Condensed Consolidated Balance Sheets (unaudited) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 11,911	$ 17,515
Prepaid expenses and other current assets	265	513
Total current assets	12,176	18,028
Property and equipment, net of accumulated depreciation of $1,817 and $1,486, respectively	1,544	1,489
Other assets	61	65
Total assets	13,781	19,582
Current liabilities:
Accounts payable	601	440
Related party payable	1,731	942
Accrued expenses	1,018	1,551
Warrant liability, current	117	54
Total current liabilities	3,467	2,987
Convertible promissory notes, net of debt discount of $18,003 and $18,088, respectively (see Note 4)	0	0
Accrued interest payable	780	228
Warrant liability, long term	10,618	5,980
Derivative liability	1,442	1,735
Deferred rent	800	791
Total liabilities	17,107	11,721
Stockholders’ equity (deficit):
Preferred stock, $0.001 par value; 5,000,000 shares authorized: Series A nonredeemable convertible preferred stock; 8,000 shares designated, 8,000 shares issued and outstanding as of September 30, 2017; no shares designated, issued or outstanding as of December 31, 2016; aggregate liquidation preference of $8,182 at September 30, 2017	0	0
Common stock, $0.001 par value; 150,000,000 shares authorized, 14,719,987 and 14,688,135 shares issued and outstanding, respectively	15	15
Additional paid-in capital	178,362	170,409
Accumulated deficit	(181,703)	(162,563)
Total stockholders’ equity (deficit)	(3,326)	7,861
Total liabilities and stockholders’ equity	$ 13,781	$ 19,582