owns the purchased shares at the time of death, then the participant will recognize ordinary income at such time equal to the lesser of (i) the amount by which the fair market value of the shares on the date of death exceeds the purchase price or (ii) 15% of the fair market value of the shares on the start date of the offering period in which those shares were acquired.

Approval of this Proposal No. 4 requires votes “FOR” from holders of a majority of the stock having voting power present in person or represented by proxy at the Annual Meeting.

Recommendation of the Board of Directors

The Board of Directors recommends that the stockholders vote FOR the adoption of the amendment to the 2010 Employee Stock Purchase Plan to increase the share reserve by 2,500,000 shares.

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PROPOSAL NO. 5:

RATIFICATION OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM

The Audit Committee has appointed Ernst & Young LLP, our independent registered public accounting firm during 2017, to serve in the same capacity for the year ending December 31, 2018, and is asking the stockholders to ratify this appointment.

Neither our Bylaws nor other governing documents or law require stockholder ratification of the selection of Ernst & Young LLP as our independent registered public accounting firm. However, the Audit Committee is submitting the selection of Ernst & Young LLP to the stockholders for ratification as a matter of good corporate practice. In the event the stockholders fail to ratify the appointment, the Audit Committee will reconsider its selection. Even if the selection is ratified, the Audit Committee in its discretion may direct the appointment of a different independent registered public accounting firm at any time during the year if the Audit Committee believes that such a change would be in the best interests of Sangamo and its stockholders.

A representative of Ernst & Young LLP is expected to be present at the annual meeting and will have the opportunity to make a statement if he or she desires to do so, and will be available to respond to appropriate questions.

Principal Accounting Fees and Services

The following table presents fees for professional audit services rendered by Ernst & Young LLP for the audit of our annual financial statements for 2017 and 2016, and fees billed for other services rendered by Ernst & Young LLP during 2017 and 2016:

Policy on Audit Committee Pre-Approval of Audit and Permissible Non-Audit Services

Under its charter, the Audit Committee must pre-approve all engagements of the independent registered public accounting firm for the performance of all audit and non-audit services that are not prohibited and the fees for such services. The Audit Committee has delegated to its Chairman the authority to evaluate and approve

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service engagements on behalf of the full committee in the event a need arises for specific pre-approval between committee meetings. If the Chairman approves any such engagements, he will report such approval to the full Audit Committee not later than the next committee meeting.

The Audit Committee has determined that the rendering of other professional services for tax compliance and tax advice by Ernst & Young LLP is compatible with maintaining their independence. The Audit Committee has established a policy governing our use of Ernst & Young LLP for non-audit services. Under the policy, management may use Ernst & Young LLP for non-audit services that are permitted under SEC rules and regulations, provided that management obtains the Audit Committee’s approval before such services are rendered.

The services provided by Ernst & Young LLP in 2017 were pre-approved in accordance with this policy.

Approval of this Proposal No. 5 requires votes “FOR” from holders of a majority of the stock having voting power present in person or represented by proxy at the Annual Meeting.

Recommendation of the Board of Directors

The Board of Directors recommends that the stockholders vote FOR the ratification of the appointment of Ernst & Young LLP to serve as our independent registered public accounting firm for the year ending December 31, 2018.

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OTHER MATTERS

The Board knows of no other matters that will be presented for consideration at the annual meeting. If any other matters properly come before the annual meeting, it is the intention of the persons named in the accompanying proxy to vote the shares they represent in accordance with their best judgment. Discretionary authority with respect to such other matters is granted by the execution of your proxy card.

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EXECUTIVE OFFICERS

The following table sets forth information regarding our executive officers as of April 24, 2018:

Alexander D. Macrae. Biographical information regarding Dr. Macrae is set forth under “Proposal No. 1: Election of Directors.”

Kathy Y. Yi has served as our Senior Vice President and Chief Financial Officer since February 2017. Ms. Yi has over 17 years of experience in corporate finance, including financial analysis in support of M&A transactions, licensing and other business development activities. Prior to joining us, Ms. Yi served as Head of Finance for Global Inhalation Technical Research & Development at Novartis Pharmaceutical Corporation since 2014. From 2007 to 2014, Ms. Yi held various financial management positions of increasing seniority at Life Technologies Corporation, a Nasdaq-listed life science company that was acquired by Thermo Fisher Scientific in 2014, including Finance Leader, Corporate FP&A from 2012 to 2014, Director of Finance, M&A/Corporate Development from 2010 to 2012, and Director of Finance, Global Manufacturing Operations from 2007 to 2010. From 2001 to 2007, Ms. Yi held increasing roles of responsibilities in Corporate Finance at Intel Corporation. Ms. Yi began her career as a process engineer for Bechtel Corporation. Ms. Yi received a B.S. in Chemical Engineering at the University of California at Berkeley and an M.B.A. from Columbia University.

Heather D. Turner, J.D., has served as our Senior Vice President and General Counsel since February 2018, and as our Secretary since March 2018. Ms. Turner has over 18 years of experience advising public and private life science companies on various matters, including corporate governance, compliance, reporting, public reporting, public offering, mergers and acquisitions, and commercial, manufacturing and development contracts. Prior to joining us, from 2015 to February 2018, Ms. Turner was at Atara Biotherapeutics, Inc. where she served as executive vice president, general counsel and secretary, and also, most recently, as head of portfolio strategy. From 2007 to 2015, she served as General Counsel and Secretary at Orexigen Therapeutics, Inc., where she led various general and administrative functions including compliance, risk management, legal, human resources and facilities. Earlier in her career, she worked as an associate in the corporate securities group at Cooley LLP. Ms. Turner holds a J.D. from the University of California Los Angeles School of Law and is a member of the State Bar of California.

Edward R. Conner, M.D. has served as our Senior Vice President and Chief Medical Officer since November 2016. He has over 10 years of industry experience in early and late stage clinical development in a broad range of disease areas including rare diseases, oncology and infectious diseases. Prior to joining us, Dr. Conner served as Vice President, Clinical Sciences at Ultragenyx Pharmaceuticals, a biopharmaceutical company developing novel products for the treatment of rare and ultra-rare diseases since January 2015. Prior to joining Ultragenyx, from October 2013 to November 2014, he served as Senior Medical Director at BioMarin Pharmaceutical Inc., where he led protocol development and regulatory interaction for its global phase 3 program in Pompe disease. From 2008 to 2013, Dr. Conner served as Medical Director at Genentech, Inc. and was the clinical science team leader of several product candidates, one of which is now a commercial drug product. Dr. Conner completed his Internal Medicine residency training at the University of Michigan and was a fellow in Clinical Immunology & Allergic Diseases at Johns Hopkins School of Medicine. He received a B.S. in Biology, cum laude, from Duke University and his M.D. from the University of California, San Francisco.

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Curt A. Herberts, III has served as our Senior Vice President and Chief Business Officer since December 2016 and oversees our business functions and plans for commercialization of its therapeutics. Mr. Herberts has over 10 years of experience in commercial strategy and corporate development. He joined us in October 2010 as Director, Corporate Development and Strategy and was promoted to Senior Director in January 2012, and Vice President and Head of Corporate Development in July 2015. During this time, we established a number of collaborative agreements, including global collaborations with Shire plc, in 2012, Biogen, Inc., in 2014, Pfizer Inc., in 2017 and Kite, a Gilead company in 2018. Prior to joining us, Mr. Herberts held several positions of increasing responsibility at Campbell Alliance Group, Inc., including leadership roles in the corporate development and commercial strategy practice areas, from June 2006 to October 2010. Mr. Herberts holds an A.B. in Human Biology from Stanford University and a M.B.S. from Keck Graduate Institute of Applied Life Sciences.

