CONDENSED BALANCE SHEETS - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Current assets:
Cash and cash equivalents	$ 21,362	$ 13,453
Marketable securities	119,749	153,582
Accounts receivable - related party	2,496	0
Inventory, net	1,907	2,584
Income tax receivable	697	697
Other receivables	438	455
Prepaid expenses	5,113	2,519
Total current assets	151,762	173,290
Operating lease right-of-use assets	2,629	2,973
Marketable securities, non-current	68,456	69,754
Property and equipment, net	611	631
Restricted cash	408	408
Total assets	223,866	247,056
Current liabilities:
Accounts payable and accrued expenses	16,501	15,861
Operating lease liabilities, current	1,795	1,755
Total current liabilities	18,296	17,616
Operating lease liabilities, non-current	1,455	1,918
Commitments and contingencies (Note 16)
Stockholders' equity:
Preferred stock; $0.001 par value; 5,000,000 shares authorized at March 31, 2022 and December 31, 2021, zero shares issued and outstanding at March 31, 2022 and December 31, 2021
Common stock; $0.001 par value; 100,000,000 shares authorized at March 31, 2022 and December 31, 2021, 53,591,225 shares and 53,480,812 shares issued and outstanding at March 31, 2022 and December 31, 2021, respectively	53	53
Additional paid-in capital	714,292	708,585
Accumulated deficit	(508,507)	(480,758)
Accumulated other comprehensive loss	(1,723)	(358)
Total stockholders' equity	204,115	227,522
Total liabilities and stockholders' equity	$ 223,866	$ 247,056