Exhibit 99.1

FOR IMMEDIATE RELEASE

Investors Contact:
Robert G. Burrows
Vice President, Investor Relations
301-795-1877
BurrowsR@ebsi.com

Media Contact:
Tracey Schmitt
Vice President, Corporate Communications
301-795-1800
SchmittT@ebsi.com

EMERGENT BIOSOLUTIONS ANNOUNCES EARLY TERMINATION OF HSR WAITING PERIOD FOR ITS ACQUISITION OF TRUBION PHARMACEUTICALS

ROCKVILLE, MD, September 8, 2010 — Emergent BioSolutions Inc. (NYSE:EBS) announced today that the U.S. Department of Justice and Federal Trade Commission granted early termination of the waiting period under the Hart-Scott-Rodino Antitrust Improvements Act of 1976 (“HSR Act”), as amended, with respect to the planned acquisition of Trubion Pharmaceuticals, Inc. (Nasdaq: TRBN) by Emergent BioSolutions announced on Aug. 12, 2010. Accordingly, the requirement under the merger agreement for the expiration or termination of any waiting period under the HSR Act has been satisfied. The closing of the transaction still remains subject to other conditions in the definitive merger agreement, including approval by Trubion’s stockholders.

About Emergent BioSolutions Inc.

Emergent BioSolutions Inc. is a biopharmaceutical company focused on the development, manufacture and commercialization of vaccines and antibody therapies that assist the body’s immune system to prevent or treat disease. Emergent’s marketed product, BioThrax^® (Anthrax Vaccine Adsorbed), is the only vaccine approved by the U.S. Food and Drug Administration for the prevention of anthrax infection. Emergent’s product pipeline targets infectious diseases and includes programs focused on anthrax, tuberculosis, typhoid, flu and chlamydia. Additional information may be found at www.emergentbiosolutions.com.

About Trubion Pharmaceuticals, Inc.

Trubion is a biopharmaceutical company that is creating a pipeline of novel protein therapeutic product candidates to treat autoimmune and inflammatory diseases and cancer. The Company’s mission is to develop a variety of first-in-class and best-in-class product candidates, customized for optimal safety, efficacy and convenience that it believes may offer improved patient experiences. Trubion’s current product candidates are novel single-chain protein, or SMIP, therapeutics, and are designed using its custom drug assembly technology. Trubion’s product pipeline includes CD20-directed SMIP therapeutics such as SBI-087 for autoimmune and inflammatory diseases, developed

under the Company’s Pfizer collaboration. Trubion’s product pipeline also includes TRU-016, a novel CD37-targeted therapy for the treatment of B-cell malignancies developed under the Company’s Abbott collaboration. In addition to Trubion’s current clinical stage product pipeline, the Company is also developing its multi-specific SCORPION technology, both for targeting cell-surface molecules as well as simultaneously neutralizing soluble ligands. More information is available in the investors section of Trubion’s website: http://investors.trubion.com/index.cfm.

Additional Information and Where to Find It

This communication is being made in connection with the proposed merger (the “Merger”) among Emergent BioSolutions Inc. (“Emergent”), Trubion Pharmaceuticals, Inc. (“Trubion”) and certain of Emergent’s direct and indirect wholly-owned subsidiaries. Emergent intends to file with the Securities and Exchange Commission (the “SEC”) a registration statement on Form S-4, which will contain a prospectus relating to the securities Emergent intends to issue in the proposed Merger. Trubion intends to file a preliminary proxy statement in connection with the proposed Merger and to mail a definitive proxy statement and other relevant documents to Trubion’s stockholders. Stockholders of Emergent and Trubion and other interested persons are advised to read, when available, the registration statement and Trubion’s preliminary proxy statement, and amendments thereto, and definitive proxy statement in connection with Trubion’s solicitation of proxies for the special meeting to be held to approve the Merger because these documents will contain important information about Trubion, Emergent and the proposed Merger. The definitive proxy statement will be mailed to stockholders as of a record date to be established for voting on the Merger. Stockholders will also be able to obtain a copy of the documents filed with the SEC, without charge, once available, at the SEC’s website at http://www.sec.gov or by directing a request to: Emergent BioSolutions Inc., Attn: Investor Relations, 2273 Research Boulevard, Suite 400, Rockville, Maryland 20850, or Trubion Pharmaceuticals, Inc., Attention: Investor Relations, 2401 4th Avenue, Suite 1050, Seattle, Washington, 98121.

Participants in Solicitation

Emergent, Trubion and their respective directors and officers may be deemed participants in the solicitation of proxies from Trubion’s stockholders. Information regarding Emergent’s directors and officers is available in Emergent’s proxy statement for its 2010 annual meeting of stockholders and its 2009 annual report on Form 10-K, which were filed with the SEC and are available at the SEC’s website at http://www.sec.gov. Information regarding Trubion’s directors and officers is available in Trubion’s proxy statement for its 2010 annual meeting of stockholders and its 2009 annual report on Form 10-K, which were filed with the SEC and are available at the SEC’s website at http://www.sec.gov. Information regarding Trubion’s directors and officers will also be contained in Trubion’s proxy statement in connection with the Merger when it becomes available. Emergent’s and Trubion’s stockholders may obtain additional information about the interests of Trubion’s directors and officers in the Merger by reading Trubion’s proxy statement when it becomes available.

Emergent BioSolutions Forward-Looking Statement

This press release includes forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995. Any statements, other than statements of historical fact, including statements regarding our strategy and how the acquisition of Trubion will impact that strategy, the financial impact of the merger on Emergent’s 2010 forecast, the provision of expected cash and NOLs, the anticipated timing for the transaction and anticipated future operations, and any other statements containing the words “believes”, “expects”, “anticipates”, “plans”, “estimates” and

similar expressions, are forward-looking statements. There are a number of important factors that could cause the company’s actual results to differ materially from those indicated by such forward-looking statements, including the parties’ ability to consummate the transaction; the conditions to the completion of the transaction, including the effectiveness of Emergent’s registration statement on Form S-4 or the regulatory approvals required for the transaction may not be obtained on the terms expected or on the anticipated schedule; and the parties’ ability to meet expectations regarding the timing, completion and financial and tax treatments of the merger; the possibility that the parties may be unable to achieve expected synergies and operating efficiencies in the merger within the expected time-frames or at all and to successfully integrate Trubion’s operations into those of Emergent; such integration may be more difficult, time-consuming or costly than expected; operating costs, partner loss and business disruption (including, without limitation, difficulties in maintaining relationships with employees, partners, licensors and others) may be greater than expected following the transaction; the retention of certain key employees of Trubion may be difficult; the parties are subject to intense competition and increased competition is expected in the future; the failure to protect either party’s intellectual property rights may weaken its competitive position; third parties may claim that either party’s products infringe their intellectual property rights; the rate and degree of market acceptance and clinical utility of the parties’ products; the success of ongoing and planned development programs, preclinical studies and clinical trials; the ability to identify and acquire or in license products and product candidates that satisfy Emergent’s selection criteria; the potential benefits of the parties existing collaboration agreements and the ability to enter into selective additional collaboration arrangements; the timing of and ability to obtain and maintain regulatory approvals for other product candidates; commercialization, marketing and manufacturing capabilities and strategy; and other factors identified in Emergent’s Quarterly Report on Form 10-Q for the quarter ended June 30, 2010 and subsequent reports filed with the SEC. The company disclaims any intention or obligation to update any forward-looking statements as a result of developments occurring after the date of this press release.

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