BALANCE SHEETS (USD $)
Dec. 31, 2014
Dec. 31, 2013
Current assets:    
Cash and cash equivalents $ 32,218,905 $ 11,483,112
Short-term investments 45,621,593 27,084,980
Receivables 2,019,293 117,527
Interest receivable 104,627 8,464
Prepaid expenses and other current assets 3,250,355 2,329,742
Total current assets 83,214,773 41,023,825
Equipment and furnishings, net 970,873 175,452
Goodwill 183,780 183,780
Other assets 1,323,156 116,998
Total assets 85,692,582 41,500,055
Current liabilities:    
Accounts payable 6,655,962 3,853,531
Accrued expenses and other current liabilities 5,994,072 2,802,833
Warrant liabilities 5,131,085 24,182,324
Total current liabilities 17,781,119 30,838,688
Commitment and contingencies      
Stockholders' equity:    
Preferred Stock, $.01 par value, 5,000,000 shares authorized, including 25,000 shares of Series A Junior Participating Preferred Stock; no shares issued and outstanding 0 0
Common stock, $.001 par value, 250,000,000 shares authorized; 55,921,986 and 42,116,964 shares issued and outstanding at December 31, 2014 and 2013, respectively 55,924 42,118
Additional paid-in capital 376,975,984 289,426,100
Treasury stock, at cost (199,275 and 143,796 shares at December 31, 2014 and 2013, respectively) (2,612,861) (2,417,247)
Accumulated deficit (306,507,584) (276,389,604)
Total stockholders' equity 67,911,463 10,661,367
Total liabilities and stockholders' equity $ 85,692,582 $ 41,500,055