Condensed Consolidated Statements of Cash Flows (Unaudited) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011
Operating activities:
Net loss	$ (3,210)	$ (2,918)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	104	333
Amortization of intangible assets	56	56
Amortization of premium on marketable securities	114	250
Stock based compensation expense	127	110
Gain on disposal of fixed assets	(146)
Change in fair value of preferred stock warrant liability	118
Changes in operating assets and liabilities
Contracts receivable	(2)	159
Interest receivable	(13)	104
Prepaid expenses and other current assets	(90)	(58)
Accounts payable	1,045	(447)
Accrued compensation	(347)	(212)
Deferred revenue	(5,630)	(7,783)
Accrued research and clinical liabilities	(576)	472
Other liabilities	(272)	(2)
Deferred rent	(14)	(195)
Net cash used in operating activities	(8,736)	(10,131)
Investing activities:
Purchases of property and equipment		(246)
Proceeds from sale of property and equipment	170
Purchases of marketable securities	(17,438)	(14,698)
Proceeds from maturities of marketable securities	14,255	24,680
Changes in restricted cash		(22)
Net cash provided by (used in) investing activities	(3,013)	9,714
Financing activities:
Payments of deferred financing costs	(541)
Proceeds from issuances of Series E preferred stock, net	18,845
Proceeds from issuances of common stock	23	5
Net cash provided by financing activities	18,327	5
Net increase (decrease) in cash and cash equivalents	6,578	(412)
Cash and cash equivalents, beginning of period	3,338	8,902
Cash and cash equivalents, end of period	$ 9,916	$ 8,490