Security	Date	Code	Shares	Price	A/D	Owned after	D/I	Nature of ownership
Common Stock^F1,F2	Jul 23, 2018	C	345,783	—	A	345,783	I	See footnote
Common Stock^F2	Jul 23, 2018	P	266,667	$15.00	A	612,450	I	See footnote
Common Stock^F1,F3	Jul 23, 2018	C	158,960	—	A	158,960	I	See footnote

Table II — derivative securities

Security	Conv. / exercise price	Date	Code	Shares	A/D	Exercisable	Expires	Underlying	Underlying shares	D/I
Series E Preferred Stock^F2,F1	—	Jul 23, 2018	C	1,333,333	D	—	—	Common Stock	155,716	I
Series E-1 Preferred Stock^F2,F1	—	Jul 23, 2018	C	342,435	D	—	—	Common Stock	31,104	I
Series F Preferred Stock^F2,F1	—	Jul 23, 2018	C	1,750,000	D	—	—	Common Stock	158,963	I
Series F Preferred Stock^F3,F1	—	Jul 23, 2018	C	1,750,000	D	—	—	Common Stock	158,960	I

Explanation of responses

F1On July 23, 2018, the Series E-1 and Series F Preferred Stock converted into Common Stock on a 11.009-for-one basis, and the Series E Preferred Stock converted into Common Stock on a 8.56256-for-one basis, upon the closing of the Issuer's initial public offering without payment of consideration. The Series E, Series E-1 and Series F Preferred Stock were convertible at any time at the holder's election and automatically upon the closing of the Issuer's initial pubic offering. The shares had no expiration date.
F2These securities are owned directly by Casdin Partners Master Fund, LP and may be deemed to be indirectly beneficially owned by (i) Casdin Capital, LLC, the investment adviser to Casdin Partners Master Fund, LP, (ii) Casdin Partners GP, LLC, the general partner of Casdin Partners Master Fund LP, and (ii) Eli Casdin, the managing member of Casdin Capital, LLC and Casdin Partners GP, LLC.
F3These securities are owned directly by Casdin Venture Opportunities Fund, LP and may be deemed to be indirectly beneficially owned by (i) Casdin Capital, LLC, the investment adviser to Casdin Venture Opportunities Fund, LP, (ii) Casdin Venture Opportunities Fund GP, LLC, the general partner of Casdin Venture Opportunities Fund, LP, and (ii) Eli Casdin, the managing member of Casdin Capital, LLC and Casdin Venture Opportunities Fund GP, LLC.