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Treatment for Chronic Myelogenous Leukemia

Update: Synribo (omacetaxine) Now FDA Approved - October 26, 2012

FDA Accepts Omapro NDA

ChemGenex Announces FDA Accepts NDA for Omapro (Omacetaxine Mepesuccinate) and Grants the Filing Priority Review Status

MELBOURNE, Australia, and MENLO PARK, California U.S.A. (10 November 2009) – ChemGenex Pharmaceuticals Limited announced today that the U.S. Food & Drug Administration (FDA) has accepted the company's New Drug Application (NDA) for Omapro (omacetaxine mepesuccinate) for the treatment of patients with chronic myeloid leukemia (CML) who have failed treatment with imatinib and who have developed the Bcr-Abl T315I mutation. The NDA has also been granted Priority Review. A Priority Review designation is given to drugs that offer major advances in treatment or provide a treatment where no adequate therapy exists, and generally denotes that the FDA review period is reduced to approximately six months. ChemGenex submitted the NDA on 8 September 2009.

"We are pleased that the FDA has accepted our NDA for Omapro and granted the filing Priority Review status which underscores the critical need for a treatment option for the CML T315I+ patient population," said Greg Collier PhD, ChemGenex's Chief Executive Officer and Managing Director.

"We look forward to working closely with the agency over the next several months as they review our filing. If approved, we plan to launch Omapro in the U.S. as the first therapy specifically indicated for CML T315I patients." Omapro has received Orphan Drug designation in the U.S. and in the European Union, and has received Fast Track status from the FDA. Omapro demonstrated clinical benefit in the pivotal Study 202 in CML patients who had failed imatinib and have the T315I mutation.

About Omapro

Omapro (omacetaxine mepesuccinate) Omacetaxine mepesuccinate is administered subcutaneously and acts differently from TKIs. It may have a therapeutic advantage for patients who have failed TKIs. Omacetaxine is currently in global phase 2/3 clinical trials for CML and has been granted Orphan Drug designations by the U.S. Food and Drug Administration (FDA) and European Medicines Agency (EMEA) as well as Fast Track status by the FDA.

Omacetaxine 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). In addition, pre-clinical research presented at the 14th Congress of the European Hematology Association (EHA) in Berlin, Germany this summer, demonstrated that omacetaxine kills human CML stem cells that are known to be insensitive to TKIs.

About Chronic Myeloid Leukemia (CML) and the Bcr-Abl T315I Mutation

Chronic myeloid leukemia (CML) is a cancer of the bone marrow with a worldwide prevalence of approximately 200,000 patients. The bone marrow is responsible for the production of specialized cells that constitute blood; these cells include red blood cells (to carry oxygen around the body), thrombocytes (to help stop bleeding) and certain white cells (part of the body's defense system against infection). In patients with CML the cell production system is diseased and defective. Cells multiply uncontrollably and do not fully develop (differentiate) into functional blood cells.

The majority of CML patients initially respond well to treatments with drugs called tyrosine kinase inhibitors (TKIs). However, a significant proportion of patients fail, or become intolerant to, one or more TKIs. In many of these situations the cause of failure can be traced to the emergence of Bcr-Abl mutations. A common mutation called T315I renders CML resistant to all currently approved TKIs, and has created a significant unmet medical need in the management of CML.

About ChemGenex Pharmaceuticals Limited

ChemGenex is an oncology focused biopharmaceutical company developing small molecules with new mechanisms of action to treat malignancies with significant unmet medical needs. The company is developing omacetaxine, its lead product candidate, for the treatment of patients with Chronic Myeloid Leukemia (CML), Acute Myeloid Leukemia (AML), and Myelodysplastic Syndrome (MDS). A New Drug Application has been submitted to the U.S. Food and Drug Administration for CML patients with the Bcr-Abl T315I mutation. The corporate strategy for ChemGenex is to commercialize omacetaxine independently in North America and to establish commercial partnerships in the rest of the world. ChemGenex currently trades on the Australian Stock Exchange under the symbol "CXS".

Omapro is a trademark of ChemGenex Pharmaceuticals Limited

Posted: November 2009

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