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SECURITY OWNERSHIP OF CERTAIN BENEFICIAL OWNERS AND MANAGEMENT

The following table sets forth certain information known to Sangamo with respect to the beneficial ownership of our common stock as of April 17, 2018, except as noted, by (i) all persons who were beneficial owners of five percent (5%) or more of our common stock based on 87,145,700 shares outstanding as of April 17, 2018, (ii) each current director and each nominee for director, (iii) the executive officers named in the Summary Compensation Table of the Executive Compensation of this Proxy Statement, and (iv) all current directors and executive officers as a group. Unless otherwise indicated, the principal address of each of the stockholders below is c/o Sangamo Therapeutics, Inc., 501 Canal Boulevard, Richmond, CA 94804. Except as otherwise indicated or to the extent authority may be shared by both spouses under applicable law, and subject to applicable community property laws, we believe the persons named in the table have sole voting and investment power with respect to all shares of common stock held by them.

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EXECUTIVE COMPENSATION

COMPENSATION DISCUSSION AND ANALYSIS

It is our intent in this CD&A to inform our stockholders of the policies and objectives underlying the compensation programs for our executive officers. Accordingly, we will address and analyze the key elements of the compensation provided to our chief executive officer, the two individuals who served as our chief financial officers during 2017 and the other executive officers named in the Summary Compensation Table which follows this discussion. We refer to these officers as our named executive officers.

Executive Summary

Our Business

We are a clinical stage biotechnology company focused on translating ground-breaking science into genomic therapies that transform patients’ lives using our industry-leading platform technologies in genome editing, gene therapy, gene regulation and cell therapy.

We are a leader in the research and development of zinc finger proteins, or ZFPs, a naturally occurring class of proteins found in humans. We have used our knowledge and expertise to develop a proprietary technology platform in both genome editing and gene regulation. ZFPs can be engineered to make zinc finger nucleases, or ZFNs, proteins that can be used to specifically modify DNA sequences by adding or knocking out specific genes, or genome editing, and ZFP transcription factors or ZFP TFs, proteins that can be used to increase or decrease gene expression, or gene regulation. In the process of developing this platform, we have accrued significant scientific, manufacturing and regulatory capabilities and know-how that are generally applicable in the broader field of gene therapy and have capitalized this knowledge into a conventional gene therapy platform based on adeno-associated viral vector, or AAV, cDNA gene transfer.

Our Business Strategy

Our strategy is to maximize the value and therapeutic use of our technology platforms. In certain therapeutic areas we intend to capture the value of our proprietary genome editing and gene therapy products by forward integrating into manufacturing, development and commercial operations. In other therapeutic areas we intend to partner with biopharmaceutical companies to develop products.

We are focused on the development of human therapeutics for diverse diseases with well-characterized genetic causes. We have several proprietary clinical and preclinical product candidates in development and have strategically partnered certain programs with biopharmaceutical companies to obtain funding for our own programs and to expedite clinical and commercial development.

2017 and Early 2018 Performance Highlights

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Alignment of Executive Compensation Program with Business Strategy

Pharmaceutical research, development and commercialization require sustained and focused effort over many years, and involves a high degree of risk, particularly in the early stages of clinical development. As a consequence, the Compensation Committee believes our compensation program must balance long-term incentives that rewards for the realization of our long-term strategic objectives with near-term compensation that rewards for the achievement of annual goals that further the attainment of our long-term objectives and align the interests of our executives with those of our stockholders.

The Compensation Committee generally believes that a formulaic or purely quantitative approach to executive compensation is not the best way to foster long-term success for us as a clinical stage biotechnology company that is not yet profitable. Instead, the Compensation Committee sets annual performance objectives on which it believes our executive officers should focus during the year in order to achieve our business goals, including, for 2017, aggressive pre-established clinical, research and development, business and corporate development objectives.

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The Compensation Committee strives to create a positive relationship between its compensation program and our corporate performance and considers competitive market dynamics, the business environment in which the results were achieved and any unplanned positive or negative events when making compensation decisions. A significant portion of the total compensation opportunity for each of our named executive officers is directly related to our stock price and to other performance factors that measure our progress against our strategic objectives.

In order to assure that the compensation programs for our named executive officers remain competitive with peer companies, accomplish our pay-for-performance objectives, and create rewards for the realization of our long-term strategic objectives, the Compensation Committee works with Radford to obtain the advice and market data needed to ensure that the compensation programs achieve these goals.

Key Features of Our Executive Compensation Program

How We Determine Executive Compensation

Role of the Compensation Committee and Executive Officers

The Compensation Committee assists the Board of Directors in fulfilling its fiduciary responsibilities with respect to the oversight of our affairs in the areas of our compensation plans, policies and programs, especially those regarding executive compensation and employee benefits. Either the Compensation Committee or the independent members of our Board of Directors, upon recommendation from the Compensation Committee, approve compensation of our Dr. Macrae, and references in this CD&A to our Board of Directors approving Dr. Macrae’s compensation refer to the independent members of our Board of Directors.

The Compensation Committee’s responsibilities include (i) adopting, administering and reviewing compensation plans and programs for our executive officers, including incentive and equity plans and programs; (ii) approving compensation arrangements for our executive officers; (iii) evaluating the performance of our executive officers; (iv) adjusting compensation arrangements as appropriate based upon performance; (v) reviewing, considering and approving compensation programs applicable to non-employee members of the Board of Directors; (vi) reviewing and monitoring management development and succession plans and activities and (vii) administering, concurrently with the Board of Directors, the 401(k) Plan. The Compensation Committee does not delegate any of its functions to others in determining executive compensation.

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In making executive compensation determinations, the Compensation Committee considers recommendations from Dr. Macrae. In making his recommendations, Dr. Macrae receives input from our human resources department and from the individuals who manage the other executive officers. While Dr. Macrae discusses his recommendations for the other executive officers with the Compensation Committee, he does not participate in the deliberations or determination of his own compensation. Members of our finance, human resources and legal departments also attend Compensation Committee meetings.

Objectives of Our Compensation Program

We are focused on translating groundbreaking science into genomic therapies that transform people’s lives using our platform technologies in genome editing, gene therapy, gene regulation and cell therapy. To achieve this strategic business objective, we emphasize recruiting executives with significant industry or scientific experience, including in the areas of clinical development, medical affairs, product development, commercial planning and research innovation. This is a highly competitive industry and our success depends upon our ability to attract and retain qualified executives through competitive compensation packages. The Compensation Committee administers the compensation programs for our executive officers with this competitive environment and need to attract and retain qualified executives in mind.

To this end, the primary objectives of our compensation program are to:

Factors Used in Determining Executive Compensation

The Compensation Committee sets the compensation of our executive officers at levels that the Compensation Committee determines to be competitive and appropriate for each named executive officer, using the Compensation Committee’s professional experience and judgment. The Compensation Committee does not use a formulaic approach to setting executive pay, but rather it considers multiple relevant factors, which may vary from year to year. The figure below reflects the factors the Compensation Committee generally considers in determining and approving the amount, form and mix of pay for our named executive officers. In the case of Dr. Macrae, the Compensation Committee also evaluates his performance against our annual goals and longer-term objectives pre-established by the Board of Directors, together with market data regarding executive compensation at comparable companies and realized and realizable values under previous equity awards.

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Role of Independent Compensation Consultant

The Compensation Committee retained the services of Radford in order to (i) assess compensation levels and mix of elements for our executive officers and vice presidents for 2017, (ii) review the peer group selection criteria and specific peer companies and (iii) advise the Compensation Committee on executive compensation and governance trends based on peer group trends and market practices. In 2017, Radford also provided comparative data in connection with setting the compensation for Ms. Yi when she joined us and for Mr. Herberts at the time of his promotion. The Compensation Committee determined that Radford was independent using criteria established by Nasdaq for evaluating the independence of advisors to the Compensation Committee.

