Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 9,388	$ 12,092
Marketable securities	83,181	46,184
Income tax receivable	731	852
Other receivables	123	87
Prepaid expenses	1,635	1,530
Restricted cash, current		700
Total current assets	95,058	61,445
Property and equipment, net	1,177	1,614
Restricted cash	769	769
Total assets	97,004	63,828
Current liabilities:
Accounts payable and accrued expenses	8,506	11,533
Total current liabilities	8,506	11,533
Deferred lease obligation	1,718	1,570
Commitments and contingencies (Note 16)
Stockholders’ equity:
Preferred stock; $0.001 par value; 5,000,000 shares authorized at December 31, 2017 and December 31, 2016; zero shares issued and outstanding at December 31, 2017 and December 31, 2016
Common stock; $0.001 par value; 100,000,000 shares authorized at December 31, 2017 and December 31, 2016; 32,662,255 shares and 27,296,863 shares issued and outstanding at December 31, 2017 and December 31, 2016, respectively	33	27
Additional paid-in capital	307,158	212,866
Accumulated deficit	(220,341)	(162,171)
Accumulated other comprehensive (loss) income	(70)	3
Total stockholders’ equity	86,780	50,725
Total liabilities and stockholders’ equity	$ 97,004	$ 63,828