Patent Infringement Dispute

Oxford Biomedica PLC
26 October 2007



For Immediate Release                                            26 OCTOBER 2007



   OXFORD BIOMEDICA AND SIGMA-ALDRICH WIN KEY RULING IN OPEN BIOYSTEMS PATENT
                              INFRINGEMENT DISPUTE

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(R) 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: [phone]

City/Financial Enquiries:
Lisa Baderoon/ Mark Court/ Mary-Jane Johnson        Tel: [phone]
Buchanan Communications

Scientific/Trade Press Enquiries:
Gemma Price/ Holly Griffiths/ Katja Stout           Tel: [phone]
Northbank Communications



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(R), 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(R) MEL, for melanoma, which
has completed two clinical trials. In neurotherapy, the Company's lead product,
ProSavin(R), 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.






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