Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 46,156	$ 35,495
Restricted cash	1,501	1,501
Accounts receivable, interest and other receivables	205	2
Prepaid expenses and other current assets	1,269	802
Assets held for sale	0	1,643
Total current assets	49,131	39,443
Operating lease right-of-use assets	0	645
Property and equipment, net	12	189
Other assets	0	307
Total assets	49,143	40,584
Current liabilities:
Accounts payable	90	891
Accrued expenses and other current liabilities	3,849	4,165
Warrant derivative liability	2,773	10,345
Private placement option liability	0	7,803
Current portion of lease liabilities	0	825
Liabilities held for sale	0	672
Total current liabilities	6,712	24,701
Long-term lease liabilities	0	344
Total liabilities	6,712	25,045
Commitments and contingencies
Redeemable Preferred stock: $0.01 par value; 10,000,000 shares authorized series 1 redeemable convertible preferred stock, $0.01 par value, 1,517,500 shares authorized at December 31, 2021 and December 31, 2020, 452,000 shares issued and outstanding at December 31, 2021 and December 31, 2020	18,036	18,036
Stockholders’ equity (deficit):
Common stock, $0.01 par value; 80,000,000 shares authorized at December 31, 2021 and December 31, 2020, respectively; 8,497,025 shares issued and 8,429,279 shares outstanding at December 31, 2021; 8,385,650 shares issued and 8,317,904 shares outstanding at December 31, 2020	85	84
Treasury stock: 67,746 shares held at December 31, 2021 and December 31, 2020	(5,056)	(5,056)
Additional paid-in capital	580,156	543,561
Accumulated other comprehensive loss	(338)	(339)
Accumulated deficit	(550,452)	(540,747)
Total stockholders’ equity (deficit)	24,395	(2,497)
Total liabilities, redeemable preferred stock and stockholders’ equity (deficit)	$ 49,143	$ 40,584