MRNA

SEC source: 0001127602-21-008118 · form4.xml · nonDerivative · entry 1

Bancel Stephane · CIK 0001443340 · Director · Chief Executive Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 6,434,868

F1 · kind: This sale was effected pursuant to a Rule 10b5-1 trading plan adopted on December 28, 2018, as amended on May 21, 2020.

SEC source: 0001209191-21-014053 · doc4.xml · nonDerivative · entry 28

AFEYAN NOUBAR · CIK 0001222012 · Director

10b5-1 filing: Not disclosed

Ownership: Indirect · By Flagship Ventures Fund IV, L.P. and Flagship Ventures Fund IV-Rx, L.P.

Disclosed balance after: 14,623,159

F1 · kind: These sales were effected by Flagship Ventures Fund IV, L.P. ("Flagship Fund IV") and Flagship Ventures Fund IV-Rx, L.P. ("Flagship Fund IV-Rx") pursuant to Rule 10b5-1 trading plans adopted on December 23, 2020.

F30 · shares: Represents 19,676 shares sold by Flagship Fund IV and 3,747 shares sold by Flagship Fund IV-Rx. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $151.08 to $151.64, inclusive. The reporting person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range.

F30 · price: Represents 19,676 shares sold by Flagship Fund IV and 3,747 shares sold by Flagship Fund IV-Rx. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $151.08 to $151.64, inclusive. The reporting person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range.

F31 · balance_after: Following the transactions reported herein, 10,417,023 shares are held directly by Flagship Fund IV and 4,206,136 shares are held directly by Flagship Fund IV-Rx.

F3 · ownership.nature: Shares held directly by Flagship Fund IV and Flagship Fund IV-Rx. Flagship Ventures Fund IV General Partner LLC ("Flagship Fund IV GP") is the general partner of each of Flagship Fund IV and Flagship Fund IV-Rx. The reporting person is the sole manager of Flagship Fund IV GP and disclaims beneficial ownership of such shares except to the extent of his pecuniary interest therein.

SEC source: 0001209191-21-014053 · doc4.xml · nonDerivative · entry 27

AFEYAN NOUBAR · CIK 0001222012 · Director

10b5-1 filing: Not disclosed

Ownership: Indirect · By Flagship Ventures Fund IV, L.P. and Flagship Ventures Fund IV-Rx, L.P.

Disclosed balance after: 14,646,582

F1 · kind: These sales were effected by Flagship Ventures Fund IV, L.P. ("Flagship Fund IV") and Flagship Ventures Fund IV-Rx, L.P. ("Flagship Fund IV-Rx") pursuant to Rule 10b5-1 trading plans adopted on December 23, 2020.

F29 · shares: Represents 160,196 shares sold by Flagship Fund IV and 30,514 shares sold by Flagship Fund IV-Rx. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $150.08 to $151.07, inclusive. The reporting person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range.

F29 · price: Represents 160,196 shares sold by Flagship Fund IV and 30,514 shares sold by Flagship Fund IV-Rx. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $150.08 to $151.07, inclusive. The reporting person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range.

F3 · ownership.nature: Shares held directly by Flagship Fund IV and Flagship Fund IV-Rx. Flagship Ventures Fund IV General Partner LLC ("Flagship Fund IV GP") is the general partner of each of Flagship Fund IV and Flagship Fund IV-Rx. The reporting person is the sole manager of Flagship Fund IV GP and disclaims beneficial ownership of such shares except to the extent of his pecuniary interest therein.

SEC source: 0001209191-21-014053 · doc4.xml · nonDerivative · entry 26

AFEYAN NOUBAR · CIK 0001222012 · Director

10b5-1 filing: Not disclosed

Ownership: Indirect · By Flagship Ventures Fund IV, L.P. and Flagship Ventures Fund IV-Rx, L.P.

Disclosed balance after: 14,837,292

F1 · kind: These sales were effected by Flagship Ventures Fund IV, L.P. ("Flagship Fund IV") and Flagship Ventures Fund IV-Rx, L.P. ("Flagship Fund IV-Rx") pursuant to Rule 10b5-1 trading plans adopted on December 23, 2020.

F28 · shares: Represents 150,585 shares sold by Flagship Fund IV and 28,683 shares sold by Flagship Fund IV-Rx. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $149.07 to $150.06, inclusive. The reporting person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range.

F28 · price: Represents 150,585 shares sold by Flagship Fund IV and 28,683 shares sold by Flagship Fund IV-Rx. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $149.07 to $150.06, inclusive. The reporting person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range.

F3 · ownership.nature: Shares held directly by Flagship Fund IV and Flagship Fund IV-Rx. Flagship Ventures Fund IV General Partner LLC ("Flagship Fund IV GP") is the general partner of each of Flagship Fund IV and Flagship Fund IV-Rx. The reporting person is the sole manager of Flagship Fund IV GP and disclaims beneficial ownership of such shares except to the extent of his pecuniary interest therein.

SEC source: 0001209191-21-014053 · doc4.xml · nonDerivative · entry 25

AFEYAN NOUBAR · CIK 0001222012 · Director

10b5-1 filing: Not disclosed

Ownership: Indirect · By Flagship Ventures Fund IV, L.P. and Flagship Ventures Fund IV-Rx, L.P.

Disclosed balance after: 15,016,560

F1 · kind: These sales were effected by Flagship Ventures Fund IV, L.P. ("Flagship Fund IV") and Flagship Ventures Fund IV-Rx, L.P. ("Flagship Fund IV-Rx") pursuant to Rule 10b5-1 trading plans adopted on December 23, 2020.

