Tengion (TNGNQ) 10-K 26 Mar 14 2013 FY Annual report Financial data

Document_and_Entity_Informatio

Document and Entity Information (USD $)	12 Months Ended
	Dec. 31, 2013	Mar. 20, 2014	Jun. 30, 2013
Document and Entity Information [Abstract]	'	'	'
Entity Registrant Name	'TENGION INC	'	'
Entity Central Index Key	'0001296391	'	'
Current Fiscal Year End Date	'--12-31	'	'
Entity Well-known Seasoned Issuer	'No	'	'
Entity Voluntary Filers	'No	'	'
Entity Current Reporting Status	'Yes	'	'
Entity Filer Category	'Smaller Reporting Company	'	'
Entity Public Float	'	'	$883,712
Entity Common Stock, Shares Outstanding	'	18,234,935	'
Document Fiscal Year Focus	'2013	'	'
Document Fiscal Period Focus	'FY	'	'
Document Type	'10-K	'	'
Amendment Flag	'false	'	'
Document Period End Date	31-Dec-13	'	'

Balance_Sheets

Balance Sheets (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Current assets:	'	'
Cash and cash equivalents	$21,510	$7,536
Restricted cash	0	1,000
Prepaid expenses and other	334	360
Total current assets	21,844	8,896
Property and equipment, net of accumulated depreciation of $13,072 and $13,339 as of December 31, 2012 and 2013, respectively	454	612
Other assets	3,426	2,927
Total assets	25,724	12,435
Current liabilities:	'	'
Current portion of long-term debt, net of debt discount of $157 and $52 as of December 31, 2012 and 2013, respectively	1,329	1,786
Current portion of lease liability	665	536
Accounts payable	853	644
Accrued expenses	2,366	2,170
Derivative liability	0	2,449
Warrant liability	11,425	6,178
Total current liabilities	16,638	13,763
Long-term debt and embedded derivative, net of debt discount of $7,515 and $7,814 as of December 31, 2012 and 2013, respectively	25,623	9,483
Lease liability	307	524
Other liabilities	12	8
Total liabilities	42,580	23,778
Commitments and contingencies (Note 15)	'	'
Stockholders' deficit:	'	'
Preferred stock, $0.001 par value; 10,000 shares authorized; zero shares issued or outstanding at December 31, 2012 and 2013, respectively	0	0
Common stock, $0.001 par value; 750,000 shares authorized; 2,499 and 6,822 shares issued and outstanding at December 31, 2012 and 2013, respectively	7	2
Additional paid-in capital	249,237	235,828
Deficit accumulated during the development stage	-266,100	-247,173
Total stockholders' deficit	-16,856	-11,343
Total liabilities and stockholders' deficit	$25,724	$12,435

Balance_Sheets_Parenthetical

Balance Sheets (Parenthetical) (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Thousands, except Share data, unless otherwise specified
Current assets:	'	'
Accumulated depreciation, property and equipment	$13,339	$13,072
Current liabilities:	'	'
Current portion of long-term debt, debt discount	52	157
Long-term debt, debt discount	$7,814	$7,515
Stockholders equity:	'	'
Preferred stock, par value ( in dollars per share)	$0.00	$0.00
Preferred stock, shares authorized (in shares)	10,000,000	10,000,000
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Common stock, par value (in dollars per share)	$0.00	$0.00
Common stock, shares authorized (in shares)	750,000,000	750,000,000
Common stock, shares issued (in shares)	6,822,000	2,449,000
Common stock, shares outstanding (in shares)	6,822,000	2,449,000

Statements_of_Operations_and_C

Statements of Operations and Comprehensive Loss (USD $)	12 Months Ended		126 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2013
Statements of Operations and Comprehensive Loss [Abstract]	'	'	'
Revenue	$0	$0	$0
Operating expenses:	'	'	'
Research and development	9,480	10,103	137,440
General and administrative	6,295	5,496	53,684
Depreciation	267	456	23,875
Impairment of property and equipment	0	0	7,371
Other expense, net	555	165	2,425
Total operating expenses	-16,597	-16,220	-224,795
Loss from operations	-16,597	-16,220	-224,795
Interest income	47	27	8,586
Interest expense	-7,622	-2,957	-25,468
Change in fair value of embedded derivative and derivative liability	-3,088	944	-2,144
Change in fair value of warrant liability	8,333	1,277	26,108
Net loss	-18,927	-16,929	-217,713
Other comprehensive loss	0	0	'
Comprehensive loss	($18,927)	($16,929)	'
Basic and diluted net loss per share (in dollars per share)	($4.70)	($7.13)	'
Weighted-average common stock outstanding - basic and diluted (in shares)	4,024	2,374	'

Statements_of_Redeemable_Conve

Statements of Redeemable Convertible Preferred Stock and Stockholders' Equity (Deficit) (USD $)	Redeemable Convertible Preferred Stock [Member]	Common Stock [Member]	Additional Paid-in Capital [Member]	Deferred Compensation [Member]	Deficit Accumulated During the Development Stage [Member]	Total
In Thousands, except Share data, unless otherwise specified
Balance at Jul. 09, 2003	$0	$0	$0	$0	$0	$0
Balance (in shares) at Jul. 09, 2003	0	0	'	'	'	'
Increase (Decrease) in Stockholders' Equity [Roll Forward]	'	'	'	'	'	'
Issuance of common stock to initial stockholder	0	0	0	0	0	0
Issuance of common stock to initial stockholder (in shares)	0	138,000	'	'	'	'
Effect of June 12 reverse stock split (see Note 3)	0	0	0	0	0	0
Effect of June 12 reverse stock split (see Note 3) (in shares)	0	-124,000	'	'	'	'
Net loss	0	0	0	0	-1,032	-1,032
Balance at Dec. 31, 2003	0	0	0	0	-1,032	-1,032
Balance (in shares) at Dec. 31, 2003	0	14,000	'	'	'	'
Increase (Decrease) in Stockholders' Equity [Roll Forward]	'	'	'	'	'	'
Issuance of Series A Redeemable Convertible Preferred stock, net of expenses	30,126	0	0	0	0	0
Issuance of Series A Redeemable Convertible Preferred stock, net of expenses (in shares)	18,741,000	0	'	'	'	'
Conversion of notes payable, including interest	3,562	0	0	0	0	0
Conversion of notes payable, including interest (in shares)	2,203,000	0	'	'	'	'
Issuance of restricted common stock to employees and nonemployees	0	1	336	-336	0	1
Issuance of restricted common stock to employees and nonemployees (in shares)	0	24,000	'	'	'	'
Issuance of common stock to consultants	0	0	21	0	0	21
Issuance of common stock to consultants (in shares)	0	14,000	'	'	'	'
Issuance of common stock to convertible noteholders	0	0	67	0	0	67
Issuance of common stock to convertible noteholders (in shares)	0	9,000	'	'	'	'
Issuance of options to purchase common stock to consultants for services rendered	0	0	14	-14	0	0
Amortization of deferred compensation	0	0	0	23	0	23
Change in value of restricted common stock subject to vesting	0	0	11	-11	0	0
Accretion of redeemable convertible preferred stock to redemption value	1,035	0	0	0	-1,035	-1,035
Net loss	0	0	0	0	-2,438	-2,438
Balance at Dec. 31, 2004	34,723	1	449	-338	-4,505	-4,393
Balance (in shares) at Dec. 31, 2004	20,944,000	61,000	'	'	'	'
Increase (Decrease) in Stockholders' Equity [Roll Forward]	'	'	'	'	'	'
Issuance of Series A Redeemable Convertible Preferred stock, net of expenses	5,223	0	0	0	0	0
Issuance of Series A Redeemable Convertible Preferred stock, net of expenses (in shares)	3,247,000	0	'	'	'	'
Issuance of restricted common stock to employees and nonemployees	0	0	140	-139	0	1
Issuance of restricted common stock to employees and nonemployees (in shares)	0	6,000	'	'	'	'
Issuance of warrants to purchase preferred stock to noteholders	0	0	681	0	0	681
Issuance of options to purchase common stock to consultants for services rendered	0	0	7	-7	0	0
Amortization of deferred compensation	0	0	0	111	0	111
Accretion of redeemable convertible preferred stock to redemption value	3,164	0	0	0	-3,164	-3,164
Net loss	0	0	0	0	-9,627	-9,627
Balance at Dec. 31, 2005	43,110	1	1,277	-373	-17,296	-16,391
Balance (in shares) at Dec. 31, 2005	24,191,000	67,000	'	'	'	'
Increase (Decrease) in Stockholders' Equity [Roll Forward]	'	'	'	'	'	'
Issuance of Series B Redeemable Convertible Preferred stock, net of expenses	50,040	0	0	0	0	0
Issuance of Series B Redeemable Convertible Preferred stock, net of expenses (in shares)	27,637,000	0	'	'	'	'
Issuance of restricted common stock to employees	0	0	0	0	0	0
Issuance of restricted common stock to employees (in shares)	0	0	'	'	'	'
Issuance of common stock upon exercise of options	0	0	9	0	0	9
Issuance of common stock upon exercise of options (in shares)	0	0	'	'	'	'
Repurchased nonvested restricted stock	0	0	0	0	0	0
Repurchased nonvested restricted stock (in shares)	0	-1,000	'	'	'	'
Reclassification of deferred compensation	0	0	-373	373	0	0
Reclassification of warrants to purchase preferred stock	0	0	-681	0	0	-681
Stock-based compensation expense	0	0	400	0	0	400
Accretion of redeemable convertible preferred stock to redemption value	5,640	0	0	0	-5,640	-5,640
Net loss	0	0	0	0	-20,873	-20,873
Balance at Dec. 31, 2006	98,790	1	632	0	-43,809	-43,176
Balance (in shares) at Dec. 31, 2006	51,828,000	66,000	'	'	'	'
Increase (Decrease) in Stockholders' Equity [Roll Forward]	'	'	'	'	'	'
Issuance of Series C Redeemable Convertible Preferred stock, net of expenses	33,219	0	0	0	0	0
Issuance of Series C Redeemable Convertible Preferred stock, net of expenses (in shares)	18,333,000	0	'	'	'	'
Issuance of common stock upon exercise of options	0	0	60	0	0	60
Issuance of common stock upon exercise of options (in shares)	0	3,000	'	'	'	'
Repurchased vested restricted stock	0	0	-94	0	0	-94
Repurchased vested restricted stock (in shares)	0	-1,000	'	'	'	'
Stock-based compensation expense	0	0	664	0	0	664
Accretion of redeemable convertible preferred stock to redemption value	8,742	0	0	0	-8,742	-8,742
Net loss	0	0	0	0	-30,988	-30,988
Balance at Dec. 31, 2007	140,751	1	1,262	0	-83,539	-82,276
Balance (in shares) at Dec. 31, 2007	70,161,000	68,000	'	'	'	'
Increase (Decrease) in Stockholders' Equity [Roll Forward]	'	'	'	'	'	'
Issuance of Series C Redeemable Convertible Preferred stock, net of expenses	21,352	0	0	0	0	0
Issuance of Series C Redeemable Convertible Preferred stock, net of expenses (in shares)	11,793,000	0	'	'	'	'
Issuance of common stock upon exercise of options	0	0	28	0	0	28
Issuance of common stock upon exercise of options (in shares)	0	0	'	'	'	'
Repurchased vested restricted stock	0	0	0	0	0	0
Repurchased vested restricted stock (in shares)	0	0	'	'	'	'
Stock-based compensation expense	0	0	1,317	0	0	1,317
Accretion of redeemable convertible preferred stock to redemption value	11,754	0	0	0	-11,754	-11,754
Net loss	0	0	0	0	-42,393	-42,393
Balance at Dec. 31, 2008	173,857	1	2,607	0	-137,686	-135,078
Balance (in shares) at Dec. 31, 2008	81,954,000	68,000	'	'	'	'
Increase (Decrease) in Stockholders' Equity [Roll Forward]	'	'	'	'	'	'
Issuance of common stock upon exercise of options	0	0	54	0	0	54
Issuance of common stock upon exercise of options (in shares)	0	2,000	'	'	'	'
Stock-based compensation expense	0	0	855	0	0	855
Accretion of redeemable convertible preferred stock to redemption value	14,059	0	0	0	-14,059	-14,059
Net loss	0	0	0	0	-29,845	-29,845
Balance at Dec. 31, 2009	187,916	1	3,516	0	-181,590	-178,073
Balance (in shares) at Dec. 31, 2009	81,954,000	70,000	'	'	'	'
Increase (Decrease) in Stockholders' Equity [Roll Forward]	'	'	'	'	'	'
Issuance of common stock upon exercise of options	0	0	14	0	0	14
Issuance of common stock upon exercise of options (in shares)	0	3,000	'	'	'	'
Stock-based compensation expense	0	0	953	0	0	953
Accretion of redeemable convertible preferred stock to redemption value	3,993	0	0	0	-3,993	-3,993
Conversion of preferred stock to common stock	-191,909	0	191,909	0	0	191,909
Conversion of preferred stock to common stock (in shares)	-81,954,000	566,000	'	'	'	'
Conversion of preferred stock warrants to common stock warrants	0	0	123	0	0	123
Proceeds from initial public offering, net of expenses	0	0	25,727	0	0	25,727
Proceeds from initial public offering, net of expenses (in shares)	0	600,000	'	'	'	'
Net loss	0	0	0	0	-25,600	-25,600
Balance at Dec. 31, 2010	0	1	222,242	0	-211,183	11,060
Balance (in shares) at Dec. 31, 2010	0	1,239,000	'	'	'	'
Increase (Decrease) in Stockholders' Equity [Roll Forward]	'	'	'	'	'	'
Proceeds from equity financing, net of expenses	0	1	28,940	0	0	28,941
Proceeds from equity financing, net of expenses (in shares)	0	1,108,000	'	'	'	'
Issuance of warrants to purchase common stock issued in connection with equity financing	0	0	-16,947	0	0	-16,947
Issuance of common stock upon exercise of options	0	0	83	0	0	83
Issuance of common stock upon exercise of options (in shares)	0	18,000	'	'	'	'
Issuance of restricted stock to employees	0	0	0	0	0	0
Issuance of restricted stock to employees (in shares)	0	31,000	'	'	'	'
Cancellation of restricted stock to employees	0	0	0	0	0	0
Cancellation of restricted stock to employees (in shares)	0	-15,000	'	'	'	'
Issuance of warrants to purchase common stock in connection with debt financing	0	0	105	0	0	105
Stock-based compensation expense	0	0	834	0	0	834
Net loss	0	0	0	0	-19,061	-19,061
Balance at Dec. 31, 2011	0	2	235,257	0	-230,244	5,015
Balance (in shares) at Dec. 31, 2011	0	2,381,000	'	'	'	'
Increase (Decrease) in Stockholders' Equity [Roll Forward]	'	'	'	'	'	'
Issuance of common stock upon exercise of options	0	0	10	0	0	10
Issuance of common stock upon exercise of options (in shares)	0	3,000	'	'	'	'
Issuance of restricted stock to employees	0	0	0	0	0	0
Issuance of restricted stock to employees (in shares)	0	68,000	'	'	'	'
Cancellation of restricted stock to employees	0	0	-5	0	0	-5
Cancellation of restricted stock to employees (in shares)	0	-3,000	'	'	'	'
Stock-based compensation expense	0	0	566	0	0	566
Conversion of notes payable, including interest	'	'	'	'	'	0
Conversion of preferred stock to common stock	'	'	'	'	'	0
Conversion of preferred stock warrants to common stock warrants	'	'	'	'	'	0
Net loss	0	0	0	0	-16,929	-16,929
Balance at Dec. 31, 2012	0	2	235,828	0	-247,173	-11,343
Balance (in shares) at Dec. 31, 2012	0	2,449,000	'	'	'	'
Increase (Decrease) in Stockholders' Equity [Roll Forward]	'	'	'	'	'	'
Issuance of common stock for payment of interest	0	3	1,535	0	0	1,538
Issuance of common stock for payment of interest (in shares)	0	2,575,000	'	'	'	'
Proceeds from Celgene Collaboration and Option Agreement and Right of First Negotiation Agreement, net of expenses and proceeds allocable to issuance of warrants	0	0	10,859	0	0	10,859
Proceeds from Celgene Collaboration and Option Agreement and Right of First Negotiation Agreement, net of expenses and proceeds allocable to issuance of warrants (in shares)	0	0	'	'	'	'
Cancellation of restricted stock to employees	0	0	-7	0	0	-7
Cancellation of restricted stock to employees (in shares)	0	-6,000	'	'	'	'
Issuance of common stock upon exercise of warrants	0	1	279	0	0	280
Issuance of common stock upon exercise of warrants (in shares)	0	577,000	'	'	'	'
Stock-based compensation expense	0	0	513	0	0	513
Conversion of notes payable, including interest	'	'	'	'	'	0
Issuance of common stock to convertible noteholders	0	1	230	0	0	231
Issuance of common stock to convertible noteholders (in shares)	0	1,227,000	'	'	'	'
Conversion of preferred stock to common stock	'	'	'	'	'	0
Conversion of preferred stock to common stock (in shares)	'	'	'	'	'	260,000
Conversion of preferred stock warrants to common stock warrants	'	'	'	'	'	57
Net loss	0	0	0	0	-18,927	-18,927
Balance at Dec. 31, 2013	$0	$7	$249,237	$0	($266,100)	($16,856)
Balance (in shares) at Dec. 31, 2013	0	6,822,000	'	'	'	'

Statements_of_Redeemable_Conve1

Statements of Redeemable Convertible Preferred Stock and Stockholders' Equity (Deficit) (Parenthetical) (USD $)	Dec. 31, 2008	Dec. 31, 2007	Dec. 31, 2006	Dec. 31, 2005	Dec. 31, 2004
Statements of Redeemable Convertible Preferred Stock and Stockholders' Equity (Deficit) [Abstract]	'	'	'	'	'
Series A Redeemable Convertible Preferred stock, value per share (in dollars per share)	'	'	'	$1.62	$1.62
Restricted common stock issued to employees and nonemployees, value per share (in dollars per share)	'	'	'	$2.32	'
Series B Redeemable Convertible Preferred stock, value per share (in dollars per share)	'	'	$1.82	'	'
Series C Redeemable Convertible Preferred stock, value per share (in dollars per share)	$1.82	$1.82	'	'	'

Statements_of_Cash_Flows

Statements of Cash Flows (USD $)	12 Months Ended		126 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2013
Cash flows from operating activities:	'	'	'
Net loss	($18,927)	($16,929)	($217,713)
Adjustments to reconcile net loss to net cash used in operating activities:	'	'	'
Depreciation	267	456	23,875
Change in fair value of embedded derivative and derivative liability	3,088	-944	2,144
Change in fair value of warrant liability	-8,333	-1,277	-26,108
Charge related to lease liability	665	165	2,535
Loss on disposition of property and equipment	0	0	119
Impairment of property and equipment	0	0	7,371
Amortization of net discount on short-term investments	0	0	-149
Noncash interest expense	6,426	1,614	10,588
Noncash rent expense	3	7	227
Stock-based compensation expense	513	566	6,258
Changes in operating assets and liabilities:	'	'	'
Prepaid expenses and other assets	21	-1,070	-2,677
Accounts payable	206	-252	824
Accrued expenses and other	-1,082	-1,797	-116
Net cash used in operating activities	-17,153	-19,461	-192,822
Cash flows from investing activities:	'	'	'
Purchases of short-term investments	0	0	-324,508
Change in restricted cash	1,000	-1,000	0
Sales and redemptions of short-term investments	0	6,066	324,657
Cash paid for property and equipment	-106	-48	-31,828
Proceeds from the sale of property and equipment	0	0	11
Net cash provided by (used in) investing activities	894	5,018	-31,668
Cash flows from financing activities:	'	'	'
Proceeds from sale of redeemable convertible preferred stock, net	0	0	139,960
Proceeds from sales of common stock and warrants, net	271	5	55,193
Repurchases of common stock	0	0	-94
Proceeds from Celgene Collaboration and Option Agreement and Right of First Negotiation Agreement, net of expenses	14,656	0	14,656
Proceeds from long-term debt and warrants, net of issuance costs	17,585	14,196	71,298
Payments on long-term debt	-2,279	-1,466	-35,013
Net cash provided by financing activities	30,233	12,735	246,000
Net (decrease) increase in cash and cash equivalents	13,974	-1,708	21,510
Cash and cash equivalents, beginning of period	7,536	9,244	0
Cash and cash equivalents, end of period	$21,510	$7,536	$21,510

