Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Current assets:
Cash and cash equivalents	$ 189,003	$ 186,753
Marketable securities	83,292	0
Prepaid expenses and other current assets	1,812	1,738
Total current assets	274,107	188,491
Property and equipment, net	959	286
Restricted cash	564	39
Deferred offering costs		200
Total assets	275,630	189,016
Current liabilities:
Accounts payable	5,957	5,159
Accrued expenses	12,382	10,148
Total current liabilities	18,339	15,307
Other liabilities	82	14
Total liabilities	18,421	15,321
Commitments and contingencies
Stockholders' equity:
Preferred stock, $0.0001 par value per share; 5,000,000 shares authorized at June 30, 2016 and December 31, 2015, respectively; no shares issued or outstanding at June 30, 2016 and December 31, 2015, respectively
Common stock, $0.0001 par value per share; 120,000,000 shares authorized at June 30, 2016 and December 31, 2015, respectively; 32,073,437 and 28,823,549 shares issued and outstanding at June 30, 2016 and December 31, 2015, respectively	3	3
Additional paid-in capital	483,797	335,032
Accumulated deficit	(226,630)	(161,340)
Accumulated other comprehensive items	39
Total stockholders' equity	257,209	173,695
Total liabilities and stockholders' equity	$ 275,630	$ 189,016