Security	Date	Code	Shares	Price	A/D	Owned after	D/I	Nature of ownership
Common Stock^F1,F2,F3	Jun 23, 2015	C	696,993	—	A	886,348	I	Through Deerfield Special Situations Fund, L.P.
Common Stock^F1,F2,F3	Jun 23, 2015	C	301,027	—	A	383,237	I	Through Deerfield Private Design Fund, L.P.
Common Stock^F1,F2,F3	Jun 23, 2015	C	484,944	—	A	617,397	I	Through Deerfield Private Design International, L.P.
Common Stock^F1,F2,F3	Jun 23, 2015	C	375,592	—	A	375,592	I	Through Deerfield Private Design Fund II, L.P.
Common Stock^F1,F2,F3	Jun 23, 2015	C	430,399	—	A	430,399	I	Through Deerfield Private Design International II, L.P.
Common Stock^F1,F2,F3	Jun 23, 2015	C	133,597	—	A	1,019,945	I	Through Deerfield Special Situations Fund, L.P.
Common Stock^F1,F2,F3	Jun 23, 2015	C	18,825	—	A	402,062	I	Through Deerfield Private Design Fund, L.P.
Common Stock^F1,F2,F3	Jun 23, 2015	C	29,755	—	A	647,152	I	Through Deerfield Private Design International, L.P.
Common Stock^F1,F2,F3	Jun 23, 2015	C	282,984	—	A	658,576	I	Through Deerfield Private Design Fund II, L.P.
Common Stock^F1,F2,F3	Jun 23, 2015	C	324,278	—	A	754,677	I	Through Deerfield Private Design International II, L.P.
Common Stock^F2,F3	Jun 23, 2015	P	104,795	$14.00	A	1,124,740	I	Through Deerfield Special Situations Fund, L.P.
Common Stock^F2,F3	Jun 23, 2015	P	67,666	$14.00	A	726,242	I	Through Deerfield Private Design Fund II, L.P.
Common Stock^F2,F3	Jun 23, 2015	P	77,539	$14.00	A	832,216	I	Through Deerfield Private Design International II, L.P.

Table II — derivative securities

Security	Conv. / exercise price	Date	Code	Shares	A/D	Exercisable	Expires	Underlying	Underlying shares	D/I
Series 1 Preferred Stock^F1,F2,F3	—	Jun 23, 2015	C	2,013,613	D	—	—	Common Stock	696,993	I
Series 1 Preferred Stock^F1,F2,F3	—	Jun 23, 2015	C	869,667	D	—	—	Common Stock	301,027	I
Series 1 Preferred Stock^F1,F2,F3	—	Jun 23, 2015	C	1,401,003	D	—	—	Common Stock	484,944	I
Series 1 Preferred Stock^F1,F2,F3	—	Jun 23, 2015	C	1,085,085	D	—	—	Common Stock	375,592	I
Series 1 Preferred Stock^F1,F2,F3	—	Jun 23, 2015	C	1,243,423	D	—	—	Common Stock	430,399	I
Series 2 Preferred Stock^F1,F2,F3	—	Jun 23, 2015	C	385,962	D	—	—	Common Stock	133,597	I
Series 2 Preferred Stock^F1,F2,F3	—	Jun 23, 2015	C	54,385	D	—	—	Common Stock	18,825	I
Series 2 Preferred Stock^F1,F2,F3	—	Jun 23, 2015	C	85,962	D	—	—	Common Stock	29,755	I
Series 2 Preferred Stock^F1,F2,F3	—	Jun 23, 2015	C	817,541	D	—	—	Common Stock	282,984	I
Series 2 Preferred Stock^F1,F2,F3	—	Jun 23, 2015	C	936,839	D	—	—	Common Stock	324,278	I

Explanation of responses

F1The Series 1 Preferred Stock and Series 2 Preferred Stock (the "Preferred Stock") were convertible at any time into the Issuer's Common Stock, on the basis of 1 share of Common Stock per 2.889 shares of Preferred Stock, and had no expiration date. The Preferred Stock converted into shares of the Issuer's Common Stock prior to the closing of the Issuer's initial public offering of Common Stock. The amounts in column 5 of Table I are presented as if conversion of Series 1 Preferred Stock occurred immediately prior to conversion of Series 2 Preferred Stock.
F2This Form 4 is being filed by the following (the "Reporting Persons"): Deerfield Special Situations Fund, L.P., Deerfield Private Design Fund, L.P., Deerfield Private Design International, L.P., Deerfield Private Design Fund II, L.P., Deerfield Private Design International II, L.P. (collectively, the "Funds"), Deerfield Mgmt, L.P., Deerfield Management Company, L.P. and James E. Flynn.
F3Deerfield Mgmt, L.P. is the general partner, and Deerfield Management Company, L.P. is the investment manager, of the Funds. In 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, 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 L.P., Deerfield Mgmt III, 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.