FORM 4 Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP OF SECURITIES Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940

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(Print or Type Responses)

1. Name and Address of Reporting Person * ORONSKY ARNOLD L   2. Issuer Name and Ticker or Trading Symbol TESARO, Inc. [TSRO] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) __X__ Director _____ 10% Owner _____ Officer (give title below) _____ Other (specify below) (Last) (First) (Middle) C/O TESARO, INC., 1000 WINTER STREET, SUITE 3300 3. Date of Earliest Transaction (Month/Day/Year) 03/18/2016 (Street) WALTHAM, MA 02451 4. If Amendment, Date Original Filed(Month/Day/Year) 6. Individual or Joint/Group Filing(Check Applicable Line) _X_ Form filed by One Reporting Person ___ Form filed by More than One Reporting Person (City) (State) (Zip) Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned

1.Title of Security (Instr. 3) 2. Transaction Date (Month/Day/Year) 2A. Deemed Execution Date, if any (Month/Day/Year) 3. Transaction Code (Instr. 8) 4. Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5) 5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4) 6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) 7. Nature of Indirect Beneficial Ownership (Instr. 4) Code V Amount (A) or (D) Price Common Stock 03/18/2016   P   142,085 (1) A $ 35.19 2,013,786 I By partnership (2) Common Stock               6,614 (3) I By partnership (4) Common Stock               1,003 (5) I By corporation (6) Common Stock               2,479 (3) (5) D

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
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Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned
(e.g., puts, calls, warrants, options, convertible securities)

1. Title of Derivative Security (Instr. 3)

2. Conversion or Exercise Price of Derivative Security

3. Transaction Date (Month/Day/Year)

3A. Deemed Execution Date, if any (Month/Day/Year)

4. Transaction Code (Instr. 8)

5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4, and 5)

6. Date Exercisable and Expiration Date (Month/Day/Year)

7. Title and Amount of Underlying Securities (Instr. 3 and 4)

8. Price of Derivative Security (Instr. 5)

9. Number of Derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)

10. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 4)

11. Nature of Indirect Beneficial Ownership (Instr. 4)

Code

V

(A)

(D)

Date Exercisable

Expiration Date

Title

Amount or Number of Shares

Reporting Owners

Reporting Owner Name / Address	Relationships
	Director	10% Owner	Officer	Other
ORONSKY ARNOLD L C/O TESARO, INC. 1000 WINTER STREET, SUITE 3300 WALTHAM, MA 02451	X

Signatures

/s/ Karen A. Wilson, Attorney-in-Fact		03/18/2016
**Signature of Reporting Person		Date

Explanation of Responses:

*	If the form is filed by more than one reporting person, see Instruction 4(b)(v).
**	Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
(1)	The shares were acquired upon the closing of a private placement that was publicly disclosed by the Issuer on February 25, 2016.
(2)	The shares are owned by InterWest Partners X, LP ("IW10"). The Reporting Person is a managing director of InterWest Management Partners X, LLC ("IMP10"), the general partner of IW10, and disclaims beneficial ownership of these shares except to the extent of his pecuniary interest therein.
(3)	This number reflects that 6,614 shares previously reported as being owned directly were assigned to IMP10.
(4)	The shares are beneficially owned by IMP10. The Reporting Person is a managing director of IMP10, and disclaims beneficial ownership of these shares except to the extent of his pecuniary interest therein.
(5)	This number reflects that 1,003 shares previously reported as being owned directly were assigned to InterWest Venture Management Company ("IVMC").
(6)	The shares are beneficially owned by IVMC. The Reporting Person is an officer and director of IVMC and may be deemed to own beneficially the shares held by IVMC.

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