BALANCE SHEETS (USD $) In Thousands	Jun. 30, 2011	Dec. 31, 2010
Current assets:
Cash and cash equivalents	$ 130,282	$ 60,392
Prepaid expenses and other current assets	1,016	424
Total current assets	131,298	60,816
Property and equipment, net	549	253
Deposits	91	87
Other non-current assets	883	364
Total assets	132,821	61,520
Current liabilities:
Accounts payable	1,784	1,031
Accrued expenses	6,084	2,538
Deferred revenue - current portion	800
Deferred rent - current portion	23	43
Total current liabilities	8,691	3,612
Deferred revenue	3,933
Deferred rent	58	44
Warrant liabilities	36,011	27,311
Total liabilities	48,693	30,967
Commitments and contingencies (note 6)
Stockholders' equity:
Preferred stock, $0.001 par value; 30,000,000 shares authorized and no shares issued and outstanding
Common stock, $0.001 par value; 250,000,000 shares authorized; 68,312,227 and 48,466,562 shares issued and outstanding at June 30, 2011 and December 31, 2010, respectively	68	48
Additional paid-in capital - common stock	243,809	131,530
Additional paid-in capital - warrants issued	13,797	22,789
Deficit accumulated during the development stage	(173,546)	(123,814)
Total stockholders' equity	84,128	30,553
Total liabilities and stockholders' equity	$ 132,821	$ 61,520