Comparative Analysis

For purposes of measuring the competitive positioning of our compensation packages, peer companies are generally selected by the Compensation Committee primarily using the following criteria: (i) companies that fall within a specific market capitalization range of approximately one-third to three times our market capitalization at the time of the peer evaluation ($100M to $1B at the time we selected our 2017 peer group); (ii) biotechnology companies in the same sector with an emphasis towards pre-commercial companies; (iii) companies with 50 to 500 employees. In addition, we prefer companies that are headquartered in the San Francisco Bay Area where we both recruit and may lose executive talent. Because the biotechnology industry is a dynamic industry, the comparator group used by the Compensation Committee to measure the competitive positioning of our compensation packages is periodically updated to ensure that companies continue to meet the established criteria. At the time the peer group was established, our market capitalization was comparable to the 50^th percentile of the peers, validating the reasonableness of the peer group.

The selected comparable companies for purposes of making compensation decisions for 2017, or the 2017 peer group, were as follows:

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Use of Comparative Data

When setting pay, the Compensation Committee examines the market data derived by Radford from the peer group that ranges from the 25^th to the 75^th percentiles. We do not have a set formula or benchmark for pay, but rather the Compensation Committee references the market data as one input before making position-specific compensation decisions. We generally seek to manage compensation between the 50^th and 75^th percentiles of the peer group data, if warranted by performance and other factors the compensation committee considers relevant in making specific decisions. A specific executive officer may be paid below or above the target range based on individual performance, experience, skills and the importance of the executive’s position to us. The Compensation Committee considers this positioning appropriate given that we are based in the San Francisco Bay Area where there is a high concentration of talent competitors creating competitive pressure that requires us to ensure that our overall compensation program is competitive to attract and retain strong leadership for our long-term success based on performance.

2017 Advisory Vote on Executive Compensation

At the 2017 Annual Meeting, we conducted our third advisory vote on executive compensation. At such meeting, approximately 81% of the votes cast on the advisory vote proposal were supportive of our named executive officer compensation program as disclosed in our proxy statement.

The Board of Directors and Compensation Committee reviewed the advisory vote results in the context of our overall compensation philosophy and programs, and based on the level of support, determined that no significant changes to our compensation policies and programs were necessary. The Compensation Committee will continue to take into account future stockholder advisory votes on executive compensation and other relevant market developments affecting executive officer compensation in order to determine whether any subsequent changes to our executive compensation programs and policies would be warranted to reflect any stockholder concerns reflected in those advisory votes or to address market developments.

Design of the Executive Compensation Program and Key Components

Target Total Compensation

As discussed above, the development and commercialization of pharmaceutical products involves a high degree of risk, particularly in the early stages of clinical development. The Compensation Committee regularly evaluates the relative importance of equity and cash components of total compensation when determining the level and structure of annual pay based on the business priorities established by the Board. Target total compensation for 2017, as shown below for Dr. Macrae, reflects annual base salary, annual target cash incentive bonus and the grant date fair value of stock options granted during the year (as such stock options are reported in the Summary Compensation Table).

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Key Elements of Our Executive Compensation Program

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2017 Compensation Decisions

2017 Base Salary

In general, the base salaries of our named executive officers for 2017 were between the 25^th and 75^th percentiles of the market data derived from the peer group.

In accordance with our practice, in December 2016 we conducted annual performance reviews for 2016 for the named executive officers. The Compensation Committee considered these reviews, our 2016 performance, advice from Radford and competitive data from the peer group. In early 2017, the Compensation Committee determined (i) not to increase Mr. Wolff’s base salary because Mr. Wolff had announced his intent to retire as Executive Vice President and Chief Financial Officer, (ii) not to increase Dr. Conner’s base salary because it had recently been determined at the time of his commencement of employment in November 2016 and (iii) to increase Mr. Herbert’s base salary by 1% given his competitive position in the peer group range and in comparison to internal peers. In early 2017, the Board of Directors approved a modest increase in annual base salary for Dr. Macrae in line with the average increase for other employees after reviewing his competitive position in the peer group range. The base salary for Ms. Yi was established in connection with her commencement of employment in February 2017.

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2017 Cash Incentive Compensation

We adopted 2017 Executive Officer Bonus Program, or the 2017 Cash Incentive Program, under the Incentive Plan that provides for annual bonus awards to reward executive officers based on our achievement of specific corporate goals and their achievement of individual performance goals. For 2017, the target cash incentive for Dr. Macrae was 60% of base salary and for each of our other named executive officers it was 35% of base salary. Dr. Macrae’s cash incentive opportunity was based solely on corporate performance and each of our other named executive officer’s cash incentive opportunity was allocated between Company and individual performance (80% and 20%, respectively). Mr. Wolff retired prior to the adoption of the 2017 Cash Incentive Program, and thus was not eligible to receive an award under the 2017 Cash Incentive Program.

The clinical, research and development, business and corporate development objectives and weightings under the 2017 Cash Incentive Program adopted in March 2017 are described in the chart below. The 2017 Cash Incentive Program also included a business development transaction objective that provided the opportunity to earn an additional payout in the event of certain business development transactions, as further described below.

In January 2018, the Compensation Committee determined that our 2017 corporate objectives were attained at 104%, as further described below. In addition, the Compensation Committee approved individual achievement percentages for our named executive officers (other than Dr. Macrae, whose cash incentive opportunity was tied solely to the achievement of the corporate objectives as approved by the Board of Directors) based on Dr. Macrae’s assessment of and recommendations regarding each executive’s accomplishments against pre-established individual objectives, as further described below. In January 2018, the Board of Directors confirmed the overall corporate achievement percentage of 104% and the Compensation Committee (and the Board of Directors with respect to Dr. Macrae) approved the bonus payout amounts described below for our named executive officers.

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The Compensation Committee and Board of Directors assessed the degree to which the 2017 Cash Incentive Program were met based on the factors described below and determined the achievement percentages described below in January 2018.

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As described above, Dr. Macrae does not have individual goals separate from our corporate objectives. For our other named executive officers, the total cash incentive payout for 2017 was based on a weighting of 80% corporate and 20% individual goals. Dr. Macrae recommends individual goals for each other named executive officer, which are aligned with our business strategy and linked with corporate goals, and our Compensation Committee approves these goals. The 2017 individual goals for the named executive officers include those listed below. These specific goals were in addition to the general responsibilities each officer had for managing his or her respective functional operational area. In early 2018, based on the recommendation of Dr. Macrae, as well as the observations by Compensation Committee members of these executive officers and its own assessment of each individual’s effectiveness, the Compensation Committee determined the level of achievement of each named executive officer’s individual performance goals as follows:

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The table below sets forth the target and actual bonus awards for our named executive officers:

2017 Equity Compensation

We have historically made annual equity grants in December of each fiscal year. However, the Compensation Committee in 2016 determined that it would be a better business and governance practice to make equity grants at the beginning of the fiscal year after our operating plan has been approved by the Board of Directors and the performance in the prior fiscal year completed. Accordingly, the Compensation Committee approved the grant of stock options to Dr. Macrae and Mr. Herberts in January 2017. The Compensation Committee determined not to grant Dr. Conner an equity award in January 2017 because Dr. Conner was granted a stock option in November 2016 in connection with the commencement of his employment with us. To emphasize pay-for-performance, the Compensation Committee determined that the entire annual equity grant would be made in the form of stock options, which provide a return to our executive officers only if the market price of our common stock appreciates over the stock option term, and that RSUs would not be used for 2017 annual grants.

