STATEMENTS OF CASH FLOWS (USD $) In Thousands	6 Months Ended		95 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011
Cash flows from operating activities:
Net loss	$ (49,732)	$ (8,614)	$ (173,546)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	95	116	1,744
Stock-based compensation	1,314	2,174	13,855
Change in fair value of warrants	8,965	(1,049)	11,827
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:
Prepaid expenses and other current assets	(592)	76	(1,016)
Other noncurrent assets	(519)	30	(883)
Deposits	(4)	(41)	(91)
Increase (decrease) in:
Accounts payable	753	(646)	1,784
Accrued expenses	3,546	(122)	6,084
Deferred revenue	4,733		4,733
Deferred rent	(5)	(28)	81
Net cash used in operating activities	(13,989)	(8,104)	(117,962)
Cash flows from investing activities:
Purchases of property and equipment	(392)	(78)	(2,303)
Proceeds from sale of property and equipment			1
Net cash used in investing activities	(392)	(78)	(2,302)
Cash flows from financing activities:
Stockholders' capital contribution			500
Proceeds from exercise of stock options	849	176	1,212
Payments to employees for repurchase of common stock	(78)	(47)	(2,126)
Proceeds from exercise of warrants	12,293	72	12,644
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	84,271	33,005	250,546
Net increase (decrease) in cash and cash equivalents	69,890	24,823	130,282
Cash and cash equivalents, beginning of period	60,392	48,839
Cash and cash equivalents, end of period	130,282	73,662	130,282
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	265	49	314
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	$ 8,992	$ 239	$ 9,249