Condensed Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 11,877	$ 9,388
Marketable securities	62,644	83,181
Income tax receivable	777	731
Other receivables	84	123
Prepaid expenses	3,431	1,635
Total current assets	78,813	95,058
Property and equipment, net	1,053	1,177
Restricted cash	769	769
Total assets	80,635	97,004
Current liabilities:
Accounts payable and accrued expenses	6,875	8,506
Total current liabilities	6,875	8,506
Deferred lease obligation	1,657	1,718
Commitments and contingencies (Note 15)
Stockholders’ equity:
Preferred stock; $0.001 par value; 5,000,000 shares authorized at March 31,2018 and December 31, 2017, zero shares issued and outstanding at March 31, 2018 and December 31, 2017
Common stock; $0.001 par value; 100,000,000 shares authorized at March 31, 2018 and December 31, 2017, 32,699,943 shares and 32,662,255 shares issued and outstanding at March 31, 2018 and December 31, 2017, respectively	33	33
Additional paid-in capital	309,292	307,158
Accumulated deficit	(237,108)	(220,341)
Accumulated other comprehensive loss	(114)	(70)
Total stockholders’ equity	72,103	86,780
Total liabilities and stockholders’ equity	$ 80,635	$ 97,004