Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Current assets:
Cash and cash equivalents	$ 77,876	$ 83,416
Restricted cash	319	533
Other current assets and prepaid expenses	1,044	1,139
Total current assets	79,239	85,088
Property and equipment, net	3,428	3,809
Other assets	253	184
Total assets	82,920	89,081
Current liabilities:
Accounts payable	885	1,221
Accrued expenses	3,788	5,271
Other current liabilities	143	163
Total current liabilities	4,816	6,655
Long-term liabilities	$ 56	$ 101
Commitments and contingencies
Stockholders’ equity:
Preferred stock, $0.0001 par value; 20,000,000 authorized and no shares issued or outstanding at March 31, 2016 and December 31, 2015	$ 0	$ 0
Common stock, $0.0001 par value; 130,000,000 shares authorized at March 31, 2016 and December 31, 2015; 30,980,181 and 30,473,083 shares issued and outstanding at March 31, 2016 and December 31, 2015, respectively	3	3
Additional paid-in capital	290,409	285,098
Accumulated other comprehensive income	80	80
Accumulated deficit	(212,444)	(202,856)
Total stockholders’ equity	78,048	82,325
Total liabilities and stockholders’ equity	$ 82,920	$ 89,081