Security	Date	Code	Shares	Price	A/D	Owned after	D/I	Nature of ownership
Common Stock^F1	Apr 24, 2017	P	4,331	$14.50	A	64,431	I	By 5AM Co-Investors III, L.P.
Common Stock^F1	Apr 24, 2017	P	168,082	$14.50	A	2,500,113	I	By 5AM Ventures III, L.P.

Table II — derivative securities

No Table II lines on this filing.

Explanation of responses

F15AM Partners III, LLC is the general partner of 5AM Ventures III, L.P. and 5AM Co-Investors III, L.P. Dr. John Diekman, Andrew Schwab and Dr. Scott Rocklage are the managing members of 5AM Partners III. 5AM Partners III, LLC may be deemed to have sole voting and investment power over the shares beneficially owned by 5AM Ventures III, L.P. and 5AM Co-Investors III, L.P. Dr. Diekman, Mr. Schwab and Dr. Rocklage may be deemed to have shared voting and investment power over the shares beneficially owned by 5AM Ventures III, L.P. and 5AM Co-Investors III, L.P. Each of 5AM Partners III, LLC, Dr. Diekman, Mr. Schwab and Dr. Rocklage disclaim beneficial ownership of such shares, except to the extent of its pecuniary interest therein.