Organization_and_Nature_of_Ope

Organization and Nature of Operations	12 Months Ended
	Dec. 31, 2013
Organization and Nature of Operations [Abstract]	'
Organization and Nature of Operations	'
	(1)           Organization and Nature of Operations
	Tengion, Inc. (the Company) was incorporated in Delaware on July 10, 2003.  The Company is a regenerative medicine company focused on discovering, developing, manufacturing and commercializing a range of neo-organs, or products composed of living cells, with or without synthetic or natural materials, implanted or injected into the body to engraft into, regenerate, or replace a damaged tissue or organ.  Using its Organ Regeneration Platform, the Company creates these neo-organs using a patient’s own cells, or autologous cells.  The Company’s mission is to: (i) utilize its Organ Regeneration Platform to extend the lives of patients suffering from life-threatening diseases; (ii) improve the quality of patients' lives while providing cost-saving treatments; and (iii) create value for the Company’s stakeholders.
	The Company believes its proprietary product candidates harness the intrinsic regenerative pathways of the body to regenerate a range of native-like organs and tissues.  The Company’s product candidates are intended to delay or eliminate the need for chronic disease therapies, organ transplantation, and the administration of anti-rejection medications.  In addition, the Company’s neo-organs are designed to replace the need to substitute other tissues of the body for a purpose to which they are poorly suited.
	Building on its clinical and preclinical experience, the Company is initially leveraging its Organ Regeneration Platform to develop its Neo-Kidney Augment for patients with advanced chronic kidney disease and its Neo-Urinary Conduit for bladder cancer patients who are in need of a urinary diversion.  The Company operates as a single business segment.  Operations of the Company are subject to certain risks and uncertainties, including, among others, uncertainty of product candidate development; technological uncertainty; dependence on collaborative partners; uncertainty regarding patents and proprietary rights; comprehensive government regulations; having no commercial manufacturing experience, marketing or sales capability or experience; and dependence on key personnel.
	On September 4, 2012, the Company was notified by NASDAQ of its determination to delist the Company’s common stock from NASDAQ effective at the open of business on September 6, 2012, due to its failure to comply with the minimum $2.5 million stockholders’ equity requirement for continued listing on the Nasdaq Capital Market. Effective at the opening of the market on September 6, 2012, the Company’s common stock was transferred from the Nasdaq Capital Market to the OTCQB, which is operated by OTC Markets, Inc., and continues to trade under the symbol “TNGN.”
	On November 15, 2013, the Company filed a Form 12b-25 to extend the deadline for the filing of its Quarterly Report on Form 10-Q for the Quarter ended September 30, 2013, while it assessed if certain prior issuances of common stock and warrants to purchase common stock should have been evaluated as triggers for anti-dilution adjustments to most of the Company’s dilutive securities in its quarterly and annual filings beginning with the quarter ended September 30, 2012. The Company completed its assessment and determined that there was an immaterial error that impacted the valuation of the Company’s dilutive securities during quarters ended March 31, 2013 and June 30, 2013. In addition, the Company determined that the cumulative correction of the error, which decreased net loss for the quarter ended September 30, 2013 by $0.3 million in the Quarterly Report on Form 10-Q was immaterial. Therefore, the financial statements for the year ending December 31, 2013 reflect these immaterial adjustments.

Managements_Plans_to_Continue_

Management's Plans to Continue as a Going Concern	12 Months Ended
	Dec. 31, 2013
Management's Plans to Continue as a Going Concern [Abstract]	'
Management's Plans to Continue as a Going Concern	'
	(2)           Management’s Plans to Continue as a Going Concern
	The accompanying financial statements have been prepared on a going-concern basis, which contemplates the realization of assets and satisfaction of liabilities in the normal course of business.  The Company has incurred losses since inception and has a deficit accumulated during the development stage of $266.1 million as of December 31, 2013, including $48.4 million of cumulative accretion of redeemable convertible preferred stock through the date of its conversion to common stock in April 2010.  The Company anticipates incurring additional losses and deficits in operating cash flows until such time, if ever, that it can generate significant sales of its therapeutic product candidates currently in development or enters into cash flow positive business development transactions.
	Based upon the Company’s current expected level of operating expenditures and required debt repayments, and assuming the Company is not required to settle any outstanding warrants in cash or redeem, or pay cash interest on, any of its convertible notes, the Company expects to be able to fund operations through December 31, 2014; however, this period could be shortened if there are any unanticipated increases in planned spending on development programs or other unforeseen events.  The Company plans to raise additional funds through collaborative arrangements, public or private sales of debt or equity securities, commercial loan facilities, or some combination thereof.  There is no assurance that additional financing will be available when needed to allow the Company to continue its operations or if available, on terms acceptable to the Company.
	In the event financing is not obtained, the Company could pursue additional headcount reductions and other cost cutting measures to preserve cash as well as explore the sale of selected assets to generate additional funds.  If the Company is required to significantly reduce operating expenses and delay, reduce the scope of, or eliminate one or more of its development programs, these events could have a material adverse effect on the Company's business, results of operations and financial condition.
	These factors raise significant doubt about the Company's ability to continue as a going concern. The financial statements do not include any adjustments relating to recoverability and classification of recorded asset amounts or the amounts and classification of liabilities that might be necessary should the Company be unable to continue in existence.

Summary_of_Significant_Account

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2013
Summary of Significant Accounting Policies [Abstract]	'
Summary of Significant Accounting Policies	'
	(3)           Summary of Significant Accounting Policies
	(a)           Use of Estimates
	The preparation of financial statements, in accordance with accounting principles generally accepted in the United States of America, requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of expenses during the reporting period.  Actual results could differ from those estimates.
	(b)           Fair Value of Financial Instruments
	As of December 31, 2012 and 2013, the carrying amounts of financial instruments held by the Company, which include cash equivalents, accounts payable, and accrued expenses, approximate fair value due to the short-term nature of those instruments.  In addition, the carrying value of the Company’s debt instruments, which do not have readily ascertainable market values, approximate fair value, given that the interest rates on outstanding borrowings approximate market rates for companies with similar credit ratings.
	(c)           Cash and Cash Equivalents
	The Company considers all highly liquid investments purchased with an original maturity of three months or less to be cash equivalents.
	(d)           Restricted Cash
	The Company deposited $1.0 million of the gross proceeds of its Senior Secured Convertible Notes (the 2012 Convertible Notes) (see footnote 9 for discussion of the 2012 Convertible Notes) financing into an escrow account in October 2012 pursuant to an Escrow Agreement between the Company, the lenders, and an escrow agent. Upon the achievement of (1) the successful completion of patient implants in the Phase I clinical trial of the Company’s Neo-Urinary Conduit and (2) analysis of in-life data from the Company’s GLP studies for the Neo-Kidney Augment that demonstrates that continued development is warranted (the Milestones), the lenders will instruct the escrow agent to release the escrowed funds to the Company. This deposit is classified as restricted cash as of December 31, 2012.  In the second quarter of 2013 the cash was released.
	(e)           Property and Equipment
	Property and equipment are stated at cost.  Depreciation is provided over the estimated useful lives of the assets using the straight-line method.  The Company uses a life of three years for computer equipment, five years for laboratory and office and warehouse equipment, seven years for furniture and fixtures, and the lesser of the useful life of the asset or the remaining life of the underlying facility lease for leasehold improvements.  Expenditures for maintenance, repairs, and improvements that do not prolong the useful life of the asset are charged to expense as incurred.  The Company capitalizes interest in connection with the construction of property and equipment.
	(f)           Impairment of Long-Lived Assets
	Long-lived assets, such as property and equipment, are reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable.  Recoverability of assets to be held and used is measured by a comparison of the carrying amount of an asset to estimated undiscounted future cash flows expected to be generated by the asset.  If the carrying amount of an asset exceeds its estimated future cash flows, then an impairment charge is recognized by the amount by which the carrying amount of the asset exceeds the fair value of the asset.
	(g)           Research and Development
	Research and development costs are charged to expense as incurred.  Research and development costs consist of personnel related expenses, including salaries, benefits, travel, and other related expenses, including stock-based compensation; payments made to third party contract research organizations for preclinical studies, investigative sites for clinical trials, and consultants; costs associated with regulatory filings and the advancement of the Company’s product candidates through preclinical studies and clinical trials; laboratory and other supplies; manufacturing development costs; and related facility maintenance.
	(h)           Income Taxes
	Income taxes are accounted for under the asset-and-liability method.  Deferred tax assets and liabilities are recognized for the future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases and operating loss and tax credit carryforwards.  Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled.  The effect on deferred tax assets and liabilities of a change in tax rates is recognized in the tax provision in the period that includes the enactment date.
	(i)           Stock-Based Compensation
	The Company measures and recognizes compensation expense for all employee stock-based payments at fair value, net of estimated forfeitures, over the vesting period of the underlying stock-based awards.  In addition, the Company accounts for stock-based compensation to nonemployees in accordance with the accounting guidance for equity instruments that are issued to other than employees.
	Determining the appropriate fair value of stock-based payment awards require the determination of subjective assumptions, including the expected life of the stock-based payment awards and stock price volatility.  The Company uses the Black-Scholes option-pricing model to value its stock option awards.  The assumptions used in calculating the fair value of stock-based payment awards represent management’s best estimates and involve inherent uncertainties and the application of management’s judgment.  As a result, if factors change and management uses different assumptions, stock-based compensation expense could be materially different in the future.  The Company’s historical stock price is used to calculate the expected volatility.
	The estimation of the number of stock awards that will ultimately vest requires judgment, and to the extent actual results or updated estimates differ from the Company’s current estimates, such amounts will be recorded as an adjustment in the period in which estimates are revised.  The Company considers many factors when estimating expected forfeitures for stock awards granted to employees, consultants and directors, including types of awards, employee class, and an analysis of the Company’s historical and known forfeitures on existing awards.  Under the true-up provisions of the stock based compensation guidance, the Company records additional expense if the actual forfeiture rate is lower than estimated, and a recovery of expense if the actual forfeiture rate is higher than estimated, during the period in which the options vest.
	(j)           Embedded Derivative Conversion Options and Call Option Derivative Liability
	The Company accounts for the Demand Note Exchange Right and the conversion feature embedded in the 2012 and 2013 Convertible Notes (the Conversion Options) in accordance with Financial Accounting Standards Board Accounting Standard Codification (ASC) 815, Derivatives and Hedging (ASC 815). Under this accounting guidance, the Company is required to bifurcate the embedded derivative from the host instrument and account for it as a free-standing derivative financial instrument.  The Company classifies these embedded derivatives as part of the carrying value of the debt host instrument.  The Company also accounted for the Call Option issued in connection with the 2012 Financing in accordance with ASC 815, as this instrument is considered a free-standing financial instrument that meets the criteria of a derivative under the guidance. The Company classified the Call Option as a derivative liability on the balance sheet.  The changes in fair value of the embedded derivative or derivative liability are remeasured at each balance sheet date and recorded in current period earnings.
	(k)           Warrants
	The Company accounts for stock warrants as either equity instruments or derivative liabilities depending on the specific terms of the warrant agreement.  Stock warrants that allow for cash settlement or provide for modification of the warrant exercise price are accounted for as derivative liabilities.  The Company classifies derivative warrant liabilities on the balance sheet as a current liability, which is revalued at each balance sheet date subsequent to the initial issuance.  The changes in fair value of the derivative warrant liabilities are remeasured at each balance sheet date and recorded in current period earnings.
	(l)           Net Loss Per Share
	Basic and diluted net loss attributable to common stockholders per share is calculated by dividing net loss attributable to common stockholders by the weighted-average number of common shares outstanding. For all periods presented, the outstanding shares of unvested restricted stock as well as the number of common shares issuable upon exercise of outstanding stock options and warrants and conversion of notes payable have been excluded from the calculation of diluted net loss attributable to common stockholders per share because their effect would be anti-dilutive. Therefore, the weighted-average shares used to calculate both basic and dilutive loss per share are the same.
	The following potentially dilutive securities have been excluded from the computations of diluted weighted-average shares outstanding, as they would be anti-dilutive:
		Year Ended December 31,
		2012		2013
	Shares underlying warrants outstanding		80,250,702		481,301,961
	Shares underlying options outstanding		234,465		230,725
	Unvested restricted stock		74,372		54,721
	Convertible notes payable		20,007,002		114,517,218
	(m)           Deferred Debt Offering Costs
	Deferred debt offering costs include costs directly attributable to the Company’s debt offerings.  In accordance with authoritative literature, these costs are deferred and recorded as other non-current assets and amortized over the term of the debt using the effective interest method.
	(n)           Reverse Stock Split
	On May 25, 2012, the Company's Board of Directors approved a reverse stock split on the basis of one share of common stock for each currently outstanding 10 shares of pre-split common stock that became effective on June 14, 2012.  All common share and per-share data included in these financial statements reflect such reverse stock split.

Supplemental_Cash_Flow_Informa

Supplemental Cash Flow Information	12 Months Ended
	Dec. 31, 2013
Supplemental Cash Flow Information [Abstract]	'
Supplemental Cash Flow Information	'
	-4	Supplemental Cash Flow Information
	The following table contains additional supplemental cash flow information for the periods reported (in thousands).
								Period from
								10-Jul-03
								(inception)
				Year Ended				through
				December 31,				December 31,
				2012		2013		2013
	Supplemental disclosure of non-cash transactions:
	Conversion of note principal to redeemable convertible preferred stock		$	—	$	—	$	3,562
	Convertible note issued to initial stockholder for consulting expense			—		—		210
	Exchange of Demand Note for Convertible Notes			1,005		—		1,005
	Fair value of embedded derivatives and derivatives issued with issuance of long-term debt			3,669		732		4,401
	Fair value of warrants issued with issuance of long-term debt			4,994		9,404		16,638
	Fair value of warrants issued with issuance of common stock			—		—		16,947
	Fair value of interest warrants issued for payment of interest			—		437		437
	Fair value of warrants issued pursuant to Celgene Collaboration and Option Agreement			—		3,796		3,796
	Conversion of redeemable convertible preferred stock into 566 shares of common stock			—		—		191,909
	Conversion of warrant liability to common stock			—		57		180
	Conversion of 2012 Convertible Notes to common stock			—		231		231
	Issuance of common stock and warrants for payment of interest			—		1,975		1,975
	Supplemental disclosure of cash flow information:
	Cash paid for interest, net of amounts capitalized			515		443		13,236
	Cash paid for issuance costs classified as interest expense			830		698		1,528

Financial_Instruments

Financial Instruments	12 Months Ended
	Dec. 31, 2013
Financial Instruments [Abstract]	'
Financial Instruments	'
	-5	Financial Instruments
	The fair value guidance requires fair value measurements be classified and disclosed in one of the following three categories:
		·	Level 1: Unadjusted quoted prices in active markets that are accessible at the measurement date for identical, unrestricted assets or liabilities;
		·	Level 2: Quoted prices in markets that are not active, or inputs which are observable, either directly or indirectly, for substantially the full term of the asset or liability;
		·	Level 3: Prices or valuation techniques that require inputs that are both significant to the fair value measurement and unobservable (i.e., supported by little or no market activity).
	The following fair value hierarchy table presents information about each major category of the Company’s financial assets and liability measured at fair value on a recurring basis as of December 31, 2012 and 2013 (in thousands).
			Fair value measurement at reporting date using:
			Quoted prices in			Significant other			Significant			Total
			active markets for			observable			unobservable
			identical assets			inputs			inputs
			(Level 1)			(Level 2)			(Level 3)
	At December 31, 2012:
	Assets:
	Cash and cash equivalents		$	7,536		$	—		$	—		$	7,536
	Liabilities:		$	—		$	—		$	2,449		$	2,449
	Derivative liability
	Embedded derivative liability			—			—			276			276
	Warrant liability			—			—			6,178			6,178
			$	—		$	—		$	8,903		$	8,903
			Fair value measurement at reporting date using:
			Quoted prices in			Significant other			Significant			Total
			active markets for			observable			unobservable
			identical assets			inputs			inputs
			(Level 1)			(Level 2)			(Level 3)
	At December 31, 2013:
	Assets:
	Cash and cash equivalents		$	21,510		$	—		$	—		$	21,510
	Liabilities:		$	—		$	—		$	226		$	226
	Embedded derivative liability
	Warrant liability			—			—			11,425			11,425
			$	—		$	—		$	11,651		$	11,651
	The Company recorded a derivative liability relating to a call option issued to the holders of convertible notes issued in 2012 (the Call Option).  See Note 11 for further discussion of the call option derivative liability.  This derivative liability was measured at fair value on a recurring basis using unobservable inputs or available market data to support the fair value (Level 3).  A reconciliation of the derivative liability is as follows (in thousands):
		Call Option
	Balance at January 1, 2012	$	—
	Issuance of derivative		3,181
	Change in fair value of derivative liability		(732	)
	Balance at December 31, 2012	$	2,449
	Change in fair value of derivative liability		3,870
	Exercise of Call Option		(6,319	)
	Balance at December 31, 2013		—
	The Company issued notes in 2012 and 2013 that are convertible into common stock at the option of the holder.  See Note 11 for further discussion of these conversion options, which are accounted for as embedded derivative liabilities. These conversion options are measured at fair value on a recurring basis using unobservable inputs or available market data to support the fair value (Level 3).  A reconciliation of the embedded derivative liabilities is as follows (in thousands):
			2012 Notes			2013 Notes			Total
	Balance at January 1, 2012		$	—		$	—		$	—
	Issuance of derivative			488			—			488
	Change in fair value of derivative liability			(212	)		—			(212	)
	Balance at December 31, 2012		$	276		$	—		$	276
	Issuance of derivative			—			732			732
	Change in fair value of derivative liability			(175	)		(607	)		(782	)
	Balance at December 31, 2013		$	101		$	125		$	226
	The Company has issued warrants to purchase common stock that are measured at fair value on a recurring basis using unobservable inputs or available market data to support the fair value (Level 3). See Note 12 for further discussion of the warrant liability. A reconciliation of the warrant liability is as follows (in thousands):
			2011			2012			2013			2013			2013			Total
			Warrants			Warrants			Warrants			Celgene			Interest
												Warrants			Warrants
	Balance at January 1, 2012		$	2,511		$	—		$	—		$	—		$	—		$	2,511
	Issuance of warrants			—			4,944			—			—			—			4,944
	Change in fair value of warrant liability			(133	)		(1,144	)		—			—			—			(1,277	)
	Balance at December 31, 2012		$	2,378		$	3,800		$	—		$	—		$	—		$	6,178
	Issuance of warrants			—			—			9,404			3,796			437			13,637
	Exercise of warrants			(15	)		—			(42	)		—			—			(57	)
	Change in fair value of warrant liability			(1,643	)		(370	)		(4,223	)		(1,713	)		(384	)		(8,333	)
	Balance at December 31, 2013		$	720		$	3,430		$	5,139		$	2,083		$	53		$	11,425
	Certain assets and liabilities, including property and equipment, severance benefits and the lease liability, are measured at fair value on a nonrecurring basis.  These assets and liabilities are recognized at fair value when they are deemed to be impaired or in the period in which the liability is incurred.  None of these assets were measured at fair value during the years ended December 31, 2012 or 2013.

