Security	Date	Code	Shares	Price	A/D	Owned after	D/I	Nature of ownership
Common Stock^F1,F2	May 29, 2018	C	437,859	—	A	437,859	I	By ARCH Venture Fund VIII, L.P.
Common Stock^F1,F2	May 29, 2018	C	634,579	—	A	1,072,438	I	By ARCH Venture Fund VIII, L.P.
Common Stock^F1,F2	May 29, 2018	C	551,807	—	A	1,624,245	I	By ARCH Venture Fund VIII, L.P.
Common Stock^F1,F2	May 29, 2018	C	719,559	—	A	2,343,804	I	By ARCH Venture Fund VIII, L.P.
Common Stock^F1,F2	May 29, 2018	C	293,813	—	A	2,637,617	I	By ARCH Venture Fund VIII, L.P.

Table II — derivative securities

Security	Conv. / exercise price	Date	Code	Shares	A/D	Exercisable	Expires	Underlying	Underlying shares	D/I
Series A-2 Preferred^F1,F2	—	May 29, 2018	C	1,249,999	D	—	—	Common Stock	437,859	I
Series A-3 Preferred^F1,F2	—	May 29, 2018	C	1,811,595	D	—	—	Common Stock	634,579	I
Series A-4 Preferred^F1,F2	—	May 29, 2018	C	1,575,299	D	—	—	Common Stock	551,807	I
Series B Preferred^F1,F2	—	May 29, 2018	C	2,054,197	D	—	—	Common Stock	719,559	I
Series C Preferred^F1,F2	—	May 29, 2018	C	838,780	D	—	—	Common Stock	293,813	I

Explanation of responses

F1Each share of Preferred Stock automatically converted into Common Stock, for no additional payment or consideration, on a 2.8548-for-1 basis at the closing of the Issuer's initial public offering on May 29, 2018 and had no expiration date.
F2The reportable securities are owned directly by ARCH Venture Fund VIII, L.P. ("ARCH Fund VIII"). The sole general partner of ARCH Fund VIII is ARCH Venture Partners VIII, L.P. or ARCH Partners VIII, which may be deemed to beneficially own the shares held by ARCH Fund VIII. The sole general partner of ARCH Partners VIII is ARCH Venture Partners VIII, LLC or ARCH VIII LLC, which may be deemed to beneficially own the shares held by ARCH Fund VIII. ARCH Partners VIII and ARCH VIII LLC disclaim beneficial ownership of such shares, except to the extent of any pecuniary interest therein. The managing directors of ARCH VIII LLC are Keith L. Crandell, Clinton Bybee and Robert Nelsen, and they may be deemed to beneficially own the shares held by ARCH Fund VIII. Messrs. Crandell, Bybee and Nelsen disclaim beneficial ownership of such shares, except to the extent of any pecuniary interest therein.