Security	Date	Code	Shares	Price	A/D	Owned after	D/I	Nature of ownership
Common Stock^F4,F1,F3	Jul 20, 2018	C	2,797,635	—	A	2,797,635	I	See footnotes
Common Stock^F4,F1,F3	Jul 20, 2018	C	451,274	—	A	3,248,909	I	See footnotes
Common Stock^F4,F2,F3	Jul 20, 2018	C	116,567	—	A	116,567	I	See footnotes
Common Stock^F4,F2,F3	Jul 20, 2018	C	18,802	—	A	135,369	I	See footnotes
Common Stock^F1,F3	Jul 20, 2018	P	110,400	$17.00	A	3,359,309	I	See footnotes
Common Stock^F2,F3	Jul 20, 2018	P	4,600	$17.00	A	139,969	I	See footnotes

Table II — derivative securities

Security	Conv. / exercise price	Date	Code	Shares	A/D	Exercisable	Expires	Underlying	Underlying shares	D/I
Series A Preferred Stock^F4,F1,F3	—	Jul 20, 2018	C	9,204,220	D	—	—	Common Stock	2,797,635	I
Series B Preferred Stock^F4,F1,F3	—	Jul 20, 2018	C	1,484,690	D	—	—	Common Stock	451,274	I
Series A Preferred Stock^F4,F2,F3	—	Jul 20, 2018	C	383,507	D	—	—	Common Stock	116,567	I
Series B Preferred Stock^F4,F2,F3	—	Jul 20, 2018	C	61,861	D	—	—	Common Stock	18,802	I

Explanation of responses

F1These securities are held of record by 5AM Ventures IV, L.P. ("Ventures IV"). Following the transactions reported herein, 3,359,309 shares of Common Stock are held of record by Ventures IV.
F2These securities are held of record by 5AM Co-Investors IV, L.P. ("Co-Investors IV"). Following the transactions reported herein, 139,969 shares of Common Stock are held of record by Co-Investors IV.
F35AM Partners IV, LLC ("Partners IV") is the sole general partner of Ventures IV and Co-Investors IV. Dr. John Diekman, Andrew J. Schwab and Dr. Scott M. Rocklage, are the managing members of Partners IV, and have shared voting and investment power over the shares beneficially owned by Ventures IV and Co-Investors IV. Each of Partners IV, Dr. Diekman, Mr. Schwab, and Dr. Rocklage disclaims beneficial ownership of such shares except to the extent of its or their pecuniary interest therein.
F4Each share of the Issuer's Series A Preferred Stock and Series B Preferred Stock automatically converted into the Issuer's Common stock on a 3.29-for-1 basis, for no additional consideration, upon the closing of the Issuer's initial public offering. The Series A Preferred Stock and the Series B Preferred Stock had no expiration date.