Property_and_equipment

Property and equipment	12 Months Ended
	Dec. 31, 2013
Property and equipment [Abstract]	'
Property and equipment	'
	-6	Property and equipment
	Property and equipment consisted of the following (in thousands):
			December 31,
			2012			2013
	Office and warehouse equipment		$	323		$	323
	Computer equipment			978			1,003
	Furniture and fixtures			524			524
	Laboratory equipment			4,961			5,035
	Leasehold improvements			6,898			6,908
				13,684			13,793
	Less accumulated depreciation			(13,072	)		(13,339	)
			$	612		$	454

Accrued_expenses

Accrued expenses	12 Months Ended
	Dec. 31, 2013
Accrued expenses [Abstract]	'
Accrued expenses	'
	-7	Accrued expenses
	Accrued expenses consist of the following (in thousands):
			December 31,
			2012		2013
	Accrued compensation and benefits		$	716	$	757
	Accrued consulting and professional fees			387		138
	Accrued research and development			453		535
	Accrued interest on convertible notes			373		843
	Other			241		93
			$	2,170	$	2,366

Lease_liability

Lease liability	12 Months Ended
	Dec. 31, 2013
Lease liability [Abstract]	'
Lease liability	'
	-8	Lease liability
	The Company entered into an agreement in February 2006 to lease warehouse space from March 1, 2011 through February 28, 2016.  On March 1, 2011, the Company determined it was not likely to utilize the space during the five-year lease term.  Therefore, the Company recorded a liability as of March 1, 2011, the cease-use date, for the fair value of its obligations under the lease.  The most significant assumptions used in determining the amount of the estimated lease liability are the potential sublease revenues and the credit-adjusted risk-free rate utilized to discount the estimated future cash flows.
	In connection with the 2011 restructuring, the Company determined it was not likely to utilize substantially all of the leased office and manufacturing space in its East Norriton, Pennsylvania facility during the remainder of the lease term.  Therefore, the Company recorded a liability as of November 30, 2011, the cease-use date, for the fair value of its obligations under the lease.
	The following table summarizes the activity related to the lease liability for the year ended December 31, 2012 and 2013 (in thousands).
			Warehouse			Office and			Total
			space			manufacturing
						space
	Balance at January 1, 2012		$	828		$	854		$	1,682
	Charges utilized			(239	)		(548	)		(787	)
	Additional charges to operations			89			76			165
	Balance at December 31, 2012			678			382			1,060
	Charges utilized			(248	)		(505	)		(753	)
	Additional charges to operations			70			595			665
	Balance at December 31, 2013			500			472			972
	Less current portion			(242	)		(423	)		(665	)
	Total long-term lease liability		$	258		$	49		$	307

Debt

Debt	12 Months Ended
	Dec. 31, 2013
Debt [Abstract]	'
Debt	'
	-9	Debt
	Senior Secured Convertible Notes
	2013 Financing
	On June 28, 2013, the Company completed a private placement (the 2013 Financing) of an aggregate principal amount of $18,576,000 of Senior Secured Convertible Notes (the 2013 Convertible Notes) along with warrants to the holders of the Convertible Notes (2013 Warrants) to purchase 26,921,741 shares of our common stock exercisable for a period of five years from the date of their issuance and warrants to purchase 53,843,479 shares of our common stock exercisable for a period of ten years from the date of their issuance. The initial conversion price of the 2013 Convertible Notes was $0.69 per share and the initial exercise price of the 2013 Warrants was $0.69 per share.  The 2013 Convertible Notes mature on June 30, 2016 and bear interest at 10% per annum, which is payable quarterly beginning on October 1, 2013. The 2013 Convertible Notes were initially convertible into 26,921,740 shares of common stock at a conversion price of $0.69 per share.  The Company recorded an embedded derivative liability for the Conversion Option (the Conversion Option-2013 Notes).  The Conversion Option-2013 Notes is presented on the Balance Sheet, net of long-term debt. See Note 11 for further discussion of this embedded derivative liability.
	We may, at our option, pay interest by the issuance of common stock (or, in certain circumstances, warrants to purchase shares of common stock), provided that an event of default has not occurred and we have publicly disclosed all material information about the Company. If we elect to pay interest on the 2013 Convertible Notes through the issuance of shares of our common stock, the number of shares that would be issued is calculated by dividing the amount of the interest payment by the lesser of: (1) the volume weighted average price (VWAP) for our common stock for the twenty trading days prior to the date the interest payment is due or (2) the closing bid price for our common stock as of the last trading day of the VWAP period. All shares of common stock issuable to the holders in lieu of interest payments will be allocated pro rata among the holders based on the outstanding principal amount of the 2013 Convertible Notes.
	On July 1, 2013, we made an interest payment to the holders of the 2012 Convertible Notes by the issuance of shares of common stock and warrants to purchase shares of common stock for nominal consideration.  The July 1, 2013 issuance of the shares and warrants was dilutive to the holders of the 2013 Warrants, 2013 Convertible Notes, 2012 Warrants, the 2012 Convertible Notes, and 2011 Warrants, and the anti-dilution provisions of each were simultaneously triggered.  The conversion price of the 2013 Convertible Notes was adjusted to $0.29 per share, the exercise price of the 2013 Warrants was adjusted to $0.29 per share, and the number of shares issuable upon exercise of the 2013 Warrants was increased to 192,165,525 shares.
	2012 Financing
	On October 2, 2012, the Company completed a private placement of an aggregate principal amount of $15,005,251 of Senior Secured Convertible Notes (the 2012 Convertible Notes) along with warrants to the holders of the Convertible Notes (2012 Warrants) to purchase 1,118,722 shares of our common stock exercisable for a period of two  years from the date of their issuance, warrants to purchase 16,672,145 shares of our common stock exercisable for a period of five years from the date of their issuance and warrants to purchase 33,344,293 shares of our common stock exercisable for a period of ten years from the date of their issuance at an initial exercise price of $0.75 per share.  The 2012 Convertible Notes mature on October 2, 2015 and bear interest at 10% per annum.  The Company recorded an embedded derivative liability for the Conversion Option (the Conversion Option-2012 Notes).  The Conversion Option-2012 Notes is presented on the Balance Sheet, net of long-term debt. See Note 11 for further discussion of this embedded derivative liability.
	At the time of the issuance of the 2012 Convertible Notes, the Company also granted the holders of the 2012 Convertible Notes the right to require the Company to sell to such holders up to an additional $20 million in securities on the same terms as the 2012 Convertible Notes and 2012 Warrants (the Call Option) (collectively with the 2012 Convertible Notes and 2012 Warrants, the 2012 Financing).  The Company recorded a derivative liability for the Call Option.  The Call Option was exercised by the holders of the 2012 Convertible Notes on June 28, 2013 before the expiration date of June 30, 2013.  See Note 11 for further discussion of this derivative liability.
	On April 2, 2013, the Company made an interest payment to the holders of the 2012 Convertible Notes by the issuance of 290,935 shares of common stock at a price of $0.65 per share.  Thus, the April 2, 2013 issuance of the shares was dilutive to the holders of the 2012 Convertible Notes and 2012 Warrants; therefore, the anti-dilution provisions were simultaneously triggered. The conversion price of the 2012 Convertible Notes was adjusted to $0.65 per share, the exercise price of the 2012 Warrants was adjusted to $0.65 per share, and the number of shares issuable upon exercise of the 2012 Warrants was increased to 60,973,081 shares.
	On July 1, 2013, we made an interest payment to the holders of the 2012 Convertible Notes by the issuance of shares of common stock and warrants to purchase shares of common stock for nominal consideration.  The July 1, 2013 issuance of the shares and warrants was dilutive to the holders of the 2013 Warrants, 2013 Convertible Notes, 2012 Warrants, the 2012 Convertible Notes, and 2011 Warrants, and the anti-dilution provisions of each were simultaneously triggered.  The conversion price of the 2012 Convertible Notes was adjusted to $0.29 per share, the exercise price of the 2012 Warrants was adjusted to $0.29 per share, and the number of shares issuable upon exercise of the 2012 Warrants was increased to 136,663,804 shares.
	Working Capital Note
	In March 2011, the Company refinanced the outstanding debt owed to one of its lenders.  Pursuant to the terms of the refinancing, the Company simultaneously borrowed $5.0 million from the lender and repaid the then outstanding principal amount of $4.5 million.
	In connection with the 2012 Financing, in October 2012, the Company amended the terms of the working capital note.  Retroactively, effective September 1, 2012, the maturity date for the working capital note was extended from January 1, 2014 to May 1, 2014.  The Company is now required to make monthly interest payments of approximately $40,000 through June 1, 2013 and monthly interest and principal payments of $0.4 million from July 1, 2013 through and including May 1, 2014.   Retroactively, effective September 1, 2012, the interest rate on the Horizon Loan was increased from 11.75% to 13.0% per annum.  As a result of the amendment, this refinancing was treated as a modification for accounting purposes.  The fees paid to the lender were amortized over the remaining term of the debt and any third party fees paid were expensed immediately.  In addition, the Company issued the lender ten-year warrants to purchase 1,138,785 shares of common stock and five-year warrants to purchase 569,392 shares of common stock in connection with the amendment.  See Note 12 for further discussion of the warrant liability.
	Borrowings under the working capital note are secured by all of the Company’s assets, except for permitted liens that have priority, including liens on certain equipment acquired to secure the purchase price or lease obligation, as defined in the loan agreement.  In October 2012, the security was extended to include a lien on the Company’s intellectual property.
	Total debt outstanding consists of the following (in thousands):
			December 31,
			2012			2013
	Senior Secured 2012 Convertible Notes		$	15,005		$	14,634
	Embedded derivative liability-2012 Notes			276			101
	Senior Secured 2013 Convertible Notes			—			18,576
	Embedded derivative liability-2013 Notes			—			125
	Working Capital Note			3,660			1,382
	Unamortized debt discount			(7,672	)		(7,866	)
				11,269			26,952
	Less current portion			(1,786	)		(1,329	)
	Total long-term debt and embedded derivative, net		$	9,483		$	25,623
	The Company recorded interest expense of $3.0 million and $7.6 million for the year ended December 31, 2012 and 2013, respectively. Included in interest expense for the year ended December 31, 2013 is $1.5 million of issuance costs and amortization of deferred financing costs and debt discount related to the 2013 Financing, $3.3 million in amortization of deferred financing costs and debt discount on the 2012 Convertible Notes and Working Capital Note and $2.8 million of interest expense on the 2012 Convertible Notes, Working Capital Note and 2013 Convertible Notes.  In the third and fourth quarters of 2013, approximately $371,000 of the 2012 Convertible Notes were converted into 1,226,902 shares of our common stock.
	Through the year ended December 31, 2013 the Company issued 2,575,631 Interest Shares and 1,057,944 Interest Warrants to satisfy $2.0 million in interest obligations for the 2012 Convertible Notes and 2013 Convertible Notes.  On January 2, 2014, we made an interest payment to the holders of the 2012 Convertible Notes and 2013 Convertible Notes by the issuance of 2,680,400 shares of common stock and warrants to purchase 1,159,631 shares of common stock for nominal consideration.  We issued the common stock and warrants to satisfy interest obligations of $0.9 million, which resulted in an effective issuance price of $0.22 per share which triggered certain dilution adjustments discussed in Note 17.
	Principal payments due as of December 31, 2013 are as follows (in thousands):
	2014		$	1,382
	2015			14,634
	2016			18,576
				34,592
	Less embedded derivative and unamortized debt discount			(7,640	)

Capital_Structure

Capital Structure	12 Months Ended
	Dec. 31, 2013
Capital Structure [Abstract]	'
Capital Structure	'
	-10	Capital Structure
	Common Stock
	Since inception, the Company has sold common stock to certain officers, directors, employees, consultants, and Scientific Advisory Board members.  As of December 31, 2013, the Company is authorized to issue 750,000,000 shares of common stock.  Each holder of common stock is entitled to one vote for each share held.  The Company has covenanted that it will, at all times, take all action necessary to reserve and keep available out of its authorized but unissued shares of common stock sufficient to effect the exercise of outstanding stock options and warrants.
	Registration Rights Agreements
	In connection with the 2013 Financing and the Celgene Collaboration and Option Agreement, we entered into a Registration Rights Agreement (the 2013 Registration Rights Agreement) with the 2013 investors and Celgene.  The 2013 Registration Rights Agreement provided that, within 30 days of the closing of the 2013 Financing, we would file a “resale” registration statement (the Registration Statement) covering up to the maximum number of shares underlying the 2013 Notes, 2013 Warrants and the Celgene Warrants that we were able to register pursuant to applicable Securities and Exchange Commission (SEC) limitations.  We filed the Registration Statement on July 26, 2013 and it was declared effective by the SEC on September 18, 2013.  Under the terms of the 2013 Registration Rights Agreement, we are obligated to maintain the effectiveness of the Registration Statement until all securities therein are sold or otherwise can be sold without registration and without any restrictions.
	In connection with the private placement we completed in October 2012 (the 2012 Financing), we entered into a registration rights agreement, which has since been amended, with the investors in the 2012 Financing (as amended, the 2012 Registration Rights Agreement).  The 2012 Registration Rights Agreement provided that, within 30 days of the closing of the 2012 Financing, we would file a “resale” registration statement covering up to the maximum number of shares of common stock issuable upon (i) the conversion of the senior secured convertible notes that were issued in the 2012 Financing and (ii) the exercise of the warrants issued in the 2012 Financing.  We filed the registration statement on November 5, 2012 and it was declared effective by the SEC on March 28, 2013.  Under the terms of the 2012 Registration Rights Agreement, we are obligated to maintain the effectiveness of the registration statements until all securities therein are sold or otherwise can be sold without registration and without any restrictions.
	In connection with the private placement we completed in March 2011 (the 2011 Financing), we entered into a registration rights agreement with the investors in the 2011 Financing (the 2011 Registration Rights Agreement).  The 2011 Registration Rights Agreement provided that, within 45 days of the closing of the 2011 Financing, we would file a “resale” registration statement covering all of the shares (i) of common stock issued in the 2011 Financing and (ii) of common stock issuable upon the exercise of warrants issued in the 2011 Financing.  We filed the registration statement on April 18, 2011 and it was declared effective on May 16, 2011.  Under the terms of the 2011 Registration Rights Agreement, we are obligated to maintain the effectiveness of the registration statements until all securities therein are sold or otherwise can be sold without registration and without any restrictions.
	Preferred Stock
	The Company is authorized to issue 10,000,000 shares of preferred stock in one or more series and to fix the rights, preferences, privileges, and restrictions thereof.  These rights, preferences and privileges could include dividend rights, conversion rights, voting rights, terms of redemption, liquidation preferences, sinking fund terms and the number of shares constituting any series or the designation of such series, any or all of which may be greater than the rights of common stock.  The issuance of the Company’s preferred stock could adversely affect the voting power of holders of common stock and the likelihood that such holders will receive dividend payments and payments upon liquidation.  In addition, the issuance of preferred stock could have the effect of delaying, deferring or preventing a change of control of the Company or other corporate action.  There are no shares issued or outstanding as of December 31, 2013.
	2013 Agreements with Celgene
	On June 28, 2013, the Company entered into a Collaboration and Option Agreement with the Celgene Companies, pursuant to which the Celgene Companies paid $15 million in exchange for (i) five-year warrants to purchase 7,425,743 shares of common stock and ten-year warrants to purchase 14,851,485 shares of common stock; (ii) a Right of First Negotiation Agreement (ROFN Agreement) to the Company’s Neo-Kidney Augment Program; and (iii) entering into the Collaboration and Option Agreement in which the Company agreed to limit development of its Esophagus Program to activities under the Collaboration and Option Agreement and in which the Company also granted to Celgene the option to acquire the rights to its Esophagus Program for 125% of the value of the program, as determined by independent valuation firms (the Option).  The Esophagus Program is the Company’s autologous neo-esophageal implants, which use certain of its intellectual property and a scientific platform relating to the potential creation of new human tissues and organs using autologous cells. The Collaboration and Option Agreement will expire June 28, 2020, unless earlier terminated in connection with a change of control transaction.
	The ROFN Agreement granted Celgene a right of first negotiation to the license, sale, assignment, transfer or other disposition by the Company of any material portion of intellectual property (including patents and trade secrets) or other assets related to the Neo-Kidney Augment program.  In the event of a change in control of the Company, the ROFN Agreement and all of Celgene’s rights pursuant thereto shall automatically terminate in all respects and be of no further force and effect.
	The Company estimated the fair value of the warrants issued to Celgene to be $3.8 million as of the date of issuance and recorded a warrant liability in that amount.  See Note 12 for further discussion of the warrant liability. The Company determined that the Collaboration and Option Agreement did not represent a revenue arrangement because the Company has no substantive performance obligations under the agreement.  The Company evaluated the terms of the Option and determined that it had de minimis value because the option exercise price is at a 25% premium to the fair value of the rights as determined by independent valuation firms at the time of exercise of the option.  The Company evaluated the terms of the ROFN Agreement and determined it had de minimis value because the rights of Celgene are limited to an exclusive negotiating period of a short duration.  As a result, none of the proceeds received from Celgene were allocated to the Option or the ROFN Agreement.  Therefore, given the factors noted above as well as Celgene’s ownership position in the Company prior to execution of the Collaboration and Option Agreement and ROFN Agreement, all of the residual proceeds of $10.9 million were credited to Additional Paid-in Capital, net of transaction fees.

