Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 49,978	$ 32,297
Short-term investments	214,514	404,273
Accounts receivable, net	411	137
Accounts receivable from related party	43	32
Inventory	851	0
Prepaid expenses and other current assets	3,380	4,831
Total current assets	269,177	441,570
Property and equipment, net	32,269	25,160
Long-term investments	97,856	23,800
Operating lease right-of-use assets	24,806	26,911
Other assets	1,544	1,458
Total assets	425,652	518,899
Current liabilities:
Accounts payable	6,746	12,875
Accrued and other current liabilities	26,358	19,794
Long-term debt, current	18,920	6,302
Deferred revenue from related party	10,993	12,587
Total current liabilities	63,017	51,558
Long-term debt, net	4,715	18,099
Non-current deferred revenue from related party	24,772	24,000
Non-current lease liabilities	46,830	38,671
Other non-current liabilities	198	958
Total liabilities	139,532	133,286
Commitments (Note 8)
Stockholders’ equity:
Preferred stock, $0.001 par value, 10,000,000 shares authorized; no shares issued and outstanding	0	0
Common stock, $0.001 par value, 200,000,000 shares authorized; 70,357,557 and 69,452,466 shares issued and outstanding at December 31, 2021 and 2020, respectively	70	69
Additional paid-in capital	903,646	870,788
Note receivable	(16)	(16)
Accumulated other comprehensive (loss) income	(483)	114
Accumulated deficit	(617,097)	(485,342)
Total stockholders’ equity	286,120	385,613
Total liabilities and stockholders’ equity	$ 425,652	$ 518,899