Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Current assets:
Cash and cash equivalents	$ 23,596	$ 62,780
Available-for-sale securities	14,931
Prepaid expenses and other current assets	1,001	772
Total current assets	39,528	63,552
Property and equipment, net	568	504
Restricted cash	113	113
Total assets	40,209	64,169
Current liabilities:
Accounts payable	1,405	1,328
Accrued expenses	3,677	3,278
Current portion of notes payable, net of discount	3,243	3,173
Total current liabilities	8,325	7,779
Deferred rent, net of current portion	53	26
Notes payable, net of current portion and discount	2,479	5,720
Other liability	266	151
Total liabilities	11,123	13,676
Commitments (Note 9)
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; 18,817,572 and 15,313,297 shares issued and outstanding at December 31, 2016 and December 31, 2015, respectively	19	15
Additional paid-in capital	173,141	158,488
Accumulated other comprehensive loss	(4)
Accumulated deficit	(144,070)	(108,010)
Total stockholders' equity	29,086	50,493
Total liabilities and stockholders' equity	$ 40,209	$ 64,169