Condensed Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	3 Months Ended		166 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Mar. 31, 2013
Cash Flows From Development Activities
Net loss	$ (7,934)	$ (4,842)	$ (113,274)
Adjustments to reconcile net loss to net cash used in development activities:
Share-based compensation	966	736	9,510
Depreciation and amortization	212	175	3,961
Loss on sale of fixed assets	0	20	38
In-process research and development expenses	0	0	1,629
Forgiveness of debt	0	0	(449)
Forgiveness of notes receivable from related parties	0	0	350
Changes in operating assets and liabilities:
Prepaid expenses	250	117	(657)
State research and development credit receivable	(85)	(45)	(627)
Other receivables	(261)	(724)	(457)
Accounts payable	(106)	(1,042)	(366)
Accrued expenses and deferred rent	335	(35)	3,483
Net cash used in development activities	(6,623)	(5,640)	(96,859)
Cash Flows From Investing Activities
Purchase of certificates of deposit	0	0	(13,282)
Sale of certificates of deposit	747	0	12,535
Notes receivable from related parties	0	0	(350)
Purchase of equipment	(62)	(709)	(8,154)
Proceeds on sale of fixed assets	0	50	50
Cash paid for OncoRx	0	0	(120)
Net cash used in investing activities	685	(659)	(9,321)
Cash Flows From Financing Activities
Cash received from noncontrolling interest investment	0	0	3,479
Issuance of common stock, net of offering costs	49,035	135	91,480
Repurchase of common stock	0	(4)	(505)
Proceeds from preferred stock	0	0	67,743
Proceeds from notes payable	0	0	8,215
Principal payments on debt	(37)	(23)	(513)
Payments under capital lease obligations	(32)	(30)	(441)
Net cash provided by financing activities	48,966	78	169,458
Net (decrease) increase in cash and cash equivalents	43,028	(6,221)	63,278
Cash and cash equivalents at beginning of period	20,250	39,490
Cash and cash equivalents at end of period	63,278	33,269	63,278
Supplemental disclosure of cash flows information:
Cash paid for interest	8	10	150
Noncash financing and investing activities:
Accretion on redeemable preferred stock	0	0	113
Purchased leasehold improvements and equipment in accounts payable	9	173	9
Common stock issued to shareholders of OncoRx as part of acquisition	0	0	1,654
Issuance of common stock dividend to Series AA preferred shareholders	0	0	6
Assets acquired under capital lease	0	0	542
Reduction of IPO offering costs	$ 0	$ 0	$ 158