Unaudited Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Operating activities
Net loss	$ (16,481)	$ (8,955)
Adjustments to reconcile net loss to net cash used for operating activities:
Share-based compensation expense	3,623	2,906
Third party share-based compensation expense	82	496
Depreciation expense	142	11
Loss on disposal of equipment	21	0
Changes in operating assets and liabilities:
Restricted cash	37	0
Prepaid clinical expenses	159	79
Prepaid expenses and other current assets	(790)	(485)
Other assets	(147)	(57)
Accounts payable	(98)	1,729
Accrued expenses	1,187	(809)
Accrued payroll and related expenses	(738)	(424)
Net cash used for operating activities	(13,003)	(5,509)
Investing activities
Purchase of property and equipment	(478)	(391)
Net cash used for investing activities	(478)	(391)
Financing activities
Net proceeds from the exercise of stock options for common stock	85	57
Net cash provided by financing activities	85	57
Net decrease in cash and cash equivalents	(13,396)	(5,843)
Cash and cash equivalents at beginning of period	126,467	48,555
Cash, cash equivalents at end of period	113,071	42,712
Series F Convertible Preferred Stock [Member]
Non-cash investing and financing activity:
Conversion of stock	$ 0	$ 61