Security	Date	Code	Shares	Price	A/D	Owned after	D/I	Nature of ownership
Common Stock^F1,F2,F3	Feb 19, 2016	P	9,228	$3.9883	A	2,158,084	I	Through Deerfield Partners, L.P.
Common Stock^F1,F2,F3	Feb 19, 2016	P	11,745	$3.9883	A	2,746,650	I	Through Deerfield International Master Fund, L.P.
Common Stock^F2,F3	holding	—	—		—	6,667,391	I	Through Deerfield Special Situations Fund, L.P.

Table II — derivative securities

No Table II lines on this filing.

Explanation of responses

F1The price reported in Column 4 is a weighted average price. The shares were purchased in multiple transactions at prices ranging from $3.96 to $4.00, inclusive. The reporting persons undertake 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 purchased at each separate price within the ranges set forth in this footnote (1) of this Form 4.
F2This 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, L.P. is the general partner of Deerfield Special Situations Fund, L.P., Deerfield Partners, L.P. and Deerfield International Master Fund, L.P. (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. and Deerfield Management Company, L.P.
F3In accordance with Instruction 4 (b)(iv) to Form 4, the entire amount of the Issuer's securities held by the Fund 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 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.