Condensed Consolidated Statements of Operations (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Revenues:
Grant and royalty revenue	$ 705,625	$ 358,090	$ 1,282,920	$ 758,710
Research and development revenue under collaborative agreements	1,845,021	1,060,057	4,396,132	4,743,170
Total revenues	2,550,646	1,418,147	5,679,052	5,501,880
Expenses:
Research and development	3,353,057	1,700,803	7,777,218	6,335,193
General and administrative	976,660	1,070,989	3,089,402	2,825,739
Total expenses	4,329,717	2,771,792	10,866,620	9,160,932
Loss from operations	(1,779,071)	(1,353,645)	(5,187,568)	(3,659,052)
Other income (expense), net	(420)	(47,926)	26,602	(43,239)
Change in fair value of warrants	(750,000)	300,000		2,600,000
Total other income (expense), net	(750,420)	252,074	26,602	2,556,761
Net loss	$ (2,529,491)	$ (1,101,571)	$ (5,160,966)	$ (1,102,291)
Basic and diluted net loss per share (in dollars per share)	$ (0.19)	$ (0.10)	$ (0.38)	$ (0.10)
Weighted-average shares outstanding used in the calculation (in shares)	13,428,623	11,004,495	13,416,748	10,516,428