Oxford, UK and St. Louis, Mo - 26 October 2007: Oxford BioMedica (LSE: OXB), a leading gene therapy company, and Sigma-Aldrich (NASDAQ:SIAL), a life science company dedicated to providing state-of-the-art chemical and biotechnology products to the world’s researchers, announced today that they received a key order confirming the strength and validity of intellectual property owned by Oxford BioMedica and licensed exclusively in the research field to Sigma-Aldrich. The ruling was part of the construction of patent claim terms in the patent infringement suit brought against Open Biosystems, Inc. The lawsuit, which is pending in the U.S. District Court for the Eastern District of Missouri, alleges that Open Biosystems infringes U.S. Patent Nos. 6,924,123 and 7,056,699 entitled Lentiviral LTR Deleted Vector, which are owned by Oxford BioMedica and exclusively licensed to Sigma-Aldrich for research use, by selling, among other products, Open Biosystems’ Lentiviral shRNAmir Library. In his order U.S. District Judge Charles A. Shaw concluded “that the constructions of the disputed terms and phrases proposed by plaintiff are correct.”

David Smoller, President, Research Biotechnology Business Unit of Sigma-Aldrich said: “We are gratified and very pleased that the Court has adopted Sigma’s and Oxford’s definitions of all disputed claim terms in this case. This Order reinforces Sigma’s belief that the Oxford BioMedica patents are ‘core patents’ in the RNA-interference field, and validates Sigma’s decision to license these patents and make other significant investments in creating a comprehensive portfolio of intellectual property that allows our customers to use this extraordinary technology without fear of interference or unfair competition. We will continue to vigorously defend Oxford’s extraordinary inventions and Sigma’s investment in this valuable intellectual property.”

Peter Nolan, SVP Commercial Development at Oxford BioMedica said “I am delighted with this Order, which validates Oxford BioMedica’s patents and strengthens our position in this field.” Oxford BioMedica’s LentiVector® system has broad applications in gene delivery and can be used to deliver shRNA-encoding DNA to cells to enable RNA Interference (RNAi) experiments. Based on discoveries by Oxford BioMedica’s Drs. Susan and Alan Kingsman and others, scientists are now able to safely use modified lentiviruses as vectors, which enable RNAi to be effectively utilised as a research tool to unlock the secrets of the genetic code. As stated in the Court’s Order, the viral vector developed by the Kingsmans is expected to be useful as a “smart bomb” to safely “deliver new genetic material into specific cells, such as cells that do not divide or that divide slowly,” giving the delivery of genes that produce dopamine into a Parkinson’s disease patient’s brain cells, as an example.

“Sigma believes this technology holds huge promise to better understand the human genome and to, ultimately, help devise techniques to defeat and diminish longstanding misery-causing diseases such as Parkinson’s and Alzheimer’s,” said Smoller.

-Ends-

For further information, please contact:

Oxford BioMedica plc:
Professor Alan Kingsman, Chief Executive
Tel: +44 (0)1865 783 000

City/Financial Enquiries:
Lisa Baderoon/ Mark Court/ Mary-Jane Johnson Buchanan Communications
Tel: +44 (0)20 7466 5000

Scientific/Trade Press Enquiries:
Gemma Price/ Holly Griffiths/ Katja Stout
Northbank Communications
Tel: +44 (0)20 7268 3002

Notes to editors

1. Oxford BioMedica
Oxford BioMedica (LSE: OXB) is a biopharmaceutical company specialising in the development and commercialisation of novel therapeutic vaccines and gene-based therapies with a focus on oncology and neurotherapy. The Company was established in 1995 as a spin-out from Oxford University, and is listed on the London Stock Exchange.

The Company has a platform of gene delivery technologies, which are based on highly engineered viral systems. Oxford BioMedica also has in-house clinical, regulatory and manufacturing know-how. In oncology, the lead product candidate is TroVax®, an immunotherapy for multiple solid cancers, which is licensed to sanofi-aventis for global development and commercialisation. A Phase III trial of TroVax in renal cancer is ongoing and sanofi-aventis is implementing a development plan for colorectal cancer. Oxford BioMedica’s oncology pipeline includes a specific immunotherapy candidate, Hi-8® MEL, for melanoma, which has completed two clinical trials. In neurotherapy, the Company’s lead product, ProSavin®, is expected to enter clinical development for Parkinson’s disease in late 2007 or early 2008. The neurotherapy pipeline also includes preclinical gene-based therapeutics for vision loss, motor neuron disease and nerve repair.

The Company is underpinned by over 80 patent families, which represent one of the broadest patent estates in the field. The Company has a staff of approximately 80 split between its main facilities in Oxford and its wholly owned subsidiary, BioMedica Inc, in San Diego, California. Corporate partners include sanofi-aventis for TroVax and Wyeth for the targeted antibody therapy. The Company also has collaborations with Sigma-Aldrich, MolMed and Virxsys. Technology licensees include Biogen Idec, Merck & Co, GlaxoSmithKline and Pfizer.

Further information is available at www.oxfordbiomedica.co.uk

2. Sigma-Aldrich
Sigma-Aldrich is a leading Life Science and High Technology company. Its biochemical and organic chemical products and kits are used in scientific and genomic research, biotechnology, pharmaceutical development, the diagnosis of disease and as key components in pharmaceutical and other high technology manufacturing. The Company has customers in life science companies, university and government institutions, hospitals, and in industry. Over one million scientists and technologists use its products. Sigma-Aldrich operates in 36 countries and has 7,800 employees providing excellent service worldwide. Sigma-Aldrich is committed to Accelerating Customer Success through Leadership in Life Science, High Technology and Service. For more information about Sigma-Aldrich, please visit its award-winning Web site at http://www.sigma-aldrich.com .