F27 · shares: Represents 225,698 shares sold by Flagship Fund IV and 42,990 shares sold by Flagship Fund IV-Rx. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $148.07 to $149.06, inclusive. The reporting person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range.

F27 · price: Represents 225,698 shares sold by Flagship Fund IV and 42,990 shares sold by Flagship Fund IV-Rx. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $148.07 to $149.06, inclusive. The reporting person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range.

F3 · ownership.nature: Shares held directly by Flagship Fund IV and Flagship Fund IV-Rx. Flagship Ventures Fund IV General Partner LLC ("Flagship Fund IV GP") is the general partner of each of Flagship Fund IV and Flagship Fund IV-Rx. The reporting person is the sole manager of Flagship Fund IV GP and disclaims beneficial ownership of such shares except to the extent of his pecuniary interest therein.

SEC source: 0001209191-21-014053 · doc4.xml · nonDerivative · entry 24

AFEYAN NOUBAR · CIK 0001222012 · Director

10b5-1 filing: Not disclosed

Ownership: Indirect · By Flagship Ventures Fund IV, L.P. and Flagship Ventures Fund IV-Rx, L.P.

Disclosed balance after: 15,285,248

F1 · kind: These sales were effected by Flagship Ventures Fund IV, L.P. ("Flagship Fund IV") and Flagship Ventures Fund IV-Rx, L.P. ("Flagship Fund IV-Rx") pursuant to Rule 10b5-1 trading plans adopted on December 23, 2020.

F26 · shares: Represents 245,686 shares sold by Flagship Fund IV and 46,797 shares sold by Flagship Fund IV-Rx. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $147.07 to $148.06, inclusive. The reporting person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range.

F26 · price: Represents 245,686 shares sold by Flagship Fund IV and 46,797 shares sold by Flagship Fund IV-Rx. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $147.07 to $148.06, inclusive. The reporting person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range.

F3 · ownership.nature: Shares held directly by Flagship Fund IV and Flagship Fund IV-Rx. Flagship Ventures Fund IV General Partner LLC ("Flagship Fund IV GP") is the general partner of each of Flagship Fund IV and Flagship Fund IV-Rx. The reporting person is the sole manager of Flagship Fund IV GP and disclaims beneficial ownership of such shares except to the extent of his pecuniary interest therein.

SEC source: 0001209191-21-014053 · doc4.xml · nonDerivative · entry 23

AFEYAN NOUBAR · CIK 0001222012 · Director

10b5-1 filing: Not disclosed

Ownership: Indirect · By Flagship Ventures Fund IV, L.P. and Flagship Ventures Fund IV-Rx, L.P.

Disclosed balance after: 15,577,731

F1 · kind: These sales were effected by Flagship Ventures Fund IV, L.P. ("Flagship Fund IV") and Flagship Ventures Fund IV-Rx, L.P. ("Flagship Fund IV-Rx") pursuant to Rule 10b5-1 trading plans adopted on December 23, 2020.

F25 · shares: Represents 258,547 shares sold by Flagship Fund IV and 49,248 shares sold by Flagship Fund IV-Rx. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $146.07 to $147.06, inclusive. The reporting person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range.

F25 · price: Represents 258,547 shares sold by Flagship Fund IV and 49,248 shares sold by Flagship Fund IV-Rx. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $146.07 to $147.06, inclusive. The reporting person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range.

F3 · ownership.nature: Shares held directly by Flagship Fund IV and Flagship Fund IV-Rx. Flagship Ventures Fund IV General Partner LLC ("Flagship Fund IV GP") is the general partner of each of Flagship Fund IV and Flagship Fund IV-Rx. The reporting person is the sole manager of Flagship Fund IV GP and disclaims beneficial ownership of such shares except to the extent of his pecuniary interest therein.

SEC source: 0001209191-21-014053 · doc4.xml · nonDerivative · entry 22

AFEYAN NOUBAR · CIK 0001222012 · Director

10b5-1 filing: Not disclosed

Ownership: Indirect · By Flagship Ventures Fund IV, L.P. and Flagship Ventures Fund IV-Rx, L.P.

Disclosed balance after: 15,885,526

F1 · kind: These sales were effected by Flagship Ventures Fund IV, L.P. ("Flagship Fund IV") and Flagship Ventures Fund IV-Rx, L.P. ("Flagship Fund IV-Rx") pursuant to Rule 10b5-1 trading plans adopted on December 23, 2020.

F24 · shares: Represents 300,146 shares sold by Flagship Fund IV and 57,170 shares sold by Flagship Fund IV-Rx. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $145.06 to $146.05, inclusive. The reporting person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range.

F24 · price: Represents 300,146 shares sold by Flagship Fund IV and 57,170 shares sold by Flagship Fund IV-Rx. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $145.06 to $146.05, inclusive. The reporting person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range.

F3 · ownership.nature: Shares held directly by Flagship Fund IV and Flagship Fund IV-Rx. Flagship Ventures Fund IV General Partner LLC ("Flagship Fund IV GP") is the general partner of each of Flagship Fund IV and Flagship Fund IV-Rx. The reporting person is the sole manager of Flagship Fund IV GP and disclaims beneficial ownership of such shares except to the extent of his pecuniary interest therein.

SEC source: 0001209191-21-014053 · doc4.xml · nonDerivative · entry 21

AFEYAN NOUBAR · CIK 0001222012 · Director

10b5-1 filing: Not disclosed

Ownership: Indirect · By Flagship Ventures Fund IV, L.P. and Flagship Ventures Fund IV-Rx, L.P.

