CONDENSED CONSOLIDATED BALANCE SHEETS (USD $) In Thousands, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Current assets:
Cash and cash equivalents	$ 132,307	$ 155,974
Prepaid expenses and other current assets	2,976	1,982
Total current assets	135,283	157,956
Property and equipment, net	604	240
Other assets	1,392	30
Restricted cash	400
Total assets	137,679	158,226
Current liabilities:
Accounts payable	3,456	1,740
Accrued expenses	2,003	1,168
Deferred revenue	36	79
Deferred rent	22
Other current liabilities	130	305
Total current liabilities	5,647	3,292
Deferred rent	201
Other long-term liabilities	151
Total Liabilities	5,999	3,292
Stockholders' equity
Convertible preferred stock, $0.0001 par value; 5,000,000 shares authorized; none issued and outstanding
Common stock, $0.0001 par value; 100,000,000 shares authorized; 29,720,422 and 29,587,258 shares issued and outstanding at June 30, 2014 and December 31, 2013, respectively	3	3
Additional paid-in capital	224,371	217,500
Accumulated deficit	(92,694)	(62,569)
Total stockholders' equity	131,680	154,934
Total liabilities and stockholders' equity	$ 137,679	$ 158,226