Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 329,152	$ 49,969
Marketable securities	406,099	363,339
Receivable from Collaboration partner	7,391	0
Prepaid expenses and other current assets	7,071	8,203
Total current assets	749,713	421,511
Property and equipment, net	27,330	30,181
Operating lease right-of-use assets	30,569	32,470
Restricted cash	1,472	1,472
Other assets	5,574	2,617
Total assets	814,658	488,251
Current liabilities:
Accounts payable	4,749	3,004
Accrued clinical supply costs	8,748	11,148
Accrued liabilities	27,460	22,538
Deferred revenue, current portion	90,803	23,886
Operating lease liabilities, current portion	7,795	7,512
Total current liabilities	139,555	68,088
Deferred revenue, long-term portion	334,415	108,417
Operating lease liabilities, long-term portion	39,806	43,744
Other long-term liabilities	158	472
Total liabilities	513,934	220,721
Commitments and contingencies
Stockholders' equity:
Common stock, $0.0001 par value; 200,000,000 shares authorized; 81,986,192 and 79,316,261 shares issued and outstanding as of December 31, 2021 and 2020, respectively	8	8
Additional paid-in capital	748,036	676,956
Accumulated other comprehensive income (loss)	(943)	614
Accumulated deficit	(446,377)	(410,048)
Total stockholders' equity	300,724	267,530
Total liabilities and stockholders' equity	$ 814,658	$ 488,251