Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 11,614	$ 12,910
Restricted cash	378	361
Prepaid expenses and other current assets	1,151	535
Total current assets	13,143	13,806
Property, equipment and leasehold improvements, net	72	157
Other assets	76	82
Total assets	13,291	14,045
Current liabilities:
Accounts payable	1,228	988
Loan payable, current portion	459	452
Derivative warrant liability	2	4
Deferred rent, current portion	30	30
Accrued expenses	2,386	1,638
Total current liabilities	4,105	3,112
Loan payable, net of current portion	283	400
Deferred rent, net of current portion	522	367
Other liabilities	58	56
Total liabilities	4,968	3,935
Commitments and contingencies (Note 6)
Stockholders' equity:
Common stock, $0.00001 par value, authorized 4,000,000 shares; 1,562,284 shares issued and outstanding at March 31, 2018; 1,370,992 shares issued and outstanding at December 31, 2017	1	1
Additional paid-in capital	197,013	194,016
Accumulated deficit	(188,691)	(183,907)
Total stockholders’ equity	8,323	10,110
Total liabilities and stockholders’ equity	$ 13,291	$ 14,045