Embedded_Derivative_Conversion

Embedded Derivative Conversion Options and Call Option Derivative Liability	12 Months Ended
	Dec. 31, 2013
Embedded Derivative Conversion Options and Call Option Derivative Liability [Abstract]	'
Embedded Derivative Conversion Options and Call Option Derivative Liability	'
	-11	Embedded Derivative Conversion Options and Call Option Derivative Liability
	The Company accounts for Conversion Options on the 2012 and 2013 Convertible Notes in accordance with ASC 815, Derivatives and Hedging (ACS 815). Under this accounting guidance, the Company is required to bifurcate the embedded derivative from the host instrument and account for it as a derivative financial instrument.  These Conversion Options are classified with debt on the balance sheet and remeasured to fair value at each reporting date, with any changes in fair value being recorded on the Statement of Operations and Comprehensive Loss.
	The Company also accounted for the Call Option issued in connection with the 2012 Financing in accordance with ASC 815, as this instrument was considered a free-standing financial instrument that met the criteria of a derivative under the guidance.  The change in fair value as of each reporting date was recorded on the Statement of Operations and Comprehensive Loss.  On June 28, 2013, $18,576,000 of the Call Option was exercised in connection with the 2013 Financing.  The remaining $1,424,000 unexercised portion of the Call Option expired on June 30, 2013.
	On October 2, 2012, the Company issued the 2012 Convertible Notes as discussed in Note 9 and classified the fair value of the Conversion Option and Call Option as a derivative liability. The Company will continue to re-measure their fair values at each reporting date, with any changes in fair value being recorded on the Statement of Operations and Comprehensive Loss.
	The fair value of the Conversion Options and Call Option as of December 31, 2012 and the Conversion Options as of December 31, 2013, was determined using a risk-neutral framework within a Monte Carlo analysis. The valuation of the Conversion Options and Call Option is subjective and is affected by changes in inputs to the valuation model including the assumptions regarding the aggregate value of the Company’s debt and equity instruments; assumptions regarding the expected amounts and dates of future debt and equity financing activities; assumptions regarding the likelihood and timing of Fundamental Transactions or Major Transactions (as defined in the agreements); the historical and prospective volatility in the value of the company’s debt and equity instruments; risk-free rates based on U.S. Treasury security yields; and the Company’s dividend yield. In performing the valuation of the Conversion Options and Call Option, the Company believed the common stock price had not fully adjusted for the potential future dilution from this private placement. Therefore, the Company used an implied enterprise value considering potential future values for the Company contingent on the outcome of its research programs in conjunction with a Monte Carlo analysis to estimate the range of possible outcomes within each scenario and to allocate value to the securities in accordance with the terms of the agreements. The valuation resulted in a model-derived common stock value of $0.04 per share and $0.02 per share as of December 31, 2012 and December 31, 2013, respectively, primarily due to the preference rights of the debt holders and the anti-dilution and net cash settlement features of warrants issued in 2011, 2012 and 2013. Changes in these assumptions can materially affect the fair value estimate.
	The following table summarizes the calculated aggregate fair values using a risk-neutral framework within a Monte Carlo analysis of the Conversion Options as of the dates indicated along with assumptions utilized in each calculation.
			Embedded Derivative Liability
			Conversion Option-2012						Conversion Option-2013
			Notes						Notes
			December 31,			December 31,			June 30,			December 31,
			2012			2013			2013			2013
			$	276		$	101		$	732		$	125
	Calculated aggregate value (in thousands)
	Equity volatility			115	%		120	%		120	%		120	%
	Asset volatility			90	%		95	%		90	%		95	%
	Probability of Fundamental Transaction or Major Transaction			100	%		100	%		100	%		100	%
	Weighted average risk-free interest rate			0.3	%		0.2	%		0.3	%		0.2	%
	Dividend yield		None			None			None			None

Warrants

Warrants	12 Months Ended
	Dec. 31, 2013
Warrants [Abstract]	'
Warrants	'
	-12	Warrants
	The Company accounts for stock warrants as either equity instruments or derivative liabilities depending on the specific terms of the warrant agreement.  Stock warrants are accounted for as derivative liabilities if the stock warrants allow for cash settlement or provide for modification of the warrant exercise price in the event that subsequent sales of common stock are at a lower price per share than the then-current warrant exercise price.  The Company classifies derivative warrant liabilities on the balance sheet as a current liability, which is measured to fair value at each balance sheet date subsequent to the initial issuance of the stock warrant.
	The following table summarizes outstanding warrants to purchase common stock:
				Shares Exercisable as of
				December 31,		December 31,			Weighted Average
									Exercise
				2012		2013			Price		Expiration
	Equity-classified warrants
	Issued to lenders and vendors			18,514		18,375		$	158.24		March 2014 through September 2019
				18,514		18,375
	Liability-classified warrants
	2013 Interest Warrants			—		1,057,944		$	0.001		July through October 2023
	2013 Warrants			—		191,213,801		$	0.29		June 2018 through June 2023
	2013 Celgene Warrants			—		77,586,207		$	0.29		June 2018 through June 2023
	2012 Warrants (1)			52,843,337		136,663,804		$	0.29		October 2014 through October 2022
	2011 Warrants (2)			27,388,851		74,761,830		$	0.4		Mar-16
				80,232,188		481,283,586
	Total			80,250,702		481,301,961
	(1)As of December 31, 2012 the 2012 Warrants had an exercise price of $0.75 per share.
	(2)As of December 31, 2012 the 2011 Warrants had an exercise price of $1.10 per share.
	2012 Warrants, 2013 Warrants and 2013 Celgene Warrants
	On October 2, 2012, as part of the 2012 Financing, the Company issued the 2012 Warrants to holders of the 2012 Convertible Notes.  The 2012 Warrants were exercisable at an exercise price of $0.75 per share subject to certain adjustments as specified in the warrant agreement.  The Company valued the 2012 Warrants as derivative financial instruments as of the date of issuance and will record their changes in fair value at each reporting date, with any changes in fair value being recorded on the Statement of Operations and Comprehensive Loss.  On April 2, 2013, the conversion price of the 2012 Convertible Notes was adjusted to $0.65 per share, the exercise price of the 2012 Warrants was adjusted to $0.65 per share, and the number of shares issuable upon exercise of the 2012 Warrants was increased to 60,973,081 shares.  On July 1, 2013, we made an interest payment to the holders of the 2012 Convertible Notes by the issuance of shares of common stock and warrants to purchase shares of common stock for nominal consideration.  The July 1, 2013 issuance of the shares and warrants was dilutive to the holders of the 2013 Warrants, 2013 Convertible Notes, 2012 Warrants, the 2012 Convertible Notes, and 2011 Warrants, and the anti-dilution provisions of each were simultaneously triggered.  The exercise price of the 2012 Warrants was adjusted to $0.29 per share, and the number of shares issuable upon exercise of the 2012 Warrants was increased to 136,663,804 shares.
	On June 28, 2013, as part of the 2013 Financing, the Company issued the 2013 Warrants to holders of the 2013 Convertible Notes.  The 2013 Warrants were initially exercisable at an exercise price of $0.69 per share subject to certain adjustments as specified in the warrant agreement.  In addition, on June 28, 2013, the Company entered into a Collaboration and Option Agreement with Celgene Corporation under which Celgene paid the Company $15 million in exchange for (i) five-year warrants to purchase 7,425,743 shares of common stock and ten-year warrants to purchase 14,851,485 shares of common stock (the Celgene Warrants); (ii) a right of first negotiation to the Company’s Neo-Kidney Augment Program; and (iii) entering into the Collaboration and Option Agreement.  The Celgene Warrants were initially exercisable at an exercise price of $1.01 per share.   The Company valued the 2013 Warrants and the Celgene Warrants as derivative financial instruments as of the date of issuance and will continue to do so at each reporting date, with any changes in fair value being recorded on the Statement of Operations and Comprehensive Loss.  On July 1, 2013, we made an interest payment to the holders of the 2012 Convertible Notes by the issuance of shares of common stock and warrants to purchase shares of common stock for nominal consideration.  The July 1, 2013 issuance of the shares and warrants was dilutive to the holders of the 2013 Warrants, 2013 Convertible Notes, 2012 Warrants, the 2012 Convertible Notes, and 2011 Warrants, and the anti-dilution provisions of each were simultaneously triggered.  The exercise price of the 2013 Warrants was adjusted to $0.29 per share, and the number of shares issuable upon exercise of the 2013 Warrants was increased to 192,165,525 shares.
	The 2012, 2013 Warrants and 2013 Celgene Warrants contain provisions that require the modification of the exercise price and shares to be issued under certain circumstances, including in the event the Company completes subsequent equity financings at a price per share lower than the then-current warrant exercise price.  In addition, the warrants contain a net cash settlement provision under which the warrant holders may require the Company to purchase the warrants in exchange for a cash payment following the announcement of specified events defined as Major Transactions involving the Company (e.g., merger, sale of all or substantially all assets, tender offer, or share exchange).  The net cash settlement provision requires use of the Black-Scholes model in calculating the cash payment value in the event of a Major Transaction.
	The fair value of the 2012, 2013 Warrants and 2013 Celgene Warrants as of December 31, 2012 and December 31, 2013 was determined using a risk-neutral framework within a Monte Carlo analysis to model the impact of potential modifications to the warrant exercise price and to include the probability of a Fundamental Transaction. In addition, the following inputs were used in the valuation model: assumptions regarding the aggregate value of the Company’s debt and equity instruments, the amounts and dates of future debt financing transaction, and the historical and prospective volatility in the value of the Company’s debt and equity instruments. The Company used an implied enterprise value considering potential future values for the Company contingent on the outcome of its research programs in conjunction with a Monte Carlo analysis to estimate the range of possible outcomes within each scenario and to allocate value to the securities in accordance with the terms of the agreements. The valuation resulted in a model-derived common stock value of $0.04 per share and $0.02 per share as of December 31, 2012 and December 31, 2013, respectively, primarily due to the preference rights of the debt holders and the anti-dilution and net cash settlement features of the 2011, 2012, 2013 Warrants and 2013 Celgene Warrants. Changes in these assumptions can materially affect the fair value estimate. The Company will continue to classify the fair value of the warrants as a liability until the warrants are exercised, expire, or are amended in a way that would no longer require these warrants to be classified as a liability.
	2011 Warrants
	In March 2011, the Company issued warrants (2011 Warrants) to purchase 1,046,102 shares of common stock in connection with a private placement transaction.  Each warrant was exercisable in whole or in part at any time until March 4, 2016 at a per share exercise price of $28.80, subject to certain adjustments as specified in the warrant agreement.  The Company classified the warrants as derivative financial instruments as of the date of issuance (March 4, 2011) and will record the changes in their fair value at each reporting date, with any changes in fair value being recorded on the Statement of Operations and Comprehensive Loss.  On December 31, 2012, the Company commenced an offer to the holders of 2011 Warrants to amend and restate the 2011 Warrants.  Following execution by the holders of the Exchange Agreements and receipt of the Amended and Restated 2011 Warrants, such holders had the right in the aggregate to purchase 27,388,851 shares of common stock at an exercise price of $1.10. On July 1, 2013, the exercise price of the 2011 Warrants was adjusted from $1.10 to $0.40 per share, and the number of shares issuable upon exercise of the 2011 Warrants was increased to 74,851,830 shares.
	The warrants contain provisions that require the modification of the exercise price and shares to be issued under certain circumstances, including in the event the Company completes subsequent equity financings at a price per share lower than the then-current warrant exercise price.  In addition, the warrants contain a net cash settlement provision under which the warrant holders may require the Company to purchase the warrants in exchange for a cash payment following the announcement of specified events defined as Fundamental Transactions involving the Company (e.g., merger, sale of all or substantially all assets, tender offer, or share exchange).  The net cash settlement provision requires use of the Black-Scholes model in calculating the cash payment value in the event of a Fundamental Transaction.
	The fair value of the 2011 Warrants as of December 31, 2012 and December 31, 2013 was determined using a risk-neutral framework within a Monte Carlo analysis to model the impact of potential modifications to the warrant exercise price and to include the probability of a Fundamental Transaction into the calculation of fair value. The valuation of warrants is subjective and is affected by changes in inputs to the valuation model including the price per share of the Company’s common stock; assumptions regarding the expected amounts and dates of future debt and equity financing activities; assumptions regarding the likelihood and timing of Fundamental Transactions and, the historical volatility of the stock prices of the Company’s common stock; risk-free rates based on U.S. Treasury security yields; and the Company’s dividend yield.
	In connection with the valuation performed on the 2011 Warrants, the Company believed the common stock price had not fully adjusted for the potential future dilution from the 2012 and 2013 Financings due to the trading restrictions on the unregistered shares of common stock issued and issuable from the conversion of debt and warrants, the uncertainty of the Company's outcome on its research programs, and the anti-dilution adjustment features of the warrants. Therefore, the Company used an implied enterprise value considering potential future values for the Company contingent on the outcome of its research programs in conjunction with a Monte Carlo analysis to estimate the range of possible outcomes within each scenario and to allocate value to the securities in accordance with the terms of the agreements. The valuation resulted in a model-derived common stock value of $0.04 per share and $0.02 per share as of December 31, 2012 and December 31, 2013, respectively, primarily due to the preference rights of the debt holders and the anti-dilution and net cash settlement features of the 2011, 2012 and 2013 Warrants. Changes in these assumptions can materially affect the fair value estimate. The Company will continue to record the fair value of the warrants as a liability until the warrants are exercised, expire, or are amended in a way that would no longer require these warrants to be classified as a liability.
	2013 Interest Warrants
	On July 1, 2013 and October 1, 2013, the Company issued warrants to purchase 537,837 and 520,107 shares of common stock, respectively (Interest Warrants) to certain of the 2012 and 2013 Investors as interest payments on the 2012 and 2013 Convertible Notes. The Interest Warrants were issued in lieu of shares of common stock that would have brought certain of the 2012 Investors above the 9.985% ownership limitation established pursuant to the October 2012 Financing and June 2013 Financing.  The warrants have an exercise price of $0.001 and have a ten-year term.  The Company valued the Interest Warrants as derivative financial instruments as of the date of issuance and will record their changes in fair value at each reporting date, with any changes in fair value being recorded on the Statement of Operations and Comprehensive Loss.
	The following table summarizes the calculated aggregate fair values for the liability-classified warrants as of the dates indicated along with the assumptions utilized in each calculation.
			Fair value as of December 31, 2013
			2011			2012				2013			2013			2013
			Warrants			Warrants				Warrants			Celgene Warrants			Interest Warrants
	Calculated aggregate value (in thousands)		$	720		$	3,430			$	5,139		$	2,083		$	53
	Exercise price per share of warrant		$	0.4		$	0.29			$	0.29		$	0.29		$	0.001
	Equity volatility			120	%		120	%			120	%		120	%		120	%
	Asset volatility			95	%		95	%			95	%		95	%		95	%
	Probability of Fundamental Transaction			100	%		100	%			100	%		100	%		100	%
	Weighted average risk-free interest rate			0.2	%		0.2	%			0.2	%		0.2	%		0.2	%
	The following table summarizes the calculated aggregate fair values for the liability-classified warrants as of the dates indicated along with the assumptions utilized in each calculation.
			Fair value as of
			31-Dec-12							30-Jun-13
			2011			2012				2013			2013
			Warrants			Warrants				Warrants			Celgene Warrants
	Calculated aggregate value (in thousands)		$	2,378		$	3,800			$	9,404		$	3,390
	Exercise price per share of warrant		$	1.1		$	0.75			$	0.76		$	0.76
	Equity volatility			115	%		115	%			120	%		120	%
	Asset volatility			90	%		90	%			90	%		90	%
	Probability of Fundamental Transaction			100	%		100	%			100	%		100	%
	Weighted average risk-free interest rate			0.3	%		0.3	%			0.3	%		0.3	%
	The following table summarizes the calculated net cash settlement values for the liability-classified warrants as of the dates indicated along with the assumptions utilized in each calculation.
			Net cash settlement as of December 31, 2013
			2011			2012				2013			2013			2013
			Warrants			Warrants				Warrants			Celgene			Interest
													Warrants			Warrants
	Calculated aggregate value (in thousands) (1)		$	8,076		$	26,004			$	38,238		$	15,503			—
	Exercise price per share of warrant		$	0.4		$	0.29			$	0.29		$	0.29			—
	Closing price per share of warrant		$	0.25		$	0.24	-2		$	0.24	-2	$	0.24	-2		—
	Equity volatility (3)			100	%		99	%			99	%		99	%		—
	Expected term (years)			2.2			7				7.8			7.8			—
Weighted average risk-free interest rate			0.5	%		2.2	%			2.5	%		2.5	%		—
Dividend yield		None			None				None			None				—
-1	Represents the net cash settlement value of the warrant as of December 31, 2013, which value was calculated utilizing the Black-Scholes model specified in the warrant agreement.
-2	Represents the five-day Company stock VWAP used to calculate the net cash settlement value as of December 31, 2013.
-3	Represents the volatility assumption used to calculate the net cash settlement value as of December 31, 2013 based on the terms of the warrant agreement.
During the year ended December 31, 2012 and 2013, the Company recorded non-operating income of $1.3 million and $8.3 million, respectively, due to a change in the estimated fair value of these warrants.
260,000 warrants were exercised on a cash basis during the year ended December 31, 2013, which resulted in receipts of $0.2 million and the issuance of 260,000 shares of common stock.  In addition, 951,724 warrants were exercised on a cashless basis during the year ended December 31, 2013, which resulted in the issuance of 317,387 shares of common stock.

Stockbased_Compensation

Stock-based Compensation	12 Months Ended
	Dec. 31, 2013
Stock-based Compensation [Abstract]	'
Stock-based Compensation	'
	-13	Stock-based Compensation
	The Company currently maintains two stock-based compensation plans.  Under the 2004 Stock Option Plan (the 2004 Plan), stock awards were granted to employees, directors, and consultants of the Company, in the form of restricted stock and stock options. The amounts and terms of options granted were determined by the Company’s compensation committee. The equity awards granted under the Plan generally vest over four years and have terms of up to ten years after the date of grant, and options are exercisable in cash or as otherwise determined by the board of directors. There are no shares available for future grants under the 2004 Plan, as grants from the 2004 Plan ceased upon the Company’s initial public offering in April 2010.
	The 2010 Stock Incentive and Option Plan (2010 Plan) became effective upon the closing of the Company’s initial public offering.  Under the 2010 Plan, stock awards may be granted to employees, directors, and consultants of the Company, in the form of restricted or unrestricted stock, stock appreciation rights, cash-based or performance share awards and stock options. The amounts and terms of options granted are determined by the Company’s compensation committee. The equity awards granted under the Plan generally vest over four years and have terms of up to ten years after the date of grant, and options are exercisable in cash or as otherwise determined by the board of directors.  The 2010 Plan allows for the transfer of forfeited shares from the 2004 Plan.  As of December 31, 2013, 155,246 shares of common stock were available for future grants under the 2010 Plan.
	Stock Options
	The following table summarizes stock option activity under the Plans:
			Number of			Weighted-		Weighted-average	Aggregate intrinsic
			shares			average		remaining	value (in thousands)
						exercise		contractual term
						price		(in years)
	Outstanding at December 31, 2011		174,872			$	16.76
	Granted		87,184			$	5.66
	Exercised		(2,432	)		$	4.4
	Forfeited		(25,159	)		$	20.45
	Outstanding at December 31, 2012		234,465			$	12.37
	Granted		—				—
	Exercised		—				—
	Forfeited		(3,740	)		$	17.68
	Outstanding at December 31, 2013		230,725			$	12.28	7.5	$	—
	Vested and expected to vest at December 31, 2013		221,246			$	12.49	7.5	$	—
	Exercisable at December 31, 2013		137,559			$	15.43	7.2	$	—
	During 2012, the Company issued options to purchase 87,184 shares of common stock, respectively, to employees and non-employee directors under the Plans.  The per-share weighted-average fair value of the options granted to employees during 2012 was estimated at $5.66 on the date of grant using the Black-Scholes option-pricing model with the following weighted-average assumptions:
			Year Ended December 31,
			2012		2013
	Volatility		84%		Not applicable
	Expected term		6.0 years		Not applicable
	Risk-free interest rate		1.10%		Not applicable
	Dividend yield		None		Not applicable
	Total stock-based compensation expense recognized for stock options to employees and non-employee directors for the years ended December 31, 2012 and 2013 was $0.4 million and $0.4 million, respectively.  As of December 31, 2013, there was $0.4 million of unrecognized compensation expense, net of forfeitures, related to non-vested employee stock options and remaining incremental expense associated with the modification of stock options and no unrecognized compensation expense related to non-vested non-employee director stock options.
	Restricted Stock
	The Company has issued restricted stock as compensation for the services of certain employees and other third parties.  The grant date fair value of restricted stock was based on the fair value of the common stock on the date of grant, and compensation expense is recognized based on the period in which the restrictions lapse.
	The following table summarizes restricted stock activity under the Plans:
			Number			Weighted-
			of shares			average
						grant date
						fair value
	Nonvested at December 31, 2011		13,988			$	24.2
	Granted		67,863			$	6.00
	Vested		(5,047	)		$	24.2
	Forfeited		(2,432	)		$	17.36
	Nonvested at December 31, 2012		74,372			$	7.81
	Granted		—				—
	Vested		(19,221	)		$	8.35
	Forfeited		(430	)		$	13.36
	Nonvested at December 31, 2013		54,721			$	7.59
	Total stock-based compensation expense for restricted stock was $0.2 million and $0.1 million for the years ended December 31, 2012 and 2013, respectively.  As of December 31, 2013, there was $0.2 million of unrecognized compensation expense related to restricted stock awards, which is expected to be recognized over a weighted- average period of 2.0 years.

Employee_Benefit_Plan

Employee Benefit Plan	12 Months Ended
	Dec. 31, 2013
Employee Benefit Plan [Abstract]	'
Employee Benefit Plan	'
	-14	Employee Benefit Plan
	The Company maintains a defined contribution 401(k) plan (the 401(k) Plan) for the benefit of its employees.  Employee contributions are voluntary and are determined on an individual basis, limited by the maximum amounts allowable under federal tax regulations.  As of December 31, 2013, the Company has not elected to match any of the employee’s contributions to the 401(k) Plan.

