Condensed Consolidated Balance Sheets (unaudited) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
CURRENT ASSETS
Cash and cash equivalents	$ 24,016	$ 29,294
Marketable securities	4,970	3,768
Restricted cash	80	80
Accounts receivable - grant	1,618	1,697
Deferred offering costs	3,195	2,535
Prepaid expenses and other current assets	1,325	912
Total current assets	35,204	38,286
Property and equipment, net	321	348
Other non-current assets	18	20
TOTAL ASSETS	35,543	38,654
CURRENT LIABILITIES
Accounts payable	509	176
Accrued and other current liabilities	3,311	2,347
Total current liabilities	3,820	2,523
Other non-current liabilities	22	27
TOTAL LIABILITIES	$ 3,842	$ 2,550
Commitments (Note 10 and 12)
STOCKHOLDERS’ DEFICIT
Common stock, $0.0001 par value; 25,000,000 authorized as of March 31, 2016 and December 31, 2015; 757,336 shares issued and outstanding as of March 31, 2016 and December 31, 2015	$ 0	$ 0
Additional paid-in capital	1,513	1,373
Accumulated other comprehensive income (loss)	3	(1)
Accumulated deficit	(28,126)	(23,579)
TOTAL STOCKHOLDERS’ DEFICIT	(26,610)	(22,207)
TOTAL LIABILITIES, CONVERTIBLE PREFERRED STOCK, AND STOCKHOLDERS’ DEFICIT	35,543	38,654
Series A Convertible Preferred Stock
CURRENT LIABILITIES
Convertible preferred stock	13,573	13,573
Series B Convertible Preferred Stock
CURRENT LIABILITIES
Convertible preferred stock	$ 44,738	$ 44,738