BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Current assets:
Cash and cash equivalents	$ 39,058	$ 76,054
Restricted cash	13,938	0
Receivables	4	1,111
Prepaid expenses and other current assets	799	1,666
Total current assets	53,799	78,831
Property and equipment, net	8,460	10,941
Right-of-use asset	2,136	4,420
Deposits	42	42
Other non-current assets	500	631
Total assets	64,937	94,865
Current liabilities:
Accounts payable	1,389	1,368
Long-term debt, current	16,765	7,868
Accrued expenses	5,454	6,076
Lease liability, current	558	729
Total current liabilities	24,166	16,041
Long-term debt	0	16,250
Lease liability, non-current	2,188	4,518
Other non-current liabilities	28	0
Total liabilities	26,382	36,809
Commitments and contingencies (Note 9)
Stockholders' equity:
Common stock $0.001 par value; 420,000,000 shares authorized, 240,410,761 shares issued and outstanding at December 31, 2022 and 350,000,000 shares authorized, 216,127,443 shares issued and outstanding at December 31, 2021	240	216
Additional paid-in capital	918,942	900,693
Accumulated deficit	(880,627)	(842,852)
Total stockholders' equity	38,555	58,057
Total liabilities and stockholders' equity	$ 64,937	$ 94,865