Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 66,408	$ 91,028
Restricted cash, current	87	2,788
Accounts receivable, interest and other receivables	127	303
Prepaid expenses and other current assets	1,528	884
Assets held for sale	0	16,851
Total current assets	68,150	111,854
Operating lease right-of-use assets	869	1,042
Property and equipment, net	1,615	2,529
Restricted cash, non-current	1,500	0
Other assets	341	825
Total assets	72,475	116,250
Current liabilities:
Accounts payable	2,486	2,643
Accrued expenses and other current liabilities	7,108	9,770
Warrant derivative liability	28,183	52,184
Private placement option liability	33,970	12,094
Current portion of long-term debt	6,390	11,000
Current portion of lease liabilities	491	454
Liabilities Held-For-Sale, Not Part Of Disposal Group, Current	0	6,273
Total current liabilities	78,628	94,418
Long-term debt, net of deferred issuance costs	20,715	25,717
Long-term lease liabilities	609	864
Total liabilities	99,952	120,999
Commitments and contingencies
Preferred stock: $0.01 par value; 10,000,000 shares authorized	21,308	21,468
Stockholders’ deficit:
Common stock, $0.01 par value; 80,000,000 and 40,000,000 shares authorized at June 30, 2020 and December 31, 2019, respectively, 5,127,525 shares issued and 5,059,779 shares outstanding at June 30, 2020; 5,076,593 shares issued and 5,008,846 shares outstanding at December 31, 2019	51	507
Treasury stock: 67,746 shares held at June 30, 2020 and December 31, 2019	(5,056)	(5,056)
Additional paid-in capital	515,252	511,684
Accumulated other comprehensive loss	(389)	(327)
Accumulated deficit	(558,643)	(533,025)
Total stockholders’ deficit	(48,785)	(26,217)
Total liabilities, preferred stock and stockholders' deficit	$ 72,475	$ 116,250