ChemGenex Personalized Medicine Clinical Trial Expanded to Patients with Breast and Ovarian Cancers

MELBOURNE, Australia, and MENLO PARK, California

September 27, 2005

ChemGenex Pharmaceuticals Limited (NASDAQ: CXSP; ASX: CXS) today announced that the Phase 2 clinical trial of its investigational anti-cancer drug, Quinamed® (amonafide dihydrochloride), has been expanded to include patients with breast and ovarian cancer.

Chief Executive Officer of ChemGenex Pharmaceuticals, Greg Collier Ph.D. said the Phase 2 trial was expanded beyond prostate cancer as planned based on results from earlier clinical studies, clinical advice and to provide the company with a broader range of target indications to choose from for the Phase 3 product registration trial.

"In the Phase 1 study, which included 32 patients, meaningful responses to Quinamed therapy were observed in patients with prostate, ovarian, breast and colon cancers," Dr Collier said. "Based on these results, we have decided to broaden the scope of the study - which commenced late last year - beyond only targeting prostate cancer patients who have failed docetaxel, to include patients with breast and ovarian cancer. As a general rule in this kind of trial, you only need to see one patient respond out of the first fourteen in a single tumor type to indicate a promising indication. By looking at three potential cancer types, we increase our chances of identifying the best indication for Phase 3 studies, which could commence as early as late 2006. In addition, Phase 2 data in more than one indication should help in partnering discussions planned for early next year."

In the United States alone, there are 221,000, 211,000 and 25,000 new cases per year of prostate, breast and ovarian cancers, respectively. ChemGenex's personalized medicine approach with Quinamed uses a genetic test to classify how each patient will metabolize the drug. The test, for variations in the NAT2 gene, is used to design a personalized dosing regimen that seeks to maximize anti-tumor response while minimizing toxicity.

Patients will be genotyped when entering the study and then dosed once weekly for three weeks each month at 400-500 mg/m2, if they are slow metabolizers, and at 320 mg/m2, if they are fast or intermediate metabolizers. The primary endpoints of the study are tumor response rate and duration of response. ChemGenex expects to complete this Phase 2 study of Quinamed in the first half of 2006. The expansion of the existing study - which already has 13 patients - has resulted in an increase in patient numbers to a total of up to 42, with 14 patients in each cancer group.

About ChemGenex Pharmaceuticals Limited (www.chemgenex.com)

ChemGenex Pharmaceuticals is a gene-based pharmaceutical company dedicated to improving the lives of patients by developing therapeutics in the areas of oncology, diabetes, obesity, and depression. ChemGenex currently has two compounds in Phase 2 clinical trials, Ceflatonin® for leukemia and Quinamed® for solid tumors, and has a significant portfolio of anti-cancer, diabetes, obesity and depression programs. The company's diabetes and obesity program is partnered with Merck KGaA and the depression program is partnered with Vernalis plc. ChemGenex currently trades on the Australian Stock Exchange under the symbol "CXS" and the NASDAQ exchange under the symbol "CXSP".

Contacts

Dr. Greg Collier (CEO and Managing Director)	Australia +61 3 5227 2752 USA +1 650 474 9800 ext 103
Dr. Dennis Brown (President and Director)	USA +1 650 474 9800 ext 108 Australia +61 3 5227 2703
Mr. Hershel Berry (Investor Relations)	Australia +61 3 5227 2703 USA (415) 392-3310

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