Condensed Consolidated Balance Sheets (unaudited) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 15,410	$ 17,417
Prepaid expenses and other current assets	455	485
Total current assets	15,865	17,902
Property and equipment, net of accumulated depreciation of $2,121 and $1,919, respectively	1,374	1,470
Other assets	39	39
Total assets	17,278	19,411
Current liabilities:
Accounts payable	635	862
Related party payable	276	2,303
Accrued expenses	1,137	1,260
Total current liabilities	2,048	4,425
Convertible promissory notes, net of debt discount of $18,003 and $18,003, respectively (see Note 4)	0	0
Accrued interest payable	1,349	967
Warrant liability, long term	747	1,073
Derivative liability	2,957	3,136
Deferred rent	809	803
Total liabilities	7,910	10,404
Stockholders’ equity:
Series A nonredeemable convertible preferred stock; 8,000 shares designated, 8,000 shares issued and outstanding as of June 30, 2018 and December 31, 2017 respectively; aggregate liquidation preference of $8,429 at June 30, 2018	0	0
Common stock, $0.001 par value; 150,000,000 shares authorized, 7,840,902 and 5,189,755 shares issued and outstanding at June 30, 2018 and December 31, 2017, respectively	8	5
Additional paid-in capital	193,958	187,805
Accumulated deficit	(184,598)	(178,803)
Total stockholders’ equity	9,368	9,007
Total liabilities and stockholders’ equity	$ 17,278	$ 19,411