Security	Date	Code	Shares	Price	A/D	Owned after	D/I	Nature of ownership
Common Stock^F1,F3,F4	Sep 3, 2015	P	131,911	$18.48	A	131,911	I	Through Deerfield Private Design Fund III, L.P.
Common Stock^F1,F3,F4	Sep 3, 2015	P	131,911	$18.48	A	131,911	I	Through Deerfield Special Situations Fund, L.P.
Common Stock^F2,F3,F4	Feb 17, 2016	C	67,448	—	A	199,359	I	Through Deerfield Private Design Fund III, L.P.
Common Stock^F2,F3,F4	Feb 17, 2016	C	1,182,941	—	A	1,382,300	I	Through Deerfield Private Design Fund III, L.P.
Common Stock^F2,F3,F4	Feb 17, 2016	C	117,996	—	A	1,500,296	I	Through Deerfield Private Design Fund III, L.P.
Common Stock^F2,F3,F4	Feb 17, 2016	C	117,998	—	A	249,909	I	Through Deerfield Special Situations Fund, L.P.
Common Stock^F3,F4	Feb 17, 2016	P	122,793	$20.00	A	1,623,089	I	Through Deerfield Private Design Fund III, L.P.
Common Stock^F3,F4	Feb 17, 2016	P	163,702	$20.00	A	413,611	I	Through Deerfield Special Situations Fund, L.P.
Common Stock^F3,F4	Feb 17, 2016	P	88,000	$20.00	A	88,000	I	Through Deerfield Partners, L.P.
Common Stock^F3,F4	Feb 17, 2016	P	112,000	$20.00	A	112,000	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	D/I
Class D Preferred Stock^F1,F3,F4	—	Sep 3, 2015	P	117,996	A	—	—	Common Stock	117,996	I
Class D Preferred Stock^F1,F3,F4	—	Sep 3, 2015	P	117,998	A	—	—	Common Stock	117,998	I
Class B-1 Preferred Stock^F2,F3,F4	—	Feb 17, 2016	C	67,448	D	—	—	Common Stock	67,448	I
Class C Preferred Stock^F2,F3,F4	—	Feb 17, 2016	C	1,182,941	D	—	—	Common Stock	1,182,941	I
Class D Preferred Stock^F2,F3,F4	—	Feb 17, 2016	C	117,996	D	—	—	Common Stock	117,996	I
Class D Preferred Stock^F2,F3,F4	—	Feb 17, 2016	C	117,998	D	—	—	Common Stock	117,998	I

Explanation of responses

F1The amounts reflect a 1.38-for-1 forward stock split of the Preferred Stock (as defined below) effected by the Issuer on February 1, 2016.
F2Each share of Class B-1 Preferred Stock, Class C Preferred Stock and Class D Preferred Stock (collectively, the "Preferred Stock") automatically converted into 1 share of the 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 Special Situations Fund, L.P., Deerfield Partners, L.P. and Deerfield International Master Fund, L.P. (together 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 S. Leff, a partner in Deerfield Management Company, L.P., serves as a director of the Issuer. Jonathan Isler, Attorney-in-Fact: Power of Attorney, which is hereby incorporated by reference to Exhibit 24 to a Form 3 with regard to Editas Medicine, Inc. filed with the Securities and Exchange Commission on February 2, 2016 by Deerfield Mgmt, L.P., Deerfield Mgmt III, L.P., Deerfield Management Company, L.P., Deerfield Special Situations Fund, L.P., Deerfield Partners, L.P., Deerfield Private Design Fund, L.P., Deerfield Private Design International, L.P., Deerfield PDI Financing, L.P., Deerfield PDI Financing II, L.P., Deerfield Private Design Fund II, L.P., Deerfield Private Design International II, L.P., Deerfield International Master Fund, L.P., Deerfield Healthcare Innovations Fund, L.P., Deerfield Mgmt HIF, L.P., Breaking Stick Holdings, LLC, Deerfield Private Design Fund III, L.P. and James E. Flynn.