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The Compensation Committee considered data related to percent of common stock outstanding as well as grant date value to determine the overall range for setting the pool of shares available for grants to executive officers and other employees in 2017 and the size of each executive’s grant. In 2017, the percent of common stock outstanding carried more weight due to the depressed stock price in light of the objective of managing overall dilution for stockholders. In general, the equity compensation of our named executive officers for 2017 fell within the competitive range of the 50^th to 75^th percentiles based on the market data provided by Radford.

In connection with her commencement of employment in February 2017, Ms. Yi was a granted a stock option to acquire 200,000 shares of common stock with an exercise price per share equal to the closing price per share on the grant date. The stock option is subject to a four-year vesting schedule with 25% of the shares subject to the option vesting upon Ms. Yi’s completion of one year of service measured from the date Ms. Yi commenced employment with us and the balance of the shares vesting monthly thereafter for the next three years. The award is subject to accelerated vesting in whole or in part in the event Ms. Yi’s employment terminates under certain circumstances in connection with a change in control of the Company.

Other Elements of Executive Compensation Program

The remaining elements of our executive compensation program, like our broader employee compensation programs, are intended to make our overall compensation program competitive with those of our peer companies and all of the remaining elements of our executive compensation program (401(k) Plan; Medical, Dental, and Vision Plans; Life and Disability Insurance; and the Purchase Plan) are available to all of our employees.

Additional Compensation Information

Severance Arrangements

In March 2017, the Compensation Committee adopted an Executive Severance Plan, or the Severance Plan, to provide severance benefits to certain of our executive officers and other key employees, including our named executive officers, whose employment terminates under certain prescribed circumstances. The Severance Plan provides financial protection against the potential loss of employment in designated circumstances, which the Compensation Committee believes will allow the executives to focus attention on the best interests of the stockholders, without undue concern as to an executive’s own financial situation. The Compensation Committee has been advised by its independent compensation consultant that the benefits provided under these agreements are consistent with peer company and broader market practices, and are fair and reasonable. The terms of the Severance Plan are described below under “—Employment Contracts and Change in Control Arrangements—2017 Executive Severance Plan.”

In connection with his retirement, Mr. Wolff entered into an amendment to his employment agreement with us, pursuant to which we agreed, in recognition of Mr. Wolff’s contributions to us, to reimburse Mr. Wolff for 12 months of COBRA expenses and to extend the post-termination exercise periods of Mr. Wolff’s outstanding stock options (to the extent vested on his termination date), such that each such stock option shall remain exercisable for a period of two years following Mr. Wolff’s termination of employment, or until the end of the term of the option, if earlier. A summary of Mr. Wolff’s severance payments and benefits may be found in the section of the Proxy Statement entitled “—Employment Contracts and Change in Control Arrangements—Senior Vice President Employment Agreements—Mr. Wolff.”

Tax and Accounting Effects of Executive Compensation

Section 162(m) of the Internal Revenue Code of 1986, as amended, or the Code, disallows a deduction to any publicly held corporation and its affiliates for certain compensation paid to “covered employees” in a taxable year to the extent that compensation to a covered employee exceeds $1 million. Prior to the recent

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enactment of the Tax Cuts and Jobs Act, compensation that qualified as “performance-based compensation” under Section 162(m) of the Code was not subject to this deduction limitation. Pursuant to the Tax Cuts and Jobs Act, this exception for “performance-based compensation” under Section 162(m) of the Code was repealed, with respect to taxable years beginning after December 31, 2017, except that certain transition relief is provided by the Tax Cuts and Jobs Act for remuneration provided pursuant to a written binding contract which was in effect on November 2, 2017 and which was not modified in any material respect on or after such date. As a result, compensation paid to any of our “covered employees” in excess of $1 million per taxable year generally will not be deductible unless among other requirements, it is intended to qualify, and is eligible to qualify, as “performance-based compensation” under Section 162(m) of the Code pursuant to the transition relief provided by the Tax Cuts and Jobs Act. Because of certain ambiguities and uncertainties as to the application and interpretation of Section 162(m) of the Code and the regulations issued thereunder, including the uncertain scope of the transition relief provided by the Tax Cuts and Jobs Act, no assurance can be given that any compensation we pay will be eligible for such transition relief and, therefore, eligible for the “performance-based compensation” exception under Section 162(m) of the Code. The Compensation Committee will continue to monitor the applicability of Section 162(m) of the Code to its ongoing compensation arrangements.

The Compensation Committee also considers the impact of Section 409A of the Code, and in general, our executive plans and programs are designed to comply with the requirements of that section so as to avoid possible adverse tax consequences that may result from non-compliance.

The accounting impact of our compensation programs is one of many factors that the Compensation Committee considers in determining the structure and size of our executive compensation programs. In general, the Company accounts for equity compensation paid to our employees under the Financial Accounting Standards Board Accounting Standards Codification Topic 718, Compensation—Stock Compensation, or ASC 718, which requires us to estimate and record an expense over the service period of the equity award, and our cash compensation is recorded as an expense at the time the obligation is accrued.

Equity Grant Timing

Equity awards are generally granted to employees, including executives, when they are hired, and employees are eligible for additional equity awards in connection with annual performance reviews each year. As described above, annual equity grants were historically made in December of each fiscal year; however, in 2016, the Compensation Committee determined that it would be a better business and governance practice to make grants at the beginning of the fiscal year after our operating plan has been approved by the Board of Directors and the performance in the prior fiscal year has completed. New hire equity awards are generally pre-authorized and become effective on the 25^th day of the month immediately following the month during which the individual commences employment, with the exercise price of any stock option grants set at the closing price of our stock on that date.

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Summary Compensation Table

The following table provides certain summary information for the years ended December 31, 2017, 2016 and 2015, when applicable, concerning the compensation earned by (i) our President and Chief Executive Officer, (ii) our current Senior Vice President and Chief Financial Officer, (iii) our former Executive Vice President and Chief Financial Officer, (iv) and our two other executive officers who were serving as executive officers at the end of 2017 and whose total compensation exceeded $100,000. We did not have any other executive officers in 2017. These individuals are referred to throughout this Proxy Statement as our “named executive officers.” We have omitted certain rows from the table when there is no disclosure of any compensation for the named executive officer for that fiscal year.

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Grants of Plan-Based Awards

The following table shows for the fiscal year ended December 31, 2017, certain information regarding grants of plan-based awards to our named executive officers.

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The amount shown as maximum reflects the payment level pursuant to the 2017 Cash Incentive Program if Sangamo had achieved a 200% corporate performance percentage and each individual (other than Dr. Macrae) had achieved a 125% individual performance percentage, which were the maximum percentages allowed for the corporate and individual performance percentages, respectively. Actual payouts differed based on the actual performance objectives achieved. The actual cash bonus award earned for the year ended December 31, 2017 pursuant to the 2017 Cash Incentive Program under the Incentive Plan for each named executive officer is set forth in the Summary Compensation Table above. As such, the amounts set forth in these columns do not represent additional compensation earned by the named executive officers for the year ended December 31, 2017. For more information regarding the 2017 Cash Incentive Program under the Incentive Plan see “—Compensation Discussion and Analysis—2017 Compensation Decisions—2017 Cash Incentive Compensation” above. For more information regarding the Incentive Plan, see “—Employment Agreements and Compensation Arrangements—Annual Cash Bonus Awards” below.

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Employment Agreements and Compensation Arrangements

Employment Agreements

Each of our named executive officers has entered into a written employment agreement with our company. For a description of these employment agreements, please see the section of this Proxy Statement under the heading “—Employment Contracts and Change in Control Arrangements” below.