Disclosed balance after: 16,242,842

F1 · kind: These sales were effected by Flagship Ventures Fund IV, L.P. ("Flagship Fund IV") and Flagship Ventures Fund IV-Rx, L.P. ("Flagship Fund IV-Rx") pursuant to Rule 10b5-1 trading plans adopted on December 23, 2020.

F23 · shares: Represents 340,662 shares sold by Flagship Fund IV and 64,889 shares sold by Flagship Fund IV-Rx. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $144.06 to $145.05, inclusive. The reporting person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range.

F23 · price: Represents 340,662 shares sold by Flagship Fund IV and 64,889 shares sold by Flagship Fund IV-Rx. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $144.06 to $145.05, inclusive. The reporting person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range.

F3 · ownership.nature: Shares held directly by Flagship Fund IV and Flagship Fund IV-Rx. Flagship Ventures Fund IV General Partner LLC ("Flagship Fund IV GP") is the general partner of each of Flagship Fund IV and Flagship Fund IV-Rx. The reporting person is the sole manager of Flagship Fund IV GP and disclaims beneficial ownership of such shares except to the extent of his pecuniary interest therein.

SEC source: 0001209191-21-014053 · doc4.xml · nonDerivative · entry 20

AFEYAN NOUBAR · CIK 0001222012 · Director

10b5-1 filing: Not disclosed

Ownership: Indirect · By Flagship Ventures Fund IV, L.P. and Flagship Ventures Fund IV-Rx, L.P.

Disclosed balance after: 16,648,393

F1 · kind: These sales were effected by Flagship Ventures Fund IV, L.P. ("Flagship Fund IV") and Flagship Ventures Fund IV-Rx, L.P. ("Flagship Fund IV-Rx") pursuant to Rule 10b5-1 trading plans adopted on December 23, 2020.

F22 · shares: Represents 333,586 shares sold by Flagship Fund IV and 63,540 shares sold by Flagship Fund IV-Rx. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $143.06 to $144.05, inclusive. The reporting person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range.

F22 · price: Represents 333,586 shares sold by Flagship Fund IV and 63,540 shares sold by Flagship Fund IV-Rx. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $143.06 to $144.05, inclusive. The reporting person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range.

F3 · ownership.nature: Shares held directly by Flagship Fund IV and Flagship Fund IV-Rx. Flagship Ventures Fund IV General Partner LLC ("Flagship Fund IV GP") is the general partner of each of Flagship Fund IV and Flagship Fund IV-Rx. The reporting person is the sole manager of Flagship Fund IV GP and disclaims beneficial ownership of such shares except to the extent of his pecuniary interest therein.

SEC source: 0001209191-21-014053 · doc4.xml · nonDerivative · entry 19

AFEYAN NOUBAR · CIK 0001222012 · Director

10b5-1 filing: Not disclosed

Ownership: Indirect · By Flagship Ventures Fund IV, L.P. and Flagship Ventures Fund IV-Rx, L.P.

Disclosed balance after: 17,045,519

F1 · kind: These sales were effected by Flagship Ventures Fund IV, L.P. ("Flagship Fund IV") and Flagship Ventures Fund IV-Rx, L.P. ("Flagship Fund IV-Rx") pursuant to Rule 10b5-1 trading plans adopted on December 23, 2020.

F21 · shares: Represents 98,290 shares sold by Flagship Fund IV and 18,721 shares sold by Flagship Fund IV-Rx. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $142.06 to $143.05, inclusive. The reporting person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range.

F21 · price: Represents 98,290 shares sold by Flagship Fund IV and 18,721 shares sold by Flagship Fund IV-Rx. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $142.06 to $143.05, inclusive. The reporting person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range.

F3 · ownership.nature: Shares held directly by Flagship Fund IV and Flagship Fund IV-Rx. Flagship Ventures Fund IV General Partner LLC ("Flagship Fund IV GP") is the general partner of each of Flagship Fund IV and Flagship Fund IV-Rx. The reporting person is the sole manager of Flagship Fund IV GP and disclaims beneficial ownership of such shares except to the extent of his pecuniary interest therein.

SEC source: 0001209191-21-014053 · doc4.xml · nonDerivative · entry 18

AFEYAN NOUBAR · CIK 0001222012 · Director

10b5-1 filing: Not disclosed

Ownership: Indirect · By Flagship Ventures Fund IV, L.P. and Flagship Ventures Fund IV-Rx, L.P.

Disclosed balance after: 17,162,530

F1 · kind: These sales were effected by Flagship Ventures Fund IV, L.P. ("Flagship Fund IV") and Flagship Ventures Fund IV-Rx, L.P. ("Flagship Fund IV-Rx") pursuant to Rule 10b5-1 trading plans adopted on December 23, 2020.

F20 · shares: Represents 59,330 shares sold by Flagship Fund IV and 11,301 shares sold by Flagship Fund IV-Rx. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $141.06 to $142.05, inclusive. The reporting person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range.

F20 · price: Represents 59,330 shares sold by Flagship Fund IV and 11,301 shares sold by Flagship Fund IV-Rx. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $141.06 to $142.05, inclusive. The reporting person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range.

F3 · ownership.nature: Shares held directly by Flagship Fund IV and Flagship Fund IV-Rx. Flagship Ventures Fund IV General Partner LLC ("Flagship Fund IV GP") is the general partner of each of Flagship Fund IV and Flagship Fund IV-Rx. The reporting person is the sole manager of Flagship Fund IV GP and disclaims beneficial ownership of such shares except to the extent of his pecuniary interest therein.

