Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Cash Flows From Operating Activities:
Net Loss	$ (11,078)	$ (12,358)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation	1,052	827
Stock issued for milestone payments	0	350
Change in fair value of warrant liabilities	498	4,152
Depreciation	37	8
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	2,403	(26)
Deposits and other assets	(12)	(12)
Accounts payable	184	563
Accrued expenses	649	1,348
Accrued employee benefits	592	(310)
Deferred rent	1	0
Net Cash Used In Operating Activities	(5,674)	(5,458)
Cash Flows From Investing Activities:
Purchases of property and equipment	(44)	(18)
Net Cash Used In Investing Activities	(44)	(18)
Net decrease in cash	(5,718)	(5,476)
Cash at beginning of period	20,818	17,525
Cash at end of period	15,100	12,049
Supplemental disclosures of cash flow information:
Cash paid for interest	0	0
Cash paid for taxes	$ 0	$ 0