Security	Date	Code	Shares	Price	A/D	Owned after	D/I	Nature of ownership
Common Stock^F1,F2,F3	Nov 20, 2017	C	18,848	—	A	18,848	I	See Footnotes
Common Stock^F1,F4	Nov 20, 2017	C	367	—	A	367	I	See Footnote
Common Stock^F1,F5	Nov 20, 2017	C	129	—	A	129	I	See Footnote
Common Stock^F1,F6	Nov 20, 2017	C	188	—	A	188	I	See Footnote
Common Stock^F7,F2,F3	Nov 20, 2017	C	243,385	—	A	262,233	I	See Footnotes
Common Stock^F7,F4	Nov 20, 2017	C	4,743	—	A	5,110	I	See Footnote
Common Stock^F7,F5	Nov 20, 2017	C	1,667	—	A	1,796	I	See Footnote
Common Stock^F7,F6	Nov 20, 2017	C	2,433	—	A	2,621	I	See Footnote
Common Stock^F8,F2,F3	Nov 20, 2017	C	317,376	—	A	579,609	I	See Footnotes
Common Stock^F8,F4	Nov 20, 2017	C	6,185	—	A	11,295	I	See Footnote
Common Stock^F8,F5	Nov 20, 2017	C	2,173	—	A	3,969	I	See Footnote
Common Stock^F8,F6	Nov 20, 2017	C	3,173	—	A	5,794	I	See Footnote
Common Stock^F9,F2,F3	Nov 20, 2017	C	110,312	—	A	689,921	I	See Footnotes
Common Stock^F9,F4	Nov 20, 2017	C	2,150	—	A	13,445	I	See Footnote
Common Stock^F9,F5	Nov 20, 2017	C	755	—	A	4,724	I	See Footnote
Common Stock^F9,F6	Nov 20, 2017	C	1,102	—	A	6,896	I	See Footnote
Common Stock^F10,F2,F3	Nov 20, 2017	C	631,041	—	A	1,320,962	I	See Footnotes
Common Stock^F10,F4	Nov 20, 2017	C	12,298	—	A	25,743	I	See Footnote
Common Stock^F10,F5	Nov 20, 2017	C	4,322	—	A	9,046	I	See Footnote
Common Stock^F10,F6	Nov 20, 2017	C	6,310	—	A	13,206	I	See Footnote
Common Stock^F2,F3	Nov 20, 2017	P	482,467	$10.00	A	1,803,429	I	See Footnotes
Common Stock^F4	Nov 20, 2017	P	9,403	$10.00	A	35,146	I	See Footnote
Common Stock^F5	Nov 20, 2017	P	3,305	$10.00	A	12,351	I	See Footnote
Common Stock^F6	Nov 20, 2017	P	4,825	$10.00	A	18,031	I	See Footnote

Table II — derivative securities

Security	Conv. / exercise price	Date	Code	Shares	A/D	Exercisable	Expires	Underlying	Underlying shares	D/I
Series A-1 Convertible Preferred Stock^F2,F3,F1	—	Nov 20, 2017	C	64,329	D	—	—	Common Stock	18,848	I
Series A-1 Convertible Preferred Stock^F4,F1	—	Nov 20, 2017	C	1,254	D	—	—	Common Stock	367	I
Series A-1 Convertible Preferred Stock^F5,F1	—	Nov 20, 2017	C	441	D	—	—	Common Stock	129	I
Series A-1 Convertible Preferred Stock^F6,F1	—	Nov 20, 2017	C	643	D	—	—	Common Stock	188	I
Series A-2 Convertible Preferred Stock^F2,F3,F7	—	Nov 20, 2017	C	680,130	D	—	—	Common Stock	243,385	I
Series A-2 Convertible Preferred Stock^F4,F7	—	Nov 20, 2017	C	13,256	D	—	—	Common Stock	4,743	I
Series A-2 Convertible Preferred Stock^F5,F7	—	Nov 20, 2017	C	4,659	D	—	—	Common Stock	1,667	I
Series A-2 Convertible Preferred Stock^F6,F7	—	Nov 20, 2017	C	6,801	D	—	—	Common Stock	2,433	I
Series B Convertible Preferred Stock^F2,F3,F8	—	Nov 20, 2017	C	710,817	D	—	—	Common Stock	317,376	I
Series B Convertible Preferred Stock^F4,F8	—	Nov 20, 2017	C	13,854	D	—	—	Common Stock	6,185	I
Series B Convertible Preferred Stock^F5,F8	—	Nov 20, 2017	C	4,869	D	—	—	Common Stock	2,173	I
Series B Convertible Preferred Stock^F6,F8	—	Nov 20, 2017	C	7,108	D	—	—	Common Stock	3,173	I
Series C Convertible Preferred Stock^F2,F3,F9	—	Nov 20, 2017	C	221,638	D	—	—	Common Stock	110,312	I
Series C Convertible Preferred Stock^F4,F9	—	Nov 20, 2017	C	4,315	D	—	—	Common Stock	2,150	I
Series C Convertible Preferred Stock^F5,F9	—	Nov 20, 2017	C	1,516	D	—	—	Common Stock	755	I
Series C Convertible Preferred Stock^F6,F9	—	Nov 20, 2017	C	2,213	D	—	—	Common Stock	1,102	I
Series D Convertible Preferred Stock^F2,F3,F10	—	Nov 20, 2017	C	2,153,746	D	—	—	Common Stock	631,041	I
Series D Convertible Preferred Stock^F4,F10	—	Nov 20, 2017	C	41,976	D	—	—	Common Stock	12,298	I
Series D Convertible Preferred Stock^F5,F10	—	Nov 20, 2017	C	14,752	D	—	—	Common Stock	4,322	I
Series D Convertible Preferred Stock^F6,F10	—	Nov 20, 2017	C	21,537	D	—	—	Common Stock	6,310	I

