CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $)	12 Months Ended			129 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2012
Operating activities:
Net loss	$ (31,735,909)	$ (50,452,165)	$ (37,330,069)	$ (215,061,410)
Adjustments to reconcile net loss to net cash used in operating activities:
Non-cash stock-based compensation	1,828,204	2,648,741	1,986,755	10,818,860
Depreciation and amortization	127,350	116,465	75,610	549,330
Stock issued for license fee	0	0	0	575,023
Non-cash interest expense	0	0	0	34,020
Loss (gain) on disposition of fixed assets	25,158	0	0	22,951
Fair value of warrants for finder's fee	0	0	0	433,750
Changes in operating assets and liabilities:
Prepaid contract research and manufacturing expenses, other prepaid expenses and other assets	615,740	(404,377)	(139,164)	(351,374)
Accounts payable, accrued contract research and manufacturing expenses and other accrued expenses	(9,848,177)	(200,603)	2,882,709	1,970,280
Accrued restructuring	841,184	0	0	841,184
Accrued compensation and related expenses	(1,219,502)	252,355	272,386	199,935
Net cash used in operating activities	(39,365,952)	(48,039,584)	(32,251,773)	(199,967,451)
Investing activities:
Acquisitions of property and equipment	(25,260)	(227,468)	(151,836)	(739,732)
Proceeds from sale of assets	12,230	0	0	15,907
Purchases of short-term investments	0	(65,605,570)	0	(115,143,906)
Redemptions of short-term investments	4,500,000	61,105,570	11,450,000	115,143,906
Security deposits	38,267	(172)	38,855	0
Net cash (used in) provided by investing activities	4,525,237	(4,727,640)	11,337,019	(723,825)
Financing activities:
Proceeds from borrowings from affiliate	0	0	0	1,745,000
(Repayment of) borrowings from line of credit	0	0	(11,466,012)	0
Proceeds from exercise of stock options	7,194	0	0	87,923
Proceeds from exercise of common stock warrants	0	8,480,135	275,331	9,054,546
Proceeds from sales of equity securities, net of issuance costs	22,151,851	37,726,538	57,403,841	218,550,016
Receipt of recovery of short-swing profits	0	73,797	0	73,797
Recapitalization of the Company	0	0	0	(400,000)
Receipt of cash for stock subscription receivable	0	0	0	4,625
Net cash provided by financing activities	22,159,045	46,280,470	46,213,160	229,115,907
Net (decrease) increase in cash and cash equivalents	(12,681,670)	(6,486,754)	25,298,406	28,424,631
Cash and cash equivalents, beginning of period	41,106,301	47,593,055	22,294,649	0
Cash and cash equivalents, end of period	28,424,631	41,106,301	47,593,055	28,424,631
Supplemental disclosure of cash flow information:
Cash paid for interest	$ 0	$ 0	$ 70,389	$ 224,328