Annual Cash Bonus Awards

In 2012, the Compensation Committee of the Board adopted the Incentive Plan, which is a performance-based cash incentive program for our executive officers. Under the Incentive Plan, which was in effect in 2017, the Compensation Committee has discretion to implement one or more performance periods under the Incentive Plan, each of a duration determined by the Compensation Committee. Within the first 90 days of each performance period, the Compensation Committee establishes the specific performance and individual objectives that must be attained in order for Incentive Plan participants to receive a bonus for that performance period. For each performance and individual objective, the Compensation Committee may set threshold, target and above-target levels of attainment. The Compensation Committee will then establish for each participant dollar levels for the bonus to which he or she may become entitled for that performance period based on the level at which the performance and individual objectives are actually attained.

Performance objectives established under the Incentive Plan are based on one or more of the following criteria: (i) revenue, organic revenue, net sales, or new-product revenue or net sales, (ii) achievement of specified objectives in the discovery and development of the our technology or of one or more of our products, (iii) achievement of specified objectives in the commercialization of one or more of our products, (iv) achievement of specified objectives in the manufacturing of one or more of our products, (v) expense targets, (vi) share price, (vii) total shareholder return, (viii) earnings per share, (ix) operating margin, (x) gross margin, (xi) return measures (including, but not limited to, return on assets, capital, equity, or sales), (xii) productivity ratios, (xiii) operating income, (xiv) net operating profit, (xv) net earnings or net income (before or after taxes), (xvi) cash flow (including, but not limited to, operating cash flow, free cash flow and cash flow return on capital), (xvii) earnings before or after interest, taxes, depreciation, amortization and/or stock-based compensation expense, (xviii) economic value added, (xix) market share, (xx) working capital targets, (xxi) achievement of specified objectives relating to corporate partnerships, collaborations, license transactions, distribution arrangements, mergers, acquisitions, dispositions or similar business transactions, and (xxii) employee retention and recruiting and human resources management.

Individual performance objectives established under the Incentive Plan are based on one or more of the following criteria: (i) the participant’s contribution toward the achievement of a specific Company performance objective, (ii) the contribution of the business unit or division supervised by the participant toward the achievement of a specific Company performance objective, and (iii) the participant’s development of professional skills.

A participant will not become entitled to a bonus under the Incentive Plan for a particular performance period unless the participant remains employed by us through the date bonuses are paid to each participant following completion of that performance period. Following the close of the applicable performance period, the Compensation Committee will determine the actual bonus amount for each participant based on the actual levels at which the actual performance objectives are attained, and bonuses will be paid promptly following the end of the applicable performance period.

Pursuant to the terms of the Incentive Plan, should a change in control transaction be consummated prior to the completion of a performance period that has been implemented under the Incentive Plan, then the performance period will terminate upon the consummation of that change in control and each participant in the Incentive Plan will receive a bonus in the dollar amount previously set by the Compensation Committee at target level attainment of each performance objective; however such bonus will be pro-rated to reflect each participant’s actual period of service from the start date of the performance period through the effective date of

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the change in control. Any pro-rated bonus paid pursuant to the terms of the Incentive Plan will reduce the amount of any severance payable to the participant based on the participant’s target bonus pursuant to the terms of any employment agreement.

In the event any payment to which a participant becomes entitled under the Incentive Plan would otherwise constitute a parachute payment under Section 280G of the Code, then that payment will be subject to reduction to the extent necessary to assure that such payment will be limited to the greater of (i) the dollar amount that can be paid to the participant without triggering a parachute payment under Code Section 280G or (ii) the dollar amount of that payment which provides the participant with the greatest after-tax amount after taking into account any excise tax the participant may incur under Code Section 4999 with respect to such payment and any other benefits or payments to which the participant may be entitled in connection with any change in control of the Company or the subsequent termination of the participant’s employment.

We adopted a 2017 Cash Incentive Program under the Incentive Plan that provides for annual bonus awards to reward executive officers based on our achievement of specific corporate goals and their achievement of individual performance goals. For more information regarding the 2017 Cash Incentive Program under the Incentive Plan, please see the section of this Proxy Statement under the heading “—Compensation Discussion and Analysis—2017 Compensation Decisions—2017 Cash Incentive Compensation” and footnote (1) to the Grants of Plan-Based Awards table above. We amended the Incentive Plan in March 2018.

Stock Awards

Discretionary options that we granted in 2017 under the 2013 Plan vest according to the following schedule: 25% of the option shares will vest and become exercisable on the one year anniversary of the option grant date and the remaining option shares will vest and become exercisable in 36 equal monthly installments over the 36-month period measured from the first anniversary of the option grant date, provided the executive officer continues to provide services through each applicable vesting date. Each option will vest on an accelerated basis in connection with certain terminations and changes, as described under the heading “—Employment Contracts and Change in Control Agreements” below. Each option has an expiration date at the end of 10-year period measured from the grant date, unless terminated earlier following the optionee’s termination of service. Options granted under the 2013 Plan have an exercise price equal to the fair market value on the date of grant (generally the closing price of our common stock on the grant date on the Nasdaq Global Select Market), and the 2013 Plan permits the exercise price of stock options to be paid by cash, check, other shares of our common stock (with some restrictions), broker assisted same-day sales, and cashless “net exercise” arrangements. Although we did not grant any discretionary RSUs in 2017 under the 2013 Plan, previous grants of discretionary RSUs to executive officers under such plan (including grants in January 2018) vest in three successive equal annual installments over the 3-year period measured from the grant date, provided the executive officer continues to provide services through each applicable vesting date. For a discussion of the effect on outstanding equity awards under the 2013 Plan in connection with certain terminations and changes in control of the Company, including accelerated vesting, see the discussion under the heading “—Employment Contracts and Change in Control Arrangements” below.

Other Compensatory Arrangements

401(k) Plan. Our executive officers are eligible to participate in the 401(k) Plan. The 401(k) Plan is intended to qualify as a tax-qualified plan under section 401 of the Code. The 401(k) Plan provides that each participant may contribute a portion of his or her pre-tax compensation, up to a statutory annual limit. The 401(k) Plan also permits us to make discretionary contributions and matching contributions, subject to established limits. In 2017, we made a matching contribution which was subject to an annual limit of $4,000 per employee.

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Other Benefits. Our executive officers are eligible to participate in all of our benefit plans, such as our medical, dental, vision, short-term disability, long-term disability and group life insurance plans and the Purchase Plan, in each case generally on the same basis as other employees. We also have a section 125 flexible benefits healthcare plan and a flexible benefits childcare plan under which employees can set aside pre-tax funds to pay for qualified healthcare expenses and qualified childcare expenses not reimbursed by insurance. We do not currently offer pension or other retirement benefits in the U.S., but do offer pension or other retirement benefits in certain other countries.

Outstanding Equity Awards at Fiscal Year-End

The following table provides certain summary information concerning outstanding equity awards held by the named executive officers as of December 31, 2017.

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Option Exercises and Stock Vested

The following table sets forth the number of shares of our common stock acquired and the value realized upon the vesting of RSU awards and on each exercise of stock options for each of the named executive officers during the year ended December 31, 2017:

Pension Benefits

We do not sponsor a tax-qualified defined benefit retirement plan or a supplemental executive retirement plan.

Nonqualified Deferred Compensation

We do not sponsor a nonqualified deferred compensation plan.