Commitments_and_Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2013
Commitments and Contingencies [Abstract]	'
Commitments and Contingencies	'
	-15	Commitments and Contingencies
	(a)           Leases and Letters of Credit
	The Company leases office space and office equipment under operating leases, which expire at various times through February 2016.  Excluding the lease liability activity described in Note 9, rent expense under these operating leases was $0.2 million and $0.2 million for each of the years ended December 31, 2012 and 2013, respectively.
	The following table summarizes future minimum lease payments as of December 31, 2013 (in thousands):
	2014		$	971
	2015			1,079
	2016			277
	Total minimum lease payments (1)		$	2,327
	(1)The future minimum lease payments above do not include the impact of any potential sublease income discussed in Note 9 related to the Company’s lease liability.
	Effective March 2011, the lease agreement for the Company’s facility in East Norriton, Pennsylvania requires us to provide a $1.0 million security deposit and $1.2 million restoration deposit to the landlord, which is recorded as a non-current other asset on our balance sheet as of December 31, 2012 and 2013.  At the end of the lease term, the landlord has the right to require us to utilize the $1.2 million restoration deposit to restore the facility to its original condition.
	In May 2011, the Company exercised the first five-year renewal option under its lease for laboratory space in Winston-Salem, North Carolina.  The amended lease extends the lease term to October 2016 and provides for payments of average annual base rent of approximately $0.2 million commencing in October 2011.
		(b)	License and Research Agreements
	In 2003, a license agreement was executed with Children’s Medical Center Corporation (CMCC), whereby CMCC granted the Company a license to utilize certain patent rights.  In accordance with the license agreement, the Company paid an initial license fee of $0.2 million, which was recorded as research and development expense.  Additionally, the license agreement requires the Company to reimburse CMCC for patent costs related to the underlying licensed rights.  In fiscal 2012, fiscal 2013, and for the period from July 10, 2003 (inception) through December 31, 2013, the Company recorded $0.1 million, $0.1 million, and $2.5 million, respectively, related to the reimbursement of such patent costs as general and administrative expenses in the accompanying statements of operations.
	The Company is obligated to make payments to CMCC upon the occurrence of various development and sales milestones.  During the fourth quarter of 2006, the Company achieved two of its development milestones for the first licensed product launched, as defined in the agreement, and paid $0.4 million, which was recorded as research and development expense for the year ended December 31, 2006.  No further milestone payments have been made.   In the second quarter of 2013 the Company achieved a development milestone and recorded $0.1 million as research and development expense, which is included in the accrued expenses on the balance sheet as of December 31, 2013.   If the Company develops and obtains regulatory approval of a licensed product in each of the four subfields covered under the license, it will be required to pay CMCC milestones aggregating approximately $6.9 million, which includes $0.4 million paid to date.  Also, if cumulative net sales of all licensed products reach a certain level, the Company will be required to make a one-time sales milestone payment of $2.0 million.  The timing and likelihood of such milestone payments are not currently known to the Company.  A portion of the milestone payments the Company makes will be credited against its future royalty payments.  The Company must pay CMCC royalties in the mid-single digit range based on net sales of licensed products as defined in the agreement by the Company, its affiliates and its sublicensees, which royalties will be reduced for certain amounts the Company is required to pay to license patents or intellectual property from third parties and under certain circumstances if there is a competing product.  No royalties will be payable with respect to sales of licensed products in countries where there is no valid patent claim, unless the Company advised CMCC not to file for patent protection in that country and later chose to market and sell licensed products in such country.  The license agreement, and the Company’s obligation to pay royalties, terminates on the later of the expiration, on a country-by-country basis, of the last patent right and October 2018.
	In January 2006 the Company entered into a license agreement with Wake Forest University Health Sciences (WFUHS), which was amended in May 2007, for the license of certain of WFUHS’s intellectual property rights.  Under the license agreement, the Company issued WFUHS a warrant to purchase 320 shares of the Company’s common stock through January 1, 2016 at an exercise price of $23.20 per share and is required to pay WFUHS a percentage of certain consideration received from a sublicensee.  While the Company is not required to pay any development milestones under the license, the Company is required to pay certain license maintenance fees with respect to each product covered by new development patents, commencing two years after the Company initiates the first animal study conducted under cGLP, with respect to such product.  These license maintenance fees, which are in the low six figure range with respect to each product, will be creditable against royalties the Company is obligated to pay to WFUHS for such product.  In addition, the Company is required to pay WFUHS royalties in the low- to mid-single digit range based on net sales of licensed products in all countries, with anti-stacking rights to offset royalties owed to third parties against the royalties owed to WFUHS, down to a floor of 50% of the rates that would otherwise be owed to WFUHS (except that such anti-stacking relief does not apply to royalties owed under the CMCC license).  In addition to royalties, the Company is required to pay to WFUHS 4% of any non-royalty consideration received from any third party sublicensees.  With respect to any product covered by an improvement patent, the Company’s obligation to pay royalties to WFUHS terminates upon the later of the expiration, on a product-by-product basis, of the last to expire patent covering such product and the date that is 15 years from the first commercial sale of such product, provided that no such royalty is payable more than seven years after expiration of the last-to-expire patent covering such product.

Income_Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2013
Income Taxes [Abstract]	'
Income Taxes	'
	-16	Income Taxes
	A reconciliation of the statutory U.S. federal rate to the Company’s effective tax rate is as follows:
			2012			2013
	Percent of pre-tax income:
	U.S. federal statutory income tax rate			(34.0	)		(34.0	)
	State taxes, net of federal benefit			(4.6	)		(3.9	)
	Interest expense –revaluation of warrants			(2.4	)		(14.9	)
	Convertible debt conversion feature			1.9			5.6
	Convertible debt discount amortization			(2.0	)		6.2
	Other			1.5			4.8
	Valuation allowance			39.6			36.2
	Effective income tax expense rate			—			—
	The tax effects of temporary differences that gave rise to significant portions of the deferred tax assets were as follows (in thousands):
			December 31,
			2012			2013
	Net operating loss carryforwards		$	61,522		$	64,659
	Research and development credits			5,636			5,950
	Depreciation and amortization			5,040			5,056
	Capitalized start-up costs			16,453			19,620
	Other temporary differences			1,340			1,376
	Gross deferred tax asset			89,991			96,661
	Deferred tax assets valuation allowance			(89,991	)		(96,661	)
			$	—		$	—
	In assessing the realizability of deferred tax assets, the Company considers whether it is more likely than not that some portion or all of the deferred tax assets will not be realized.  The ultimate realization of deferred tax assets is dependent upon the generation of future taxable income during the periods in which the temporary differences representing net future deductible amounts become deductible.  Due to the Company’s history of losses, the deferred tax assets are fully offset by a valuation allowance at December 31, 2012 and 2013.  The valuation allowance in 2012 increased by $5.8 million over 2011 and the valuation allowance in 2013 increased by $6.7 million over 2012, related primarily to additional net operating losses incurred by the Company and additional capitalized start-up expenses.
	The Company moved its corporate headquarters to its leased facility in Winston-Salem, North Carolina during the first quarter of 2012.   As a result of differences in effective tax rates in North Carolina versus Pennsylvania, the deferred effective state tax rate was reduced.  As the Company has a full valuation allowance on its deferred taxes, there is no impact related to the change in the effective state tax rate on the balance sheet and statement of operations.   The Company is updating its forecasted effective state tax rate to consider this impact on its deferred taxes and will continue to monitor and update the rate as necessary.  Additionally, the Company has approximately $8.4 million of deferred tax asset related to Pennsylvania net operating loss carryforwards.  The ultimate use of this deferred tax asset may be impacted by the size of operations remaining in Pennsylvania in the future.  This deferred tax asset is currently offset by a full valuation allowance.
	As of December 31, 2012 and 2013, approximately $42.7 million and $51.8 million, respectively, of the Company’s expenses had been capitalized for tax purposes as start-up costs.  For tax purposes, capitalized start-up costs will be amortized over fifteen years beginning when the Company commences operations, as defined under the Internal Revenue Code.
	The following table summarizes carryforwards of net operating losses and tax credits as of December 31, 2013 (in thousands).
			Amount			Expiration
	Federal net operating losses		$	159,413		2024 to 2033
	State net operating losses			172,587		2019 to 2033
	Research and development credits			5,950		2024 to 2033
	The Tax Reform Act of 1986 (the Act) provides for a limitation on the annual use of net operating loss and research and development tax credit carryforwards following certain ownership changes (as defined by the Act) that could limit the Company’s ability to utilize these carryforwards.  The Company has not completed a study to assess whether an ownership change has occurred, or whether there have been multiple ownership changes since its formation, due to the significant costs and complexities associated with such a study.  The Company may have experienced various ownership changes, as defined by the Act, as a result of past financings.  Accordingly, the Company’s ability to utilize the aforementioned carryforwards may be limited.  Additionally, U.S. tax laws limit the time during which these carryforwards may be applied against future taxes; therefore, the Company may not be able to take full advantage of these carryforwards for federal or state income tax purposes.

Subsequent_Events

Subsequent Events	12 Months Ended
	Dec. 31, 2013
Subsequent Events [Abstract]	'
Subsequent Events	'
	-17	Subsequent Events
	During January 1, 2014 through March 19, 2014, approximately $1.9 million of the 2012 and 2013 Convertible Notes, were converted into an aggregate of 8,778,955 shares of the Company's common stock.
	On February 24, 2014, a special meeting of the shareholders was held to approve an amendment to the Company’s Fourth Amended and Restated Certificate of Incorporation, as amended, to increase the number of authorized shares of common stock from 750,000,000 to 10,000,000,000 shares.
	On January 2, 2014, the Company made an interest payment to the holders of the 2012 and 2013 Convertible Notes by the issuance of shares of common stock and warrants to purchase shares of common stock for nominal consideration. The January 2, 2014 issuance of the shares and warrants was dilutive to the holders of the 2013 Warrants, 2013 Celgene Warrants, 2013 Convertible Notes, 2012 Warrants, the 2012 Convertible Notes, and 2011 Warrants, and the anti-dilution provisions of each were simultaneously triggered. The conversion price of the 2012 and 2013 Convertible Notes was adjusted to $0.22 per share. The adjustments to the exercise price and the number of shares issuable upon exercise of the Warrants was as follows:
			2-Jan-14		Exercise price
	2013 Warrants		253,309,106	$	0.22
	2013 Celgene Warrants		102,272,727	$	0.22
	2012 Warrants		180,147,740	$	0.22
	2011 Warrants		99,682,445	$	0.3

Summary_of_Significant_Account1

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2013
Summary of Significant Accounting Policies [Abstract]	'
Use of Estimates	'
	(a)           Use of Estimates
	The preparation of financial statements, in accordance with accounting principles generally accepted in the United States of America, requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of expenses during the reporting period.  Actual results could differ from those estimates.
Fair Value of Financial Instruments	'
	(b)           Fair Value of Financial Instruments
	As of December 31, 2012 and 2013, the carrying amounts of financial instruments held by the Company, which include cash equivalents, accounts payable, and accrued expenses, approximate fair value due to the short-term nature of those instruments.  In addition, the carrying value of the Company’s debt instruments, which do not have readily ascertainable market values, approximate fair value, given that the interest rates on outstanding borrowings approximate market rates for companies with similar credit ratings.
Cash and Cash Equivalents	'
	(c)           Cash and Cash Equivalents
	The Company considers all highly liquid investments purchased with an original maturity of three months or less to be cash equivalents.
Restricted Cash	'
	(d)           Restricted Cash
	The Company deposited $1.0 million of the gross proceeds of its Senior Secured Convertible Notes (the 2012 Convertible Notes) (see footnote 9 for discussion of the 2012 Convertible Notes) financing into an escrow account in October 2012 pursuant to an Escrow Agreement between the Company, the lenders, and an escrow agent. Upon the achievement of (1) the successful completion of patient implants in the Phase I clinical trial of the Company’s Neo-Urinary Conduit and (2) analysis of in-life data from the Company’s GLP studies for the Neo-Kidney Augment that demonstrates that continued development is warranted (the Milestones), the lenders will instruct the escrow agent to release the escrowed funds to the Company. This deposit is classified as restricted cash as of December 31, 2012.  In the second quarter of 2013 the cash was released.
Property and Equipment	'
	(e)           Property and Equipment
	Property and equipment are stated at cost.  Depreciation is provided over the estimated useful lives of the assets using the straight-line method.  The Company uses a life of three years for computer equipment, five years for laboratory and office and warehouse equipment, seven years for furniture and fixtures, and the lesser of the useful life of the asset or the remaining life of the underlying facility lease for leasehold improvements.  Expenditures for maintenance, repairs, and improvements that do not prolong the useful life of the asset are charged to expense as incurred.  The Company capitalizes interest in connection with the construction of property and equipment.
Impairment of Long-Lived Assets	'
	(f)           Impairment of Long-Lived Assets
	Long-lived assets, such as property and equipment, are reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable.  Recoverability of assets to be held and used is measured by a comparison of the carrying amount of an asset to estimated undiscounted future cash flows expected to be generated by the asset.  If the carrying amount of an asset exceeds its estimated future cash flows, then an impairment charge is recognized by the amount by which the carrying amount of the asset exceeds the fair value of the asset.
Research and Development	'
	(g)           Research and Development
	Research and development costs are charged to expense as incurred.  Research and development costs consist of personnel related expenses, including salaries, benefits, travel, and other related expenses, including stock-based compensation; payments made to third party contract research organizations for preclinical studies, investigative sites for clinical trials, and consultants; costs associated with regulatory filings and the advancement of the Company’s product candidates through preclinical studies and clinical trials; laboratory and other supplies; manufacturing development costs; and related facility maintenance.
Income Taxes	'
	(h)           Income Taxes
	Income taxes are accounted for under the asset-and-liability method.  Deferred tax assets and liabilities are recognized for the future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases and operating loss and tax credit carryforwards.  Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled.  The effect on deferred tax assets and liabilities of a change in tax rates is recognized in the tax provision in the period that includes the enactment date.
Stock-Based Compensation	'
	(i)           Stock-Based Compensation
	The Company measures and recognizes compensation expense for all employee stock-based payments at fair value, net of estimated forfeitures, over the vesting period of the underlying stock-based awards.  In addition, the Company accounts for stock-based compensation to nonemployees in accordance with the accounting guidance for equity instruments that are issued to other than employees.
	Determining the appropriate fair value of stock-based payment awards require the determination of subjective assumptions, including the expected life of the stock-based payment awards and stock price volatility.  The Company uses the Black-Scholes option-pricing model to value its stock option awards.  The assumptions used in calculating the fair value of stock-based payment awards represent management’s best estimates and involve inherent uncertainties and the application of management’s judgment.  As a result, if factors change and management uses different assumptions, stock-based compensation expense could be materially different in the future.  The Company’s historical stock price is used to calculate the expected volatility.
	The estimation of the number of stock awards that will ultimately vest requires judgment, and to the extent actual results or updated estimates differ from the Company’s current estimates, such amounts will be recorded as an adjustment in the period in which estimates are revised.  The Company considers many factors when estimating expected forfeitures for stock awards granted to employees, consultants and directors, including types of awards, employee class, and an analysis of the Company’s historical and known forfeitures on existing awards.  Under the true-up provisions of the stock based compensation guidance, the Company records additional expense if the actual forfeiture rate is lower than estimated, and a recovery of expense if the actual forfeiture rate is higher than estimated, during the period in which the options vest.
Embedded Derivative Conversion Options and Call Option Derivative Liability	'
	(j)           Embedded Derivative Conversion Options and Call Option Derivative Liability
	The Company accounts for the Demand Note Exchange Right and the conversion feature embedded in the 2012 and 2013 Convertible Notes (the Conversion Options) in accordance with Financial Accounting Standards Board Accounting Standard Codification (ASC) 815, Derivatives and Hedging (ASC 815). Under this accounting guidance, the Company is required to bifurcate the embedded derivative from the host instrument and account for it as a free-standing derivative financial instrument.  The Company classifies these embedded derivatives as part of the carrying value of the debt host instrument.  The Company also accounted for the Call Option issued in connection with the 2012 Financing in accordance with ASC 815, as this instrument is considered a free-standing financial instrument that meets the criteria of a derivative under the guidance. The Company classified the Call Option as a derivative liability on the balance sheet.  The changes in fair value of the embedded derivative or derivative liability are remeasured at each balance sheet date and recorded in current period earnings.
Warrants	'
	(k)           Warrants
	The Company accounts for stock warrants as either equity instruments or derivative liabilities depending on the specific terms of the warrant agreement.  Stock warrants that allow for cash settlement or provide for modification of the warrant exercise price are accounted for as derivative liabilities.  The Company classifies derivative warrant liabilities on the balance sheet as a current liability, which is revalued at each balance sheet date subsequent to the initial issuance.  The changes in fair value of the derivative warrant liabilities are remeasured at each balance sheet date and recorded in current period earnings.
Net Loss Per Share	'
	(l)           Net Loss Per Share
	Basic and diluted net loss attributable to common stockholders per share is calculated by dividing net loss attributable to common stockholders by the weighted-average number of common shares outstanding. For all periods presented, the outstanding shares of unvested restricted stock as well as the number of common shares issuable upon exercise of outstanding stock options and warrants and conversion of notes payable have been excluded from the calculation of diluted net loss attributable to common stockholders per share because their effect would be anti-dilutive. Therefore, the weighted-average shares used to calculate both basic and dilutive loss per share are the same.
	The following potentially dilutive securities have been excluded from the computations of diluted weighted-average shares outstanding, as they would be anti-dilutive:
		Year Ended December 31,
		2012		2013
	Shares underlying warrants outstanding		80,250,702		481,301,961
	Shares underlying options outstanding		234,465		230,725
	Unvested restricted stock		74,372		54,721
	Convertible notes payable		20,007,002		114,517,218
Deferred Debt Offering Costs	'
	(m)           Deferred Debt Offering Costs
	Deferred debt offering costs include costs directly attributable to the Company’s debt offerings.  In accordance with authoritative literature, these costs are deferred and recorded as other non-current assets and amortized over the term of the debt using the effective interest method.
Reverse Stock Split	'
	(n)           Reverse Stock Split
	On May 25, 2012, the Company's Board of Directors approved a reverse stock split on the basis of one share of common stock for each currently outstanding 10 shares of pre-split common stock that became effective on June 14, 2012.  All common share and per-share data included in these financial statements reflect such reverse stock split.

