Consolidated Balance Sheets (Unaudited) (USD $) In Thousands	Jun. 30, 2011	Dec. 31, 2010
Current assets:
Cash and cash equivalents	$ 25,789	$ 29,572
Investments in marketable securities	57,257	77,873
Receivable due from GSK	1,977	0
Prepaid expenses and other current assets	3,076	2,236
Total current assets	88,099	109,681
Property and equipment, accumulated depreciation and amortization of $8,095 and $8,959 at December 31, 2010 and June 30, 2011, respectively	1,922	2,604
Other non-current assets	267	267
Total Assets	90,288	112,552
Current liabilities:
Accounts payable and accrued expenses	7,019	8,290
Current portion of capital lease obligations	0	40
Current portion of deferred revenue	8,606	6,640
Current portion of secured loan	1,253	1,253
Total current liabilities	16,878	16,223
Deferred revenue, less current portion	22,319	25,639
Warrant liability	6,066	4,712
Secured loan, less current portion	418	1,044
Commitments and contingencies
Stockholders' equity:
Common stock, $.01 par value, 50,000,000 shares authorized, 34,508,932 shares issued and outstanding at December 31, 2010, 50,000,000 shares authorized, 34,596,809 shares issued and outstanding at June 30, 2011	406	406
Additional paid-in capital	295,898	290,248
Accumulated other comprehensive loss	(14)	(28)
Deficit accumulated during the development stage	(251,683)	(225,692)
Total stockholders' equity	44,607	64,934
Total Liabilities and Stockholders' Equity	$ 90,288	$ 112,552