SEC source: 0001209191-21-014053 · doc4.xml · nonDerivative · entry 17

AFEYAN NOUBAR · CIK 0001222012 · Director

10b5-1 filing: Not disclosed

Ownership: Indirect · By Flagship Ventures Fund IV, L.P. and Flagship Ventures Fund IV-Rx, L.P.

Disclosed balance after: 17,233,161

F1 · kind: These sales were effected by Flagship Ventures Fund IV, L.P. ("Flagship Fund IV") and Flagship Ventures Fund IV-Rx, L.P. ("Flagship Fund IV-Rx") pursuant to Rule 10b5-1 trading plans adopted on December 23, 2020.

F19 · shares: Represents 86,395 shares sold by Flagship Fund IV and 16,457 shares sold by Flagship Fund IV-Rx. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $140.05 to $140.92, inclusive. The reporting person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range.

F19 · price: Represents 86,395 shares sold by Flagship Fund IV and 16,457 shares sold by Flagship Fund IV-Rx. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $140.05 to $140.92, inclusive. The reporting person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range.

F3 · ownership.nature: Shares held directly by Flagship Fund IV and Flagship Fund IV-Rx. Flagship Ventures Fund IV General Partner LLC ("Flagship Fund IV GP") is the general partner of each of Flagship Fund IV and Flagship Fund IV-Rx. The reporting person is the sole manager of Flagship Fund IV GP and disclaims beneficial ownership of such shares except to the extent of his pecuniary interest therein.

SEC source: 0001209191-21-014053 · doc4.xml · nonDerivative · entry 16

AFEYAN NOUBAR · CIK 0001222012 · Director

10b5-1 filing: Not disclosed

Ownership: Indirect · By Flagship Ventures Fund IV, L.P. and Flagship Ventures Fund IV-Rx, L.P.

Disclosed balance after: 17,336,013

F1 · kind: These sales were effected by Flagship Ventures Fund IV, L.P. ("Flagship Fund IV") and Flagship Ventures Fund IV-Rx, L.P. ("Flagship Fund IV-Rx") pursuant to Rule 10b5-1 trading plans adopted on December 23, 2020.

F18 · shares: Represents 47,406 shares sold by Flagship Fund IV and 9,029 shares sold by Flagship Fund IV-Rx. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $139.05 to $140.04, inclusive. The reporting person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range.

F18 · price: Represents 47,406 shares sold by Flagship Fund IV and 9,029 shares sold by Flagship Fund IV-Rx. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $139.05 to $140.04, inclusive. The reporting person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range.

F3 · ownership.nature: Shares held directly by Flagship Fund IV and Flagship Fund IV-Rx. Flagship Ventures Fund IV General Partner LLC ("Flagship Fund IV GP") is the general partner of each of Flagship Fund IV and Flagship Fund IV-Rx. The reporting person is the sole manager of Flagship Fund IV GP and disclaims beneficial ownership of such shares except to the extent of his pecuniary interest therein.

SEC source: 0001209191-21-014053 · doc4.xml · nonDerivative · entry 15

AFEYAN NOUBAR · CIK 0001222012 · Director

10b5-1 filing: Not disclosed

Ownership: Indirect · By Flagship Ventures Fund IV, L.P. and Flagship Ventures Fund IV-Rx, L.P.

Disclosed balance after: 17,392,448

F1 · kind: These sales were effected by Flagship Ventures Fund IV, L.P. ("Flagship Fund IV") and Flagship Ventures Fund IV-Rx, L.P. ("Flagship Fund IV-Rx") pursuant to Rule 10b5-1 trading plans adopted on December 23, 2020.

F17 · shares: Represents 38,826 shares sold by Flagship Fund IV and 7,396 shares sold by Flagship Fund IV-Rx. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $138.03 to $139.01, inclusive. The reporting person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range.

F17 · price: Represents 38,826 shares sold by Flagship Fund IV and 7,396 shares sold by Flagship Fund IV-Rx. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $138.03 to $139.01, inclusive. The reporting person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range.

F3 · ownership.nature: Shares held directly by Flagship Fund IV and Flagship Fund IV-Rx. Flagship Ventures Fund IV General Partner LLC ("Flagship Fund IV GP") is the general partner of each of Flagship Fund IV and Flagship Fund IV-Rx. The reporting person is the sole manager of Flagship Fund IV GP and disclaims beneficial ownership of such shares except to the extent of his pecuniary interest therein.

SEC source: 0001209191-21-014053 · doc4.xml · nonDerivative · entry 14

AFEYAN NOUBAR · CIK 0001222012 · Director

10b5-1 filing: Not disclosed

Ownership: Indirect · By Flagship Ventures Fund IV, L.P. and Flagship Ventures Fund IV-Rx, L.P.

Disclosed balance after: 17,438,670

F1 · kind: These sales were effected by Flagship Ventures Fund IV, L.P. ("Flagship Fund IV") and Flagship Ventures Fund IV-Rx, L.P. ("Flagship Fund IV-Rx") pursuant to Rule 10b5-1 trading plans adopted on December 23, 2020.

F16 · shares: Represents 102,600 shares sold by Flagship Fund IV and 19,542 shares sold by Flagship Fund IV-Rx. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $137.01 to $137.96, inclusive. The reporting person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range.

F16 · price: Represents 102,600 shares sold by Flagship Fund IV and 19,542 shares sold by Flagship Fund IV-Rx. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $137.01 to $137.96, inclusive. The reporting person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range.

