Condensed Consolidated Balance Sheets (USD $) In Thousands	Jun. 30, 2011	Dec. 31, 2010
Current assets:
Cash and cash equivalents	$ 25,891	$ 31,310
Marketable securities	36,998	19,663
Collaboration receivable		116
Prepaid expenses and other current assets	832	431
Total current assets	63,721	51,520
Property and equipment, net	1,403	2,181
Other assets	497	366
Total assets	65,621	54,067
Current liabilities:
Accounts payable	1,999	1,925
Accrued contract research costs	2,871	2,511
Other accrued liabilities	2,909	4,194
Capital lease obligations	31	201
Deferred collaboration revenue	4,446	4,572
Current portion of term loans	3,093	3,333
Total current liabilities	15,349	16,736
Long-term liabilities:
Capital lease obligations	20	26
Deferred collaboration revenue		2,159
Term loans, net of current portion	13,815	11,667
Total long-term liabilities	13,835	13,852
Total liabilities	29,184	30,588
Stockholders' equity:
Preferred stock, par value $0.0001 per share Authorized: 5,000,000 shares at June 30, 2011 and December 31, 2010; no shares issued and outstanding at June 30, 2011 and December 31, 2010
Common stock, par value $0.0001 per share Authorized: 100,000,000 shares at June 30, 2011 and December 31, 2010; 49,473,070 and 42,090,205 shares issued and outstanding at June 30, 2011 and December 31, 2010, respectively	5	4
Additional paid-in-capital	411,375	374,528
Accumulated other comprehensive income (loss)	10	(3)
Accumulated deficit	(374,953)	(351,050)
Total stockholders' equity	36,437	23,479
Total liabilities and stockholders' equity	$ 65,621	$ 54,067