Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Current assets
Cash	$ 15,662	$ 10,261
Prepaid expenses and other current assets	1,832	835
Total current assets	17,494	11,096
Total assets	17,494	11,096
Current liabilities
Accounts payable	1,887	796
Accrued expenses	1,924	1,919
License payables	125	7,100
Convertible debt	2,431	0
Warrant liabilities, at fair value	1,062	963
Total current liabilities	7,429	10,778
License payables, long-term	200	325
Note payable	147	0
Convertible debt, long-term	7,146	0
Total liabilities	14,922	11,103
Commitments and contingencies (note 11)
Stockholders' equity (deficit)
Preferred stock, $.001 par value, 10,000,000 shares authorized, no shares issued or outstanding as of December 31, 2020 and 2019	0	0
Common stock, $.001 par value, 120,000,000 shares authorized, 54,535,891 and 27,028,533 issued and outstanding as of December 31, 2020 and 2019, respectively	54	27
Additional paid-in-capital	77,680	56,027
Accumulated deficit	(75,162)	(56,061)
Total stockholders' equity (deficit)	2,572	(7)
Total liabilities and stockholders' equity (deficit)	$ 17,494	$ 11,096