Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 60,383	$ 31,087
Restricted cash	62	0
Contract and other receivables	0	503
Prepaid materials, net	3,010	3,314
Prepaid expenses and other current assets	1,780	1,826
Total current assets	65,235	36,730
Property and equipment, net	281	472
Intangibles, net	83	125
Right of use asset	2,564	253
Other assets	291	24
Total assets	68,454	37,604
Current liabilities:
Accounts payable	285	535
Accrued liabilities	821	581
Accrued research and development expenses	810	1,097
Accrued compensation	2,016	1,743
Current portion of term loan, less debt issuance costs	0	4,652
Other current liabilities	1,295	2,970
Total current liabilities	5,227	11,578
Operating lease liability, less current portion	2,417	0
Term loan, less current portion and debt issuance costs	4,673	0
Other long-term liabilities	1,179	0
Total liabilities	13,496	11,578
Stockholders’ equity (deficit):
Common stock, $0.001 par value; 400,000,000 shares authorized, 145,971,184 and 67,432,712 shares issued and outstanding at December 31, 2021 and 2020, respectively	146	67
Additional paid-in capital	509,660	453,002
Accumulated deficit	(454,853)	(427,045)
Total stockholders’ equity	54,958	26,026
Total liabilities and stockholders’ equity	68,454	37,604
Class A-1 Convertible Preferred Stock
Stockholders’ equity (deficit):
Convertible preferred stock	0	0
Class A-2 Convertible Preferred Stock
Stockholders’ equity (deficit):
Convertible preferred stock	1	1
Class A-3 Convertible Preferred Stock
Stockholders’ equity (deficit):
Convertible preferred stock	0	1
Class A-4 Convertible Preferred Stock
Stockholders’ equity (deficit):
Convertible preferred stock	$ 4	$ 0