F3 · ownership.nature: Shares held directly by Flagship Fund IV and Flagship Fund IV-Rx. Flagship Ventures Fund IV General Partner LLC ("Flagship Fund IV GP") is the general partner of each of Flagship Fund IV and Flagship Fund IV-Rx. The reporting person is the sole manager of Flagship Fund IV GP and disclaims beneficial ownership of such shares except to the extent of his pecuniary interest therein.

SEC source: 0001209191-21-014053 · doc4.xml · nonDerivative · entry 13

AFEYAN NOUBAR · CIK 0001222012 · Director

10b5-1 filing: Not disclosed

Ownership: Indirect · By Flagship Ventures Fund IV, L.P. and Flagship Ventures Fund IV-Rx, L.P.

Disclosed balance after: 17,560,812

F1 · kind: These sales were effected by Flagship Ventures Fund IV, L.P. ("Flagship Fund IV") and Flagship Ventures Fund IV-Rx, L.P. ("Flagship Fund IV-Rx") pursuant to Rule 10b5-1 trading plans adopted on December 23, 2020.

F15 · shares: Represents 8,387 shares sold by Flagship Fund IV and 1,598 shares sold by Flagship Fund IV-Rx. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $136.01 to $137.00, inclusive. The reporting person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range.

F15 · price: Represents 8,387 shares sold by Flagship Fund IV and 1,598 shares sold by Flagship Fund IV-Rx. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $136.01 to $137.00, inclusive. The reporting person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range.

F3 · ownership.nature: Shares held directly by Flagship Fund IV and Flagship Fund IV-Rx. Flagship Ventures Fund IV General Partner LLC ("Flagship Fund IV GP") is the general partner of each of Flagship Fund IV and Flagship Fund IV-Rx. The reporting person is the sole manager of Flagship Fund IV GP and disclaims beneficial ownership of such shares except to the extent of his pecuniary interest therein.

SEC source: 0001127602-21-007951 · form4.xml · derivative · entry 18

Hoge Stephen · CIK 0001760669 · President

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 597,431

Underlying: Common Stock · 10,000 shares

Expires 2023-08-19

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · kind: The reported transaction was effected pursuant to a Rule 10b5-1 trading plan adopted on December 27, 2018, as amended on June 1, 2020.

F16 · derivative.exercise_date: This option is fully vested and exercisable.

SEC source: 0001127602-21-007951 · form4.xml · nonDerivative · entry 14

Hoge Stephen · CIK 0001760669 · President

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 1,614,597

F1 · kind: The reported transaction was effected pursuant to a Rule 10b5-1 trading plan adopted on December 27, 2018, as amended on June 1, 2020.

F14 · price: The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $150.60 to $151.05. Full information regarding the number of shares sold at each separate price can be furnished to the SEC staff upon request.

SEC source: 0001127602-21-007951 · form4.xml · nonDerivative · entry 13

Hoge Stephen · CIK 0001760669 · President

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 1,619,897

F1 · kind: The reported transaction was effected pursuant to a Rule 10b5-1 trading plan adopted on December 27, 2018, as amended on June 1, 2020.

F13 · price: The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $149.51 to $150.42. Full information regarding the number of shares sold at each separate price can be furnished to the SEC staff upon request.

SEC source: 0001127602-21-007951 · form4.xml · nonDerivative · entry 12

Hoge Stephen · CIK 0001760669 · President

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 1,620,582

F1 · kind: The reported transaction was effected pursuant to a Rule 10b5-1 trading plan adopted on December 27, 2018, as amended on June 1, 2020.

F12 · price: The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $148.37 to $149.10. Full information regarding the number of shares sold at each separate price can be furnished to the SEC staff upon request.

SEC source: 0001127602-21-007951 · form4.xml · nonDerivative · entry 11

Hoge Stephen · CIK 0001760669 · President

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 1,621,382

F1 · kind: The reported transaction was effected pursuant to a Rule 10b5-1 trading plan adopted on December 27, 2018, as amended on June 1, 2020.

F11 · price: The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $147.36 to $148.31. Full information regarding the number of shares sold at each separate price can be furnished to the SEC staff upon request.

SEC source: 0001127602-21-007951 · form4.xml · nonDerivative · entry 10

Hoge Stephen · CIK 0001760669 · President

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 1,622,933

F1 · kind: The reported transaction was effected pursuant to a Rule 10b5-1 trading plan adopted on December 27, 2018, as amended on June 1, 2020.

F10 · price: The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $146.30 to $147.22. Full information regarding the number of shares sold at each separate price can be furnished to the SEC staff upon request.

SEC source: 0001127602-21-007951 · form4.xml · nonDerivative · entry 9

Hoge Stephen · CIK 0001760669 · President

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 1,624,133

F1 · kind: The reported transaction was effected pursuant to a Rule 10b5-1 trading plan adopted on December 27, 2018, as amended on June 1, 2020.

F9 · price: The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $145.10 to $146.04. Full information regarding the number of shares sold at each separate price can be furnished to the SEC staff upon request.

SEC source: 0001127602-21-007951 · form4.xml · nonDerivative · entry 8

Hoge Stephen · CIK 0001760669 · President

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 1,625,233

F1 · kind: The reported transaction was effected pursuant to a Rule 10b5-1 trading plan adopted on December 27, 2018, as amended on June 1, 2020.

F8 · price: The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $144.06 to $145.05. Full information regarding the number of shares sold at each separate price can be furnished to the SEC staff upon request.

