CONDENSED BALANCE SHEETS (Unaudited) - USD ($)	Jun. 30, 2015	Dec. 31, 2014
Current assets:
Cash and cash equivalents	$ 38,833,736	$ 32,218,905
Short-term investments	15,002,213	45,621,593
Receivables	5,175,007	2,019,293
Interest receivable	14,196	104,627
Prepaid expenses and other current assets	976,325	3,250,355
Total current assets	60,001,477	83,214,773
Equipment and furnishings, net	879,359	970,873
Goodwill	183,780	183,780
Other assets	1,569,193	1,323,156
Total assets	62,633,809	85,692,582
Current liabilities:
Accounts payable	5,328,351	6,655,962
Accrued expenses and other current liabilities	10,376,415	5,994,072
Warrant liability	4,566,515	5,131,085
Total current liabilities	$ 20,271,281	$ 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; 55,927,197 shares issued and outstanding at June 30, 2015; 55,921,986 shares issued and outstanding at December 31, 2014	55,927	55,924
Additional paid-in capital	380,638,689	376,975,984
Treasury stock, at cost (199,275 shares)	(2,612,861)	(2,612,861)
Accumulated deficit	(335,719,227)	(306,507,584)
Total stockholders' equity	42,362,528	67,911,463
Total liabilities and stockholders' equity	$ 62,633,809	$ 85,692,582