Summary_of_Significant_Account2

Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2013
Summary of Significant Accounting Policies [Abstract]	'
Potentially Dilutive Securities	'
	The following potentially dilutive securities have been excluded from the computations of diluted weighted-average shares outstanding, as they would be anti-dilutive:
		Year Ended December 31,
		2012		2013
	Shares underlying warrants outstanding		80,250,702		481,301,961
	Shares underlying options outstanding		234,465		230,725
	Unvested restricted stock		74,372		54,721
	Convertible notes payable		20,007,002		114,517,218

Supplemental_Cash_Flow_Informa1

Supplemental Cash Flow Information (Tables)	12 Months Ended
	Dec. 31, 2013
Supplemental Cash Flow Information [Abstract]	'
Supplemental Cash Flow Information	'
	The following table contains additional supplemental cash flow information for the periods reported (in thousands).
							Period from
							10-Jul-03
							(inception)
			Year Ended				through
			December 31,				December 31,
			2012		2013		2013
	Supplemental disclosure of non-cash transactions:
	Conversion of note principal to redeemable convertible preferred stock	$	—	$	—	$	3,562
	Convertible note issued to initial stockholder for consulting expense		—		—		210
	Exchange of Demand Note for Convertible Notes		1,005		—		1,005
	Fair value of embedded derivatives and derivatives issued with issuance of long-term debt		3,669		732		4,401
	Fair value of warrants issued with issuance of long-term debt		4,994		9,404		16,638
	Fair value of warrants issued with issuance of common stock		—		—		16,947
	Fair value of interest warrants issued for payment of interest		—		437		437
	Fair value of warrants issued pursuant to Celgene Collaboration and Option Agreement		—		3,796		3,796
	Conversion of redeemable convertible preferred stock into 566 shares of common stock		—		—		191,909
	Conversion of warrant liability to common stock		—		57		180
	Conversion of 2012 Convertible Notes to common stock		—		231		231
	Issuance of common stock and warrants for payment of interest		—		1,975		1,975
	Supplemental disclosure of cash flow information:
	Cash paid for interest, net of amounts capitalized		515		443		13,236
	Cash paid for issuance costs classified as interest expense		830		698		1,528

Financial_Instruments_Tables

Financial Instruments (Tables)	12 Months Ended
	Dec. 31, 2013
Financial Instruments [Abstract]	'
Financial Assets and Liabilities Measured at Fair Value on a Recurring Basis	'
	The following fair value hierarchy table presents information about each major category of the Company’s financial assets and liability measured at fair value on a recurring basis as of December 31, 2012 and 2013 (in thousands).
			Fair value measurement at reporting date using:
			Quoted prices in			Significant other			Significant			Total
			active markets for			observable			unobservable
			identical assets			inputs			inputs
			(Level 1)			(Level 2)			(Level 3)
	At December 31, 2012:
	Assets:
	Cash and cash equivalents		$	7,536		$	—		$	—		$	7,536
	Liabilities:		$	—		$	—		$	2,449		$	2,449
	Derivative liability
	Embedded derivative liability			—			—			276			276
	Warrant liability			—			—			6,178			6,178
			$	—		$	—		$	8,903		$	8,903
			Fair value measurement at reporting date using:
			Quoted prices in			Significant other			Significant			Total
			active markets for			observable			unobservable
			identical assets			inputs			inputs
			(Level 1)			(Level 2)			(Level 3)
	At December 31, 2013:
	Assets:
	Cash and cash equivalents		$	21,510		$	—		$	—		$	21,510
	Liabilities:		$	—		$	—		$	226		$	226
	Embedded derivative liability
	Warrant liability			—			—			11,425			11,425
			$	—		$	—		$	11,651		$	11,651
Reconciliation of the Derivative Liability and Embedded Derivative Liability Measured at Fair Value on a Recurring Basis using Unobservable Inputs (Level 3)	'
	A reconciliation of the derivative liability is as follows (in thousands):
		Call Option
	Balance at January 1, 2012	$	—
	Issuance of derivative		3,181
	Change in fair value of derivative liability		(732	)
	Balance at December 31, 2012	$	2,449
	Change in fair value of derivative liability		3,870
	Exercise of Call Option		(6,319	)
	Balance at December 31, 2013		—
	The Company issued notes in 2012 and 2013 that are convertible into common stock at the option of the holder.  See Note 11 for further discussion of these conversion options, which are accounted for as embedded derivative liabilities. These conversion options are measured at fair value on a recurring basis using unobservable inputs or available market data to support the fair value (Level 3).  A reconciliation of the embedded derivative liabilities is as follows (in thousands):
			2012 Notes			2013 Notes			Total
	Balance at January 1, 2012		$	—		$	—		$	—
	Issuance of derivative			488			—			488
	Change in fair value of derivative liability			(212	)		—			(212	)
	Balance at December 31, 2012		$	276		$	—		$	276
	Issuance of derivative			—			732			732
	Change in fair value of derivative liability			(175	)		(607	)		(782	)
	Balance at December 31, 2013		$	101		$	125		$	226
Reconciliation of Warrant Liability Measured at Fair Value on a Recurring Basis using Unobservable Inputs (Level 3)	'
	A reconciliation of the warrant liability is as follows (in thousands):
			2011			2012			2013			2013			2013			Total
			Warrants			Warrants			Warrants			Celgene			Interest
												Warrants			Warrants
	Balance at January 1, 2012		$	2,511		$	—		$	—		$	—		$	—		$	2,511
	Issuance of warrants			—			4,944			—			—			—			4,944
	Change in fair value of warrant liability			(133	)		(1,144	)		—			—			—			(1,277	)
	Balance at December 31, 2012		$	2,378		$	3,800		$	—		$	—		$	—		$	6,178
	Issuance of warrants			—			—			9,404			3,796			437			13,637
	Exercise of warrants			(15	)		—			(42	)		—			—			(57	)
	Change in fair value of warrant liability			(1,643	)		(370	)		(4,223	)		(1,713	)		(384	)		(8,333	)
	Balance at December 31, 2013		$	720		$	3,430		$	5,139		$	2,083		$	53		$	11,425

Property_and_equipment_Tables

Property and equipment (Tables)	12 Months Ended
	Dec. 31, 2013
Property and equipment [Abstract]	'
Property and Equipment	'
	Property and equipment consisted of the following (in thousands):
		December 31,
		2012			2013
	Office and warehouse equipment	$	323		$	323
	Computer equipment		978			1,003
	Furniture and fixtures		524			524
	Laboratory equipment		4,961			5,035
	Leasehold improvements		6,898			6,908
			13,684			13,793
	Less accumulated depreciation		(13,072	)		(13,339	)
		$	612		$	454

Accrued_expenses_Tables

Accrued expenses (Tables)	12 Months Ended
	Dec. 31, 2013
Accrued expenses [Abstract]	'
Accrued Expenses	'
	Accrued expenses consist of the following (in thousands):
		December 31,
		2012		2013
	Accrued compensation and benefits	$	716	$	757
	Accrued consulting and professional fees		387		138
	Accrued research and development		453		535
	Accrued interest on convertible notes		373		843
	Other		241		93
		$	2,170	$	2,366

Lease_liability_Tables

Lease liability (Tables)	12 Months Ended
	Dec. 31, 2013
Lease liability [Abstract]	'
Activity Related to Lease Liability	'
	The following table summarizes the activity related to the lease liability for the year ended December 31, 2012 and 2013 (in thousands).
		Warehouse			Office and			Total
		space			manufacturing
					space
	Balance at January 1, 2012	$	828		$	854		$	1,682
	Charges utilized		(239	)		(548	)		(787	)
	Additional charges to operations		89			76			165
	Balance at December 31, 2012		678			382			1,060
	Charges utilized		(248	)		(505	)		(753	)
	Additional charges to operations		70			595			665
	Balance at December 31, 2013		500			472			972
	Less current portion		(242	)		(423	)		(665	)
	Total long-term lease liability	$	258		$	49		$	307

Debt_Tables

Debt (Tables)	12 Months Ended
	Dec. 31, 2013
Debt [Abstract]	'
Debt Outstanding	'
	Total debt outstanding consists of the following (in thousands):
		December 31,
		2012			2013
	Senior Secured 2012 Convertible Notes	$	15,005		$	14,634
	Embedded derivative liability-2012 Notes		276			101
	Senior Secured 2013 Convertible Notes		—			18,576
	Embedded derivative liability-2013 Notes		—			125
	Working Capital Note		3,660			1,382
	Unamortized debt discount		(7,672	)		(7,866	)
			11,269			26,952
	Less current portion		(1,786	)		(1,329	)
	Total long-term debt and embedded derivative, net	$	9,483		$	25,623
Principal Payments Due	'
	Principal payments due as of December 31, 2013 are as follows (in thousands):
	2014	$	1,382
	2015		14,634
	2016		18,576
			34,592
	Less embedded derivative and unamortized debt discount		(7,640	)
		$	26,952

Embedded_Derivative_Conversion1

Embedded Derivative Conversion Options and Call Option Derivative Liability (Tables)	12 Months Ended
	Dec. 31, 2013
Embedded Derivative Conversion Options and Call Option Derivative Liability [Abstract]	'
Aggregate Fair Values of the Conversion Options	'
	The following table summarizes the calculated aggregate fair values using a risk-neutral framework within a Monte Carlo analysis of the Conversion Options as of the dates indicated along with assumptions utilized in each calculation.
		Embedded Derivative Liability
		Conversion Option-2012						Conversion Option-2013
		Notes						Notes
		December 31,			December 31,			June 30,			December 31,
		2012			2013			2013			2013
		$	276		$	101		$	732		$	125
	Calculated aggregate value (in thousands)
	Equity volatility		115	%		120	%		120	%		120	%
	Asset volatility		90	%		95	%		90	%		95	%
	Probability of Fundamental Transaction or Major Transaction		100	%		100	%		100	%		100	%
	Weighted average risk-free interest rate		0.3	%		0.2	%		0.3	%		0.2	%
	Dividend yield	None			None			None			None

Warrants_Tables

Warrants (Tables)	12 Months Ended
	Dec. 31, 2013
Warrants [Abstract]	'
Outstanding Warrants	'
	The following table summarizes outstanding warrants to purchase common stock:
				Shares Exercisable as of
				December 31,		December 31,			Weighted Average
									Exercise
				2012		2013			Price		Expiration
	Equity-classified warrants
	Issued to lenders and vendors			18,514		18,375		$	158.24		March 2014 through September 2019
				18,514		18,375
	Liability-classified warrants
	2013 Interest Warrants			—		1,057,944		$	0.001		July through October 2023
	2013 Warrants			—		191,213,801		$	0.29		June 2018 through June 2023
	2013 Celgene Warrants			—		77,586,207		$	0.29		June 2018 through June 2023
	2012 Warrants (1)			52,843,337		136,663,804		$	0.29		October 2014 through October 2022
	2011 Warrants (2)			27,388,851		74,761,830		$	0.4		Mar-16
				80,232,188		481,283,586
	Total			80,250,702		481,301,961
	(1)As of December 31, 2012 the 2012 Warrants had an exercise price of $0.75 per share.
	(2)As of December 31, 2012 the 2011 Warrants had an exercise price of $1.10 per share.
Aggregate fair values for the liability-classified warrants	'
	The following table summarizes the calculated aggregate fair values for the liability-classified warrants as of the dates indicated along with the assumptions utilized in each calculation.
			Fair value as of December 31, 2013
			2011			2012				2013			2013			2013
			Warrants			Warrants				Warrants			Celgene Warrants			Interest Warrants
	Calculated aggregate value (in thousands)		$	720		$	3,430			$	5,139		$	2,083		$	53
	Exercise price per share of warrant		$	0.4		$	0.29			$	0.29		$	0.29		$	0.001
	Equity volatility			120	%		120	%			120	%		120	%		120	%
	Asset volatility			95	%		95	%			95	%		95	%		95	%
	Probability of Fundamental Transaction			100	%		100	%			100	%		100	%		100	%
	Weighted average risk-free interest rate			0.2	%		0.2	%			0.2	%		0.2	%		0.2	%
	The following table summarizes the calculated aggregate fair values for the liability-classified warrants as of the dates indicated along with the assumptions utilized in each calculation.
			Fair value as of
			31-Dec-12							30-Jun-13
			2011			2012				2013			2013
			Warrants			Warrants				Warrants			Celgene Warrants
	Calculated aggregate value (in thousands)		$	2,378		$	3,800			$	9,404		$	3,390
	Exercise price per share of warrant		$	1.1		$	0.75			$	0.76		$	0.76
	Equity volatility			115	%		115	%			120	%		120	%
	Asset volatility			90	%		90	%			90	%		90	%
	Probability of Fundamental Transaction			100	%		100	%			100	%		100	%
	Weighted average risk-free interest rate			0.3	%		0.3	%			0.3	%		0.3	%
Net cash settlement values for the liability-classified warrants	'
	The following table summarizes the calculated net cash settlement values for the liability-classified warrants as of the dates indicated along with the assumptions utilized in each calculation.
			Net cash settlement as of December 31, 2013
			2011			2012				2013			2013			2013
			Warrants			Warrants				Warrants			Celgene			Interest
													Warrants			Warrants
	Calculated aggregate value (in thousands) (1)		$	8,076		$	26,004			$	38,238		$	15,503			—
	Exercise price per share of warrant		$	0.4		$	0.29			$	0.29		$	0.29			—
	Closing price per share of warrant		$	0.25		$	0.24	-2		$	0.24	-2	$	0.24	-2		—
	Equity volatility (3)			100	%		99	%			99	%		99	%		—
	Expected term (years)			2.2			7				7.8			7.8			—
	Weighted average risk-free interest rate			0.5	%		2.2	%			2.5	%		2.5	%		—
	Dividend yield		None			None				None			None				—
	-1	Represents the net cash settlement value of the warrant as of December 31, 2013, which value was calculated utilizing the Black-Scholes model specified in the warrant agreement.
	-2	Represents the five-day Company stock VWAP used to calculate the net cash settlement value as of December 31, 2013.
	-3	Represents the volatility assumption used to calculate the net cash settlement value as of December 31, 2013 based on the terms of the warrant agreement.

Stockbased_Compensation_Tables

Stock-based Compensation (Tables)	12 Months Ended
	Dec. 31, 2013
Stock-based Compensation [Abstract]	'
Stock Option Activity	'
	The following table summarizes stock option activity under the Plans:
		Number of			Weighted-		Weighted-average	Aggregate intrinsic
		shares			average		remaining	value (in thousands)
					exercise		contractual term
					price		(in years)
	Outstanding at December 31, 2011	174,872			$	16.76
	Granted	87,184			$	5.66
	Exercised	(2,432	)		$	4.4
	Forfeited	(25,159	)		$	20.45
	Outstanding at December 31, 2012	234,465			$	12.37
	Granted	—				—
	Exercised	—				—
	Forfeited	(3,740	)		$	17.68
	Outstanding at December 31, 2013	230,725			$	12.28	7.5	$	—
	Vested and expected to vest at December 31, 2013	221,246			$	12.49	7.5	$	—
	Exercisable at December 31, 2013	137,559			$	15.43	7.2	$	—
Weighted-average Assumptions	'
	The per-share weighted-average fair value of the options granted to employees during 2012 was estimated at $5.66 on the date of grant using the Black-Scholes option-pricing model with the following weighted-average assumptions:
		Year Ended December 31,
		2012		2013
	Volatility	84%		Not applicable
	Expected term	6.0 years		Not applicable
	Risk-free interest rate	1.10%		Not applicable
	Dividend yield	None		Not applicable
Restricted Stock Activity	'
	The following table summarizes restricted stock activity under the Plans:
		Number			Weighted-
		of shares			average
					grant date
					fair value
	Nonvested at December 31, 2011	13,988			$	24.2
	Granted	67,863			$	6.00
	Vested	(5,047	)		$	24.2
	Forfeited	(2,432	)		$	17.36
	Nonvested at December 31, 2012	74,372			$	7.81
	Granted	—				—
	Vested	(19,221	)		$	8.35
	Forfeited	(430	)		$	13.36
	Nonvested at December 31, 2013	54,721			$	7.59

Commitments_and_Contingencies_

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2013
Commitments and Contingencies [Abstract]	'
Future Minimum Lease Payments	'
	The following table summarizes future minimum lease payments as of December 31, 2013 (in thousands):
	2014	$	971
	2015		1,079
	2016		277
	Total minimum lease payments (1)	$	2,327

Income_Taxes_Tables

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2013
Income Taxes [Abstract]	'
Reconciliation of Statutory U.S. Federal Rate to Effective Tax Rate	'
	A reconciliation of the statutory U.S. federal rate to the Company’s effective tax rate is as follows:
		2012			2013
	Percent of pre-tax income:
	U.S. federal statutory income tax rate		(34.0	)		(34.0	)
	State taxes, net of federal benefit		(4.6	)		(3.9	)
	Interest expense –revaluation of warrants		(2.4	)		(14.9	)
	Convertible debt conversion feature		1.9			5.6
	Convertible debt discount amortization		(2.0	)		6.2
	Other		1.5			4.8
	Valuation allowance		39.6			36.2
	Effective income tax expense rate		—			—
Deferred Tax Assets	'
	The tax effects of temporary differences that gave rise to significant portions of the deferred tax assets were as follows (in thousands):
		December 31,
		2012			2013
	Net operating loss carryforwards	$	61,522		$	64,659
	Research and development credits		5,636			5,950
	Depreciation and amortization		5,040			5,056
	Capitalized start-up costs		16,453			19,620
	Other temporary differences		1,340			1,376
	Gross deferred tax asset		89,991			96,661
	Deferred tax assets valuation allowance		(89,991	)		(96,661	)
		$	—		$	—
Summary of Carryforwards of Net Operating Losses and Tax Credits	'
	The following table summarizes carryforwards of net operating losses and tax credits as of December 31, 2013 (in thousands).
		Amount			Expiration
	Federal net operating losses	$	159,413		2024 to 2033
	State net operating losses		172,587		2019 to 2033
	Research and development credits		5,950		2024 to 2033

Subsequent_Events_Tables

Subsequent Events (Tables)	12 Months Ended
	Dec. 31, 2013
Subsequent Events [Abstract]	'
Adjustments to exercise price and number of shares issuable upon exercise of Warrants	'
	The adjustments to the exercise price and the number of shares issuable upon exercise of the Warrants was as follows:
		2-Jan-14		Exercise price
	2013 Warrants	253,309,106	$	0.22
	2013 Celgene Warrants	102,272,727	$	0.22
	2012 Warrants	180,147,740	$	0.22
	2011 Warrants	99,682,445	$	0.3

Organization_and_Nature_of_Ope1

Organization and Nature of Operations (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2013
Organization and Nature of Operations [Abstract]	'	'
Minimum stockholders equity requirement for continued listing on Nasdaq Capital Market	'	$2.50
Decrease of net loss	($0.30)	'

Managements_Plans_to_Continue_1

Management's Plans to Continue as a Going Concern (Details) (USD $)	12 Months Ended							126 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2010	Dec. 31, 2009	Dec. 31, 2008	Dec. 31, 2007	Dec. 31, 2006	Dec. 31, 2005	Dec. 31, 2004	Dec. 31, 2013	Dec. 31, 2012
Management's Plans to Continue as a Going Concern [Abstract]	'	'	'	'	'	'	'	'	'
Deficit accumulated during the development stage	'	'	'	'	'	'	'	$266,100	$247,173
Cumulative accretion on redeemable convertible preferred stock	$3,993	$14,059	$11,754	$8,742	$5,640	$3,164	$1,035	$48,400	'

Summary_of_Significant_Account3

Summary of Significant Accounting Policies (Details) (USD $)	12 Months Ended
In Millions, except Share data, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Restricted cash [Abstract]	'	'
Gross proceeds of Senior Secured Convertible Notes financing into escrow account	1	'
Reverse Stock Split [Abstract]	'	'
Reverse stock split conversion ratio (in shares)	10	'
Shares underlying warrants outstanding [Member]	'	'
Potentially dilutive securities have been excluded from computations of diluted weighted-average shares outstanding [Abstract]	'	'
Potentially dilutive securities have been excluded from computations of diluted weighted-average shares outstanding (in shares)	481,301,961	80,250,702
Shares underlying options outstanding [Member]	'	'
Potentially dilutive securities have been excluded from computations of diluted weighted-average shares outstanding [Abstract]	'	'
Potentially dilutive securities have been excluded from computations of diluted weighted-average shares outstanding (in shares)	230,725	234,465
Unvested restricted stock [Member]	'	'
Potentially dilutive securities have been excluded from computations of diluted weighted-average shares outstanding [Abstract]	'	'
Potentially dilutive securities have been excluded from computations of diluted weighted-average shares outstanding (in shares)	54,721	74,372
Convertible notes payable [Member]	'	'
Potentially dilutive securities have been excluded from computations of diluted weighted-average shares outstanding [Abstract]	'	'
Potentially dilutive securities have been excluded from computations of diluted weighted-average shares outstanding (in shares)	114,517,218	20,007,002
Computer Equipment [Member]	'	'
Property, Plant and Equipment [Line Items]	'	'
Property and equipment estimated useful life	'3 years	'
Laboratory, Office and Warehouse Equipment [Member]	'	'
Property, Plant and Equipment [Line Items]	'	'
Property and equipment estimated useful life	'5 years	'
Furniture and Fixtures [Member]	'	'
Property, Plant and Equipment [Line Items]	'	'
Property and equipment estimated useful life	'7 years	'

