| FMR LLC | 7,172,894 | $298.9m | 0.0% |
| TRV GP V, LLC | 6,280,525 | $261.7m | 52.5% |
| ARCH Venture Management, LLC | 3,728,738 | $155.4m | 14.1% |
| Capital International Investors | 2,921,958 | $121.8m | 0.0% |
| GOLDMAN SACHS GROUP INC | 2,910,449 | $121.3m | 0.0% |
| BlackRock, Inc. | 2,699,786 | $112.5m | 0.0% |
| Cormorant Asset Management, LP | 2,657,521 | $110.7m | 5.7% |
| Sofinnova Investments, Inc. | 1,904,408 | $79.4m | 4.1% |
| JOHNSON & JOHNSON | 1,784,517 | $74.4m | 9.3% |
| Polar Capital Holdings Plc | 1,608,514 | $67.0m | 0.2% |
| BAKER BROS. ADVISORS LP | 1,547,090 | $64.5m | 0.3% |
| VANGUARD CAPITAL MANAGEMENT LLC | 1,346,512 | $56.1m | 0.0% |
| TRV GP VI, LLC | 969,218 | $40.4m | 17.4% |
| STATE STREET CORP | 818,712 | $34.1m | 0.0% |
| GEODE CAPITAL MANAGEMENT, LLC | 793,453 | $33.1m | 0.0% |
| PRICE T ROWE ASSOCIATES INC /MD/ | 787,446 | $32.8m | 0.0% |
| PERCEPTIVE ADVISORS LLC | 773,342 | $32.2m | 0.5% |
| Vestal Point Capital, LP | 730,000 | $30.4m | 0.7% |
| UBS AM, a distinct business unit of UBS ASSET MANAGEMENT AMERICAS LLC | 644,082 | $26.8m | 0.0% |
| Siren, L.L.C. | 641,469 | $26.7m | 0.5% |
| Capital World Investors | 551,657 | $23.0m | 0.0% |
| ALLIANCEBERNSTEIN L.P. | 693,384 | $21.7m | 0.0% |
| T. Rowe Price Investment Management, Inc. | 393,200 | $16.4m | 0.0% |
| DIMENSIONAL FUND ADVISORS LP | 362,114 | $15.1m | 0.0% |
| VANGUARD PORTFOLIO MANAGEMENT LLC | 359,944 | $15.0m | 0.0% |