Transaction Details

Footnotes

The reported transaction represents the receipt by the reporting person of his pro rata share of a distribution made by one or more entities affiliated with Third Rock Ventures, for no consideration, of shares of the Issuer's common stock, which distribution was made in accordance with the exemption afforded by Rule 16a-9 of the Securities Exchange Act of 1934, as amended. | These securities are directly held by the Charles J. Homcy Revocable Trust UA 11/4/1998, of which the reporting person is the trustee.