Security	Conv. / exercise price	Date	Code	Shares	A/D	Exercisable	Expires	Underlying	Underlying shares	Owned after	D/I
Series A Warrant (right to buy)^F1,F2,F3	$0.65	Apr 3, 2018	P	1,150,000	A	Apr 3, 2018	Oct 3, 2018	Common Stock	1,150,000	1,150,000	I
Series B Warrant (right to buy)^F1,F2,F3	$0.75	Apr 3, 2018	P	1,150,000	A	Apr 3, 2018	Apr 3, 2023	Common Stock	1,150,000	1,150,000	I

Explanation of responses

F1The reported securities were included within 1,150,000 Units purchased by ARCH Venture Fund VII, L.P. ("ARCH VII") for $0.65 per Unit. Each Unit consisted of one share of common stock, one Series A Warrant to purchase one share of common stock at an exercise price of $0.65 per share, and one Series B Warrant to purchase one share of common stock at an exercise price of $0.75 per share.
F2Securities held of record byARCH VII. The sole general partner of ARCH VII is ARCH Venture Partners VII, L.P. ("ARCH Partners VII"), which may be deemed to have shared voting and investment power over the shares held by ARCH VII. The sole general partner of ARCH Partners VII is ARCH Venture Partners VII, LLC ("ARCH VII LLC"), which may be deemed to have shared voting and investment power over the shares held by ARCH VII. ARCH Partners VII and ARCH VII LLC disclaim beneficial ownership of such shares, except to the extent of any pecuniary interest therein.
F3The managing directors of ARCH VII LLC are Keith Crandell, Clinton Bybee and Robert Nelsen and they may be deemed to have shared voting and investment power over the shares held by ARCH VII. Dr. Steve Gillis owns an interest in ARCH Partners VII, but does not have dispositive or voting power. Messrs. Crandell, Bybee and Nelsen and Dr. Gillis disclaim beneficial ownership of such shares, except to the extent of any pecuniary interest therein.