Sec Form 4 Filing - Flagship Pioneering Inc. @ Sana Biotechnology, Inc. - 2023-09-13

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 Pioneering Inc. 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) 09/13/2023 (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 09/13/2023 J( 1 ) 2,825,989 D 8,615,337 I By Flagship VentureLabs V, LLC ( 2 ) Common Stock 09/13/2023 J( 3 ) 4,926,378 D 8,057,470 ( 4 ) I By Flagship Ventures Fund V, L.P. ( 4 ) Common Stock 09/13/2023 J( 3 ) 345,069 D 1,035,208 I By Flagship V VentureLabs Rx Fund, L.P. ( 5 ) Common Stock 09/13/2023 J( 3 ) 1,181,745 D 0 I By Flagship Ventures Fund V General Partner LLC ( 6 ) Common Stock 09/13/2023 J( 7 ) 2,431,281 D 7,293,841 I By Flagship Pioneering Fund VI, L.P. ( 8 ) Common Stock 09/13/2023 J( 7 ) 70,813 D 0 I By Flagship Pioneering Fund VI General Partner LLC ( 9 ) Common Stock 581,695 ( 10 ) I See footnote ( 10 )

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

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other Flagship Pioneering Inc. 55 CAMBRIDGE PARKWAY, SUITE 800E CAMBRIDGE, MA02142 X Flagship Ventures Fund V General Partner LLC 55 CAMBRIDGE PARKWAY, SUITE 800E CAMBRIDGE, MA02142 X Flagship Ventures Fund V, L.P. 55 CAMBRIDGE PARKWAY, SUITE 800E CAMBRIDGE, MA02142 X Flagship V VentureLabs Rx Fund, 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 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 AFEYAN NOUBAR 55 CAMBRIDGE PARKWAY, SUITE 800E CAMBRIDGE, MA02142 X Signatures Flagship Pioneering, Inc., By: /s/ Noubar B. Afeyan, Ph.D., Title: CEO 09/15/2023 Signature of Reporting Person Date Flagship Ventures Fund V General Partner LLC, By: /s/ Noubar B. Afeyan, Ph.D., Title: Manager 09/15/2023 Signature of Reporting Person Date Flagship Ventures Fund V, L.P., By: Flagship Ventures Fund V General Partner LLC, its General Partner, By: /s/ Noubar B. Afeyan, Ph.D., Title: Manager 09/15/2023 Signature of Reporting Person Date Flagship V VentureLabs Rx Fund, L.P., By: Flagship Ventures Fund V General Partner LLC, its General Partner, By: /s/ Noubar B. Afeyan, Ph.D., Title: Manager 09/15/2023 Signature of Reporting Person Date Flagship VentureLabs V Manager, LLC, By: Flagship Pioneering, Inc., its Manager, By: /s/ Noubar B. Afeyan. Ph.D., Title: CEO 09/15/2023 Signature of Reporting Person Date Flagship VentureLabs V LLC, By: Flagship VentureLabs V Manager, LLC, its Manager, By: Flagship Pioneering, Inc., its Manager, By: /s/ Noubar B. Afeyan. Ph.D., Title: CEO 09/15/2023 Signature of Reporting Person Date Flagship Pioneering Fund VI General Partner LLC, By: Flagship Pioneering, Inc., its Manager, By: /s/ Noubar B. Afeyan, Ph.D., Title: CEO 09/15/2023 Signature of Reporting Person Date Flagship Pioneering Fund VI, L.P., By: Flagship Pioneering Fund VI General Partner LLC, its General Partner, By: Flagship Pioneering, Inc., its Manager, By: /s/ Noubar B. Afeyan, Ph.D., Title: CEO 09/15/2023 Signature of Reporting Person Date /s/ Noubar B. Afeyan, Ph.D. 09/15/2023 Signature of Reporting Person Date

Explanation of Responses:

