CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Current assets:
Cash and cash equivalents	$ 25,660	$ 18,592
Prepaid expenses and other current assets	2,050	1,960
Total current assets	27,710	20,552
Property and equipment, net	0	0
Other	490	733
Total assets	28,200	21,285
Current liabilities:
Accounts payable	6,431	3,890
Accrued expenses	9,182	9,058
Accrued dividends payable	63	64
Total current liabilities	15,676	13,012
Convertible notes payable and accrued interest, net of discounts - related party (Note 5)	30,902	29,964
Derivative liabilities (Note 6)	1,004	573
Borrowing and accrued interest under convertible line of credit, net of debt discount - related party (Note 10)	40,839	9,864
Other liabilities	20	66
Total liabilities	88,441	53,479
Commitments and contingencies (Note 12)
Series C 6% super dividend redeemable convertible preferred stock; 1,000 shares authorized, 176 issued and outstanding at December 31, 2023 and 2022, redemption value: $8,177,000, liquidation value: $1,786,000 at December 31,2023	1,723	1,723
Stockholders' equity (deficit):
Undesignated stock, $0.01 par value; 20,000,000 shares authorized at December 31, 2023 and 2022, 20,000,000 shares designated at December 31, 2023 and 2022, respectively	0	0
Series A 12% convertible preferred stock; 1,742,500 shares authorized, 1,235,000 and 1,260,000 issued and outstanding at December 31, 2023 and 2022, respectively, liquidation value $1,235,000 at December 31, 2023	500	510
Common stock, $0.001 par value; 150,000,000 shares authorized at December 31, 2023 and 2022, 61,852,914 and 59,426,005 issued and outstanding at December 31, 2023 and 2022, respectively	61	59
Additional paid-in capital	291,847	275,081
Accumulated deficit	(354,372)	(309,567)
Total stockholders' deficit	(61,964)	(33,917)
Total liabilities, redeemable convertible preferred stock and stockholders' deficit	$ 28,200	$ 21,285