Sec Form 4 Filing - SEIDENBERG BETH C @ TESARO, Inc. - 2018-06-01

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 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 SEIDENBERG BETH C 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 3. Date of Earliest Transaction (MM/DD/YY) 06/01/2018 (Street) WALTHAM, MA02451 4. If Amendment, Date Original Filed (MM/DD/YY) 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 (MM/DD/YY) 2A. Deemed Execution Date, if any (MM/DD/YY) 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 06/01/2018 A 1,332 ( 1 ) A $ 0 45,907 D Common Stock 1,994,768 I See footnotes ( 2 ) ( 3 ) Common Stock 168,755 I See footnotes ( 3 ) ( 4 ) Common Stock 10,998 I See footnotes ( 3 ) ( 5 ) Common Stock 868 I By Michael J. Seidenberg Irrevocable Trust ( 6 ) Common Stock 868 I By Samuel B. Seidenberg Irrevocable Trust ( 6 )

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 (MM/DD/YY) 3A. Deemed Execution Date, if any (MM/DD/YY) 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 (MM/DD/YY) 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 Director Nonqualified Stock Option (right to buy) $ 46.89 06/01/2018 A 7,209 ( 7 ) 06/01/2028 Common Stock 7,209 $ 0 7,209 D Director Restricted Stock Units ( 8 ) 06/01/2018 A 4,052 ( 9 ) ( 9 ) Common Stock 4,052 $ 0 4,052 D

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other SEIDENBERG BETH C C/O TESARO, INC. 1000 WINTER STREET WALTHAM, MA02451 X Signatures /s/ Scott Ryles, Attorney-in-Fact 06/05/2018 Signature of Reporting Person Date

Explanation of Responses:

( 1 )The Reporting Person has elected to receive common stock in lieu of cash for board retainers and fees otherwise payable in cash, and has elected to defer delivery of that common stock until the date that she separates from service on the Issuer's board of directors. ( 2 )The shares are held directly by Kleiner Perkins Caufield & Byers XIV, LLC ("KPCB XIV"). The managing member of KPCB XIV is KPCB XIV Associates, LLC ("KPCB XIV Associates"), of which the Reporting Person is a member. The voting and dispositive control over the shares is shared by the members of KPCB XIV Associates. The shares are held for convenience in the name of "KPCB Holdings, Inc. as nominee." ( 3 )The Reporting Person disclaims beneficial ownership over all Issuer shares held for convenience in the name of "KPCB Holdings, Inc. as nominee," except to the extent of her pecuniary interest therein, and the filing of this report is not an admission that the Reporting Person is the beneficial owner of these shares for the purposes of Section 16 or for any other purpose. ( 4 )The shares are held directly by KPCB XIV Founders Fund, LLC ("KPCB XIV Founders"). The managing member of KPCB XIV Founders is KPCB XIV Associates, of which the Reporting Person is a member. The voting and dispositive control over the shares is shared by the members of KPCB XIV Associates. The shares are held for convenience in the name of "KPCB Holdings, Inc. as nominee." ( 5 )The shares are held directly by KPCB XIV Associates, of which the Reporting Person is a member. The voting and dispositive control over the shares is shared by the members of KPCB XIV Associates. The shares are held for convenience in the name of "KPCB Holdings, Inc. as nominee." ( 6 )The Reporting Person and her spouse are co-trustees of the trust and their son is beneficiary of the trust. The Reporting Person disclaims beneficial ownership of these shares, except to the extent of her pecuniary interest therein, and the filing of this report is not an admission that the Reporting Person is the beneficial owner of these shares for purposes of Section 16 or for any other purpose. ( 7 )The option vests on the earlier of the one-year anniversary of the date of grant and the next annual meeting of the Issuer's stockholders, subject to the Reporting Person's continued service on the Issuer's board of directors. ( 8 )Each restricted stock unit ("RSU") represents a contingent right to receive one share of TESARO common stock. ( 9 )The RSUs vest on the earlier of the one-year anniversary of the date of grant and the next annual meeting of the Issuer's stockholders, subject to the Reporting Person's continued service on the Issuer's board of directors.

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.

* 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).

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