CONDENSED BALANCE SHEETS (Unaudited) (USD $)	Mar. 31, 2014	Dec. 31, 2013
Current assets:
Cash and cash equivalents	$ 62,028,328	$ 11,483,112
Short-term investments	50,584,980	27,084,980
Receivables	31,767	117,527
Interest receivable	27,775	8,464
Prepaid expenses and other current assets	1,725,893	2,329,742
Total current assets	114,398,743	41,023,825
Equipment and furnishings, net	156,958	175,452
Goodwill	183,780	183,780
Other assets	99,008	116,998
Total assets	114,838,489	41,500,055
Current liabilities:
Accounts payable	4,271,182	3,853,531
Accrued expenses and other current liabilities	3,047,388	2,802,833
Warrant liabilities	9,479,420	24,182,324
Total current liabilities	16,797,990	30,838,688
Commitments and contingencies
Stockholders' equity
Preferred Stock, $0.01 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, $0.001 par value, 250,000,000 shares authorized; 55,920,319 shares issued and outstanding at March 31, 2014; 42,116,964 shares issued and outstanding at December 31, 2013	55,922	42,118
Additional paid-in capital	372,126,910	289,426,100
Treasury stock, at cost (143,796 shares at March 31, 2014 and December 31, 2013)	(2,417,247)	(2,417,247)
Accumulated deficit	(271,725,086)	(276,389,604)
Total stockholders' equity	98,040,499	10,661,367
Total liabilities and stockholders' equity	$ 114,838,489	$ 41,500,055