Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Current assets:
Cash and cash equivalents	$ 95,894	$ 43,224
Short-term investments	51,759	83,438
Prepaid expenses and other current assets	2,458	3,002
Restricted cash	0	197
Total current assets	150,111	129,861
Property and equipment, net	8,149	8,313
Restricted cash	439	439
Other long-term assets	23	0
Total assets	158,722	138,613
Current liabilities:
Accounts payable	2,466	3,352
Accrued expenses and other current liabilities	8,274	7,891
Total current liabilities	10,740	11,243
Deferred rent and other non-current liabilities	1,425	520
Total liabilities	12,165	11,763
Stockholders’ equity:
Preferred stock, $0.001 par value; 5,000,000 shares authorized, no shares issued and outstanding	0	0
Common stock, $0.001 par value; 100,000,000 shares authorized; 35,560,346 and 27,296,747 shares issued and outstanding at June 30, 2016 and December 31, 2015, respectively	36	27
Additional paid-in capital	354,755	294,910
Accumulated other comprehensive income (loss)	9	(170)
Accumulated deficit	(208,243)	(167,917)
Total stockholders’ equity	146,557	126,850
Total liabilities and stockholders’ equity	$ 158,722	$ 138,613