SEC source: 0001127602-21-007951 · form4.xml · nonDerivative · entry 7

Hoge Stephen · CIK 0001760669 · President

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 1,626,797

F1 · kind: The reported transaction was effected pursuant to a Rule 10b5-1 trading plan adopted on December 27, 2018, as amended on June 1, 2020.

F7 · price: The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $142.96 to $143.90. Full information regarding the number of shares sold at each separate price can be furnished to the SEC staff upon request.

SEC source: 0001127602-21-007951 · form4.xml · nonDerivative · entry 6

Hoge Stephen · CIK 0001760669 · President

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 1,628,097

F1 · kind: The reported transaction was effected pursuant to a Rule 10b5-1 trading plan adopted on December 27, 2018, as amended on June 1, 2020.

F6 · price: The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $141.37 to $141.91. Full information regarding the number of shares sold at each separate price can be furnished to the SEC staff upon request.

SEC source: 0001127602-21-007951 · form4.xml · nonDerivative · entry 5

Hoge Stephen · CIK 0001760669 · President

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 1,628,397

F1 · kind: The reported transaction was effected pursuant to a Rule 10b5-1 trading plan adopted on December 27, 2018, as amended on June 1, 2020.

F5 · price: The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $140.10 to $140.20. Full information regarding the number of shares sold at each separate price can be furnished to the SEC staff upon request.

SEC source: 0001127602-21-007951 · form4.xml · nonDerivative · entry 4

Hoge Stephen · CIK 0001760669 · President

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 1,628,597

F1 · kind: The reported transaction was effected pursuant to a Rule 10b5-1 trading plan adopted on December 27, 2018, as amended on June 1, 2020.

F4 · price: The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $138.90 to $139.38. Full information regarding the number of shares sold at each separate price can be furnished to the SEC staff upon request.

SEC source: 0001127602-21-007951 · form4.xml · nonDerivative · entry 3

Hoge Stephen · CIK 0001760669 · President

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 1,628,797

F1 · kind: The reported transaction was effected pursuant to a Rule 10b5-1 trading plan adopted on December 27, 2018, as amended on June 1, 2020.

F3 · price: The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $137.85 to $138.07. Full information regarding the number of shares sold at each separate price can be furnished to the SEC staff upon request.

SEC source: 0001127602-21-007951 · form4.xml · nonDerivative · entry 2

Hoge Stephen · CIK 0001760669 · President

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 1,629,097

F1 · kind: The reported transaction was effected pursuant to a Rule 10b5-1 trading plan adopted on December 27, 2018, as amended on June 1, 2020.

F2 · price: The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $136.71 to $137.05. Full information regarding the number of shares sold at each separate price can be furnished to the SEC staff upon request.

SEC source: 0001127602-21-007951 · form4.xml · nonDerivative · entry 1

Hoge Stephen · CIK 0001760669 · President

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 1,629,597

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · kind: The reported transaction was effected pursuant to a Rule 10b5-1 trading plan adopted on December 27, 2018, as amended on June 1, 2020.

SEC source: 0001127602-21-007564 · form4.xml · derivative · entry 12

Zaks Tal Zvi · CIK 0001690927 · Chief Medical Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 6,478

Underlying: Common Stock · 5,000 shares

Expires 2027-02-23

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · kind: The reported transaction was effected pursuant to a Rule 10b5-1 trading plan adopted on March 13, 2020.

F10 · derivative.exercise_date: 25% of this option vested and became exercisable on February 22, 2018 with the remainder vesting in 12 equal quarterly installments thereafter.

SEC source: 0001127602-21-007564 · form4.xml · nonDerivative · entry 11

Zaks Tal Zvi · CIK 0001690927 · Chief Medical Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 0

F1 · kind: The reported transaction was effected pursuant to a Rule 10b5-1 trading plan adopted on March 13, 2020.

SEC source: 0001127602-21-007564 · form4.xml · nonDerivative · entry 10

Zaks Tal Zvi · CIK 0001690927 · Chief Medical Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 100

F1 · kind: The reported transaction was effected pursuant to a Rule 10b5-1 trading plan adopted on March 13, 2020.

F9 · price: The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $168.75 to $169.15. Full information regarding the number of shares sold at each separate price can be furnished to the SEC staff upon request.

SEC source: 0001127602-21-007564 · form4.xml · nonDerivative · entry 9

Zaks Tal Zvi · CIK 0001690927 · Chief Medical Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 381

F1 · kind: The reported transaction was effected pursuant to a Rule 10b5-1 trading plan adopted on March 13, 2020.

F8 · price: The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $167.72 to $168.43. Full information regarding the number of shares sold at each separate price can be furnished to the SEC staff upon request.

SEC source: 0001127602-21-007564 · form4.xml · nonDerivative · entry 8

Zaks Tal Zvi · CIK 0001690927 · Chief Medical Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 737

F1 · kind: The reported transaction was effected pursuant to a Rule 10b5-1 trading plan adopted on March 13, 2020.

F7 · price: The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $166.47 to $167.43. Full information regarding the number of shares sold at each separate price can be furnished to the SEC staff upon request.

SEC source: 0001127602-21-007564 · form4.xml · nonDerivative · entry 7

Zaks Tal Zvi · CIK 0001690927 · Chief Medical Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 1,437

F1 · kind: The reported transaction was effected pursuant to a Rule 10b5-1 trading plan adopted on March 13, 2020.

F6 · price: The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $165.44 to $166.43. Full information regarding the number of shares sold at each separate price can be furnished to the SEC staff upon request.

