CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 143,663	$ 89,798
Accounts receivable	488	10,000
Prepaid expenses	17,434	5,762
Other current assets	169	4
Total current assets	161,754	105,564
Property, equipment, and software—net	25,154	35,090
Intangible assets—net	2,048	1,373
Right-of-use assets—net	4,180	6,410
Investment in equity securities	3,091
Equity method investments	3,751
Note receivable—net	6,879
Other assets	4,641	1,721
Total assets	211,498	150,158
Current liabilities:
Accounts payable	1,144	792
Accrued compensation	6,765	5,745
Accrued clinical research and development expenses	4,028	3,269
Deferred revenue	21,244	30,236
Lease liabilities	1,822	1,933
Other current liabilities	977	854
Total current liabilities	35,980	42,829
Deferred revenue	67,015	53,926
Lease liabilities	4,813	8,586
Long term debt—net	2,478
Contract liabilities	10,000
Other noncurrent liabilities	44	392
Total liabilities	120,330	105,733
Stockholders’ equity:
Preferred stock, $0.0001 par value— 10,000,000 shares authorized as of December 31, 2021 and December 31, 2020; no shares issued and outstanding as of December 31, 2021 and December 31, 2020
Common stock; $0.000005 par value— 200,000,000 shares authorized, 61,712,577 shares issued and 60,902,105 shares outstanding as of December 31, 2021; 53,503,124 shares issued and 52,692,652 shares outstanding as of December 31, 2020
Additional paid-in capital	408,795	331,450
Accumulated deficit	(316,675)	(286,073)
Treasury stock	(952)	(952)
Total stockholders’ equity	91,168	44,425
Total liabilities and stockholders’ equity	$ 211,498	$ 150,158