Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	12 Months Ended			163 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2012
Cash Flows From Development Activities
Net loss	$ (23,321)	$ (18,088)	$ (16,562)	$ (105,340)
Adjustments to reconcile net loss to net cash used in development activities:
Share-based compensation	3,195	2,545	1,525	8,544
Depreciation and amortization	788	687	655	3,749
Loss on sale of fixed assets	38	0	819	38
In-process research and development expenses	0	0	201	1,629
Forgiveness of debt	0	0	0	(449)
Forgiveness of notes receivable from related parties	0	0	350	350
Changes in operating assets and liabilities:
Prepaid expenses	498	(550)	849	907
State research and development credit receivable	340	(28)	60	542
Other receivables	0	(416)	(797)	196
Accounts payable	(700)	637	(528)	(260)
Accrued expenses and deferred rent	367	276	382	3,148
Net cash used in development activities	(20,471)	(12,949)	(13,270)	(90,236)
Cash Flows From Investing Activities
Purchase of certificates of deposit	(1,992)	(2,490)	(277)	(13,282)
Sale of certificates of deposit	2,988	2,269	0	11,788
Notes receivable from related parties	0	0	500	(350)
Purchase of equipment	(1,323)	(281)	(2,932)	(8,092)
Proceeds on sale of fixed assets	50	0	0	50
Cash paid for OncoRx	0	0	0	(120)
Net cash used in investing activities	(277)	(502)	(2,709)	(10,006)
Cash Flows From Financing Activities
Cash received from noncontrolling interest investment	0	0	911	3,479
Issuance of common stock, net of offering costs	1,285	37,574	2,082	42,445
Repurchase of common stock	(4)	0	(468)	(505)
Repayments of notes receivable for common stock	0	13	25	0
Proceeds from subsidiary common stock option exercise	0	0	121	0
Proceeds from preferred stock	0	5,000	7,723	67,743
Proceeds from notes payable	456	0	1,100	8,215
Principal payments on debt	(107)	(92)	(67)	(476)
Payments under capital lease obligations	(122)	(126)	(93)	(409)
Net cash provided by financing activities	1,508	42,369	11,334	120,492
Net (decrease) increase in cash and cash equivalents	(19,240)	28,918	(4,645)	20,250
Cash and cash equivalents at beginning of period	39,490	10,572	15,217
Cash and cash equivalents at end of period	20,250	39,490	10,572	20,250
Supplemental disclosure of cash flows information:
Cash paid for interest	38	42	44	142
Noncash financing and investing activities:
Accretion on redeemable preferred stock	0	8	2	113
Purchased leasehold improvements and equipment in accounts payable	53	481	0	53
Common stock issued to shareholders of OncoRx as part of acquisition	0	0	932	1,654
Issuance of common stock dividend to Series AA preferred shareholders	0	1	1	6
Assets acquired under capital lease	0	80	282	542
Reduction of IPO offering costs	$ 158			$ 158