Condensed Consolidated Balance Sheets (unaudited) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 15,912	$ 17,515
Prepaid expenses and other current assets	441	513
Total current assets	16,353	18,028
Property and equipment, net of accumulated depreciation of $1,718 and $1,561, respectively	1,534	1,489
Other assets	84	65
Total assets	17,971	19,582
Current liabilities:
Accounts payable	658	440
Related party payable	1,678	942
Accrued expenses	769	1,551
Warrant liability, current	315	54
Total current liabilities	3,420	2,987
Convertible promissory notes, net of debt discount of $18,038 and $18,088, respectively (see Note 4)	0	0
Accrued interest payable	594	228
Warrant liability, long term	15,401	5,980
Derivative liability	1,194	1,735
Deferred rent	797	791
Total liabilities	21,406	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 June 30, 2017; no shares designated, issued or outstanding as of December 31, 2016; aggregate liquidation preference of $8,100 at June 30, 2017	0	0
Common stock, $0.001 par value; 150,000,000 shares authorized, 14,709,971 and 14,688,135 shares issued and outstanding, respectively	15	15
Additional paid-in capital	178,138	170,409
Accumulated deficit	(181,588)	(162,563)
Total stockholders’ equity (deficit)	(3,435)	7,861
Total liabilities and stockholders’ equity	$ 17,971	$ 19,582