Sec Form 4 Filing - Flagship Ventures Fund V General Partner LLC @ Sana Biotechnology, Inc. - 2021-02-08

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 Flagship Ventures Fund V General Partner LLC 2. Issuer Name and Ticker or Trading Symbol Sana Biotechnology, Inc. [ SANA] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director X __ 10% Owner _____ Officer (give title below) _____ Other (specify below) (Last) (First) (Middle) 55 CAMBRIDGE PARKWAY, SUITE 800E 3. Date of Earliest Transaction (MM/DD/YY) 02/08/2021 (Street) CAMBRIDGE, MA02142 4. If Amendment, Date Original Filed (MM/DD/YY) 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 (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 02/08/2021 C 1,487,371 A 1,487,371 I See footnotes ( 2 ) ( 6 ) ( 7 ) Common Stock 02/08/2021 C 9,725,122 A 9,725,122 I See footnotes ( 3 ) ( 6 ) ( 7 ) Common Stock 02/08/2021 C 11,441,326 A 11,441,326 I See footnotes ( 4 ) ( 6 ) ( 7 ) Common Stock 02/08/2021 C 11,585,199 A 11,585,199 I See footnotes ( 5 ) ( 6 ) ( 7 )

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 Series A-2 Convertible Preferred Stock ( 1 ) 02/08/2021 C 1,487,371 ( 1 ) ( 8 ) Common Stock 1,487,371 $ 0 0 I See footnotes ( 2 ) ( 6 ) ( 7 ) Series A-2 Convertible Preferred Stock ( 1 ) 02/08/2021 C 9,725,122 ( 1 ) ( 8 ) Common Stock 9,725,122 $ 0 0 I See footnotes ( 3 ) ( 6 ) ( 7 ) Series A-2 Convertible Preferred Stock ( 1 ) 02/08/2021 C 11,441,326 ( 1 ) ( 8 ) Common Stock 11,441,326 $ 0 0 I See footnotes ( 4 ) ( 6 ) ( 7 ) Series A-2 Convertible Preferred Stock ( 1 ) 02/08/2021 C 11,585,199 ( 1 ) ( 8 ) Common Stock 11,585,199 $ 0 0 I See footnotes ( 5 ) ( 6 ) ( 7 )

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other Flagship Ventures Fund V General Partner LLC 55 CAMBRIDGE PARKWAY SUITE 800E CAMBRIDGE, MA02142 X Flagship V VentureLabs Rx Fund, L.P. 55 CAMBRIDGE PARKWAY, SUITE 800E CAMBRIDGE, MA02142 X Flagship Ventures Fund V, L.P. 55 CAMBRIDGE PARKWAY, SUITE 800E CAMBRIDGE, MA02142 X Flagship Pioneering Inc. 55 CAMBRIDGE PARKWAY, SUITE 800E CAMBRIDGE, MA02142 X Flagship Pioneering Fund VI General Partner LLC 55 CAMBRIDGE PARKWAY, SUITE 800E CAMBRIDGE, MA02142 X Flagship Pioneering Fund VI, L.P. 55 CAMBRIDGE PARKWAY, SUITE 800E CAMBRIDGE, MA02142 X Flagship VentureLabs V Manager LLC 55 CAMBRIDGE PARKWAY, SUITE 800E CAMBRIDGE, MA02142 X Flagship VentureLabs V LLC 55 CAMBRIDGE PARKWAY, SUITE 800E CAMBRIDGE, MA02142 X AFEYAN NOUBAR 55 CAMBRIDGE PARKWAY, SUITE 800E CAMBRIDGE, MA02142 X Signatures /s/ Flagship Ventures Fund V General Partner LLC, By: Noubar B. Afeyan, Title: Manager 02/10/2021 Signature of Reporting Person Date /s/ Flagship V VentureLabs Rx Fund, L.P., By: Flagship Ventures Fund V General Partner LLC, its General Partner, By: Noubar B. Afeyan, Title: Manager 02/10/2021 Signature of Reporting Person Date /s/ Flagship Ventures Fund V, L.P., By: Flagship Ventures Fund V General Partner LLC, its General Partner, By: Noubar B. Afeyan, Title: Manager 02/10/2021 Signature of Reporting Person Date /s/ Flagship Pioneering, Inc., By: Noubar B. Afeyan, Title: Director 02/10/2021 Signature of Reporting Person Date /s/ Flagship Pioneering Fund VI General Partner LLC, By: Flagship Pioneering, Inc., its Manager, By: Noubar B. Afeyan, Title: Director 02/10/2021 Signature of Reporting Person Date /s/ Flagship Pioneering Fund VI, L.P., By: Flagship Pioneering Fund VI General Partner LLC, its General Partner, By: Flagship Pioneering, Inc., its Manager, By: Noubar B. Afeyan, Title: Director 02/10/2021 Signature of Reporting Person Date /s/ Flagship VentureLabs V Manager LLC, By: Flagship Pioneering, Inc., its Manager, By: Noubar B. Afeyan, Title: Director 02/10/2021 Signature of Reporting Person Date /s/ Flagship VentureLabs V LLC., By: Flagship VentureLabs V Manager LLC its Manager, By: Flagship Pioneering, Inc., its Manager, By: Noubar B. Afeyan, Title: Director 02/10/2021 Signature of Reporting Person Date /s/ Noubar B. Afeyan, Name: Noubar B. Afeyan, Ph.D. 02/10/2021 Signature of Reporting Person Date

