Security	Date	Code	Shares	Price	A/D	Owned after	D/I	Nature of ownership
Common Stock^F1,F3,F4	Apr 2, 2018	C	669,034	—	A	669,034	I	Through Deerfield Healthcare Innovations Fund, L.P.
Common Stock^F1,F3,F4	Apr 2, 2018	C	669,034	—	A	669,034	I	Through Deerfield Private Design Fund III, L.P.
Common Stock^F2,F3,F4	Apr 2, 2018	C	1,319,484	—	A	1,988,518	I	Through Deerfield Healthcare Innovations Fund, L.P.
Common Stock^F2,F3,F4	Apr 2, 2018	C	1,319,483	—	A	1,988,517	I	Through Deerfield Private Design Fund III, L.P.
Common Stock^F3,F4	Apr 2, 2018	P	625,000	$16.00	A	2,613,517	I	Through Deerfield Private Design Fund III, L.P.
Common Stock^F3,F4	Apr 2, 2018	P	625,000	$16.00	A	625,000	I	Through Deerfield Partners, L.P.

Table II — derivative securities

Security	Conv. / exercise price	Date	Code	Shares	A/D	Exercisable	Expires	Underlying	Underlying shares	D/I
Series A Preferred Stock^F1,F3,F4	—	Apr 2, 2018	C	3,521,126	D	—	—	Common Stock	669,034	I
Series A Preferred Stock^F1,F3,F4	—	Apr 2, 2018	C	3,521,126	D	—	—	Common Stock	669,034	I
Series B Preferred Stock^F2,F3,F4	—	Apr 2, 2018	C	6,944,445	D	—	—	Common Stock	1,319,484	I
Series B Preferred Stock^F2,F3,F4	—	Apr 2, 2018	C	6,944,444	D	—	—	Common Stock	1,319,483	I

Explanation of responses

F1Each share of Series A Preferred Stock automatically converted into 0.1900057 shares of the Issuer's common stock upon the closing of the Issuer's initial public offering (on an adjusted basis, after giving effect to the 1-for-5.263 reverse stock split effected by the Issuer in connection with its initial public offering).
F2Each share of Series B Preferred Stock automatically converted into 0.1900057 shares of the Issuer's common stock upon the closing of the Issuer's initial public offering (on an adjusted basis, after giving effect to the 1-for-5.263 reverse stock split effected by the Issuer in connection with its initial public offering).
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. ("Deerfield Partners"). Deerfield Mgmt HIF, L.P. is the general partner of Deerfield Healthcare Innovations Fund, L.P. (collectively with Fund III and Deerfield Partners, 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., Deerfield Mgmt HIF, 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

Cameron Wheeler, an employee of Deerfield Management, 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 Proteon Therapeutics, Inc. filed with the Securities and Exchange Commission on August 4, 2017 by Deerfield Special Situations Fund, L.P., Deerfield Partners, L.P., Deerfield International Master Fund, L.P., Deerfield Private Design Fund III, L.P., Deerfield Private Design Fund IV, L.P., Deerfield Mgmt, L.P., Deerfield Mgmt III, L.P., Deerfield Mgmt IV, L.P., Deerfield Management Company, L.P., and James E. Flynn.