Condensed Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Current assets:
Cash and cash equivalents	$ 111,116	$ 52,663
Income tax receivable	450	200
Other receivables	2,143
Prepaid expenses	1,971	287
Total current assets	115,680	53,150
Property and equipment, net	1,517	2,084
Restricted cash	700	700
Total assets	117,897	55,934
Current liabilities:
Accounts payable and accrued expenses	3,374	1,946
Deferred revenue		1,452
Total current liabilities	3,374	3,398
Deferred lease obligation	$ 660	$ 874
Commitments and contingencies (Note 11)
Stockholders' equity:
Preferred stock; $0.001 par value; 5,000,000 shares authorized at September 30, 2015 and December 31, 2014, zero shares issued and outstanding at September 30, 2015 and December 31, 2014
Common stock; $0.001 par value; 100,000,000 shares authorized at September 30, 2015 and December 31, 2014, 27,231,583 shares and 22,802,039 shares issued and outstanding at September 30, 2015 and December 31, 2014, respectively	$ 27	$ 23
Additional paid-in capital	209,197	131,840
Accumulated deficit	(95,361)	(80,201)
Total stockholders' equity	113,863	51,662
Total liabilities and stockholders' equity	$ 117,897	$ 55,934