CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Current assets:
Cash and cash equivalents	$ 56,845	$ 34,871
Restricted cash	364	364
Marketable securities	115,901	148,851
Interest and other receivables	3,144	1,763
Prepaid and other current assets	3,992	1,357
Total current assets	180,246	187,206
Noncurrent marketable securities		28,651
Property and equipment, net	793	650
Operating leases, right-of-use assets	4,147	4,727
Deposits and other assets	5,389	4,800
Total assets	190,575	226,034
Current liabilities:
Accounts payable	10,190	6,687
Accrued compensation and benefits	11,534	8,099
Operating lease liabilities	925	901
Debt	20,945
Accrued liabilities	33,100	29,834
Total current liabilities	76,694	45,521
Noncurrent operating lease liabilities	3,671	4,267
Noncurrent debt	30,212	49,830
Total liabilities	110,577	99,618
Commitments and contingencies
Stockholders' equity:
Preferred stock, $0.001 par value; 3,000,000 shares authorized; no shares issued and outstanding at December 31, 2022 and 2021
Common stock, $0.001 par value; 675,000,000 shares authorized; 390,262,524 and 323,731,591 shares issued and outstanding at December 31, 2022 and 2021, respectively	390	324
Additional paid-in capital	1,493,469	1,398,006
Accumulated deficit	(1,413,642)	(1,271,741)
Accumulated other comprehensive loss	(219)	(173)
Total stockholders' equity	79,998	126,416
Total liabilities and stockholders' equity	$ 190,575	$ 226,034