Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 57,052	$ 96,713
Marketable securities	55,862
Accounts receivable	2,000
Unbilled accounts receivable	531
Prepaid expenses and other current assets	4,065	3,370
Total current assets	119,510	100,083
Property and equipment, net	8,397	9,205
Restricted cash	1,092	1,092
Other assets	578	59
Total assets	129,577	110,439
Current liabilities:
Accounts payable	4,079	2,186
Accrued expenses and other current liabilities	7,267	5,496
Deferred lease incentive, current portion	469	469
Deferred revenue, current portion	14,910	3,989
Total current liabilities	26,725	12,140
Deferred rent, excluding current portion	1,649	1,559
Deferred lease incentive, excluding current portion	3,051	3,521
Deferred revenue, excluding current portion	2,971	6,011
Other liabilities, excluding current portion		55
Total liabilities	34,396	23,286
Stockholders’ equity:
Common stock, $0.001 par value; 200,000,000 shares authorized; 28,067,402 and 23,335,514 shares issued as of December 31, 2020 and December 31, 2019, respectively; 27,941,566 and 22,654,444 shares outstanding as of December 31, 2020 and December 31, 2019, respectively	28	23
Additional paid-in capital	316,775	237,931
Accumulated other comprehensive loss	(2)
Accumulated deficit	(221,620)	(150,801)
Total stockholders’ equity	95,181	87,153
Total liabilities and stockholders’ equity	$ 129,577	$ 110,439