SEC source: 0001127602-21-007564 · form4.xml · nonDerivative · entry 6

Zaks Tal Zvi · CIK 0001690927 · Chief Medical Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 2,437

F1 · kind: The reported transaction was effected pursuant to a Rule 10b5-1 trading plan adopted on March 13, 2020.

F5 · price: The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $164.26 to $165.22. Full information regarding the number of shares sold at each separate price can be furnished to the SEC staff upon request.

SEC source: 0001127602-21-007564 · form4.xml · nonDerivative · entry 5

Zaks Tal Zvi · CIK 0001690927 · Chief Medical Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 2,737

F1 · kind: The reported transaction was effected pursuant to a Rule 10b5-1 trading plan adopted on March 13, 2020.

F4 · price: The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $163.19 to $164.12. Full information regarding the number of shares sold at each separate price can be furnished to the SEC staff upon request.

SEC source: 0001127602-21-007564 · form4.xml · nonDerivative · entry 4

Zaks Tal Zvi · CIK 0001690927 · Chief Medical Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 3,837

F1 · kind: The reported transaction was effected pursuant to a Rule 10b5-1 trading plan adopted on March 13, 2020.

F3 · price: The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $161.97 to $162.89. Full information regarding the number of shares sold at each separate price can be furnished to the SEC staff upon request.

SEC source: 0001127602-21-007564 · form4.xml · nonDerivative · entry 3

Zaks Tal Zvi · CIK 0001690927 · Chief Medical Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 4,637

F1 · kind: The reported transaction was effected pursuant to a Rule 10b5-1 trading plan adopted on March 13, 2020.

SEC source: 0001127602-21-007564 · form4.xml · nonDerivative · entry 2

Zaks Tal Zvi · CIK 0001690927 · Chief Medical Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 4,737

F1 · kind: The reported transaction was effected pursuant to a Rule 10b5-1 trading plan adopted on March 13, 2020.

F2 · price: The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $159.13 to $159.63. Full information regarding the number of shares sold at each separate price can be furnished to the SEC staff upon request.

SEC source: 0001127602-21-007564 · form4.xml · nonDerivative · entry 1

Zaks Tal Zvi · CIK 0001690927 · Chief Medical Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 5,000

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · kind: The reported transaction was effected pursuant to a Rule 10b5-1 trading plan adopted on March 13, 2020.

SEC source: 0001209191-21-014053 · doc4.xml · nonDerivative · entry 12

AFEYAN NOUBAR · CIK 0001222012 · Director

10b5-1 filing: Not disclosed

Ownership: Indirect · By Flagship Ventures Fund IV, L.P. and Flagship Ventures Fund IV-Rx, L.P.

Disclosed balance after: 17,570,797

F1 · kind: These sales were effected by Flagship Ventures Fund IV, L.P. ("Flagship Fund IV") and Flagship Ventures Fund IV-Rx, L.P. ("Flagship Fund IV-Rx") pursuant to Rule 10b5-1 trading plans adopted on December 23, 2020.

F14 · shares: Represents 25,989 shares sold by Flagship Fund IV and 4,949 shares sold by Flagship Fund IV-Rx. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $169.85 to $170.35, inclusive. The reporting person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range.

F14 · price: Represents 25,989 shares sold by Flagship Fund IV and 4,949 shares sold by Flagship Fund IV-Rx. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $169.85 to $170.35, inclusive. The reporting person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range.

F3 · ownership.nature: Shares held directly by Flagship Fund IV and Flagship Fund IV-Rx. Flagship Ventures Fund IV General Partner LLC ("Flagship Fund IV GP") is the general partner of each of Flagship Fund IV and Flagship Fund IV-Rx. The reporting person is the sole manager of Flagship Fund IV GP and disclaims beneficial ownership of such shares except to the extent of his pecuniary interest therein.

SEC source: 0001209191-21-014053 · doc4.xml · nonDerivative · entry 11

AFEYAN NOUBAR · CIK 0001222012 · Director

10b5-1 filing: Not disclosed

Ownership: Indirect · By Flagship Ventures Fund IV, L.P. and Flagship Ventures Fund IV-Rx, L.P.

Disclosed balance after: 17,601,735

F1 · kind: These sales were effected by Flagship Ventures Fund IV, L.P. ("Flagship Fund IV") and Flagship Ventures Fund IV-Rx, L.P. ("Flagship Fund IV-Rx") pursuant to Rule 10b5-1 trading plans adopted on December 23, 2020.

F13 · shares: Represents 45,589 shares sold by Flagship Fund IV and 8,685 shares sold by Flagship Fund IV-Rx. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $168.80 to $169.79, inclusive. The reporting person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range.

F13 · price: Represents 45,589 shares sold by Flagship Fund IV and 8,685 shares sold by Flagship Fund IV-Rx. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $168.80 to $169.79, inclusive. The reporting person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range.

F3 · ownership.nature: Shares held directly by Flagship Fund IV and Flagship Fund IV-Rx. Flagship Ventures Fund IV General Partner LLC ("Flagship Fund IV GP") is the general partner of each of Flagship Fund IV and Flagship Fund IV-Rx. The reporting person is the sole manager of Flagship Fund IV GP and disclaims beneficial ownership of such shares except to the extent of his pecuniary interest therein.

SEC source: 0001209191-21-014053 · doc4.xml · nonDerivative · entry 10

AFEYAN NOUBAR · CIK 0001222012 · Director

10b5-1 filing: Not disclosed

Ownership: Indirect · By Flagship Ventures Fund IV, L.P. and Flagship Ventures Fund IV-Rx, L.P.

