Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 13,453	$ 31,683
Marketable securities	153,582	149,242
Income tax receivable	697	1,507
Other receivables	455	557
Inventory, net	2,584
Prepaid expenses	2,519	12,076
Total current assets	173,290	195,065
Operating lease right-of-use assets	2,973	4,279
Marketable securities, non-current	69,754	70,565
Property and equipment, net	631	840
Restricted cash	408	408
Total assets	247,056	271,157
Current liabilities:
Accounts payable and accrued expenses	15,861	16,881
Operating lease liabilities, current	1,755	1,602
Total current liabilities	17,616	18,483
Operating lease liabilities, non-current	1,918	3,673
Commitments and contingencies (Note 18)
Stockholders' equity:
Preferred stock; $0.001 par value; 5,000,000 shares authorized at December 31, 2021 and December 31, 2020, zero shares issued and outstanding at December 31, 2021 and December 31, 2020
Common stock; $0.001 par value; 100,000,000 shares authorized at December 31, 2021 and December 31, 2020, 53,480,812 shares and 49,872,213 shares issued and outstanding at December 31, 2021 and December 31, 2020, respectively	53	50
Additional paid-in capital	708,585	641,195
Accumulated deficit	(480,758)	(392,317)
Accumulated other comprehensive (loss) income	(358)	73
Total stockholders' equity	227,522	249,001
Total liabilities and stockholders' equity	$ 247,056	$ 271,157