Risk Assessment of Compensation Policies and Practices

Our compensation programs throughout the organization are designed to maintain an appropriate balance between long-term and near-term incentives by utilizing a combination of compensation components, including base salary, annual cash incentive awards, and long-term equity awards. Although not all employees in the organization may have compensation comprising all three of those components, the compensation programs are generally structured so that any near-term cash incentives are not likely to constitute the predominant element of an employee’s total compensation. The Compensation Committee annually reviews our compensation policies and practices to assess whether they encourage employees to take inappropriate risks. After reviewing each of our compensation plans, and the checks and balances built into, and oversight of, each plan, in April 2017, the

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Compensation Committee determined that any risks arising from our compensation policies and practices for our employees are not reasonably likely to have a material adverse effect on us as a whole. In addition, the Compensation Committee believes that the mix and design of the elements of executive compensation do not encourage management to assume excessive risks, and significant compensation decisions, as well as decisions concerning the compensation of our executive officers, include subjective considerations by the compensation committee or the board of directors, which restrain the influence of formulae or objective factors on excessive risk taking. Finally, the mix of short-term compensation (in the form of salary and annual bonus, if any) and long-term compensation (in the form of stock options and RSUs) also prevents undue focus on short-term results and helps align the interests of our executive officers with the interests of our stockholders.

Employment Contracts and Change in Control Arrangements

Chief Executive Officer Employment Agreement

Dr. Macrae

In May 2016 we entered into an employment agreement with Dr. Macrae that took effect June 1, 2016, which sets forth the terms and conditions of his employment as President and Chief Executive Officer. Pursuant to his employment agreement, Dr. Macrae will receive a base salary of $600,000 per year and an annual cash bonus based upon our company’s achievement of specified objectives under our Incentive Plan with a target bonus of 60% of his base salary. Dr. Macrae’s base salary and target bonus percentage are subject to annual review by the Compensation Committee and adjustment from time to time by such Committee, and was subject to pro-ration for partial service in 2016.

Dr. Macrae’s employment agreement also provided for a $200,000 sign-on bonus, which was subject to repayment in the event Dr. Macrae’s employment was terminated without cause or by him without good reason within one year of his appointment, as well as an initial equity grant of stock options under the 2013 Plan to acquire 700,000 shares of our common stock, which is vesting on the same terms as other discretionary awards under the 2013 Plan. Dr. Macrae is also entitled to be nominated for election to our Board of Directors for so long as his employment agreement is in effect.

Although Dr. Macrae’s employment agreement includes certain benefits payable to him in connection with separation from service, such terms were waived by Dr. Macrae in connection with the March 2017 adoption of our Executive Severance Plan (the “Severance Plan”) which now governs his severance benefits. The terms of the Severance Plan are described below under “—2017 Executive Severance Plan.”

Senior Vice President Employment Agreements

Ms. Yi

Effective February 28, 2017, we entered into an employment agreement with Kathy Y. Yi, which sets forth the terms and conditions of her employment as Chief Financial Officer. Pursuant to her employment agreement, Ms. Yi will receive a base salary of $350,000 per year and an annual cash bonus based upon our company’s and her individual achievement of specified objectives under our Incentive Plan with a target cash bonus of 35% of her base salary. Ms. Yi’s base salary and target bonus percentage are subject to annual review by the Compensation Committee and adjustment from time to time by such Committee, and were also subject to pro-ration for partial service in 2017.

Ms. Yi’s employment agreement also provided for an initial equity grant of stock options under the 2013 Plan to acquire 200,000 shares of our common stock, which is vesting on the same terms as other discretionary awards under the 2013 Plan.

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Although Ms. Yi’s employment agreement includes certain severance benefits payable to her in connection with separation from service, such terms were waived by Ms. Yi in connection with the March 2017 adoption of the Severance Plan, which now governs her severance benefits. The terms of the Severance Plan are described below under “—2017 Executive Severance Plan.”

Mr. Wolff

In November 2007, we entered into an employment agreement with H. Ward Wolff, our former Executive Vice President and Chief Financial Officer, which was amended and restated in December 2008 and December 2011 in order to implement technical changes. Pursuant to the terms of the agreement as amended and restated, Mr. Wolff’s annual base salary was set at a minimum of $375,000, increasing to $390,000 effective January 1, 2012, or such higher rate as the Board determined from time to time, and he was eligible to receive an annual performance bonus of up to 40% of his base salary each calendar year, based on our company’s and his individual achievement of specific performance criteria established by the Board.

If we had terminated Mr. Wolff’s employment without cause, or Mr. Wolff terminated his employment for good reason, within 12 months following a change in control and Mr. Wolff executed a general release of all claims in our favor, then Mr. Wolff would have received the following severance benefits: (i) a severance payment equal to his annual base salary in effect on his termination date plus his target bonus for the year in which such termination occurred, (ii) reimbursement of his health care coverage costs under COBRA for up to twelve months, (iii) accelerated vesting of all of his outstanding equity awards and (iv) a one-year period measured from his termination date to exercise any outstanding options for all the option shares, but in no event would any such option have remained exercisable following the expiration of the maximum option term. If we had terminated Mr. Wolff’s employment without cause, or Mr. Wolff had terminated his employment for good reason, in the absence of a change in control or more than 12 months after a change in control and Mr. Wolff executed a general release of all claims in our favor, then Mr. Wolff would have received (i) salary continuation payments for a 12 month period following his termination date at his rate of base salary in effect on his termination date and (ii) reimbursement of his health care coverage costs under COBRA for up to 12 months.

Effective as of February 28, 2017, Mr. Wolff retired from his position as our Executive Vice President and Chief Financial Officer. In connection with his retirement, Mr. Wolff entered into an amendment to his employment agreement, pursuant to which Mr. Wolff agreed that he would not be entitled to receive any cash severance in connection with his retirement; however, we agreed to reimburse Mr. Wolff for the 12 months of COBRA expenses, and his outstanding stock options (to the extent vested on his termination date), will remain exercisable for a period of two years following Mr. Wolff’s termination of employment, or until the end of the term of the stock option, if earlier. We estimate the value of the COBRA expense payments to be $30,608 (of which $25,365 was paid during the year ending December 31, 2017) and have calculated the value of his option modifications to be $836,136.65, which represents the aggregate incremental fair value associated with the modifications of Mr. Wolff’s stock options as calculated in accordance with ASC 718.

Dr. Conner

Effective November 1, 2016, we entered into an employment agreement with Dr. Conner, which sets forth the terms and conditions of his employment as Chief Medical Officer. Pursuant to his employment agreement, Dr. Conner will receive a base salary of $400,000 per year, and an annual cash bonus based upon our company’s and his individual achievement of specified objectives under our Incentive Plan with a target cash bonus of 35% of his base salary. Dr. Conner’s base salary and target bonus percentage are subject to annual review by the Compensation Committee and adjustment from time to time by such Committee, and his salary was subject to pro ration for partial service in 2016. Dr. Conner was not eligible for a target cash bonus in 2016.

Dr. Conner’s employment agreement also provided for an initial equity grant of stock options under the 2013 Plan to acquire 200,000 shares of our common stock, which is vesting on the same terms as other discretionary awards under the 2013 Plan.

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Although Dr. Conner’s employment agreement includes certain severance benefits payable to him in connection with separation from service, such terms were waived by Dr. Conner in connection with the March 2017 adoption of the Severance Plan, which now governs his severance benefits. The terms of the Severance Plan are described below under “—2017 Executive Severance Plan.”

Mr. Herberts

In August 2010, we entered into an employment agreement with Mr. Herberts setting forth the terms and conditions of his employment as a Director, Corporate Development. In November 2016, Mr. Herberts was promoted to Chief Business Officer. As a Chief Business Officer, Mr. Herberts’ base salary was set a $340,000 per year and Mr. Herberts was eligible for an annual cash bonus based upon our company’s and his individual achievement of specified objectives under our Incentive Plan with a target cash bonus of 35% of his base salary. Mr. Herberts’ base salary and target bonus percentage are subject to annual review by the Compensation Committee and adjustment from time to time by such Committee.

Mr. Herberts’ employment agreement does not provide for any severance benefits. As an executive, Mr. Herberts is an eligible employee under the Severance Plan and may receive benefits under such plan, which is described below.

