Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 22,320	$ 12,910
Restricted cash	12	361
Prepaid expenses and other current assets	1,235	535
Total current assets	23,567	13,806
Property, equipment and leasehold improvements, net	125	157
Restricted cash	90
Other assets	77	82
Total assets	23,859	14,045
Current liabilities:
Accounts payable	914	988
Loan payable, current portion	330	452
Derivative warrant liability	21,469	4
Deferred rent, current portion		30
Accrued expenses	2,996	1,638
Total current liabilities	25,709	3,112
Loan payable, net of current portion		400
Deferred rent, net of current portion		367
Other liabilities	59	56
Total liabilities	25,768	3,935
Commitments and contingencies (Note 6)
Stockholders' equity (deficit):
Common stock, $0.00001 par value, authorized 25,000,000 shares; 4,077,667 shares issued and outstanding at June 30, 2018; 1,370,992 shares issued and outstanding at December 31, 2017	1	1
Additional paid-in capital	199,720	194,016
Accumulated deficit	(201,630)	(183,907)
Total stockholders’ equity (deficit)	(1,909)	10,110
Total liabilities and stockholders’ equity (deficit)	$ 23,859	$ 14,045