Security	Date	Code	Shares	Price	A/D	Owned after	D/I	Nature of ownership
Common Stock^F1,F6,F7,F8	Dec 15, 2017	S	719,665	$8.0179	D	4,530,335	I	See footnotes
Common Stock^F2,F6,F7,F8	Dec 15, 2017	S	102,882	$8.636	D	4,427,453	I	See footnotes
Common Stock^F3,F6,F7,F8	Dec 18, 2017	S	300,000	$7.5048	D	4,127,453	I	See footnotes
Common Stock^F4,F6,F7,F8	Dec 19, 2017	S	94,771	$7.6209	D	4,032,682	I	See footnotes
Common Stock^F5,F6,F7,F8	Dec 19, 2017	S	55,229	$7.1055	D	3,977,453	I	See footnotes

Table II — derivative securities

No Table II lines on this filing.

Explanation of responses

F1On December 15, 2017, Bain Capital Life Sciences Fund, L.P. ("BC LS") and BCIP Life Sciences Associates, LP ("BCIP LS" and, together with BC LS, the "Bain Life Sciences Entities") sold 652,840 and 66,825 shares of common stock, respectively, at a weighted average price of $8.0179. The shares were sold in multiple transactions at prices ranging from $7.89 to $8.495. Following such sales, BC LS and BCIP LS held 4,109,671 and 420,664 shares of common stock, respectively.
F2On December 15, 2017, BC LS and BCIP LS sold 93,329 and 9,553 shares of common stock, respectively, at a weighted average price of $8.636. The shares were sold in multiple transactions at prices ranging from $8.50 to $9.045. Following such sales, BC LS and BCIP LS held 4,016,342 and 411,111 shares of common stock, respectively.
F3On December 18, 2017, BC LS and BCIP LS sold 272,143 and 27,857 shares of common stock, respectively, at a weighted average price of $7.5048. The shares were sold in multiple transactions at prices ranging from $7.05 to $7.905. Following such sales, BC LS and BCIP LS held 3,744,199 and 383,254 shares of common stock, respectively.
F4On December 19, 2017, BC LS and BCIP LS sold 85,971 and 8,800 shares of common stock, respectively, at a weighted average price of $7.6209. The shares were sold in multiple transactions at prices ranging from $7.50 to $8.02. Following such sales, BC LS and BCIP LS held 3,658,228 and 374,454 shares of common stock, respectively.
F5On December 19, 2017, BC LS and BCIP LS sold 50,101 and 5,128 shares of common stock, respectively, at a weighted average price of $7.1055. The shares were sold in multiple transactions at prices ranging from $6.86 to $7.498. Following such sales, BC LS and BCIP LS held 3,608,127 and 369,326 shares of common stock, respectively.
F6Each of the Bain Life Sciences Entities 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 ranges set forth in footnotes (1) through (5) to this Form 4.
F7Bain Capital Life Sciences Investors, LLC ("BCI LS") is the general partner of Bain Capital Life Sciences Partners, LP ("BC LS P"), which is the general partner of BC LS. As a result, BC LS P may be deemed to share voting and dispositive power with respect to the securities held by BC LS.
F8The governance, investment strategy and decision-making process with respect to the investments held by the Bain Life Sciences Entities is directed by BCI LS, whose managers are Jeffrey Schwartz and Adam Koppel. As a result, BCI LS, Mr. Schwartz and Dr. Koppel may each be deemed to share voting and dispositive power with respect to the securities held by the Bain Life Sciences Entities. BCI LS, Mr. Schwartz and Dr. Koppel each disclaim beneficial ownership of such securities except to the extent of their pecuniary interest therein.