STATEMENTS OF CASH FLOWS (USD $) In Thousands	9 Months Ended		98 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011
Cash flows from operating activities:
Net loss	$ (50,534)	$ (20,819)	$ (174,348)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	172	153	1,821
Stock-based compensation	1,900	3,198	14,441
Change in fair value of warrants	(4,423)	2,663	(1,561)
Common stock issued in exchange for in-process research and development	17,457		17,457
Loss on disposal of fixed assets			9
(Increase) decrease in:
Collaboration receivable	(79)		(79)
Prepaid expenses and other current assets	(981)	3	(1,405)
Other noncurrent assets	(518)	(67)	(882)
Deposits	(4)	(41)	(91)
Increase (decrease) in:
Accounts payable	1,129	(703)	2,160
Accrued expenses	6,251	1,717	8,789
Deferred revenue	4,533		4,533
Deferred rent	12	(15)	98
Net cash used in operating activities	(25,085)	(13,911)	(129,058)
Cash flows from investing activities:
Purchases of property and equipment	(806)	(128)	(2,717)
Proceeds from sale of property and equipment			1
Net cash used in investing activities	(806)	(128)	(2,716)
Cash flows from financing activities:
Stockholders' capital contribution			500
Proceeds from exercise of stock options	904	225	1,267
Payments to employees for repurchase of common stock	(78)	(1,429)	(2,126)
Proceeds from exercise of warrants	12,399	71	12,750
Proceeds from issuance of common stock and warrants, net	71,207	32,804	221,556
Proceeds from issuance of preferred stock, net			16,760
Net cash provided by financing activities	84,432	31,671	250,707
Net increase (decrease) in cash and cash equivalents	58,541	17,632	118,933
Cash and cash equivalents, beginning of period	60,392	48,839
Cash and cash equivalents, end of period	118,933	66,471	118,933
Supplementary disclosure of cash flow information:
Cash paid for interest
Cash paid for income taxes
Supplementary disclosure of noncash investing and financing activities:
Warrants issued to placement agents and investors			47,276
Exercise of liability-classified warrants to common shares	303	49	352
Convertible Preferred Stock
Supplementary disclosure of noncash investing and financing activities:
Preferred stock conversion/exercise of equity-classified warrants to common stock			16,760
Warrant
Supplementary disclosure of noncash investing and financing activities:
Preferred stock conversion/exercise of equity-classified warrants to common stock	$ 9,067	$ 257	$ 9,324