2017 Executive Severance Plan

In March 2017, the Compensation Committee of the Board adopted the Severance Plan to provide severance benefits to certain of our executive officers and other key employees whose employment terminates under certain prescribed circumstances. These eligible employees include our named executive officers Drs. Macrae and Conner, Ms. Yi and Mr. Herberts.

Under the Severance Plan, which replaced the severance arrangement set forth in Dr. Macrae’s employment agreement, Dr. Macrae is eligible to receive the following severance benefits: (a) cash equal to the sum of (i) 18 months of his base salary and (ii) his target bonus for the year of termination, payable over 12 months, reimbursement for his health care coverage costs under COBRA for 12 months, and full acceleration of his outstanding equity awards, and any outstanding options as so accelerated will remain exercisable for a period of 12 months following termination, in the event of an involuntary termination during the 12-month period following a change of control of the Company (“the Change in Control Period”) or (b) cash equal to 12 months of his base salary, payable over 12 months, and COBRA reimbursement for 12 months, if he has an involuntary termination other than during the Change in Control Period. These cash severance benefits under the Severance Plan are identical to the severance benefits he was eligible to receive under his employment agreement; however, under his employment agreement, only 50% of the shares subject to any outstanding equity award accelerated if the change in control was within two years following the effective date of the employment agreement and 100% of the shares accelerated if the change in control was more than two years after the effective date.

Under the Severance Plan, which replaced the severance arrangements set forth in Dr. Conner’s and Ms. Yi’s respective employment agreements, Dr. Conner, Ms. Yi and Mr. Herberts are eligible to receive the following severance benefits: (a) cash equal to the sum of (i) 12 months of base salary and (ii) target bonus for the year of termination, payable over 12 months, reimbursement for health care coverage costs under COBRA for 12 months, and accelerated vesting of all outstanding equity awards, and any outstanding options as so accelerated will remain exercisable for a period of 12 months following termination, in the event of an involuntary termination during the Change in Control Period; or (b) cash equal to 9 months of base salary, payable over 9 months, and COBRA reimbursement for 9 months, if there is an involuntary termination other than during the Change in Control Period. These cash severance benefits under the Severance Plan are similar to the severance benefits Dr. Conner and Ms. Yi were eligible to receive under their respective employment agreements; however, under the employment agreements, only 50% of the shares subject to any outstanding equity award accelerated if the change in control was within two years following the effective date of the employment agreement and 100% of the shares accelerated if the change in control was more than two years

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after the effective date, and (b) the base salary and COBRA reimbursement continuation period was six months under the employment agreements (instead of 12 months in the event of an involuntary termination during the Change in Control Period or 9 months in the event of an involuntary termination other than during the Change in Control Period, under the Severance Plan, as described above).

If any of the severance benefits under the Severance Plan would constitute a “parachute payment” within the meaning of section 280G of the Code, such payments are subject to reduction to the extent doing so would put the recipient in a better after-tax position after taking into account any excise tax that may be incurred under Code Section 4999 in connection with any change in control of the Company or subsequent termination of employment,

2013 Plan

The Compensation Committee of the Board of Directors, as the administrator of the 2013 Plan, has the authority to provide that any outstanding options held by the Chief Executive Officer or any other executive officer or any other unvested equity award made to such individual under the 2013 Plan will vest on an accelerated basis in connection with certain changes in control of the Company or the subsequent termination of the officer’s employment following the change in control event. In addition, all outstanding options and RSUs under the 2013 Plan will immediately vest upon a change in control, to the extent not assumed or continued in effect by the successor entity or replaced with an incentive compensation program that preserves the intrinsic value of the award at that time and provides for the subsequent vesting and concurrent payout of that value in accordance with the pre-existing vesting schedules for those awards.

Incentive Compensation Plan

The Incentive Plan is a performance-based cash incentive program for our executive officers. Pursuant to the terms of the Incentive Plan as in effect in 2017, should a change in control transaction be consummated prior to the completion of a performance period that has been implemented under the Incentive Plan, then the performance period will terminate upon the consummation of that change in control and each participant in the Incentive Plan will receive a bonus in the dollar amount previously set by the Compensation Committee at target level attainment of each performance objective; however such bonus will be pro-rated to reflect each participant’s actual period of service from the start date of the performance period through the effective date of the change in control. Any pro-rated bonus paid pursuant to the terms of the Incentive Plan will reduce the amount of any severance payable to the participant based on the participant’s target bonus pursuant to the terms of any employment agreement. The 2017 Cash Incentive Program adopted for the 2017 year under the Incentive Plan is summarized in detail under the heading “—Compensation Discussion and Analysis—2017 Compensation Decisions—2017 Cash Incentive Compensation. We eliminated the provision in the Incentive Plan providing for these payouts when we amended the Incentive Plan in March 2018.

Potential Payments Upon Termination or Change in Control

The charts below quantify the potential payments our named executive officers, other than Mr. Wolff, would receive under various scenarios. The value attributed to the accelerated vesting of equity awards represents the intrinsic value of each stock option or RSU award vesting on an accelerated basis in connection with the identified triggering event, which is assumed to occur on December 31, 2017. The intrinsic value is calculated by multiplying (i) the aggregate number of shares that vest on an accelerated basis by (ii) the amount by which the $16.40 closing selling price per share of our common stock on December 31, 2017, exceeds the exercise price or other issue price (if any) payable per vested share.

Quantification of Benefits Upon Involuntary Termination in the Absence of a Change in Control

The chart below quantifies the compensation each named executive officer would have received had the officer’s employment terminated without cause in the absence of a change in control of the Company but under circumstances entitling the officer to severance benefits under the Severance Plan.

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For information with respect to the compensation and benefits we provided to Mr. Wolff in connection with his retirement, see “—Senior Vice President Employment Agreements—Mr. Wolff” above.

Benefits Upon Involuntary Termination in Connection With a Change in Control

The chart below quantifies the payments our named executive officers (other than Mr. Wolff who retired during the year) would each have received had their employment terminated without cause or with good reason in connection with a change in control under circumstances entitling them to severance benefits under the Severance Plan.

Benefits Upon a Change in Control (No Termination)

The chart below quantifies the value of the accelerated equity the named executive officers (other than Mr. Wolff who retired during the year) are entitled to receive under the 2013 Plan upon a change in control of the Company in which their outstanding equity awards are not assumed or otherwise continued in effect, terminated or cancelled in connection therewith.

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The chart below quantifies the cash award for the 2017 year the named executive officers are entitled to receive under the Incentive Plan upon a change in control of the Company. This benefit was eliminated by the March 2018 amendment of the Incentive Plan.

Benefits upon Death or Disability

Under the 2013 Plan, if a named executive officer’s service with us is terminated as a result of death or permanent disability, or a named executive officer dies or becomes permanently disabled during the three months after a termination other than for misconduct, the period of time in which an option may be exercised following termination shall be the earlier of twelve months following the date of such named executive officer’s death or the expiration date of the option, whichever is earlier, rather than the standard three-month post-termination exercise period provided for in the 2013 Plan.

Pay Ratio Disclosure

Under SEC rules, we are required to calculate and disclose the annual total compensation of our median employee, as well as the ratio of the annual total compensation of our median employee as compared to the annual total compensation of our President and Chief Executive Officer, Dr. Macrae (our “CEO”), for our last fiscal year (“CEO Pay Ratio”). To identify our median employee, we used the following methodology:

Using this approach, we determined our median employee. Because the median employee we initially identified had anomalous compensation characteristics due to the employee’s commencement of employment in 2017, we substituted another employee to serve as our median employee who received substantially similar compensation as the initially identified median employee during 2017 but who had been employed for all of 2017. This individual was directly adjacent to our initially identified median employee, based on the determination method described above. Once the median employee was identified, we then calculated the annual total compensation of this employee for 2017 in accordance with the requirements of the Summary Compensation Table.