( 1 )On September 13, 2023, Flagship VentureLabs V LLC ("VentureLabs V") distributed in-kind to its m embers, pro rata and without consideration, 2,825,989 shares of the Issuer's common stock. The aforementioned distribution was made in accordance with the exemptions afforded by Rule 16a-13 and Rule 16a-9 of the Securities Exchange Act of 1934, as amended. ( 2 )Represents shares held directly by VentureLabs V. Flagship 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. Dr. Afeyan is the CEO and sole stockholder of Flagship Pioneering. Each of the reporting persons except VentureLabs V disclaims beneficial ownership of such shares except to the extent of his or its pecuniary interest therein, if any. ( 3 )On September 13, 2023, Flagship Ventures Fund V, L.P. ("Flagship Fund V") and Flagship V VentureLabs Rx Fund, L.P. ("Flagship Fund V Rx") distributed in-kind to their respective limited partners and sole general partner, Flagship Ventures Fund V General Partner, LLC ("Flagship Fund V GP"), pro rata and without consideration, 4,926,378 shares and 345,069 shares, respectively, of the Issuer's common stock. Flagship Fund V GP, in turn, distributed in-kind to its members, pro rata and without consideration, the aggregate of 1,181,745 shares it received from Flagship Fund V and Flagship Fund V Rx. The aforementioned distributions were made in accordance with the exemptions afforded by Rule 16a-13 and Rule 16a-9 of the Securities Exchange Act of 1934, as amended. ( 4 )Represents shares held directly by Flagship Fund V. Includes 2,240,555 shares received in the distribution-in-kind from VentureLabs V described in footnote (1) above. Flagship V GP is the general partner of Flagship Fund V. Dr. Afeyan is the sole manager of Flagship V GP. Each of the reporting persons except Flagship Fund V disclaims beneficial ownership of such shares except to the extent of his or its pecuniary interest therein, if any. ( 5 )Represents shares held directly by Flagship Fund V Rx. Flagship V GP is the general partner of Flagship Fund V Rx. Each of the reporting persons except Flagship Fund V Rx disclaims beneficial ownership of such shares except to the extent of his or its pecuniary interest therein, if any. ( 6 )Represents shares held directly by Flagship Fund V GP. Each of the reporting persons except Flagship Fund V GP disclaims beneficial ownership of such shares except to the extent of his or its pecuniary interest therein, if any. ( 7 )On September 13, 2023, Flagship Pioneering Fund VI, L.P. ("Flagship Fund VI") distributed in-kind to its limited partners and sole general partner, Flagship Pioneering Fund VI General Partner LLC ("Flagship Fund VI GP"), pro rata and without consideration, 2,431,281 shares of the Issuer's common stock. Flagship Fund VI GP, in turn, distributed in-kind to its members, pro rata and without consideration, the 70,813 shares it received from Flagship Fund VI. The aforementioned distributions were made in accordance with the exemptions afforded by Rule 16a-13 and Rule 16a-9 of the Securities Exchange Act of 1934, as amended. ( 8 )Represents shares held directly by Flagship Fund VI. Flagship Fund VI GP is the general partner of Flagship Fund VI. Flagship Pioneering is the manager of Flagship Fund VI GP. Each of the reporting persons except Flagship Fund VI disclaims beneficial ownership of such shares except to the extent of his or its pecuniary interest therein, if any. ( 9 )Represents shares held directly by Flagship Fund VI GP. Each of the reporting persons except Flagship Fund VI GP disclaims beneficial ownership of such shares except to the extent of his or its pecuniary interest therein, if any. ( 10 )Consists of (i) 21,641 shares held directly by Dr. Afeyan, (ii) 20,606 shares held through a trust for the benefit of Dr. Afeyan's children (the "Trust") and (iii) 539,448 shares held by VENBA Holdings LLC ("VENBA"), an estate planning entity of which Dr. Afeyan is the sole manager. Represents an aggregate of 581,695 shares received in the distributions-in-kind described in footnotes (1), (3) and (7) above. Dr. Afeyan disclaims beneficial ownership of the shares held by the Trust and VENBA except to the extent of his pecuniary interest therein, if any.

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