Re: Licencing Agreement

Cambridge Antibody Tech Group PLC
22 September 2003



03/CAT/25

FOR IMMEDIATE RELEASE

07:00 BST, 02.00 EST 22 September 2003

For further information contact:
Cambridge Antibody Technology                             Weber Shandwick Square Mile (Europe)
Tel: [phone]                                 Tel: [phone]
Peter Chambre, Chief Executive Officer                    Kevin Smith
John Aston, Chief Financial Officer                       Rachel Lankester
Rowena Gardner, Director of Corporate Communications

Dyax:                                                     BMC Communications/The Trout Group (USA)
Tel: [phone]                                      Tel: [phone]
Ivana Maravic-Magovcevic, PhD, JD,                        Brad Miles, ext 17 (media)
Vice President Legal Affairs and Chief Patent Counsel     Brandon Lewis, ext 15 (investors)





                  CAMBRIDGE ANTIBODY TECHNOLOGY AND DYAX CORP.

                       FURTHER EXPAND LICENCING AGREEMENT





Cambridge, UK and Cambridge, Mass... Cambridge Antibody Technology (LSE: CAT)
and Dyax Corp. (NASDAQ: DYAX ) today announced a further amendment to their
existing licensing agreement.



The new agreement extends the arrangement that was previously announced in
January 2003 and grants Dyax, amongst other benefits, an increased number of
options for licences to develop therapeutic and diagnostic antibody products
under CAT's patents for Dyax's own use and on behalf of its partners. CAT and
Dyax have further agreed that, as a result of this agreement, royalties will not
be due to Dyax in respect of HUMIRA(TM).



Peter Chambre, CAT's Chief Executive Officer, commented: "We are delighted to
have expanded our agreement with Dyax and to have resolved the position with
respect to HUMIRA."



Henry E. Blair, Dyax's Chairman, President and Chief Executive Officer,
commented "We are very pleased to expand further our Licensing Arrangement with
CAT. This expansion significantly increases the potential number of antibody
products Dyax can discover both for our own pipeline and for collaborators."







-ENDS-





Cambridge Antibody Technology (CAT):

•         CAT is a UK-based biotechnology company using its proprietary
technologies and capabilities in human monoclonal antibodies for drug discovery
and drug development. Based near Cambridge, England, CAT currently employs
around 290 people.

•         CAT is a leader in the discovery and development of human therapeutic
antibodies and has an advanced proprietary platform technology for rapidly
isolating human monoclonal antibodies using phage display and ribosome display
systems. CAT has extensive phage antibody libraries, currently incorporating
more than 100 billion distinct antibodies. These libraries form the basis for
the Company's strategy to develop a portfolio of antibody-based drugs.

•         HUMIRA, the leading CAT-derived antibody, isolated and optimised in
collaboration with Abbott has been approved by the US Food and Drug
Administration for marketing in the US as a treatment for rheumatoid arthritis.

•         Eight further CAT-derived human therapeutic antibodies are at various
stages of clinical trials. There are five candidate therapeutic antibodies in
pre-clinical development.

•         CAT has alliances with a number of pharmaceutical and biotechnology
companies to discover, develop and commercialise human monoclonal antibody-based
products. CAT has co-development programmes with Amgen, Amrad, Elan and Genzyme.

•         CAT has also licensed its proprietary technologies to several
companies. CAT's licensees include: Abbott, Amgen, Chugai, Human Genome
Sciences, Merck & Co, Pfizer and Wyeth Research.

•         CAT is listed on the London Stock Exchange and on NASDAQ since June
2001. CAT raised £41m in its IPO in March 1997 and £93m in a secondary offering
in March 2000.



For CAT:

Application of the Safe Harbor of the Private Securities Litigation Reform Act
of 1995: This press release contains statements about Cambridge Antibody
Technology Group plc ("CAT") that are forward looking statements. All statements
other than statements of historical facts included in this press release may be
forward looking statements within the meaning of Section 21E of the Securities
Exchange Act of 1934. These forward looking statements are based on numerous
assumptions regarding the company's present and future business strategies and
the environment in which the company will operate in the future. Certain factors
that could cause the company's actual results, performance or achievements to
differ materially from those in the forward looking statements include: market
conditions, CAT's ability to enter into and maintain collaborative arrangements,
success of product candidates in clinical trials, regulatory developments and
competition. We caution investors not to place undue reliance on the forward
looking statements contained in this press release. These statements speak only
as of the date of this press release, and we undertake no obligation to update
or revise the statements.





Dyax Corp.

Dyax Corp. is a biopharmaceutical company principally focused on the discovery,
development and commercialization of therapeutics for inflammatory conditions
and in oncology.  Dyax currently has two recombinant proteins in clinical
development, DX-88 and DX-890.  DX-88 is being studied in
phase II clinical trials for the treatment of hereditary angioedema in
collaboration with Genzyme Corporation. Dyax is also studying DX-88 in a phase I
/II clinical trial for use during cardiopulmonary bypass surgery. DX-890 is
being studied in phase IIa clinical trials for the treatment of cystic fibrosis
in collaboration with Debiopharm, S.A.  Dyax utilizes its proprietary phage
display technology to rapidly identify a broad range of recombinant protein,
peptide, and fully human monoclonal antibody compounds that bind with high
affinity and specificity to targets of interest, with the objective of selecting
those compounds with the greatest potential for advancement into clinical
development.  Dyax leverages broadly its phage display technology through
revenue generating licenses and collaborations in both its core therapeutics
area, as well as in non-core areas of affinity separations, diagnostic imaging,
and research reagents. Through its subsidiary, Biotage, Inc., Dyax develops,
manufactures and sells chromatography separations systems and products to
pharmaceutical companies worldwide for drug discovery and purification.  For
more information on Dyax Corp., please visit its website at www.dyax.com.





For Dyax:

This press release contains forward-looking statements, including statements
regarding Dyax's ability to discover and develop antibody products for itself
and its collaborators. Statements that are not historical facts are based on
Dyax's current expectations, beliefs, assumptions, estimates, forecasts and
projections about the industry and markets in which Dyax competes. The
statements contained in this release are not guarantees of future performance
and involve certain risks, uncertainties and assumptions, which are difficult to
predict. Therefore, actual outcomes and results may differ materially from what
is expressed in such forward-looking statements. Important factors which may
affect Dyax's ability to discover and develop antibody products for itself and
its collaborators include the risks that: Dyax's technologies and products may
not gain market acceptance Dyax may not be able to obtain and maintain
intellectual property protection for its products and technologies; others may
develop technologies or products superior to Dyax's technologies or products;
and other risk factors described or referred to in Dyax's most recent Annual
Report on Form 10-K and other periodic reports filed with the Securities and
Exchange Commission. Dyax cautions investors not to place undue reliance on the
forward-looking statements contained in this release. These statements speak
only as of the date of this release, and Dyax undertakes no obligations to
update or revise these statements, except as may be required by law. Dyax
specifically disclaims responsibility for information describing CAT and its
business other than the license with Dyax. Dyax and the Dyax logo are the
registered trademarks of Dyax Corp.








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