CONDENSED BALANCE SHEETS (Unaudited) - USD ($)	Sep. 30, 2015	Dec. 31, 2014
Current assets:
Cash and cash equivalents	$ 55,779,620	$ 32,218,905
Short-term investments	15,022,454	45,621,593
Receivables	1,667,905	2,019,293
Interest receivable	6,754	104,627
Prepaid expenses and other current assets	1,462,014	3,250,355
Total current assets	73,938,747	83,214,773
Equipment and furnishings, net	1,057,988	970,873
Goodwill	183,780	183,780
Other assets	1,565,542	1,323,156
Total assets	76,746,057	85,692,582
Current liabilities:
Accounts payable	6,210,567	6,655,962
Accrued expenses and other current liabilities	5,967,309	5,994,072
Warrant liability	1,051,337	5,131,085
Total current liabilities	$ 13,229,213	$ 17,781,119
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; 66,679,340 shares issued and outstanding at September 30, 2015; 55,921,986 shares issued and outstanding at December 31, 2014	66,679	55,924
Additional paid-in capital	408,855,605	376,975,984
Treasury stock, at cost (199,275 shares)	(2,612,861)	(2,612,861)
Accumulated deficit	(342,792,579)	(306,507,584)
Total stockholders' equity	63,516,844	67,911,463
Total liabilities and stockholders' equity	$ 76,746,057	$ 85,692,582