Condensed Consolidated Balance Sheets (USD $) In Thousands	Sep. 30, 2011	Dec. 31, 2010
Current assets:
Cash and cash equivalents	$ 20,643	$ 31,310
Marketable securities	30,017	19,663
Collaboration receivable		116
Prepaid expenses and other current assets	1,362	431
Total current assets	52,022	51,520
Property and equipment, net	1,316	2,181
Other assets	530	366
Total assets	53,868	54,067
Current liabilities:
Accounts payable	2,921	1,925
Accrued contract research costs	3,010	2,511
Other accrued liabilities	3,249	4,194
Capital lease obligations	20	201
Deferred collaboration revenue	3,303	4,572
Current portion of term loans	4,613	3,333
Total current liabilities	17,116	16,736
Long-term liabilities:
Capital lease obligations	17	26
Deferred collaboration revenue		2,159
Term loans, net of current portion	12,154	11,667
Total long-term liabilities	12,171	13,852
Total liabilities	29,287	30,588
Stockholders' equity:
Preferred stock, par value $0.0001 per share Authorized: 5,000,000 shares at September 30, 2011 and December 31, 2010; no shares issued and outstanding at September 30, 2011 and December 31, 2010
Common stock, par value $0.0001 per share Authorized: 100,000,000 shares at September 30, 2011 and December 31, 2010; 49,498,350 and 42,090,205 shares issued and outstanding at September 30, 2011 and December 31, 2010, respectively	5	4
Additional paid-in-capital	412,262	374,528
Accumulated other comprehensive income (loss)	1	(3)
Accumulated deficit	(387,687)	(351,050)
Total stockholders' equity	24,581	23,479
Total liabilities and stockholders' equity	$ 53,868	$ 54,067