Explanation of Responses:

( 1 )The shares of Issuer's Preferred Stock automatically convert into shares of Issuer's Common Stock, for no additional consideration, on a 1-for-1 basis immediately prior to the consummation of Issuer's initial public offering. ( 2 )Represents shares held directly by Flagship V VentureLabs Rx Fund, L.P. ("Flagship Fund V Rx"). ( 3 )Represents shares held directly by Flagship Pioneering Fund VI, L.P. ("Flagship Pioneering VI"). ( 4 )Represents shares held directly by Flagship VentureLabs V LLC. ("VentureLabs V"). ( 5 )Represents shares held directly by Flagship Ventures Fund V, L.P. ("Flagship Fund V" and together with Flagship Fund V Rx, Flagship Pioneering VI, and VentureLabs V, the "Flagship Pioneering Funds"). ( 6 )VentureLabs V Manager LLC ("VentureLabs V Manager") is the manager of VentureLabs V. Flagship Pioneering, Inc. ("Flagship Pioneering") is the manager of VentureLabs V Manager. The General Partner of Flagship Pioneering VI is Flagship Pioneering Fund VI General Partner LLC ("Flagship Pioneering VI GP"). The manager of Flagship Pioneering VI GP is Flagship Pioneering. The General Partner of Flagship Fund V and Flagship Fund V Rx is Flagship Ventures Fund V General Partner LLC ("Flagship V GP" and, together with VentureLabs V Manager, Flagship Pioneering, and Flagship Pioneering VI GP, the "Flagship General Partners"). ( 7 )(continued from footnote 6) Noubar B. Afeyan, Ph.D. is the sole Director of Flagship Pioneering and may be deemed to have sole voting and investment control over all the shares held by VentureLabs V and Flagship Fund VI. In addition, Noubar B. Afeyan, Ph.D. serves as the sole manager of Flagship V GP and may be deemed to possess sole voting and investment control over all the shares held by Flagship Fund V and Flagship Fund V Rx. None of the Flagship General Partners nor Noubar B. Afeyan, Ph.D. directly own any of the shares held by the Flagship Pioneering Funds, and each of the Flagship General Partners and Noubar Afeyan, Ph.D. disclaims beneficial ownership of such shares except to the extent of its or his pecuniary interest therein. ( 8 )The expiration date is not relevant to the conversion of these securities.

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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