CAT's Patent Upheld

Cambridge Antibody Tech Group PLC
3 July 2000


For Further Information Contact:

Cambridge Antibody Technology        
Tel: [phone]
John Aston, Finance Director
Rowena Gardner, Communications Manager       
    
HCC De Facto (Europe)
Tel: [phone]
Nikul Odedra (trade)
Sue Charles (city/financial)

BMC Communications/The Trout Group (USA)
Tel: [phone]
Brad Miles, ext .17 (media)
Jonathan Fassberg, ext.16 (investors)

CATs McCAFFERTY PATENT UPHELD BY EUROPEAN PATENT OFFICE

Melbourn, UK Cambridge Antibody Technology ('CAT') announced today that the
Opposition Division of the European Patent Office ('EPO') upheld without
amendment both the independent claims of its 'McCafferty' patent
(EP-0-589-877) in oral proceedings held today. The Opposition Division
dismissed arguments made by  CATs opponents Dyax, MorphoSys and BioInvent and
upheld the patent. The claims of the McCafferty patent cover methods of
obtaining scFv molecules by display on phage (or phagemid) and libraries of
such phage (or phagemid).

CATs CEO, David Chiswell, said 'We are extremely pleased with the decision to
uphold this patent. The 'McCafferty' patent reflects the pioneering work
performed by CAT on the phage display of antibodies and this decision
reinforces our strong global intellectual property portfolio in this field.'

This decision strengthens CATs strong world-wide patent position which also
includes US patents covering the display of single chain antibodies
(McCafferty US 5,969,108) and the use of phage display to isolate human
antibodies against human targets  (Griffiths US 5,885,793) along with the
European patent covering methods of making  antibody   libraries  (Winter
EP-0-368-684).  The EPO also accepted an amendment filed by CAT that deleted
certain minor subsidiary claims and which did not reduce the scope of the
patent.


Notes to Editors:

Cambridge Antibody Technology (LSE:CAT)
CAT is a UK biotechnology company using its proprietary technologies in fully
human monoclonal antibodies for drug discovery and drug development.  Based in
Melbourn, 10 miles south of Cambridge, England, CAT currently employs around
160 people.  
CAT is listed on the London Stock Exchange, having raised £41m in its IPO in
March 1997. An Open Offer and International Offering in March 2000 raised
£93m.
CAT has a world-leading platform technology for rapidly isolating fully human
monoclonal antibodies using phage display systems.  CAT has an extensive phage
display antibody library, currently incorporating around 100 billion distinct
antibodies. This library forms the basis for the companys strategy to develop
a portfolio of clinical development programs and for discovering new drug
leads using functional genomics.  Four fully human therapeutic antibodies
developed by CAT are at various stages of clinical trials.
CAT has a number of license and collaborative agreements in place with
pharmaceutical and biotechnology companies including: Eli Lilly, Pfizer, BASF
Pharma, Genentech, ICOS Corporation, Genetics Institute, Wyeth-Ayerst, Human
Genome Sciences, AstraZeneca and Searle. 

Opposition Procedures. European patents can be challenged at the European
Patent Office ('EPO') up to nine months after grant. The opposing party files
a written opposition to the patent, to which the Patentee can respond in
writing. After a preliminary ruling, by the Opposition Division ('OD'), the
parties may request Oral Proceedings to resolve the dispute. The Patentee may
submit a number of alternative claims (auxiliary requests) for consideration
should the OD object to the original claims. Any party which is adversely
affected may appeal against the decision reached by the OD at Oral
Proceedings. 

Related Legal Action. CAT has commenced legal proceedings against MorphoSys in
Germany. This action claims infringement by MorphoSys, not only of the
McCafferty patent (the subject of this Opposition hearing), but also of
another CAT patent, 'Winter II' (cloning immunoglobulin variable domain
sequences). This legal action is ongoing.

Related Patents. The McCafferty patent has been granted in the US (patent
number 5,969,108), Australia and South Korea, and is under examination in
Canada and Japan.

The independent claims 1 and 27 of the originally granted McCafferty patent
were the claims that were upheld without amendment.