BALANCE SHEETS (USD $) In Thousands	Sep. 30, 2010	Dec. 31, 2009
Current assets:
Cash and cash equivalents	$ 66,471	$ 48,839
Prepaid expenses and other current assets	352	354
Total current assets	66,823	49,193
Property and equipment, net	230	255
Deposits	87	46
Other non-current assets	310	242
Total assets	67,450	49,736
Current liabilities:
Accounts payable	1,088	1,789
Accrued expenses	2,978	1,261
Deferred rent - current portion	40	45
Total current liabilities	4,106	3,095
Deferred rent	55	66
Warrant liabilities	21,085	18,471
Total liabilities	25,246	21,632
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; 48,557,678 and 41,583,528 shares issued and outstanding at September 30, 2010 and December 31, 2009, respectively	49	42
Additional paid-in capital - common stock	131,284	96,133
Additional paid-in capital - warrants issued	22,834	23,073
Deficit accumulated during the development stage	(111,963)	(91,144)
Total stockholders' equity	42,204	28,104
Total liabilities and stockholders' equity	$ 67,450	$ 49,736