Pivotal Study Results: ChemGenex`s Omacetaxine May Provide the First Viable Drug Treatment Option for Patients With a Highly Resistant Form of CML

* Data Intended for NDA Submission Presented at ASCO
* Findings Suggest Omacetaxine Offers an Important Breakthrough in the Treatment
of CML Patients with the T315I Resistance Mutation

MELBOURNE, Australia & MENLO PARK, Calif.--(Business Wire)--
ChemGenex Pharmaceuticals Limited (ChemGenex) (ASX:CXS) (NASDAQ:CXSP) announced
that the latest data from its pivotal study of omacetaxine in patients with
T315I-positive chronic myeloid leukemia (CML) was the subject of an oral
presentation and discussion today at the 2009 American Society of Clinical
Oncology (ASCO) Annual Meeting in Orlando, Florida. The open label Phase 2/3
study (CGX-635-CML-202) investigated the use of omacetaxine, administered
subcutaneously in CML patients who had failed imatinib and who have the highly
drug resistant T315I kinase domain mutation.

Dr. Jorge Cortes, MD, Professor of Medicine and Deputy Chair in the Department
of Leukemia at The University of Texas, MD Anderson Cancer Center, a lead
investigator in the study, presented the data. Dr. Cortes said, "It appears that
omacetaxine was well tolerated in this study and durable hematological and
cytogenetic responses were observed in some CML patients with the T315I
mutation." He added that "Several novel drugs have already been investigated in
this difficult-to-treat population, but they have not had a reasonable
risk:benefit ratio. These results suggest that omacetaxine may represent the
first viable treatment option for this population of patients who currently have
no established treatment options."

Data were presented from 66 patients: 40 in chronic phase, 16 in accelerated
phase and 10 in blast phase. Highlights of the data were:

Chronic phase patients

* Complete hematologic response (CHR) rate of 85% with a median response
duration 8.9 months
* Major cytogenetic response (MCyR) rate of 15% with a median response duration
6.1 months

Accelerated phase patients

* CHR rate of 31% with a median duration 4.1 months
* MCyR rate of 6% with a median response duration 1.8 months

Blast phase patients

* CHR rate of 20% with a median duration 3.3 months

Tolerability

Investigators reported that omacetaxine is generally well tolerated, and that
the most common side effect is reversible and transient myelosuppression.

Commenting on the presentation, Dr. Greg Collier, Chief Executive Officer and
Managing Director of ChemGenex, said, "This is a very important milestone in the
development of omacetaxine and in the evolution of ChemGenex. The data presented
today will be provided to the FDA in the final part of our rolling NDA
submission; this project remains on target for completion in Q3 this year." Dr.
Collier finished by expressing his deep appreciation for patients and
investigators who participated in this important trial.

Dr. Collier and ChemGenex`s Chief Medical OfficerDr. Adam Craig will host an
investor conference call and webcast to discuss the clinical results from both
ASCO and the EHA Congress on Thursday 11th of June at 10 am AEST. Details of
this event will be advised in coming days.

Omacetaxine Overview

Omacetaxine mepesuccinate is a first-in-class cetaxine with demonstrated
clinical activity as a single agent in a range of hematological malignancies.
Omacetaxine has a novel mechanism of action, specifically binding to the
ribosomal A-site cleft and inhibiting protein translation of short-lived
oncoproteins that are upregulated in leukemic cells (particularly Cyclin-D1,
Mcl-1 and c-Myc). As omacetaxine acts independently of tyrosine kinase
inhibitors, it may have a therapeutic advantage for patients who have developed
resistance to TKIs. Omacetaxine is administered subcutaneously.

About ChemGenex Pharmaceuticals Limited(http://www.chemgenex.com)

ChemGenex Pharmaceuticals is a pharmaceutical development company dedicated to
improving the lives of patients by developing personalized oncology medicines.
ChemGenex harnesses the power of genomics both to discover novel targets and
drug compounds, and in clinical trials to develop more individualized treatment
outcomes. ChemGenex`s lead compound, omacetaxine mepesuccinate, is currently in
phase 2/3 clinical trials for chronic myeloid leukemia (CML). ChemGenex has a
second anticancer compound, amonafide dihydrochloride (Quinamed®), which is in
phase 2 clinical development for various solid cancers, and a portfolio of
assets in pre-clinical development. ChemGenex currently trades on the Australian
Stock Exchange under the symbol "CXS" and on NASDAQ under the symbol "CXSP". For
additional information on ChemGenex Pharmaceuticals, please visit our web site
at http://www.chemgenex.com.

Details on the clinical trials can be accessed from the following websites;
http://clinicaltrials.gov/ct2/show/NCT00375219?term=homoharringtonine&rank=9 and
http://www.tkiresistantcmltrials.com

Safe Harbor Statement

Certain statements made herein (including for this purpose sites to which a
hyperlink has been provided) that use the words "estimate", "project", "intend",
"expect", "believe" and similar expressions are intended to identify
forward-looking statements within the meaning of the US Private Securities
Litigation Reform Act of 1995. These forward-looking statements involve known
and unknown risks and uncertainties which could cause the actual results,
performance or achievements of the company to be materially different from those
which may be expressed or implied by such statements, including, among others,
risks or uncertainties associated with the development of the company`s
technology, the ability to successfully market products in the clinical
pipeline, the ability to advance promising therapeutics through clinical trials,
the ability to establish our fully integrated technologies, the ability to enter
into additional collaborations and strategic alliances and expand current
collaborations and obtain milestone payments, the suitability of internally
discovered genes for drug development, the ability of the company to meet its
financial requirements, the ability of the company to protect its proprietary
technology, potential limitations on the company`s technology, the market for
the company`s products, government regulation in Australia and the United
States, changes in tax and other laws, changes in competition and the loss of
key personnel. These statements are based on our management`s current
expectations and are subject to a number of uncertainties that could change the
results described in the forward-looking statements. Investors should be aware
that there are no assurances that results will not differ from those projected.

ChemGenex
Dr. Greg Collier
CEO and Managing Director
Cell (Australia): +61 419 897501
Cell (USA): +1-650-200-8145
collier@chemgenex.com
or
Buchan Consulting
Rebecca Wilson, +61 (0)3 9866 4722
Cell: + 61 (0)417 382 391
Media Relations - Australia
rwilson@bcg.com.au
or
Kureczka/Martin Associates
Joan Kureczka, +1-415-821-2413
Cell: +1-415-690-0210
Media Relations - USA
Jkureczka@comcast.net

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