Condensed Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Current assets:
Cash and cash equivalents	$ 5,426	$ 15,101
Marketable securities	65,994	91,640
Income tax receivable	663	384
Other receivables	115	80
Prepaid expenses	4,820	1,729
Total current assets	77,018	108,934
Property and equipment, net	1,665	1,263
Restricted cash	1,469	700
Total assets	80,152	110,897
Current liabilities:
Accounts payable and accrued expenses	6,825	5,268
Total current liabilities	6,825	5,268
Deferred lease obligation	1,525	585
Commitments and contingencies (Note 14)
Stockholders' equity:
Preferred stock; $0.001 par value; 5,000,000 shares authorized at September 30, 2016 and December 31, 2015, zero shares issued and outstanding at September 30, 2016 and December 31, 2015.
Common stock; $0.001 par value; 100,000,000 shares authorized at September 30, 2016 and December 31, 2015, 27,282,863 shares and 27,254,863 shares issued and outstanding at September 30, 2016 and December 31, 2015, respectively.	27	27
Additional paid-in capital	211,954	209,943
Accumulated deficit	(140,199)	(104,891)
Accumulated other comprehensive income (loss)	20	(35)
Total stockholders' equity	71,802	105,044
Total liabilities and stockholders' equity	$ 80,152	$ 110,897