Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Current assets:
Cash and cash equivalents	$ 69,702	$ 114,185
Investments	149,641
Prepaid expenses and other current assets	3,020	58
Total current assets	222,363	114,243
Property and equipment, net	4,543	1,264
Restricted cash	139	139
Deferred offering costs		1,684
Deferred financing costs		15
Total assets	227,045	117,345
Current liabilities:
Accounts payable	2,089	2,166
Accrued expenses and other current liabilities	2,757	1,737
Notes payable, current portion		1,200
Total current liabilities	4,846	5,103
Notes payable, net of discount		1,304
Preferred stock warrant liability		1,582
Total liabilities	$ 4,846	$ 7,989
Commitments and contingencies
Stockholders’ equity (deficit):
Common stock, $0.001 par value; 200,000,000 and 38,000,000 shares authorized at September 30, 2015 and December 31, 2014, respectively; 39,055,767 and 6,890,250 shares issued and outstanding at September 30, 2015 and December 31, 2014 , respectively	$ 39	$ 7
Additional paid-in capital	285,148	1,104
Accumulated other comprehensive loss	(10)
Accumulated deficit	(62,978)	(27,832)
Total stockholders’ equity (deficit)	222,199	(26,721)
Total liabilities, convertible preferred stock and stockholders’ equity (deficit)	$ 227,045	117,345
Convertible Preferred Stock Series A, A-2, B, C, D and D-1 [Member]
Current liabilities:
Convertible preferred stock (Series A, A-2, B, C, D and D-1), value		$ 136,077