Condensed Balance Sheets (Unaudited) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Current assets:
Cash and cash equivalents	$ 53,494	$ 54,059
Prepaid expenses and other current assets	938	342
Total current assets	54,432	54,401
Property and equipment, net	580	486
Restricted cash	94	94
Other assets	16	19
Total assets	55,122	55,000
Current liabilities:
Accounts payable	1,880	2,458
Accrued expenses	618	1,987
Notes payable, current portion	2,523	251
Deferred revenue	451	506
Total current liabilities	5,472	5,202
Other liabilities	164	4
Notes payable, net of current portion	12,171	9,749
Warrant liability	$ 96	$ 3,219
Commitments and contingencies
Stockholders’ equity:
Preferred stock, $0.001 par value per share; 5,000,000 shares authorized at June 30, 2015 and December 31, 2014 and no shares issued and outstanding at June 30, 2015 and December 31, 2014	$ 0	$ 0
Common stock, $0.001 par value per share; 200,000,000 shares authorized at June 30, 2015 and December 31, 2014 and 19,307,975 and 17,933,260 shares issued and outstanding at June 30, 2015 and December 31, 2014, respectively	19	18
Additional paid-in capital	142,380	128,558
Accumulated deficit	(105,180)	(91,750)
Total stockholders’ equity	37,219	36,826
Total liabilities and stockholders’ equity	$ 55,122	$ 55,000