Condensed Consolidated Balance Sheets (Unaudited) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Current assets:
Cash and cash equivalents	$ 18,526	$ 14,902	[1]
Marketable securities		2,001	[1]
Restricted cash	7,847
Receivables		10,000	[1]
Prepaid expenses and other current assets	522	649	[1]
Total current assets	26,895	27,552	[1]
Property and equipment, net	17,875	20,425	[1]
Other assets	615	628	[1]
Total assets	45,385	48,605	[1]
Current liabilities:
Accounts payable	1,384	3,603	[1]
Accrued clinical trial expenses	96	134	[1]
Other accrued expenses	2,248	2,872	[1]
Current portion of contingent consideration liability	5,100	12,300	[1]
Financing obligations	9,473	12,280	[1]
Current portion of deferred revenue	2,915	3,759	[1]
Total current liabilities	21,216	34,948	[1]
Deferred rent	9,089	12,274	[1]
Noncurrent portion of contingent consideration liability	5,200	4,200	[1]
Noncurrent portion of deferred revenues	6,558	6,875	[1]
Stockholders' equity:
Preferred stock			[1]
Common stock	1	1	[1]
Additional paid-in-capital	320,740	296,942	[1]
Deficit accumulated during development stage	(317,419)	(306,635)	[1]
Total stockholders' equity (deficit)	3,322	(9,692)	[1]
Total liabilities and stockholders' equity	$ 45,385	$ 48,605	[1]

[1] The condensed consolidated balance sheet at December 31, 2011 has been derived from audited consolidated financial statements at that date.