CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 178,622	$ 25,078
Marketable securities	141,452
Prepaid expenses and other current assets	2,154	1,061
Total current assets	322,228	26,139
Property and equipment, net	12,667	11,492
Operating lease right-of-use assets	6,035	6,214
Restricted cash	1,317	1,317
Total assets	342,247	45,162
Current liabilities:
Accounts payable	817	339
Accrued expenses and other current liabilities	6,730	4,962
Operating lease liabilities	1,071	641
Total current liabilities	8,618	5,942
Operating lease liabilities, net of current portion	12,321	13,143
Other long‑term liabilities		188
Total liabilities	20,939	19,273
Commitments and contingencies (See Note 11)
Convertible preferred stock (Series Seed, Seed 1, A, and B), $0.0001 par value; no shares authorized at September 30, 2020 and 178,349,005 shares authorized at December 31, 2019; no shares issued and outstanding at September 30, 2020 and 178,349,005 shares issued and outstanding at December 31, 2019		58,690
Stockholders’ equity (deficit):
Common stock, $0.0001 par value; 200,000,000 shares authorized at September 30, 2020 and 235,000,000 shares authorized at December 31, 2019; 34,374,348 shares issued and outstanding at September 30, 2020; and 997,165 shares issued and outstanding at December 31, 2019	3
Additional paid-in capital	390,473	323
Accumulated other comprehensive income	8
Accumulated deficit	(69,176)	(33,124)
Total stockholders’ equity (deficit)	321,308	(32,801)
Total liabilities, convertible preferred stock and stockholders’ equity	$ 342,247	$ 45,162