Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 162,745	$ 181,727
Marketable securities, current	239,326	189,962
Accounts receivable	4,845	4,484
Prepaid expenses and other current assets	5,378	4,836
Total current assets	412,294	381,009
Marketable securities, non-current	78,191
Property and equipment, net	3,323	3,323
Right-of-use asset	12,249	13,229
Restricted cash	1,276	2,577
Other assets	578
Total assets	507,911	400,138
Current liabilities:
Accounts payable	3,745	5,683
Accrued expenses and other current liabilities	11,471	9,524
Deferred revenue, current	32,294	27,603
Operating lease liability, current	1,177	1,042
Total current liabilities	48,687	43,852
Deferred revenue, net of current	38,936	53,617
Operating lease liability, net of current	10,920	11,826
Long-term debt − related party	10,588	10,052
Total liabilities	109,131	119,347
Commitments and contingencies
Stockholders’ equity:
Preferred stock, par value of $0.0001 per share; 10,000,000 shares authorized, and no shares issued or outstanding as of September 30, 2021 and December 31, 2020, respectively
Common stock, par value of $0.0001 per share; 150,000,000 shares authorized, and 48,593,398 and 43,059,632 shares issued and outstanding as of September 30, 2021 and December 31, 2020, respectively	5	4
Additional paid-in capital	650,987	464,597
Accumulated other comprehensive (loss) income	(155)	13
Accumulated deficit	(252,057)	(183,823)
Total stockholders’ equity	398,780	280,791
Total liabilities and stockholders’ equity	$ 507,911	$ 400,138