CAT and Dyax expand agreement

Cambridge Antibody Tech Group PLC
05 January 2003


03/CAT/02


FOR IMMEDIATE RELEASE


07.00 GMT 02.00 EST, 6 January 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                         Graham Herring
Rowena Gardner, Director of Corporate Communications


Dyax Corp                                                   BMC Communications/The Trout Group (USA)
_________                                                   ________________________________________

Jack Morgan, Senior Vice President,                         Tel: [phone]
Corporate Development & Business Operations                 Brad Miles, ext 17 (media)
Tel: [phone]                                       Brandon Lewis, ext.15 (investors)
Sondra Henrichon, Director Investor Relations and 
Corporate Communications
Tel: [phone]



CAMBRIDGE ANTIBODY TECHNOLOGY AND DYAX
EXPAND LICENSING AGREEMENT


Cambridge, UK and Cambridge, MA ... Cambridge Antibody Technology (LSE: CAT;
NASDAQ:CATG) and Dyax Corp. (NASDAQ: DYAX) today announce an agreement to expand
access and freedom to operate under each other's phage display patents.


This agreement expands upon those reached in 1997 under which Dyax licensed its
Ladner phage display patents to CAT and CAT granted certain limited rights to
Dyax under antibody phage display patents controlled by CAT.  Under the terms of
this expanded agreement, CAT is granting Dyax worldwide licences for research
and certain other purposes under all the antibody phage display patents
controlled by CAT.  Dyax will also receive options for licences to develop
therapeutic and diagnostic antibody products under CAT's patents.  In return,
CAT will receive milestone and royalty payments on antibody products advanced
into clinical trials by Dyax and Dyax's customers. CAT also gains the option to
co-fund and co-develop with Dyax antibodies discovered by Dyax, as well as the
right to share in Dyax's revenues from certain other applications of antibody
phage display.


In addition, CAT's obligation to pay royalties under the 1997 Agreements to Dyax
for rights with respect to Dyax's Ladner patents on antibody products CAT
develops is removed, except in relation to HumiraTM. CAT has options to buy out
under a predetermined schedule any royalty obligation which CAT may have in
respect of Humira.


Peter Chambre, CAT's Chief Executive Officer, commented "We are delighted to
have reached this agreement with Dyax and are particularly pleased with the
associated reduction in CAT's royalty burden. Importantly also the agreement
enables CAT to share in Dyax' success as it develops products under the licence
in the future.  This agreement is further evidence of CAT's commitment to
licensing its phage antibody patent portfolio; it is the third patent licensing
agreement we have executed in the last month."


Jack Morgan, Senior Vice President of Dyax Corp., commented: "We believe this
agreement will expand pharmaceutical and biotechnology companies' access to
state-of-the-art technology and ultimately benefit patients by facilitating
expanded discoveries utilising antibody phage display.  This represents the
fourth and most important patent cross licensing agreement Dyax has entered into
over the past ten months.  We are particularly excited to utilise the options to
develop therapeutic antibodies for both Dyax's pipeline and for our customers."


- ENDS-


Notes to Editors

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 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.

HumiraTM, the leading CAT-derived antibody, has been approved by the US Food and
Drug Administration for marketing in the US as a treatment for rheumatoid
arthritis. Six further CAT-derived human therapeutic antibodies are at various
stages of clinical trials.

CAT has alliances with a large number of pharmaceutical and biotechnology
companies to discover, develop and commercialise human monoclonal antibody-based
products. CAT has also licensed its proprietary human phage antibody libraries
to several companies for target validation and drug discovery. CAT's
collaborators include: Abbott, Amgen, Amrad, Chugai, Elan, Genzyme, Human Genome
Sciences, Merck & Co, Pharmacia 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 CAT's present and future business strategies and the environment in
which CAT will operate in the future.  Certain factors that could cause CAT'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.


Dyax Corp:


Dyax Corp. is a biopharmaceutical company focused on the discovery, development
and commercialization of therapeutic products. The Company uses its patented
phage display technology to rapidly identify a broad range of protein, peptide,
and antibody compounds that bind with high affinity and high specificity to
targets of interest, with the objective of selecting those compounds with the
greatest potential for advancement into clinical development.

Dyax currently has two recombinant proteins in phase I and II clinical trials.
DX-88 is being studied in two indications (hereditary angioedema and
cardiopulmonary bypass), while DX-890 is being studied for cystic fibrosis.

Dyax leverages its technology broadly through licenses and collaborations in
therapeutics and in non-core areas of affinity separations, diagnostics and
imaging, and research reagents.

Through its subsidiary, Biotage, Inc., Dyax develops, manufactures and sells
chromatography separations systems and products worldwide for drug discovery and
purification.



As to Dyax:

This press release contains forward-looking statements, including statements
regarding Dyax's ability to develop products under the antibody phage display
patents for itself and its customers. 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 develop products under the antibody
phage display patents for itself and its customers include the risks that 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 and the Dyax logo are the registered trademarks of Dyax
Corp.



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