Explanation of responses

F1The Series A-1 Convertible Preferred Stock converted into Common Stock on a 0.29300-for-one basis upon the closing of the Issuer's initial public offering without payment of consideration. The Series A-1 Convertible Preferred Stock was convertible at any time at the holder's election and automatically upon the closing at the Issuer's initial public offering. The shares had no expiration date.
F10The Series D Convertible Preferred Stock converted into Common Stock on a 0.29300-for-one basis upon the closing of the Issuer's initial public offering without payment of consideration. The Series D Convertible Preferred Stock was convertible at any time at the holder's election and automatically upon the closing at the Issuer's initial public offering. The shares had no expiration date.
F2These shares are owned directly by Polaris Venture Partners V, L.P. ("Polaris V"), whose general partner is Polaris Venture Management Co. V, L.L.C. ("Polaris Management"). Each of Jonathan A. Flint ("Flint") and Terrance G. McGuire ("McGuire"), who is a member of the Issuer's Board of Directors and whose beneficial ownership is reported on a separate Form 4, are the managing members of Polaris Management and may each be deemed to share voting and dispositive power with respect to the shares held by each of Polaris V, Polaris Venture Partners Entrepreneurs' Fund V, L.P. ("Polaris Entrepreneurs' V"), Polaris Venture Partners Founders' Fund V, L.P. ("Polaris Founders' V") and Polaris Venture Partners Special Founders' Fund V, L.P. ("Polaris Special Founders' V", and together with Polaris V, Polaris Entrepreneurs' V and Polaris Founders' V, the "Polaris V Funds").
F3(Continued from footnote 2) Polaris Management may be deemed to have sole power to vote and dispose of the shares held by the Polaris V Funds. Each of Flint, McGuire and Polaris Management disclaims beneficial ownership of these securities and this report shall not be deemed to be an admission that any of them is the beneficial owner of such securities for purposes of Section 16 or any other purpose, except to the extent of their respective pecuniary interests therein.
F4These shares are owned directly by Polaris Entrepreneurs' V, whose general partner is Polaris Management. Each of Flint and McGuire are the managing members of Polaris Management and may each be deemed to share voting and dispositive power over the shares held by each of the Polaris V Funds. Polaris Management may be deemed to have sole power to vote and dispose of the shares held by the Polaris V Funds. Each of Flint, McGuire and Polaris Management disclaims beneficial ownership of these securities and this report shall not be deemed to be an admission that any of them is the beneficial owner of such securities for purposes of Section 16 or any other purpose, except to the extent of their respective pecuniary interests therein.
F5These shares are owned directly by Polaris Founders' V, whose general partner is Polaris Management. Each of Flint and McGuire are the managing members of Polaris Management and may each be deemed to share voting and dispositive power over the shares held by each of the Polaris V Funds. Polaris Management may be deemed to have sole power to vote and dispose of the shares held by the Polaris V Funds. Each of Flint, McGuire and Polaris Management disclaims beneficial ownership of these securities and this report shall not be deemed to be an admission that any of them is the beneficial owner of such securities for purposes of Section 16 or any other purpose, except to the extent of their respective pecuniary interests therein.
F6These shares are owned directly by Polaris Special Founders' V, whose general partner is Polaris Management. Each of Flint and McGuire are the managing members of Polaris Management and, may each be deemed to share voting and dispositive power over the shares held by each of the Polaris V Funds. Polaris Management may be deemed to have sole power to vote and dispose of the shares held by the Polaris V Funds. Each of Flint, McGuire and Polaris Management disclaims beneficial ownership of these securities and this report shall not be deemed to be an admission that any of them is the beneficial owner of such securities for purposes of Section 16 or any other purpose, except to the extent of their respective pecuniary interests therein.
F7The Series A-2 Convertible Preferred Stock converted into Common Stock on a 0.35785-for-one basis upon the closing of the Issuer's initial public offering without payment of consideration. The Series A-2 Convertible Preferred Stock was convertible at any time at the holder's election and automatically upon the closing at the Issuer's initial public offering. The shares had no expiration date.
F8The Series B Convertible Preferred Stock converted into Common Stock on a 0.44650-for-one basis upon the closing of the Issuer's initial public offering without payment of consideration. The Series B Convertible Preferred Stock was convertible at any time at the holder's election and automatically upon the closing at the Issuer's initial public offering. The shares had no expiration date.
F9The Series C Convertible Preferred Stock converted into Common Stock on a 0.49832-for-one basis upon the closing of the Issuer's initial public offering without payment of consideration. The Series C Convertible Preferred Stock was convertible at any time at the holder's election and automatically upon the closing at the Issuer's initial public offering. The shares had no expiration date.