Supplemental_Cash_Flow_Informa2

Supplemental Cash Flow Information (Details) (USD $)	12 Months Ended				126 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2010	Dec. 31, 2004	Dec. 31, 2013
Supplemental disclosure of non-cash transactions [Abstract]	'	'	'	'	'
Conversion of note principal to redeemable convertible preferred stock	$0	$0	'	$0	$3,562
Convertible note issued to initial stockholder for consulting expense	0	0	'	'	210
Exchange of Demand Note for Convertible Notes	0	1,005	'	'	1,005
Fair value of embedded derivatives and derivatives issued with issuance of long-term debt	732	3,669	'	'	4,401
Fair value of warrants issued with issuance of long term debt	9,404	4,994	'	'	16,638
Fair value of warrants issued with issuance of common stock	0	0	'	'	16,947
Fair value of interest warrants issued for payment of interest	437	0	'	'	437
Fair value of warrants issued pursuant to Celgene Collaboration and Option Agreement	3,796	0	'	'	3,796
Conversion of redeemable convertible preferred stock into 566 shares of common stock	0	0	191,909	'	191,909
Conversion of warrant liability to common stock	57	0	123	'	180
Conversion of 2012 Convertible Notes to common stock	231	0	'	'	231
Issuance of common stock and warrants for payment of interest	1,975	0	'	'	1,975
Supplemental disclosure of cash flow information [Abstract]	'	'	'	'	'
Cash paid for interest, net of amounts capitalized	443	515	'	'	13,236
Cash paid for issuance costs classified as interest expense	$698	$830	'	'	$1,528
Conversion of redeemable convertible preferred stock into shares of common stock (in shares)	566	'	'	'	566

Financial_Instruments_Details

Financial Instruments (Details) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Assets:	'	'
Cash and cash equivalents	$21,510,000	$7,536,000
Liabilities:	'	'
Total fair value of liabilities	11,651,000	8,903,000
Reconciliation of embedded derivative warrant liability measured at fair value on a recurring basis using unobservable inputs (Level 3) [Abstract]	'	'
Balance	6,178,000	2,511,000
Issuance	13,637,000	4,944,000
Exercise of warrants	-57,000	'
Change in fair value	-8,333,000	-1,277,000
Balance	11,425,000	6,178,000
2011 Warrants [Member]	'	'
Reconciliation of embedded derivative warrant liability measured at fair value on a recurring basis using unobservable inputs (Level 3) [Abstract]	'	'
Balance	2,378,000	2,511,000
Issuance	0	0
Exercise of warrants	-15,000	'
Change in fair value	-1,643,000	-133,000
Balance	720,000	2,378,000
2012 Warrants [Member]	'	'
Reconciliation of embedded derivative warrant liability measured at fair value on a recurring basis using unobservable inputs (Level 3) [Abstract]	'	'
Balance	3,800,000	0
Issuance	0	4,944,000
Exercise of warrants	0	'
Change in fair value	-370,000	-1,144,000
Balance	3,430,000	3,800,000
2013 Warrants [Member]	'	'
Reconciliation of embedded derivative warrant liability measured at fair value on a recurring basis using unobservable inputs (Level 3) [Abstract]	'	'
Balance	0	0
Issuance	9,404,000	0
Exercise of warrants	-42,000	'
Change in fair value	-4,223,000	0
Balance	5,139,000	0
2013 Celgene Warrants [Member]	'	'
Reconciliation of embedded derivative warrant liability measured at fair value on a recurring basis using unobservable inputs (Level 3) [Abstract]	'	'
Balance	0	0
Issuance	3,796,000	0
Exercise of warrants	0	'
Change in fair value	-1,713,000	0
Balance	2,083,000	0
2013 Interest Warrants [Member]	'	'
Reconciliation of embedded derivative warrant liability measured at fair value on a recurring basis using unobservable inputs (Level 3) [Abstract]	'	'
Balance	0	0
Issuance	437,000	0
Exercise of warrants	0	'
Change in fair value	-384,000	0
Balance	53,000	0
2012 Notes [Member]	'	'
Reconciliation of embedded derivative warrant liability measured at fair value on a recurring basis using unobservable inputs (Level 3) [Abstract]	'	'
Balance	276,000	0
Issuance	0	488,000
Change in fair value	-175,000	-212,000
Balance	101,000	276,000
2013 Notes [Member]	'	'
Reconciliation of embedded derivative warrant liability measured at fair value on a recurring basis using unobservable inputs (Level 3) [Abstract]	'	'
Balance	0	0
Issuance	732,000	0
Change in fair value	-607,000	0
Balance	125,000	0
Conversion Option [Member]	'	'
Reconciliation of embedded derivative warrant liability measured at fair value on a recurring basis using unobservable inputs (Level 3) [Abstract]	'	'
Balance	276,000	0
Issuance	732,000	488,000
Change in fair value	-782,000	-212,000
Balance	226,000	276,000
Call Option [Member]	'	'
Reconciliation of embedded derivative warrant liability measured at fair value on a recurring basis using unobservable inputs (Level 3) [Abstract]	'	'
Balance	2,449,000	0
Issuance	'	3,181,000
Exercise of call option	-6,319,000	'
Change in fair value	3,870,000	-732,000
Balance	0	2,449,000
Derivative liability [Member]	'	'
Liabilities:	'	'
Total fair value of liabilities	'	2,449,000
Embedded Derivative liability [Member]	'	'
Liabilities:	'	'
Total fair value of liabilities	226,000	276,000
Warrant liability [Member]	'	'
Liabilities:	'	'
Total fair value of liabilities	11,425,000	6,178,000
Quoted prices in active markets for identical assets (Level 1) [Member]	'	'
Assets:	'	'
Cash and cash equivalents	21,510,000	7,536,000
Liabilities:	'	'
Total fair value of liabilities	0	0
Quoted prices in active markets for identical assets (Level 1) [Member] | Derivative liability [Member]	'	'
Liabilities:	'	'
Total fair value of liabilities	'	0
Quoted prices in active markets for identical assets (Level 1) [Member] | Embedded Derivative liability [Member]	'	'
Liabilities:	'	'
Total fair value of liabilities	0	0
Quoted prices in active markets for identical assets (Level 1) [Member] | Warrant liability [Member]	'	'
Liabilities:	'	'
Total fair value of liabilities	0	0
Significant other observable inputs (Level 2) [Member]	'	'
Assets:	'	'
Cash and cash equivalents	0	0
Liabilities:	'	'
Total fair value of liabilities	0	0
Significant other observable inputs (Level 2) [Member] | Derivative liability [Member]	'	'
Liabilities:	'	'
Total fair value of liabilities	'	0
Significant other observable inputs (Level 2) [Member] | Embedded Derivative liability [Member]	'	'
Liabilities:	'	'
Total fair value of liabilities	0	0
Significant other observable inputs (Level 2) [Member] | Warrant liability [Member]	'	'
Liabilities:	'	'
Total fair value of liabilities	0	0
Significant unobservable inputs (Level 3) [Member]	'	'
Assets:	'	'
Cash and cash equivalents	0	0
Liabilities:	'	'
Total fair value of liabilities	11,651,000	8,903,000
Significant unobservable inputs (Level 3) [Member] | Derivative liability [Member]	'	'
Liabilities:	'	'
Total fair value of liabilities	'	2,449,000
Significant unobservable inputs (Level 3) [Member] | Embedded Derivative liability [Member]	'	'
Liabilities:	'	'
Total fair value of liabilities	226,000	276,000
Significant unobservable inputs (Level 3) [Member] | Warrant liability [Member]	'	'
Liabilities:	'	'
Total fair value of liabilities	$11,425,000	$6,178,000

Property_and_equipment_Details

Property and equipment (Details) (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Property, Plant and Equipment [Line Items]	'	'
Property and equipment, gross	$13,793	$13,684
Less accumulated depreciation	-13,339	-13,072
Property and equipment, net	454	612
Office and warehouse equipment [Member]	'	'
Property, Plant and Equipment [Line Items]	'	'
Property and equipment, gross	323	323
Computer equipment [Member]	'	'
Property, Plant and Equipment [Line Items]	'	'
Property and equipment, gross	1,003	978
Furniture and fixtures [Member]	'	'
Property, Plant and Equipment [Line Items]	'	'
Property and equipment, gross	524	524
Laboratory equipment [Member]	'	'
Property, Plant and Equipment [Line Items]	'	'
Property and equipment, gross	5,035	4,961
Leasehold improvements [Member]	'	'
Property, Plant and Equipment [Line Items]	'	'
Property and equipment, gross	$6,908	$6,898

Accrued_expenses_Details

Accrued expenses (Details) (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Accrued expenses [Abstract]	'	'
Accrued compensation and benefits	$757	$716
Accrued consulting and professional fees	138	387
Accrued research and development current	535	453
Accrued interest on convertible notes	843	373
Other	93	241
Accrued expenses	$2,366	$2,170

Lease_liability_Details

Lease liability (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Activity related to lease liability [Abstract]	'	'
Balance at January 1, 2011	$1,060	$1,682
Charges utilized	-753	-787
Additional charges to operations	665	165
Balance at December 31, 2011	972	1,060
Less current portion	-665	-536
Total long-term lease liability	307	524
Warehouse space [Member]	'	'
Capital Leased Assets [Line Items]	'	'
Lease term	'5 years	'
Activity related to lease liability [Abstract]	'	'
Balance at January 1, 2011	678	828
Charges utilized	-248	-239
Additional charges to operations	70	89
Balance at December 31, 2011	500	678
Less current portion	-242	'
Total long-term lease liability	258	'
Office and manufacturing space [Member]	'	'
Activity related to lease liability [Abstract]	'	'
Balance at January 1, 2011	382	854
Charges utilized	-505	-548
Additional charges to operations	595	76
Balance at December 31, 2011	472	382
Less current portion	-423	'
Total long-term lease liability	$49	'

Debt_Details

Debt (Details) (USD $)

12 Months Ended

126 Months Ended

0 Months Ended

12 Months Ended

0 Months Ended

0 Months Ended

12 Months Ended

12 Months Ended

12 Months Ended

0 Months Ended

12 Months Ended

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2013

Apr. 02, 2013

Oct. 02, 2012

Dec. 31, 2013

Dec. 31, 2012

Oct. 02, 2012

Oct. 02, 2012

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2012

Jun. 28, 2013

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2013

Jan. 02, 2014

Dec. 31, 2013

Dec. 31, 2013

Senior Secured 2012 Convertible Notes [Member]

Senior Secured 2012 Convertible Notes [Member]

Senior Secured 2012 Convertible Notes [Member]

Senior Secured 2012 Convertible Notes [Member]

Senior Secured 2012 Convertible Notes [Member]

Senior Secured 2012 Convertible Notes [Member]

Senior Secured 2012 Convertible Notes [Member]

Embedded derivative liability-2012 Notes [Member]

Embedded derivative liability-2012 Notes [Member]

Senior Secured 2013 Convertible Notes [Member]

Senior Secured 2013 Convertible Notes [Member]

Senior Secured 2013 Convertible Notes [Member]

Embedded derivative liability-2013 Notes [Member]

Embedded derivative liability-2013 Notes [Member]

Working Capital Note [Member]

Working Capital Note [Member]

Working Capital Note [Member]

Working Capital Note [Member]

Working Capital Note [Member]

Senior Secured 2012 And 2013 Convertible Notes [Member]

Senior Secured 2012 And 2013 Convertible Notes [Member]

Senior Secured 2012 And 2013 Convertible Notes And Working Capital Note [Member]

Senior Secured 2012 Convertible Notes And Working Capital Note [Member]

Warrants issued for five years [Member]

Warrants issued for ten years [Member]

Call Option [Member]

Warrants issued for five years [Member]

Warrants issued for ten years [Member]

Subsequent Event [Member]

Debt Instrument [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Convertible notes to purchase common stock (in shares)

'

'

'

'

1,118,722

'

'

'

'

'

'

'

26,921,741

'

'

'

'

'

'

'

'

'

'

'

'

'

Exercise period of convertible notes

'

'

'

'

'2 years

'

'

'

'

'

'

'

'5 years

'

'

'

'

'

'

'

'

'

'

'

'

'

Warrants to purchase common stock (in shares)

481,301,961

80,250,702

481,301,961

60,973,081

'

136,663,804

'

16,672,145

33,344,293

'

'

'

53,843,479

192,165,525

'

'

'

'

'

'

569,392

1,138,785

'

'

'

'

Exercise period of warrants

'

'

'

'

'

'

'

'5 years

'10 years

'

'

'

'10 years

'

'

'

'

'

'

'

'5 years

'10 years

'

'

'

'

Exercise price of warrants (in dollars per share)

'

'

'

$0.65

$0.75

$0.29

'

'

'

'

'

'

$0.69

$0.29

'

'

'

'

'

'

'

'

'

'

'

'

Conversion price (in dollars per share)

'

'

'

$0.65

'

$0.29

'

'

'

'

'

'

$0.69

$0.29

'

'

'

'

'

'

'

'

'

'

'

'

Debt instrument, maturity date

'

'

'

'

2-Oct-15

'

'

'

'

'

'

'

30-Jun-16

'

'

'

'

1-May-14

'

'

'

'

'

'

'

'

Debt interest rate (in hundredths)

'

'

'

'

10.00%

'

'

'

'

'

'

'

10.00%

'

'

'

'

13.00%

'

11.75%

'

'

'

'

'

'

Number of trading days considered for volume weighted average price of stock

'

'

'

'

'

'

'

'

'

'

'

'

'

'20 days

'

'

'

'

'

'

'

'

'

'

'

'

Maximum value of securities that may be called by right holders

'

'

'

'

'

'

'

'

'

$20,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Issuance of common stock for payment of interest (in shares)

'

'

'

290,935

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

2,575,631

2,680,400

'

'

Share price (in dollars per share)

$0.02

$0.04

$0.02

$0.65

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$0.22

'

'

Total debt

26,952,000

11,269,000

26,952,000

'

'

14,634,000

15,005,000

'

'

'

101,000

276,000

'

18,576,000

0

125,000

0

1,382,000

3,660,000

5,000,000

'

'

'

'

'

'

Repayment of debt

2,279,000

1,466,000

35,013,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

4,500,000

'

'

'

'

'

'

'

'

Monthly interest payments

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

40,000

'

'

'

'

'

'

'

'

Monthly interest and principal payments

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

400,000

'

'

'

'

'

'

'

'

Interest expense

7,622,000

2,957,000

25,468,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

2,000,000

900,000

2,800,000

'

Amortization of deferred financing costs

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

3,300,000

Debt issuance costs

'

'

'

'

'

'

'

'

'

'

'

'

'

1,500,000

'

'

'

'

'

'

'

'

'

'

'

'

Issuance of common stock to convertible noteholders (in shares)

'

'

'

'

'

1,226,902

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Debt conversion original debt amount

'

'

'

'

'

$371,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Issuance of warrants for payment of interest (in shares)

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

1,057,944

1,159,631

'

'

Debt_Debt_Outstanding_Details

Debt, Debt Outstanding (Details) (USD $)	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
In Thousands, unless otherwise specified
Total debt outstanding [Abstract]	'	'	'
Total debt	$26,952	$11,269	'
Unamortized debt discount	-7,866	-7,672	'
Less current portion	-1,329	-1,786	'
Total long-term debt and embedded derivative, net	25,623	9,483	'
Senior Secured 2012 Convertible Notes [Member]	'	'	'
Total debt outstanding [Abstract]	'	'	'
Total debt	14,634	15,005	'
Embedded derivative liability-2012 Notes [Member]	'	'	'
Total debt outstanding [Abstract]	'	'	'
Total debt	101	276	'
Senior Secured 2013 Convertible Notes [Member]	'	'	'
Total debt outstanding [Abstract]	'	'	'
Total debt	18,576	0	'
Embedded derivative liability-2013 Notes [Member]	'	'	'
Total debt outstanding [Abstract]	'	'	'
Total debt	125	0	'
Working Capital Note [Member]	'	'	'
Total debt outstanding [Abstract]	'	'	'
Total debt	$1,382	$3,660	$5,000

Debt_Principal_Payments_Due_De

Debt, Principal Payments Due (Details) (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Principal payments maturity [Abstract]	'	'
2014	$1,382	'
2015	14,634	'
2016	18,576	'
Long-term debt including unamortized debt discount	34,592	'
Less embedded derivative and unamortized debt discount	-7,640	'
Total debt	$26,952	$11,269

Capital_Structure_Details

Capital Structure (Details) (USD $)	12 Months Ended		126 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2013
Capital Structure [Abstract]	'	'	'
Common stock, shares authorized (in shares)	750,000,000	750,000,000	750,000,000
Common stock, voting rights	'Each holder of common stock is entitled to one vote for each share held.	'	'
Subsidiary, Sale of Stock [Line Items]	'	'	'
Preferred stock, shares authorized (in shares)	10,000,000	10,000,000	10,000,000
Preferred stock, shares issued (in shares)	0	0	0
Preferred stock, shares outstanding (in shares)	0	0	0
Proceeds from collaboration and option agreement	$14,656,000	$0	$14,656,000
Number of shares covered by warrants (in shares)	481,301,961	80,250,702	481,301,961
Proceeds attributable to the collaboration credited to additional paid-in capital	10,859,000	'	'
2013 Agreements with Celgene [Member]	'	'	'
Subsidiary, Sale of Stock [Line Items]	'	'	'
Proceeds from collaboration and option agreement	15,000,000	'	'
Option to acquire the rights of esophagus program (in hundredths)	125.00%	'	'
Warrant liability, fair value	3,800,000	'	3,800,000
Percentage of option exercise price premium to the fair value of rights (in hundredths)	25.00%	'	'
Proceeds attributable to the collaboration credited to additional paid-in capital	$10,900,000	'	'
Warrants issued pursuant to Celgene agreement for five years [Member] | 2013 Agreements with Celgene [Member]	'	'	'
Subsidiary, Sale of Stock [Line Items]	'	'	'
Warrant term	'5 years	'	'
Number of shares covered by warrants (in shares)	7,425,743	'	7,425,743
Warrants issued pursuant to Celgene agreement for ten years [Member] | 2013 Agreements with Celgene [Member]	'	'	'
Subsidiary, Sale of Stock [Line Items]	'	'	'
Warrant term	'10 years	'	'
Number of shares covered by warrants (in shares)	14,851,485	'	14,851,485

Embedded_Derivative_Conversion2

Embedded Derivative Conversion Options and Call Option Derivative Liability (Details) (USD $)	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Jun. 30, 2013	Dec. 31, 2013	Jun. 30, 2013
			Conversion Option - 2012 Notes [Member]	Conversion Option - 2012 Notes [Member]	Conversion Option - 2013 Notes [Member]	Conversion Option - 2013 Notes [Member]	Call Option [Member]
			Derivative Liability [Member]	Derivative Liability [Member]	Derivative Liability [Member]	Derivative Liability [Member]	2013 Financing [Member]
Derivative [Line Items]	'	'	'	'	'	'	'
Common stock value per share (in dollars per share)	$0.02	$0.04	'	'	'	'	'
Exercise of call option	'	'	'	'	'	'	$18,576,000
Expiration of call option	'	'	'	'	'	'	1,424,000
Summary of aggregate fair values along with assumptions utilized [Abstract]	'	'	'	'	'	'	'
Calculated aggregate value	'	'	$101,000	$276,000	$732,000	$125,000	'
Equity volatility (in hundredths)	'	'	120.00%	115.00%	120.00%	120.00%	'
Asset volatility (in hundredths)	'	'	95.00%	90.00%	90.00%	95.00%	'
Probability of Fundamental Transaction or Major Transaction (in hundredths)	'	'	100.00%	100.00%	100.00%	100.00%	'
Weighted average risk-free interest rate (in hundredths)	'	'	0.20%	0.30%	0.30%	0.20%	'
Dividend yield (in hundredths)	'	'	0.00%	0.00%	0.00%	0.00%	'

