Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015
Cash Flows From Operating Activities:
Net Loss	$ (25,331)	$ (33,488)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation	2,906	2,059
Stock issued for milestone payments	0	1,350
Stock issued for exclusive channel collaboration agreement	0	3,000
Change in fair value of warrant liabilities	(3,681)	3,906
Depreciation	111	39
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	6,428	(8,783)
Deposits and other assets	(12)	(8)
Accounts payable	(171)	5,030
Accrued expenses	1,193	(1,054)
Accrued employee benefits	1,063	(224)
Deferred rent	(23)	253
Net Cash Used In Operating Activities	(17,517)	(27,920)
Cash Flows From Investing Activities:
Purchases of property and equipment	(199)	(457)
Net Cash Used In Investing Activities	(199)	(457)
Cash Flows From Financing Activities:
Proceeds from issuance of common stock	0	46,000
Cash paid as direct offering costs	0	(3,357)
Proceeds from issuance of common stock for stock option exercises	814	0
Proceeds from "at the market" stock issuance, net of issuance costs	633	15
Net Cash Provided By Financing Activities	1,447	42,658
Net increase (decrease) in cash	(16,269)	14,281
Cash at beginning of period	20,818	17,525
Cash at end of period	4,549	31,806
Supplemental disclosures of cash flow information:
Cash paid for interest	0	0
Cash paid for taxes	$ 0	$ 0