For fiscal 2017, the median of the annual total compensation of our employees (other than our CEO) was $169,202 and the annual total compensation of our CEO, as reported in the Summary Compensation Table included in this Proxy Statement, was $1,795,856. Based on this information, the ratio of the annual total compensation of our CEO to the median of the annual total compensation of all our employees was approximately 11 to 1.

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The CEO Pay Ratio above represents our reasonable estimate calculated in a manner consistent with SEC rules and applicable guidance. SEC rules and guidance provide significant flexibility in how companies identify the median employee, and each company may use a different methodology and make different assumptions particular to that company. As a result, and as explained by the SEC when it adopted these rules, in considering the pay ratio disclosure, stockholders should keep in mind that the rule was not designed to facilitate comparisons of pay ratios among different companies, even companies within the same industry, but rather to allow stockholders to better understand and assess each particular company’s compensation practices and pay ratio disclosures.

Neither the Compensation Committee nor our management used our CEO Pay Ratio measure in making compensation decisions.

Compensation Committee Report¹

The Compensation Committee has reviewed and discussed the Compensation Discussion and Analysis contained in this Proxy Statement with management, and based on such review and such discussions, the Compensation Committee recommended to the Board of Directors that the Compensation Discussion and Analysis, as contained herein, be included in this Proxy Statement.

Equity Compensation Plan Information

The following table provides information as of December 31, 2017, with respect to the shares of our common stock that may be issued under our existing equity compensation plans. There are no outstanding options that we have assumed in connection with our acquisition of other companies, and there are currently no assumed plans under which we can grant options.

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Report of the Audit Committee of the Board of Directors¹

The information contained under the heading “Report of the Audit Committee of the Board of Directors” in this Proxy Statement shall not be deemed to be “soliciting material” or to be “filed” with the Securities and Exchange Commission, nor shall such information be incorporated by reference into any filing of the Company with the Securities and Exchange Commission, whether made before or after the date hereof and irrespective of any general incorporation language in any such filing, or subject to the liabilities of Section 18 of the Securities Exchange Act of 1934, as amended.

The Audit Committee has reviewed and discussed the audited financial statements for the fiscal year ended December 31, 2017 with the management of the Company.

The Audit Committee has discussed with Ernst & Young LLP, the independent registered public accounting firm that audited our financial statements for the fiscal year ended December 31, 2017, the matters required to be discussed by Public Company Accounting Oversight Board (PCAOB) Auditing Standard No. 1301, Communications with Audit Committees,” or any successor standard.

The Audit Committee has received the written disclosures and the letter from Ernst & Young LLP required by applicable requirements of the PCAOB regarding Ernst & Young LLP’s communications with the Audit Committee concerning independence, and has discussed with Ernst & Young LLP its independence from the Company.

Based on the review of the audited financial statements and the discussions noted above, the Audit Committee recommended to our Board of Directors that the audited financial statements be included in our Annual Report on Form 10-K for the fiscal year ended December 31, 2017 for filing with the Securities and Exchange Commission.

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CERTAIN RELATIONSHIPS AND RELATED TRANSACTIONS

Since January 1, 2017, there has not been nor is there currently proposed any transaction or series of similar transactions to which we were or are to be a party in which the amount involved exceeds $120,000 and in which any director, executive officer, holder of more than 5% of our common stock, or any member of the immediate family of any of the foregoing persons, had or will have a direct or indirect material interest other than compensation agreements and other arrangements, which are described elsewhere in this Proxy Statement.

In addition to the indemnification provisions contained in our Seventh Amended and Restated Certificate of Incorporation, as amended, we have entered into separate indemnification agreements with each of our directors containing provisions that may require us to, among other things, indemnify them against certain liabilities that may arise by reason of their status or service as directors.

POLICIES AND PROCEDURES

Consistent with the requirement under Nasdaq listing rules, the Audit Committee of the Board of Directors is responsible for reviewing and approving all related party transactions as defined under SEC rules and regulations. While we do not have a formal written policy or procedure for the review, approval or ratification of related party transactions, the Audit Committee must review the material facts of any such transaction and approve that transaction.

To identify related party transactions, each year we submit and require our directors and officers to complete director and officer questionnaires identifying transactions with us in which the director or officer or their family members have a conflict of interest. We review the questionnaire for potential related party transactions. In addition, at meetings of the Audit Committee, management may recommend related party transactions to the committee, including the material terms of the proposed transactions, for its consideration. In making its decision to approve or ratify a related party transaction, the Audit Committee will consider all relevant facts and circumstances available to the committee, including factors such as the aggregate value of the transaction, whether the terms of the related party transaction are no less favorable than terms generally available in an arms’ length transaction and the benefit of such transaction to us.

SECTION 16(a) BENEFICIAL OWNERSHIP REPORTING COMPLIANCE

The members of the Board of Directors, our executive officers and persons who beneficially own more than 10% of our outstanding common stock are subject to the reporting requirements of Section 16 of the Exchange Act, as amended, which require them to file reports with respect to their beneficial ownership of the common stock and their transactions in such common stock. Based upon (i) the copies of Section 16 reports that we received from such persons for their 2017 year transactions in the common stock and their common stock holdings, and (ii) written representation that no other reports were required, we believe that all reporting requirements under Section 16 for such year were met in a timely manner by our directors, executive officers and greater than 10% beneficial owners.

HOUSEHOLDING OF PROXY MATERIALS

The SEC has adopted rules that permit companies and intermediaries to satisfy the delivery requirements for Notices of Internet Availability of Proxy Materials or other Annual Meeting materials with respect to two or more stockholders sharing the same address by delivering a single Notice of Internet Availability of Proxy Materials or other Annual Meeting materials addressed to those stockholders. This process, which is commonly referred to as “householding,” potentially means extra convenience for stockholders and cost savings for companies.

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This year, a number of brokers with account holders who are our stockholders will be “householding” our proxy materials. A single Notice of Internet Availability of Proxy Materials will be delivered to multiple stockholders sharing an address unless contrary instructions have been received from the affected stockholders. Once you have received notice from your broker that they will be “householding” communications to your address, “householding” will continue until you are notified otherwise or until you revoke your consent. If, at any time, you no longer wish to participate in “householding” and would prefer to receive a separate Notice of Internet Availability of Proxy Materials, please notify your broker or us. Direct your written request to Sangamo Therapeutics, Inc., Heather Turner, Secretary, 501 Canal Boulevard, Richmond, California 94804 or contact McDavid Stilwell at 510-970-6000. Stockholders who currently receive multiple copies of the Notices of Internet Availability of Proxy Materials at their addresses and would like to request “householding” of their communications should contact their brokers. In addition, we will promptly deliver, upon written or oral request to the address or telephone number above, a separate copy of the Notice of Internet Availability of Proxy Materials or the full set of proxy materials, as applicable, to a stockholder at a shared address to which a single copy of the documents was delivered.

Our Annual Report on Form 10-K for the year ended December 31, 2017 is available without charge upon written request to: Corporate Secretary, Sangamo Therapeutics, Inc., 501 Canal Boulevard, Richmond, California 94804. Our Annual Report on Form 10-K is not incorporated into this Proxy Statement and is not considered proxy soliciting material.

Dated: April 24, 2018

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Appendix A

SANGAMO THERAPEUTICS, INC.

2018 EQUITY INCENTIVE PLAN

ADOPTED BY THE COMPENSATION COMMITTEE OF THE BOARD: APRIL 23, 2018

APPROVED BY THE STOCKHOLDERS:                 , 2018

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