CAT and Immunex Alliance

Cambridge Antibody Tech Group PLC
1 December 2000


For further information contact:

Cambridge Antibody Technology        
Tel: [phone]
David Chiswell, CEO
John Aston, Finance Director       
Rowena Gardner, Head of Corporate Communications       

HCC De Facto (Europe)
Tel: [phone]
Nikul Odedra (trade)
Sue Charles (city/financial)

Immunex Corporation
Tel: [phone] 
Mark R. Leahy, Director, Investor Relations 
Kris Greco, Manager, Communications                                           
                                                 
                                                                              
BMC Communications/The Trout Group (USA)
Tel: [phone]
Brad Miles, ext.17 (media)
Brandon Lewis, ext.15 (investors)



CAMBRIDGE ANTIBODY TECHNOLOGY PARTNERS WITH IMMUNEX CORPORATION TO DEVELOP
NOVEL HUMAN MONOCLONAL ANTIBODIES

Commitment to the custom development of human antibody-based therapeutics

Melbourn, UK Cambridge Antibody Technology  (LSE: CAT) today announced an
agreement with Immunex Corporation (NASDAQ: IMNX) to license CAT's proprietary
antibody phage display library for the discovery, development and potential
commercialisation of human monoclonal antibodies. 

Under the terms of the agreement, CAT will receive a licence fee from Immunex
to utilise the antibody library for reagent generation and target validation
in support of drug discovery programmes at Immunex. In addition, Immunex will
receive eight exclusive therapeutic antibody product options and CAT will
receive clinical milestones and royalty payments on product sales. Further
financial details were not disclosed.

Dr. David Chiswell, Chief Executive Officer of CAT commented 'We are delighted
to be joining forces with Immunex in the validation of human
disease-associated targets and the development of human monoclonal
antibody-based drugs. CAT shares with Immunex the view that the significant
long-term value in novel human proteins to treat human disease is best
captured through collaborative, strategic partnerships. Furthermore, CAT
believes that tailoring human monoclonal antibodies to target fundamental
physiological processes in disease is the future of successful drug
development.' 

Doug Williams, PhD, Executive Vice President and Chief Technology Officer of
Immunex added, 'Immunex is pleased to have access to the CAT library. Our
research programs in target validation and the development of fully human
monoclonal antibodies as therapeutics will be significantly advanced as a
result of this alliance.'

CAT is the world leading company in fully human antibodies derived by phage
display and is developing proprietary antibody-based products, both
independently and in partnership, as powerful drug discovery tools and for
therapeutic application in man. 

CAT has previously entered into broad strategic alliances for the discovery
and development of human monoclonal antibody-based drugs with a number of
leading pharmaceutical and biotechnology companies, most recently with
Pharmacia Corporation and Human Genome Sciences.

Immunex Corporation is a leading biopharmaceutical company dedicated to
improving lives through immune system science innovations.


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 nearly
200 people.  
CAT is listed on the London Stock Exchange, having raised £41m in its IPO in
March 1997. A secondary 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 company's 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 works in partnership with other companies at all stages of the drug
discovery and development process. CAT's collaborations, past and present,
include: AstraZeneca, BASF Pharma, Eli Lilly, Genentech, Genetics Institute,
Genzyme, Human Genome Sciences, Oxford GlycoSciences, Pharmacia Corporation,
Pfizer, Wyeth-Ayerst 

Immunex Corporation 
Immunex Corporation is a biopharmaceutical company based in Seattle,
Washington, and has nearly 1500 employees in the United States.
The company discovers, develops, manufactures and markets innovative
therapeutic products for the treatment of human diseases, including cancer and
immunological disorders such as rheumatoid arthritis. The company's research
focus has produced a pipeline of potential products that targets some of the
most serious medical challenges people face, including cancer, multiple
sclerosis, heart disease and asthma.