Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Current assets:
Cash and cash equivalents	$ 27,436	$ 38,320
Inventories	906	906
Prepaid expenses and other current assets	2,425	1,782
Total current assets	30,767	41,008
Restricted cash	1,968	1,960
Property and equipment, net	1,406	1,488
Right-of-use lease asset	4,092	4,224
Other assets	59
Total assets	38,292	48,680
Current liabilities:
Accounts payable, net	1,664	2,372
Accrued expenses and other current liabilities	5,429	5,461
Lease liability	926	899
Total current liabilities	8,019	8,732
Loans payable, net	13,476	13,430
Leases, net of current portion	5,194	5,436
Warrant liability	1,449	5,483
Total liabilities	28,138	33,081
Stockholders' equity:
Preferred stock-$0.001 par value; 5,000,000 shares authorized, none issued or outstanding at March 31, 2023 and December 31, 2022
Common stock-$0.001 par value; 200,000,000 shares authorized at March 31, 2023 and December 31, 2022; 8,975,072 and 7,744,692 shares issued and outstanding at March 31, 2023 and December 31, 2022, respectively	9	8
Additional paid-in capital	565,736	563,362
Accumulated deficit	(555,591)	(547,772)
Accumulated other comprehensive income		1
Total stockholders' equity	10,154	15,599
Total liabilities and stockholders' equity	$ 38,292	$ 48,680