CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Costs and Expenses:
Research and development	$ 19,525	$ 24,479	$ 37,723	$ 37,778
General and administrative	7,394	2,279	12,000	5,457
Loss from Operations	(26,919)	(26,758)	(49,723)	(43,235)
Other Income/(Loss)
Interest and investment income/(expense), net (includes interest expense of $3,388 and $7,139 on Senior Convertible Debentures and $1,899 and $2,516 in amortization of deferred financing costs for the three and six months ended June 30, 2015)	(5,207)	(1)	(9,524)	28
State R&D tax credits		83		83
Change in fair value of derivative instruments-warrants	(1,542)	756	(1,810)	979
Total Other Income/(Loss)	(6,749)	838	(11,334)	1,090
Net Loss	$ (33,668)	$ (25,920)	$ (61,057)	$ (42,145)
Weighted Average Common Shares Outstanding
Basic and Diluted (in shares)	100,343,637	94,069,703	98,523,696	93,068,476
Net Loss per Common Share, Basic and Diluted
Net Loss per Common Share, Basic and Diluted (in dollars per share)	$ (0.34)	$ (0.28)	$ (0.62)	$ (0.45)