Condensed Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Current assets:
Cash and cash equivalents	$ 7,922	$ 15,101
Marketable securities	88,322	91,640
Income tax receivable	529	384
Other receivables	128	80
Prepaid expenses	2,573	1,729
Total current assets	99,474	108,934
Property and equipment, net	1,070	1,263
Restricted cash	1,469	700
Total assets	102,013	110,897
Current liabilities:
Accounts payable and accrued expenses	6,089	5,268
Total current liabilities	6,089	5,268
Deferred lease obligation	$ 997	$ 585
Commitments and contingencies (Note 12)
Stockholders' equity:
Preferred stock; $0.001 par value; 5,000,000 shares authorized at March 31, 2016 and December 31, 2015, zero shares issued and outstanding at March 31, 2016 and December 31, 2015
Common stock; $0.001 par value; 100,000,000 shares authorized at March 31, 2016 and December 31, 2015, 27,282,863 shares and 27,254,863 shares issued and outstanding at March 31, 2016 and December 31, 2015, respectively	$ 27	$ 27
Additional paid-in capital	210,479	209,943
Accumulated deficit	(115,583)	(104,891)
Accumulated other comprehensive income (loss)	4	(35)
Total stockholders' equity	94,927	105,044
Total liabilities and stockholders' equity	$ 102,013	$ 110,897