Disclosed balance after: 17,656,009

F1 · kind: These sales were effected by Flagship Ventures Fund IV, L.P. ("Flagship Fund IV") and Flagship Ventures Fund IV-Rx, L.P. ("Flagship Fund IV-Rx") pursuant to Rule 10b5-1 trading plans adopted on December 23, 2020.

F12 · shares: Represents 49,037 shares sold by Flagship Fund IV and 9,340 shares sold by Flagship Fund IV-Rx. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $167.79 to $168.75, inclusive. The reporting person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range.

F12 · price: Represents 49,037 shares sold by Flagship Fund IV and 9,340 shares sold by Flagship Fund IV-Rx. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $167.79 to $168.75, inclusive. The reporting person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range.

F3 · ownership.nature: Shares held directly by Flagship Fund IV and Flagship Fund IV-Rx. Flagship Ventures Fund IV General Partner LLC ("Flagship Fund IV GP") is the general partner of each of Flagship Fund IV and Flagship Fund IV-Rx. The reporting person is the sole manager of Flagship Fund IV GP and disclaims beneficial ownership of such shares except to the extent of his pecuniary interest therein.

SEC source: 0001209191-21-014053 · doc4.xml · nonDerivative · entry 9

AFEYAN NOUBAR · CIK 0001222012 · Director

10b5-1 filing: Not disclosed

Ownership: Indirect · By Flagship Ventures Fund IV, L.P. and Flagship Ventures Fund IV-Rx, L.P.

Disclosed balance after: 17,714,386

F1 · kind: These sales were effected by Flagship Ventures Fund IV, L.P. ("Flagship Fund IV") and Flagship Ventures Fund IV-Rx, L.P. ("Flagship Fund IV-Rx") pursuant to Rule 10b5-1 trading plans adopted on December 23, 2020.

F11 · shares: Represents 103,081 shares sold by Flagship Fund IV and 19,634 shares sold by Flagship Fund IV-Rx. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $166.79 to $167.78, inclusive. The reporting person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range.

F11 · price: Represents 103,081 shares sold by Flagship Fund IV and 19,634 shares sold by Flagship Fund IV-Rx. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $166.79 to $167.78, inclusive. The reporting person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range.

F3 · ownership.nature: Shares held directly by Flagship Fund IV and Flagship Fund IV-Rx. Flagship Ventures Fund IV General Partner LLC ("Flagship Fund IV GP") is the general partner of each of Flagship Fund IV and Flagship Fund IV-Rx. The reporting person is the sole manager of Flagship Fund IV GP and disclaims beneficial ownership of such shares except to the extent of his pecuniary interest therein.

SEC source: 0001209191-21-014053 · doc4.xml · nonDerivative · entry 8

AFEYAN NOUBAR · CIK 0001222012 · Director

10b5-1 filing: Not disclosed

Ownership: Indirect · By Flagship Ventures Fund IV, L.P. and Flagship Ventures Fund IV-Rx, L.P.

Disclosed balance after: 17,837,101

F1 · kind: These sales were effected by Flagship Ventures Fund IV, L.P. ("Flagship Fund IV") and Flagship Ventures Fund IV-Rx, L.P. ("Flagship Fund IV-Rx") pursuant to Rule 10b5-1 trading plans adopted on December 23, 2020.

F10 · shares: Represents 295,016 shares sold by Flagship Fund IV and 56,194 shares sold by Flagship Fund IV-Rx. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $165.79 to $166.78, inclusive. The reporting person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range.

F10 · price: Represents 295,016 shares sold by Flagship Fund IV and 56,194 shares sold by Flagship Fund IV-Rx. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $165.79 to $166.78, inclusive. The reporting person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range.

F3 · ownership.nature: Shares held directly by Flagship Fund IV and Flagship Fund IV-Rx. Flagship Ventures Fund IV General Partner LLC ("Flagship Fund IV GP") is the general partner of each of Flagship Fund IV and Flagship Fund IV-Rx. The reporting person is the sole manager of Flagship Fund IV GP and disclaims beneficial ownership of such shares except to the extent of his pecuniary interest therein.

SEC source: 0001209191-21-014053 · doc4.xml · nonDerivative · entry 7

AFEYAN NOUBAR · CIK 0001222012 · Director

10b5-1 filing: Not disclosed

Ownership: Indirect · By Flagship Ventures Fund IV, L.P. and Flagship Ventures Fund IV-Rx, L.P.

Disclosed balance after: 18,188,311

F1 · kind: These sales were effected by Flagship Ventures Fund IV, L.P. ("Flagship Fund IV") and Flagship Ventures Fund IV-Rx, L.P. ("Flagship Fund IV-Rx") pursuant to Rule 10b5-1 trading plans adopted on December 23, 2020.

F9 · shares: Represents 139,086 shares sold by Flagship Fund IV and 26,492 shares sold by Flagship Fund IV-Rx. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $164.79 to $165.78, inclusive. The reporting person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range.

F9 · price: Represents 139,086 shares sold by Flagship Fund IV and 26,492 shares sold by Flagship Fund IV-Rx. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $164.79 to $165.78, inclusive. The reporting person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range.

F3 · ownership.nature: Shares held directly by Flagship Fund IV and Flagship Fund IV-Rx. Flagship Ventures Fund IV General Partner LLC ("Flagship Fund IV GP") is the general partner of each of Flagship Fund IV and Flagship Fund IV-Rx. The reporting person is the sole manager of Flagship Fund IV GP and disclaims beneficial ownership of such shares except to the extent of his pecuniary interest therein.