CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended
Mar. 31, 2015	Mar. 31, 2014
Costs and Expenses:
Research and development	$ 18,198	$ 13,299
General and administrative	4,606us-gaap_GeneralAndAdministrativeExpense	3,178us-gaap_GeneralAndAdministrativeExpense
Loss from Operations	(22,804)us-gaap_OperatingIncomeLoss	(16,477)us-gaap_OperatingIncomeLoss
Other Income/(Loss)
Amortization of deferred financing costs	(617)us-gaap_AmortizationOfFinancingCosts
Interest and investment income/ (expense), net (includes interest expense of $3,750 on Senior Convertible Debentures for the three months ended March 31, 2015	(3,700)us-gaap_InvestmentIncomeNet	29us-gaap_InvestmentIncomeNet
Change in fair value of derivative instruments-warrants	(268)us-gaap_UnrealizedGainLossOnDerivatives	223us-gaap_UnrealizedGainLossOnDerivatives
Total Other Income/(Loss)	(4,585)us-gaap_NonoperatingIncomeExpense	252us-gaap_NonoperatingIncomeExpense
Net loss	$ (27,389)	$ (16,225)
Weighted Average Common Shares Outstanding
Basic and Diluted (in shares)	96,683,525	92,056,124
Net Loss per Common Share, Basic and Diluted
Net Loss per Common Share, Basic and Diluted (in dollars per share)	$ (0.28)us-gaap_EarningsPerShareBasicAndDiluted	$ (0.18)us-gaap_EarningsPerShareBasicAndDiluted

Amount of noncash expense included in interest expense to issue debt and obtain financing associated with the related debt instruments. Alternate captions include noncash interest expense.

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