Security	Date	Code	Shares	Price	A/D	Owned after	D/I	Nature of ownership
Common Stock^F1,F2,F3	Mar 8, 2016	C	1,138,210	—	A	1,138,210	I	See footnote
Common Stock^F4,F2,F5	Mar 8, 2016	C	718,396	—	A	1,856,606	I	See footnote
Common Stock^F6,F2,F7	Mar 8, 2016	C	312,085	—	A	2,168,691	I	See footnote

Table II — derivative securities

Security	Conv. / exercise price	Date	Code	Shares	A/D	Exercisable	Expires	Underlying	Underlying shares	D/I
Series A-1 Preferred Stock^F1,F2	—	Mar 8, 2016	C	1,138,210	D	—	—	Common Stock	1,138,210	I
Series B-1 Preferred Stock^F4,F2	—	Mar 8, 2016	C	718,396	D	—	—	Common Stock	718,396	I
Series C-1 Preferred Stock^F6,F2	—	Mar 8, 2016	C	312,085	D	—	—	Common Stock	312,085	I

Explanation of responses

F1The shares were converted as follows: 948,247 by MPM BioVentures IV-QP, L.P. ("BV IV QP"), 36,532 by MPM BioVentures IV GmbH & Co. Beteiligungs KG ("BV IV KG"), 26,964 by MPM Asset Management Investors BV4 LLC ("AM BV4") and 126,467 shares held by MPM BioVentures IV Strategic Fund, L.P. ("BV IV SF"). MPM BioVentures IV GP LLC and MPM BioVentures IV LLC ("BV LLC") are the direct and indirect general partners of BV IV QP, BV IV KG and BV IV SF and BV LLC is the manager of AM BV4. Ansbert Gadicke, Luke Evnin, Vaughn M. Kailian, James Paul Scopa and Todd Foley are the members of BV LLC. Each Reporting Person disclaims beneficial ownership of the securities except to the extent of his or its respective pecuniary interest therein.
F2The shares of Series A-1 Preferred Stock, Series B-1 Preferred Stock and Series C-1 Preferred Stock converted into one share of the Issuer's Common Stock immediately prior to the closing of the Issuer's initial public offering without payment of further consideration. The shares had no expiration date.
F3The shares are held as follows: 948,247 by BV IV QP, 36,532 by MPM BV IV KG, 26,964 by AM BV4 and 126,467 shares held by BV IV SF. Each Reporting Person disclaims beneficial ownership of the securities except to the extent of his or its respective pecuniary interest therein.
F4The shares were converted as follows: 598,509 by BV IV QP, 23,053 by BV IV KG, 17,013 by AM BV4 and 79,821 shares held by BV IV SF. Each Reporting Person disclaims beneficial ownership of the securities except to the extent of his or its respective pecuniary interest therein.
F5The shares are held as follows: 1,546,756 by BV IV QP, 59,585 by MPM BV IV KG, 43,977 by AM BV4 and 206,288 shares held by BV IV SF. Each Reporting Person disclaims beneficial ownership of the securities except to the extent of his or its respective pecuniary interest therein.
F6The shares were converted as follows: 260,003 by BV IV QP, 10,015 by BV IV KG, 7,392 by AM BV4 and 34,675 shares held by BV IV SF. Each Reporting Person disclaims beneficial ownership of the securities except to the extent of his or its respective pecuniary interest therein.
F7The shares are held as follows: 1,806,759 by BV IV QP, 69,600 by MPM BV IV KG, 51,369 by AM BV4 and 240,963 shares held by BV IV SF. Each Reporting Person disclaims beneficial ownership of the securities except to the extent of his or its respective pecuniary interest therein.