Warrants_Details

Warrants (Details) (USD $)

12 Months Ended

6 Months Ended

12 Months Ended

6 Months Ended

12 Months Ended

12 Months Ended

12 Months Ended

12 Months Ended

12 Months Ended

12 Months Ended

12 Months Ended

12 Months Ended

12 Months Ended

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2013

Dec. 31, 2012

Apr. 02, 2013

Jun. 30, 2013

Dec. 31, 2013

Jun. 30, 2013

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Mar. 31, 2011

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2013

Oct. 01, 2013

Dec. 31, 2012

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2012

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2013

Jun. 28, 2013

Dec. 31, 2013

Oct. 01, 2013

Cashless Warrants [Member]

2011 Warrants [Member]

2011 Warrants [Member]

2012 Warrants [Member]

2012 Warrants [Member]

2012 Warrants [Member]

2013 Warrants [Member]

2013 Warrants [Member]

2013 Celgene Warrants [Member]

2013 Celgene Warrants [Member]

2013 Interest Warrants [Member]

2012,2013 and 2013 Celgene Warrants [Member]

2012,2013 and 2013 Celgene Warrants [Member]

Equity classified warrants [Member]

Equity classified warrants [Member]

Equity classified warrants [Member]

Equity classified warrants [Member]

Liability classified warrants [Member]

Liability classified warrants [Member]

Liability classified warrants [Member]

Liability classified warrants [Member]

Liability classified warrants [Member]

Liability classified warrants [Member]

Liability classified warrants [Member]

Liability classified warrants [Member]

Liability classified warrants [Member]

Liability classified warrants [Member]

Liability classified warrants [Member]

Liability classified warrants [Member]

Liability classified warrants [Member]

Liability classified warrants [Member]

Liability classified warrants [Member]

Liability classified warrants [Member]

Liability classified warrants [Member]

Liability classified warrants [Member]

Liability classified warrants [Member]

Liability classified warrants [Member]

Liability classified warrants [Member]

Liability classified warrants [Member]

Liability classified warrants [Member]

Warrants issued to vendors, expired from September 2015 through December 2016 [Member]

Warrants issued to vendors, expired from September 2015 through December 2016 [Member]

Warrants issued pursuant to March 2011 equity financing, expired in March 2016 [Member]

Warrants issued pursuant to March 2011 equity financing, expired in March 2016 [Member]

Warrants issued pursuant to March 2011 equity financing, expired in March 2016 [Member]

Warrants issued pursuant to March 2011 equity financing, expired in March 2016 [Member]

Warrants issued pursuant to October 2012 debt financing, expired from October 2014 through October 2023 [Member]

Warrants issued pursuant to October 2012 debt financing, expired from October 2014 through October 2023 [Member]

Interest Warrants Issued to Lenders From July 2013 through October 2023 [Member]

Interest Warrants Issued to Lenders From July 2013 through October 2023 [Member]

Interest Warrants Issued to Lenders From July 2013 through October 2023 [Member]

Warrants Issued to lenders from June 2013 through June 2023 [Member]

Warrants Issued to lenders from June 2013 through June 2023 [Member]

Celgene Warrants Issued to lenders from June 2013 through June 2023 [Member]

Celgene Warrants Issued to lenders from June 2013 through June 2023 [Member]

2011 Warrants [Member]

2012 Warrants [Member]

2012 Warrants [Member]

2013 Warrants [Member]

2013 Warrants [Member]

2013 Celgene Warrants [Member]

2013 Celgene Warrants [Member]

2013 Interest Warrants [Member]

Warrants issued pursuant to March 2011 equity financing, expired in March 2016 [Member]

Ten-Year Warrants [Member]

Cashless Warrants [Member]

Two-Year Warrants [Member]

Cashless Warrants [Member]

Five-Year Warrants [Member]

Ten-Year Warrants [Member]

Outstanding warrants to purchase common stock [Abstract]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Shares Exercisable (in shares)

481,301,961

80,250,702

'

'

'

'

'

60,973,081

'

'

'

'

'

'

'

18,375

18,514

18,375

18,514

481,283,586

80,232,188

136,663,804

52,843,337

[1]

'

1,046,102

74,761,830

27,388,851

[2]

1,057,944

537,837

0

191,213,801

0

77,586,207

0

27,388,851

192,165,525

7,425,743

'

1,118,722

'

14,851,485

520,107

Warrants converted to common shares (in shares)

260,000

'

951,724

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Shares issued from conversion of warrants (in shares)

260,000

'

317,387

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Exercise price (in dollars per share)

'

'

'

'

$1.10

'

$0.75

$0.65

'

'

'

'

'

'

'

'

'

$158.24

'

$0.69

'

$0.29

'

$28.80

'

$0.40

'

$0.00

'

'

$0.29

'

$0.29

'

'

'

'

'

'

$1.01

$1.01

'

Expiration

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'March 2014 through September 2019

'

'

'

'March 2016

'

'

'

'October 2014 through October 2022

'

'July through October 2023

'

'

'June 2018 through June 2023

'

'June 2018 through June 2023

'

'

'

'

'

'

'

'

'

Closing price per share of common stock (in dollars per share)

$0.02

$0.04

'

'

'

'

'

'

'

'

'

'

'

$0.04

$0.02

'

'

'

'

'

$0.04

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Warrants expiration period

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'5 years

'2 years

'

'

'10 years

'

Non-operating income

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$8,300,000

$1,300,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Threshold value of ownership limitation (in hundredths)

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

9.99%

'

'

'

'

'

'

'

'

'

'

'

'

'

Proceeds from exercise of warrants

200,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

15,000,000

'

Fair value [Abstract]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Calculated aggregate value

'

'

'

720,000

2,378,000

3,430,000

3,800,000

'

9,404,000

5,139,000

3,390,000

2,083,000

53,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Exercise price per share of warrant (in dollars per share)

'

'

'

$0.40

$1.10

$0.29

$0.75

'

$0.76

$0.29

$0.76

$0.29

$0.00

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Equity volatility (in hundredths)

'

'

'

120.00%

115.00%

120.00%

115.00%

'

120.00%

120.00%

120.00%

120.00%

120.00%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Asset volatility (in hundredths)

'

'

'

95.00%

90.00%

95.00%

90.00%

'

90.00%

95.00%

90.00%

95.00%

95.00%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Probability of Fundamental Transaction (in hundredths)

'

'

'

100.00%

100.00%

100.00%

100.00%

'

100.00%

100.00%

100.00%

100.00%

100.00%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Weighted average risk-free interest rate (in hundredths)

'

'

'

0.20%

0.30%

0.20%

0.30%

'

0.30%

0.20%

0.30%

0.20%

0.20%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Net cash settlement value [Abstract]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Calculated aggregate value

'

'

'

$8,076,000

[3]

'

$26,004,000

[3]

'

'

'

$38,238,000

[3]

'

$15,503,000

[3]

$0

[3]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Exercise price per share of warrant (in dollars per share)

'

'

'

$0.40

'

$0.29

'

'

'

$0.29

'

$0.29

$0

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Closing price per share of common stock (in dollars per share)

'

'

'

$0.25

'

$0.24

[4]

'

'

'

$0.24

[4]

'

$0.24

[4]

$0

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Equity volatility (in hundredths)

'

'

'

100.00%

[5]

'

99.00%

[5]

'

'

'

99.00%

[5]

'

99.00%

[5]

0.00%

[5]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Expected term (years)

'

'

'

'2 years 2 months 12 days

'

'7 years

'

'

'

'7 years 9 months 18 days

'

'7 years 9 months 18 days

'0 years

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Weighted average risk-free interest rate (in hundredths)

'

'

'

0.50%

'

2.20%

'

'

'

2.50%

'

2.50%

0.00%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Period of volume weighted average price used to calculate net cash settlement value

'

'5 days

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

[1]

As of December 31, 2012 the 2012 Warrants had an exercise price of $0.75 per share.

[2]

As of December 31, 2012 the 2011 Warrants had an exercise price of $1.10 per share.

[3]

Represents the net cash settlement value of the warrant as of December 31, 2013, which value was calculated utilizing the Black-Scholes model defined in the warrant agreement.

[4]

Represents the five day Tengion stock VWAP used to calculate the net cash settlement value as of December 31, 2013.

[5]

Represents the volatility assumption used to calculate the net cash settlement value as of December 31, 2013, defined in the warrant agreement.

Stockbased_Compensation_Detail

Stock-based Compensation (Details) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'
Number of share based compensation plans	2	'
Employee [Member]	'	'
Weighted-average assumptions [Abstract]	'	'
Volatility (in hundredths)	'	84.00%
Expected term	'	'6 years
Risk free interest rate (in hundredths)	'	1.10%
Dividend yield (in hundredths)	'	0.00%
Stock Options [Member]	'	'
Number of shares [Abstract]	'	'
Outstanding (in shares)	234,465	174,872
Granted (in shares)	0	87,184
Exercised (in shares)	0	-2,432
Forfeited (in shares)	-3,740	-25,159
Outstanding (in shares)	230,725	234,465
Vested and expected to vest at December 31, 2013 (in shares)	221,246	'
Exercisable at December 31, 2013 (in shares)	137,559	'
Weighted-average exercise price [Abstract]	'	'
Outstanding (in dollars per share)	$12.37	$16.76
Granted (in dollars per share)	$0	$5.66
Exercised (in dollars per share)	$0	$4.40
Forfeited (in dollars per share)	$17.68	$20.45
Outstanding (in dollars per share)	$12.28	$12.37
Vested and expected to vest at December 31, 2013 (in dollars per share)	$12.49	'
Exercisable at December 31, 2013 (in dollars per share)	$15.43	'
Weighted-average remaining contractual term [Abstract]	'	'
Outstanding	'7 years 6 months	'
Vested and expected to vest at December 31, 2013	'7 years 6 months	'
Exercisable at December 31, 2013	'7 years 2 months 12 days	'
Aggregate intrinsic value [Abstract]	'	'
Outstanding	$0	'
Vested and expected to vest at December 31, 2013	0	'
Exercisable at December 31, 2013	0	'
Stock options issued for purchase of common stock (in shares)	0	87,184
Stock Options [Member] | Employee [Member]	'	'
Aggregate intrinsic value [Abstract]	'	'
Fair value of options (in dollars per share)	'	$5.66
Weighted-average assumptions [Abstract]	'	'
Unrecognized compensation expense	400,000	'
Stock Options [Member] | Non-Employee Director [Member]	'	'
Weighted-average assumptions [Abstract]	'	'
Unrecognized compensation expense	0	'
Stock Options [Member] | Employee And Non Employee Director [Member]	'	'
Number of shares [Abstract]	'	'
Granted (in shares)	'	87,184
Aggregate intrinsic value [Abstract]	'	'
Stock options issued for purchase of common stock (in shares)	'	87,184
Weighted-average assumptions [Abstract]	'	'
Stock-based compensation expense	400,000	400,000
Restricted Stock [Member]	'	'
Weighted-average assumptions [Abstract]	'	'
Stock-based compensation expense	200,000	100,000
Weighted average period for recognizing compensation expense	'2 years	'
Number of shares [Abstract]	'	'
Nonvested (in shares)	74,372	13,988
Granted (in shares)	0	67,863
Vested (in shares)	-19,221	-5,047
Forfeited (in shares)	-430	-2,432
Nonvested (in shares)	54,721	74,372
Weighted-average grant date fair value [Abstract]	'	'
Nonvested (in dollars per share)	$7.81	$24.20
Granted (in dollars per share)	$0	$6
Vested (in dollars per share)	$8.35	$24.20
Forfeited (in dollars per share)	$13.36	$17.36
Nonvested (in dollars per share)	$7.59	$7.81
Unrecognized compensation expense related to restricted stock awards	$200,000	'
2004 Stock Option Plan [Member] | Minimum [Member]	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'
Equity awards granted under plan vesting period	'4 years	'
2004 Stock Option Plan [Member] | Maximum [Member]	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'
Equity awards granted under plan vesting period	'10 years	'
2010 Stock Option Plan [Member]	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'
Number of shares available for future grants (in shares)	155,246	'
2010 Stock Option Plan [Member] | Minimum [Member]	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'
Equity awards granted under plan vesting period	'4 years	'
2010 Stock Option Plan [Member] | Maximum [Member]	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'
Equity awards granted under plan vesting period	'10 years	'

Commitments_and_Contingencies_1

Commitments and Contingencies (Details) (USD $)

12 Months Ended

126 Months Ended

12 Months Ended

126 Months Ended

12 Months Ended

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2006

Dec. 31, 2003

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2007

Children's Medical Center Corporation (CMCC) [Member]

Children's Medical Center Corporation (CMCC) [Member]

Children's Medical Center Corporation (CMCC) [Member]

Children's Medical Center Corporation (CMCC) [Member]

Children's Medical Center Corporation (CMCC) [Member]

Wake Forest University Health Sciences (WFUHS) [Member]

Wake Forest University Health Sciences (WFUHS) [Member]

Subfield

Milestone

Leases and Letters of Credit [Abstract]

'

'

'

'

'

'

'

'

'

'

'

Rent expenses under operating lease

$200,000

$200,000

'

'

'

'

'

'

'

'

'

Summarizes future minimum lease payments [Abstract]

'

'

'

'

'

'

'

'

'

'

'

2014

971,000

'

'

971,000

'

'

'

'

'

'

'

2015

1,079,000

'

'

1,079,000

'

'

'

'

'

'

'

2016

277,000

'

'

277,000

'

'

'

'

'

'

'

Total minimum lease payments

2,327,000

[1]

'

'

2,327,000

[1]

'

'

'

'

'

'

'

Security and restoration deposits

1,200,000

1,200,000

'

1,200,000

'

'

'

'

'

'

'

Security deposit

'

'

1,000,000

'

'

'

'

'

'

'

'

Number of years for which lease is to be renewed

'5 years

'

'

'

'

'

'

'

'

'

'

Extended lease term

31-Oct-16

'

'

'

'

'

'

'

'

'

'

Payments for rent

'

'

200,000

'

'

'

'

'

'

'

'

License and Research Agreements [Abstract]

'

'

'

'

'

'

'

'

'

'

'

Initial license fee

'

'

'

'

'

'

'

200,000

'

'

'

Patent costs recorded as general and administrative expense

6,295,000

5,496,000

'

53,684,000

100,000

100,000

'

'

2,500,000

'

'

Number of development milestones achieved

'

'

'

'

'

'

2

'

'

'

'

Research and development

9,480,000

10,103,000

'

137,440,000

100,000

'

400,000

'

'

'

'

Number of subfields for specified aggregate payments

'

'

'

'

'

'

4

'

'

'

'

Aggregate milestones payments to be paid based on condition

'

'

'

'

'

'

6,900,000

'

'

'

'

Sales milestone payment based on specified condition

'

'

'

'

'

'

$2,000,000

'

'

'

'

Warrants to purchase common stock (in shares)

481,301,961

80,250,702

'

481,301,961

'

'

'

'

'

'

320

Exercise price (in dollars per share)

'

'

'

'

'

'

'

'

'

'

$23.20

Period after which license maintenance fees required to be paid

'

'

'

'

'

'

'

'

'

'2 years

'

Percentage of floor rates owed to licensor (in hundredths)

'

'

'

'

'

'

'

'

'

50.00%

'

Percentage of non-royalty consideration from sublicensees payable to licensor (in hundredths)

'

'

'

'

'

'

'

'

'

4.00%

'

Period for which royalty is to be paid after first sale

'

'

'

'

'

'

'

'

'

'15 years

'

Maximum period for payment of royalty after expiration of product

'

'

'

'

'

'

'

'

'

'7 years

'

[1]

The future minimum lease payments above do not include the impact of any potential sublease income discussed in Note 9 related to the Companybs lease liability.

Income_Taxes_Details

Income Taxes (Details) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Percent of pre-tax income [Abstract]	'	'
U.S. federal statutory income tax rate (in hundredths)	-34.00%	-34.00%
State taxes, net of federal benefit (in hundredths)	-3.90%	-4.60%
Interest expense -revaluation of warrants (in hundredths)	-14.90%	-2.40%
Convertible debt conversion feature (in hundredths)	5.60%	1.90%
Convertible debt discount amortization (in hundredths)	6.20%	-2.00%
Other (in hundredths)	4.80%	1.50%
Valuation allowance (in hundredths)	36.20%	39.60%
Effective income tax expense rate (in hundredths)	0.00%	0.00%
Deferred tax assets [Abstract]	'	'
Net operating loss carryforwards	$64,659,000	$61,522,000
Research and development credits	5,950,000	5,636,000
Depreciation and amortization	5,056,000	5,040,000
Capitalized start-up costs	19,620,000	16,453,000
Other temporary differences	1,376,000	1,340,000
Gross deferred tax asset	96,661,000	89,991,000
Deferred tax assets valuation allowance	-96,661,000	-89,991,000
Total deferred tax assets	0	0
Increase in valuation allowance	6,700,000	5,800,000
Deferred tax asset related to domestic net operating loss carryforwards	8,400,000	'
Capitalized start-up cost	51,800,000	42,700,000
Amortization period for capitalized start up costs	'15 years	'
Carryforwards of net operating losses and tax credits [Abstract]	'	'
Carryforwards of net operating losses, expiration dates	'2024 to 2033	'
Research and development credits	5,950,000	'
Federal Net Operating Losses [Member]	'	'
Carryforwards of net operating losses and tax credits [Abstract]	'	'
Carryforwards of net operating losses	159,413,000	'
Carryforwards of net operating losses, expiration dates	'2024 to 2033	'
State Net Operating Losses [Member]	'	'
Carryforwards of net operating losses and tax credits [Abstract]	'	'
Carryforwards of net operating losses	$172,587,000	'
Carryforwards of net operating losses, expiration dates	'2019 to 2033	'

Subsequent_Events_Details

Subsequent Events (Details) (USD $)

12 Months Ended

126 Months Ended

3 Months Ended

3 Months Ended

In Thousands, except Share data, unless otherwise specified

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2013

Jan. 02, 2014

Jan. 02, 2014

Jan. 02, 2014

Jan. 02, 2014

Mar. 19, 2014

Feb. 24, 2014

Jan. 02, 2014

Jan. 02, 2014

Mar. 19, 2014

2013 Warrants [Member]

2013 Celgene Warrants [Member]

2012 Warrants [Member]

2011 Warrants [Member]

Subsequent Event [Member]

Subsequent Event [Member]

Subsequent Event [Member]

Subsequent Event [Member]

Subsequent Event [Member]

2012 Convertible Notes [Member]

2013 Convertible Notes [Member]

2012 and 2013 Convertible Notes [Member]

Subsequent Event [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

Convertible notes value, converted into common stock

$231

$0

$231

'

'

'

'

'

'

'

'

$1,900

Number of common stock issued for conversion of convertible notes (in shares)

'

'

'

'

'

'

'

8,778,955

'

'

'

'

Common stock, shares authorized (in shares)

750,000,000

750,000,000

750,000,000

'

'

'

'

'

10,000,000,000

'

'

'

Conversion price of convertible notes (in dollars per share)

'

'

'

'

'

'

'

'

'

$0.22

$0.22

'

Warrants to purchase common stock (in shares)

481,301,961

80,250,702

481,301,961

253,309,106

102,272,727

180,147,740

99,682,445

'

'

'

'

'

Exercise price of warrants (in dollars per share)

'

'

'

$0.22

$0.22

$0.22

$0.30

'

'

'

'

'