Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 18,655	$ 24,266
Marketable securities	79,253	86,335
Prepaid expenses and other current assets	2,930	1,788
Total current assets	100,838	112,389
Property and equipment, net	1,096	1,059
Restricted cash	1,193	1,193
Intangible asset, net	13	13
Total assets	103,140	114,654
Current liabilities:
Accounts payable	4,712	8,749
Accrued expenses and other current liabilities	2,367	8,208
Current portion of loans payable, net	3,912	5,039
Deferred rent	54	52
Total current liabilities	11,045	22,048
Loans payable, net	23,999	13,270
Capital leases, net of current portion	16	18
Deferred rent, net of current portion	173	187
Warrant liability	40	75
Other long term liabilities	567	475
Total liabilities	35,840	36,073
Commitments and contingencies (Note 6)
Stockholders’ equity:
Common stock—$0.001 par value; 100,000,000 shares authorized, 57,133,959 and 55,768,414 shares issued and outstanding at March 31, 2017 and December 31, 2016, respectively	57	56
Preferred stock—$0.001 par value; 5,000,000 shares authorized, none issued or outstanding at March 31, 2017 and December 31, 2016	0	0
Additional paid-in capital	373,631	364,148
Accumulated deficit	(306,339)	(285,625)
Accumulated other comprehensive income (loss)	(49)	2
Total stockholders’ equity	67,300	78,581
Total liabilities and stockholders’ equity	$ 103,140	$ 114,654