Security	Date	Code	Shares	Price	A/D	Owned after	D/I	Nature of ownership
Common Stock^F1,F3,F4	Sep 22, 2015	C	771,963	—	A	771,963	I	Through Deerfield Private Design III Fund, L.P.
Common Stock^F2,F3,F4	Sep 22, 2015	C	397,079	—	A	1,169,042	I	Through Deerfield Private Design III Fund, L.P.
Common Stock^F3,F4	Sep 22, 2015	P	87,500	$22.00	A	1,256,542	I	Through Deerfield Private Design III Fund, L.P.
Common Stock^F3,F4	Sep 22, 2015	P	38,500	$22.00	A	38,500	I	Through Deerfield Partners, L.P.
Common Stock^F3,F4	Sep 22, 2015	P	49,000	$22.00	A	49,000	I	Through Deerfield International Master Fund, L.P.

Table II — derivative securities

Security	Conv. / exercise price	Date	Code	Shares	A/D	Exercisable	Expires	Underlying	Underlying shares	Owned after	D/I
Series C Convertible Preferred Stock^F1,F3,F4	—	Sep 22, 2015	C	771,963	D	—	—	Common Stock	771,963	0	I
Series D Convertible Preferred Stock^F2,F3,F4	—	Sep 22, 2015	C	397,079	D	—	—	Common Stock	397,079	0	I

Explanation of responses

F1Each share of Series C Convertible Preferred Stock automatically converted into one (1) share of Issuer's common stock upon the closing of the Issuer's initial public offering of common stock.
F2Each share of Series D Convertible Preferred Stock automatically converted into one (1) share of Issuer's common stock upon the closing of the Issuer's initial public offering of common stock.
F3This Form 4 is being filed by the undersigned as well as the entities listed on the Joint Filer Information Statement attached as an exhibit hereto (the "Reporting Persons"). Deerfield Mgmt III, L.P. is the general partner of Deerfield Private Design Fund III, L.P. ("Fund III"). Deerfield Mgmt, L.P. is the general partner of Deerfield Partners, L.P., and Deerfield International Master Fund, L.P. (collectively with Fund III, the "Funds"). Deerfield Management Company, L.P. is the investment manager of the Funds. James E. Flynn is the sole member of the general partner of each of Deerfield Mgmt, L.P., Deerfield Mgmt III, L.P. and Deerfield Management Company, L.P.
F4In accordance with Instruction 4 (b)(iv) to Form 4, the entire amount of the Issuer's securities held by the Funds is reported herein. For purposes of Section 16 of the Securities Exchange Act of 1934, as amended, each Reporting Person disclaims beneficial ownership of any such securities, except to the extent of his/its indirect pecuniary interest therein, if any, and this report shall not be deemed an admission that such Reporting Person is the beneficial owner of such securities for purposes of Section 16 or otherwise.

Remarks

Jonathan Isler, Attorney-in-Fact: Power of Attorney, which is hereby incorporated by reference to Exhibit 24 to a Form 3 with regard to Avalanche Biotechnologies, Inc. filed with the Securities and Exchange Commission on July 30, 2014 by Deerfield Mgmt III, L.P., Deerfield Mgmt, L.P., Deerfield Management Company, L.P., Deerfield Special Situations Fund, L.P., Deerfield Special Situations International Master Fund, L.P., Deerfield Private Design Fund III, L.P. and James E. Flynn.