Condensed Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 96,729	$ 9,388
Marketable securities	109,348	83,181
Income tax receivable	539	731
Other receivables	193	123
Prepaid expenses	4,218	1,635
Restricted cash, current	361
Total current assets	211,388	95,058
Property and equipment, net	908	1,177
Restricted cash	408	769
Total assets	212,704	97,004
Current liabilities:
Accounts payable and accrued expenses	14,003	8,506
Current portion of deferred revenue	29,242
Total current liabilities	43,245	8,506
Deferred revenue, non-current	18,300
Deferred lease obligation	1,629	1,718
Commitments and contingencies (Note 15)
Stockholders’ equity:
Preferred stock; $0.001 par value; 5,000,000 shares authorized at September 30, 2018 and December 31, 2017, zero shares issued and outstanding at September 30, 2018 and December 31, 2017
Common stock; $0.001 par value; 100,000,000 shares authorized at September 30, 2018 and December 31, 2017, 39,389,515 shares and 32,662,255 shares issued and outstanding at September 30, 2018 and December 31, 2017, respectively	39	33
Additional paid-in capital	423,180	307,158
Accumulated deficit	(273,702)	(220,341)
Accumulated other comprehensive income (loss)	13	(70)
Total stockholders’ equity	149,530	86,780
Total liabilities and stockholders’ equity	$ 212,704	$ 97,004