Statements of Operations (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Licensing revenue		$ 2,000,000
Operating expenses:
Research and development	15,770,166	19,863,836	14,714,460
General and administrative	6,372,551	5,154,933	4,922,967
Total operating expenses	22,142,717	25,018,769	19,637,427
Loss from operations	(22,142,717)	(23,018,769)	(19,637,427)
Other (expense) income:
(Loss) gain from valuation of common stock warrant liability	(4,117,534)	81,733	573,760
Investment income	52,322	174,064	32,289
Interest expense	(359,413)	(501,855)	(31,517)
Other (expense) income	(1,040)	42,149	244,460
Total other (expense) income	(4,425,665)	(203,909)	818,992
Net loss	$ (26,568,382)	$ (23,222,678)	$ (18,818,435)
Net loss per common share – basic and diluted (in Dollars per share)	$ (0.76)	$ (1.11)	$ (1.52)
Weighted average common shares outstanding – basic and diluted (in Shares)	34,789,068	20,917,678	12,375,402