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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1. Name and Address of Reporting Person * INTERWEST PARTNERS X LP   2. Issuer Name and Ticker or Trading Symbol TESARO, Inc. [TSRO] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director _____ 10% Owner _____ Officer (give title below) __X__ Other (specify below) Former 10% Owner (Last) (First) (Middle) 2710 SAND HILL ROAD, SUITE 200 3. Date of Earliest Transaction (Month/Day/Year) 08/05/2013 (Street) MENLO PARK, CA 94025 4. If Amendment, Date Original Filed(Month/Day/Year) 6. Individual or Joint/Group Filing(Check Applicable Line) ___ Form filed by One Reporting Person _X_ 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 08/05/2013   J(1)   600,000 D $ 0 2,471,701 D (2)

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
INTERWEST PARTNERS X LP 2710 SAND HILL ROAD SUITE 200 MENLO PARK, CA 94025				Former 10% Owner
CLEVELAND BRUCE A 2710 SAND HILL ROAD SUITE 200 MENLO PARK, CA 94025				Former 10% Owner
GIANOS PHILIP T 2710 SAND HILL ROAD SUITE 200 MENLO PARK, CA 94025				Former 10% Owner
Holmes W Stephen 2710 SAND HILL ROAD SUITE 200 MENLO PARK, CA 94025				Former 10% Owner
Kjellson Nina S 2710 SAND HILL ROAD SUITE 200 MENLO PARK, CA 94025				Former 10% Owner
Kliman Gilbert H 2710 SAND HILL ROAD SUITE 200 MENLO PARK, CA 94025				Former 10% Owner
Pepper Douglas A 2710 SAND HILL ROAD SUITE 200 MENLO PARK, CA 94025				Former 10% Owner

Signatures

/s/ W. Stephen Holmes, Managing Director		08/07/2013
**Signature of Reporting Person		Date
/s/ Bruce A. Cleveland by Karen A. Wilson Power of Attorney		08/07/2013
**Signature of Reporting Person		Date
/s/ Philip T. Gianos by Karen A. Wilson Power of Attorney		08/07/2013
**Signature of Reporting Person		Date
/s/ W. Stephen Holmes		08/07/2013
**Signature of Reporting Person		Date
/s/ Nina S. Kjellson by Karen A. Wilson Power of Attorney		08/07/2013
**Signature of Reporting Person		Date
/s/ Gilbert H. Kliman by Karen A. Wilson Power of Attorney		08/07/2013
**Signature of Reporting Person		Date
/s Douglas A. Pepper by Karen A. Wilson Power of Attorney		08/07/2013
**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)	Represents pro rata in-kind distribution of 600,00 shares by InterWest Partners X, LP ("IW10") without consideration to its limited and general partners in accordance wiith the terms of the InterWest Partners X, LP Limited Partnership Agreement.
(2)	The shares are owned by InterWest Partners X, LP ("IW10"). InterWest Management Partners X, LLC ("IMP10") is the general partner of IW10. Bruce A. Cleveland, Philip T. Gianos, W. Stephen Holmes, Nina S. Kjellson, Gilbert H. Kliman, Arnold L. Oronsky, and Douglas A. Pepper are managing directors of IMP10. Keval Desai, Douglas Fisher and Khaled A. Nasr are venture members of IMP10. Each managing director and venture member of IMP10 disclaims beneficial ownership of such shares, except to the extent of their pecuniary interest therein.
Remarks: Due to limitations of the EDGAR software, this Form 4 is filed on behalf of InterWest Partners X, LP and certain other Reporting Persons, and is being filed on two Forms 4 (Part I and Part II) (collectively, the "InterWest Form 4"). This filing represents Part I of the InterWest Form 4 and should be read together with Part II. Part I and Part II of the InterWest Form 4 shall constitute one filing.

Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.

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