Security	Date	Code	Shares	Price	A/D	Owned after	D/I	Nature of ownership
Common Stock^F1	Jun 25, 2018	C	315,489	$0.00	A	315,489	D
Common Stock^F1,F2	Jun 25, 2018	C	315,489	$0.00	A	315,489	I	By Omega IV
Common Stock^F3	Jun 25, 2018	C	377,783	$0.00	A	693,272	D
Common Stock^F3,F2	Jun 25, 2018	C	377,783	$0.00	A	693,272	I	By Omega IV

Table II — derivative securities

Security	Conv. / exercise price	Date	Code	Shares	A/D	Exercisable	Expires	Underlying	Underlying shares	D/I
Series A Redeemable Convertible Preferred Stock^F1	—	Jun 25, 2018	C	315,489	D	—	—	Common Stock	315,489	D
Series A Redeemable Convertible Preferred Stock^F2,F1	—	Jun 25, 2018	C	315,489	D	—	—	Common Stock	315,489	I
Series B Redeemable Convertible Preferred Stock^F3	—	Jun 25, 2018	C	377,783	D	—	—	Common Stock	377,783	D
Series B Redeemable Convertible Preferred Stock^F2,F3	—	Jun 25, 2018	C	377,783	D	—	—	Common Stock	377,783	I

Explanation of responses

F1The Series A Redeemable Convertible Preferred Stock ("Series A") converted automatically into shares of the issuer's common stock on a one-for-one basis upon the completion of the issuer's public offering of common stock pursuant the issuer's amended registration statement under the Securities Act of 1933, as amended, filed with the Commission on June 18, 2018 (the "IPO"). The Series A had no expiration date.
F2The reported securities are beneficially owned by Omega Fund IV GP, L.P. ("Omega IV GP"), as the general partner of Omega Fund IV, L.P. ("Omega IV"). Omega Fund IV G.P. Manager, Ltd. ("Omega IV GP Manager"), is the general partner of Omega IV GP. Otello Stampacchia, Richard Lim and Anne-Mari Paster are all the shareholders and directors of Omega IV GP Manager and have shared voting and investment power over the shares held by Omega Fund IV, L.P. Each of the Reporting Persons disclaims beneficial ownership of these securities, except to the extent of his, her or its pecuniary interest therein.
F3The Series B Redeemable Convertible Preferred Stock ("Series B") converted automatically into shares of the issuer's common stock on a one-for-one basis upon the completion of the IPO. The Series B had no expiration date.