STATEMENTS OF OPERATIONS (USD $)
12 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Revenue:      
Licensing revenue $ 100,000 $ 300,000 $ 100,000
Expenses:      
Research and development 36,677,706 17,500,469 12,684,793
General and administrative 12,845,231 10,273,576 8,353,330
Depreciation and amortization 182,927 120,399 113,936
Total expenses 49,705,864 27,894,444 21,152,059
Loss before other income (loss) (49,605,864) (27,594,444) (21,052,059)
Other income (loss):      
Interest income 305,331 137,676 131,666
Other income, net 132,114 183,025 191,416
(Gain) loss on warrant liability 19,051,239 (20,210,094) 2,766,704
Loss before provision for income taxes (30,117,180) (47,483,837) (17,962,273)
Income tax expense (800) (1,600) (1,600)
Net loss $ (30,117,980) $ (47,485,437) $ (17,963,873)
Basic and diluted loss per share $ (0.55) $ (1.44) $ (0.78)
Basic weighted average shares outstanding (in shares) 54,371,151 32,891,202 22,973,905
Diluted weighted average shares outstanding (in shares) 54,371,151 32,891,202 22,973,905