CONDENSED BALANCE SHEETS - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Current assets:
Cash and cash equivalents	$ 8,484	$ 36,079
Prepaid expenses and other current assets	350	232
Total current assets	8,834	36,311
Property and equipment, net	314	407
Restricted cash	119	94
Other assets	0	13
Total assets	9,267	36,825
Current liabilities:
Accounts payable	1,855	1,246
Accrued expenses	1,153	1,794
Notes payable, current portion	0	4,134
Deferred revenue	0	406
Total current liabilities	3,008	7,580
Other liabilities	73	423
Notes payable, net of current portion	0	9,763
Warrant liability	13	115
Commitments and contingencies
Stockholders’ equity:
Preferred stock, $0.001 par value per share; 5,000,000 shares authorized at June 30, 2016 and December 31, 2015 and no shares issued and outstanding at June 30, 2016 and December 31, 2015	0	0
Common stock, $0.001 par value per share; 200,000,000 shares authorized at June 30, 2016 and December 31, 2015 and 20,005,771 and 19,619,124 shares issued and outstanding at June 30, 2016 and December 31, 2015, respectively	20	20
Additional paid-in capital	145,420	144,126
Accumulated deficit	(139,267)	(125,202)
Total stockholders’ equity	6,173	18,944
Total liabilities and stockholders’ equity	$ 9,267	$ 36,825