Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 31,795	$ 23,596
Available-for-sale securities		14,931
Prepaid expenses and other current assets	1,020	1,001
Total current assets	32,815	39,528
Property and equipment, net	494	568
Restricted cash	113	113
Total assets	33,422	40,209
Current liabilities:
Accounts payable	942	1,405
Accrued expenses	3,294	3,677
Current portion of notes payable, net of discount	3,260	3,243
Total current liabilities	7,496	8,325
Deferred rent, net of current portion	26	53
Notes payable, net of current portion and discount	1,657	2,479
Other liability	288	266
Total liabilities	9,467	11,123
Commitments (Note 7)
Stockholders' equity:
Preferred stock, $0.001 par value per share, 5,000,000 shares authorized and no shares issued and outstanding
Common stock, $0.001 par value per share, 150,000,000 shares authorized; 19,997,197 and 18,817,572 shares issued and outstanding at March 31, 2017 and December 31, 2016, respectively	20	19
Additional paid-in capital	175,881	173,141
Accumulated other comprehensive loss		(4)
Accumulated deficit	(151,946)	(144,070)
Total stockholders' equity	23,955	29,086
Total liabilities and stockholders' equity	$ 33,422	$ 40,209