Balance Sheets (USD $)	Dec. 31, 2012	Dec. 31, 2011
Current assets:
Cash and cash equivalents	$ 14,991,488	$ 20,145,854
Investment securities – available for sale	8,037,620	10,157,160
Accrued interest receivable on investment securities	65,925	243,745
Advances and deposits on investigator grants	246,352	758,297
Vendor reimbursements receivable	116,872
Other current assets	190,727	203,429
Total current assets	23,648,984	31,508,485
Property and equipment (at cost, less accumulated depreciation of $924,961 and $643,472, respectively)	1,114,621	782,720
Other assets:
Deferred financing fees	306,495
Security deposit on letter of credit	250,000	250,000
Patent license fees, net	28,125	35,625
Deposits and other assets	10,693	72,629
Total other assets	595,313	358,254
Total assets	25,358,918	32,649,459
Current liabilities:
Accounts payable - trade	2,339,768	4,010,203
Other accrued liabilities	1,254,979	2,031,934
Note payable - current portion	1,410,455	110,287
Total current liabilities	5,005,202	6,152,424
Common stock warrant liability	4,283,932	166,398
Note payable – non-current portion	3,661,147	71,602
Other liabilities - noncurrent	446,779	65,467
Total liabilities	13,397,060	6,455,891
Stockholders’ equity:
Common stock - $0.01 par value (75,000,000 shares authorized; 37,967,708 and 33,899,057 shares issued at December 31, 2012 and 2011 and 37,302,785 and 33,186,325 shares outstanding at December 31, 2012 and 2011, respectively)	379,677	338,991
Additional paid-in capital	165,276,069	153,237,225
Accumulated other comprehensive loss	(126,607)	(276,700)
Accumulated deficit	(150,876,770)	(124,221,823)
Subtotal	14,652,369	29,077,693
Treasury stock, at cost (664,923 and 712,732 shares at December 31, 2012 and 2011, respectively)	(2,690,511)	(2,884,125)
Total stockholders’ equity	11,961,858	26,193,568
Total liabilities and stockholders’ equity	$ 25,358,918	$ 32,649,459