Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Current assets:
Cash and cash equivalents	$ 66,809	$ 62,944
Marketable securities	92,693	48,303
Accounts receivable		95
Prepaid expenses and other current assets	1,584	761
Total current assets	161,086	112,103
Property and equipment, net	11,223	7,442
Long-term investments	2,003	7,357
Other assets	30	157
Restricted cash	80	80
Total assets	174,422	127,139
Current liabilities:
Accounts payable	2,029	3,692
Accrued expenses and other current liabilities	3,724	4,367
Current portion of long-term debt	6,634
Total current liabilities	12,387	8,059
Long-term debt	23,664	15,002
Other long-term liabilities	339	91
Total liabilities	36,390	23,152
Commitments and contingencies
Preferred Stock, $0.001 par value; 10,000,000 shares authorized at September 30, 2016 and December 31, 2015 and 0 shares issued and outstanding at September 30, 2016 and December 31, 2015
Stockholders’ equity:
Common stock, $0.001 par value; 100,000,000 shares authorized; 27,527,419 and 21,570,395 shares issued and outstanding, at September 30, 2016 and December 31, 2015, respectively	28	22
Additional paid-in capital	326,605	243,854
Accumulated other comprehensive income	(27)	(97)
Accumulated deficit	(188,574)	(139,792)
Total stockholders’ equity	138,032	103,987
Total liabilities and stockholders’ equity	$ 174,422	$ 127,139