X0306 4 2021-02-08 0 0001770121 Sana Biotechnology, Inc. SANA 0001724575 Flagship Ventures Fund V General Partner LLC 55 CAMBRIDGE PARKWAY SUITE 800E CAMBRIDGE MA 02142 0 0 1 0 0001724939 Flagship V VentureLabs Rx Fund, L.P. 55 CAMBRIDGE PARKWAY, SUITE 800E CAMBRIDGE MA 02142 0 0 1 0 0001627639 Flagship Ventures Fund V, L.P. 55 CAMBRIDGE PARKWAY, SUITE 800E CAMBRIDGE MA 02142 0 0 1 0 0001400240 Flagship Pioneering Inc. 55 CAMBRIDGE PARKWAY, SUITE 800E CAMBRIDGE MA 02142 0 0 1 0 0001724957 Flagship Pioneering Fund VI General Partner LLC 55 CAMBRIDGE PARKWAY, SUITE 800E CAMBRIDGE MA 02142 0 0 1 0 0001716926 Flagship Pioneering Fund VI, L.P. 55 CAMBRIDGE PARKWAY, SUITE 800E CAMBRIDGE MA 02142 0 0 1 0 0001768987 Flagship VentureLabs V Manager LLC 55 CAMBRIDGE PARKWAY, SUITE 800E CAMBRIDGE MA 02142 0 0 1 0 0001724959 Flagship VentureLabs V LLC 55 CAMBRIDGE PARKWAY, SUITE 800E CAMBRIDGE MA 02142 0 0 1 0 0001222012 AFEYAN NOUBAR 55 CAMBRIDGE PARKWAY, SUITE 800E CAMBRIDGE MA 02142 0 0 1 0 Common Stock 2021-02-08 4 C 0 1487371 A 1487371 I See footnotes Common Stock 2021-02-08 4 C 0 9725122 A 9725122 I See footnotes Common Stock 2021-02-08 4 C 0 11441326 A 11441326 I See footnotes Common Stock 2021-02-08 4 C 0 11585199 A 11585199 I See footnotes Series A-2 Convertible Preferred Stock 2021-02-08 4 C 0 1487371 0.00 D Common Stock 1487371 0 I See footnotes Series A-2 Convertible Preferred Stock 2021-02-08 4 C 0 9725122 0.00 D Common Stock 9725122 0 I See footnotes Series A-2 Convertible Preferred Stock 2021-02-08 4 C 0 11441326 0.00 D Common Stock 11441326 0 I See footnotes Series A-2 Convertible Preferred Stock 2021-02-08 4 C 0 11585199 0.00 D Common Stock 11585199 0 I See footnotes 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. Represents shares held directly by Flagship V VentureLabs Rx Fund, L.P. ("Flagship Fund V Rx"). Represents shares held directly by Flagship Pioneering Fund VI, L.P. ("Flagship Pioneering VI"). Represents shares held directly by Flagship VentureLabs V LLC. ("VentureLabs V"). 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"). 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"). (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. The expiration date is not relevant to the conversion of these securities. /s/ Flagship Ventures Fund V General Partner LLC, By: Noubar B. Afeyan, Title: Manager 2021-02-10 /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 2021-02-10 /s/ Flagship Ventures Fund V, L.P., By: Flagship Ventures Fund V General Partner LLC, its General Partner, By: Noubar B. Afeyan, Title: Manager 2021-02-10 /s/ Flagship Pioneering, Inc., By: Noubar B. Afeyan, Title: Director 2021-02-10 /s/ Flagship Pioneering Fund VI General Partner LLC, By: Flagship Pioneering, Inc., its Manager, By: Noubar B. Afeyan, Title: Director 2021-02-10 /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 2021-02-10 /s/ Flagship VentureLabs V Manager LLC, By: Flagship Pioneering, Inc., its Manager, By: Noubar B. Afeyan, Title: Director 2021-02-10 /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 2021-02-10 /s/ Noubar B. Afeyan, Name: Noubar B. Afeyan, Ph.D. 2021-02-10