MELBOURNE, Australia, and MENLO PARK, California U.S.A. (June 4, 2007). ChemGenex Pharmaceuticals (ASX: CXS, NASDAQ: CXSP) announced today the presentation of data from its Quinamed (amonafide dihydrochloride) phase 1/2a dose-escalation study, designed to identify a genotypically optimised dose of Quinamed in heavily pre-treated patients with a variety of solid tumors. The key outcomes from this study were (i) demonstration that dose level could be optimised according to patient genotype, (ii) the drug was well tolerated, with predictable and manageable side effects, and (iii) there was evidence of anticancer activity in several solid tumor types.

Dr. John Kuhn of the University of Texas Health Science Center in San Antonio, TX, along with the investigators at Sarah Cannon Cancer Center, TN and University of Louisville, KY discussed the data in an oral presentation at the American Association of Clinical Oncology (ASCO) 43rd Annual Meeting in Chicago, Illinois.

The clinical activity of amonafide against a variety of cancers has long been recognized, but development has been hampered by the unpredictable side effect profile for patients said Dr Kuhn. We are excited by the new opportunities that personalized dosing of Quinamed offers for a range of solid tumor patients who have developed resistance to existing therapies.

Highlights of the presentation included:

• Confirmation that genotyping of patients prior to treatment allows for optimized personalized dosing and improved drug tolerance.
• Patients with rapid and intermediate acetylator genotypes (who more rapidly metabolize the drug to the acetylated derivative associated with side effects) achieved a maximum tolerated dose (MTD) of 320 mg/m2 of Quinamed weekly, whilst patients with slow acetylator genotypes achieved an MTD of 400 mg/m2 of Quinamed weekly (three weeks on treatment followed by one week off treatment, repeated). Using these dosing regimens, 64% of
  '"/>