Cambridge Antibody Technology Announces Acquisition Of Oncology Product Candidate From Enzon

Cambridge, UK… Cambridge Antibody Technology (CAT) announces the acquisition of product candidate SS1P (renamed CAT-5001) from Enzon Pharmaceuticals, Inc., based in Bridgewater, New Jersey in May 2006. The safety profile of CAT-5001 has been characterised in two Phase I clinical trials in patients with mesothelioma, ovarian and pancreatic cancer. CAT intends to conduct further pre-clinical studies and to initiate a clinical study in early 2007 exploring dosing of CAT-5001 in combination with cytotoxic chemotherapy.

CAT-5001 was discovered and initially developed by the National Cancer Institute (NCI), which is part of the US National Institutes of Health (NIH). The programme was licensed to Enzon and that licence has now been assigned to CAT. Under the original licence agreement with the NIH, CAT will have rights to a portfolio of intellectual property associated with the programmes and will pay future royalties to NIH.

CAT-5001 is an immunotoxin fusion protein between a murine anti-mesothelin dsFv and the Pseudomonas exotoxin PE38. Mesothelin is a glycosylphosphatidylinositol-linked cell surface glycoprotein present on normal mesothelial cells that is overexpressed in numerous cancers including mesothelioma, ovarian cancer and pancreatic cancer. The immunotoxin CAT-5001, like CAT-3888 and CAT-8015, comprises a disulphide-linked Fv antibody fragment (dsFv) that targets the antigen, fused with a specifically engineered toxin molecule that minimises non-targeted toxicity, resulting in a highly specific, highly potent therapeutic molecule. The molecule acts by releasing the toxin intracellularly after the whole immunotoxin has been internalised.

Dr Patrick Round, Senior Vice President Development at CAT, commented: "Following the acquisition of CAT-3888 and CAT-8015 in October last year, the acquisition of CAT-5001 is a further step in enhancing our pipeline and presence in oncology and we are delighted to have broadened our relationship with Dr Ira Pastan and his team at the NCI."

-ENDS-

Notes to Editors:

Cambridge Antibody Technology (CAT):

• Cambridge Antibody Technology (CAT) is a biopharmaceutical company using its capabilities and technologies in the discovery and development of new and innovative antibody medicines in selected therapeutic areas to bring improvements to seriously ill patients' lives. Following the recent acquisition of CAT by AstraZeneca, CAT is a subsidiary of the AstraZeneca group of companies. CAT employs around 300 people and is based near Cambridge, UK and in Palo Alto, USA.
• 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.

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.