Condensed Consolidated Balance Sheets (unaudited) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 12,201	$ 17,417
Prepaid expenses and other current assets	497	485
Total current assets	12,698	17,902
Property and equipment, net of accumulated depreciation of $2,020 and $1,919, respectively	1,408	1,470
Other assets	39	39
Total assets	14,145	19,411
Current liabilities:
Accounts payable	508	862
Related party payable	374	2,303
Accrued expenses	1,005	1,260
Total current liabilities	1,887	4,425
Convertible promissory notes, net of debt discount of $18,003 and $18,003, respectively (see Note 4)	0	0
Accrued interest payable	1,157	967
Warrant liability, long term	838	1,073
Derivative liability	3,199	3,136
Deferred rent	805	803
Total liabilities	7,886	10,404
Stockholders’ equity:
Series A nonredeemable convertible preferred stock; 8,000 shares designated, 8,000 shares issued and outstanding as of March 31, 2018 and December 31, 2017 respectively; aggregate liquidation preference of $8,346 at March 31, 2018	0	0
Common stock, $0.001 par value; 150,000,000 shares authorized, 28,356,351 and 25,940,247 shares issued and outstanding at March 31, 2018 and December 31, 2017, respectively	28	26
Additional paid-in capital	187,935	187,784
Accumulated deficit	(181,704)	(178,803)
Total stockholders’ equity	6,259	9,007
Total liabilities and stockholders’ equity	$ 14,145	$ 19,411