ChemGenex on path to diagnostic for approval of anti-leukaemia drug

Melbourne-based targeted therapy company, ChemGenex, met with the US Food and Drug Administration's (FDA) Center for Devices and Radiological Health (CDRH) on April 9 to discuss the path forward for the development of a diagnostic test for the T315I mutation.

The company agreed to work with the CDRH on developing a well defined diagnostic test that meets the FDA's requirements.

This follows the March 22 decision by the FDA that there must be a validated diagnostic for this mutation in order for ChemGenex's flagship anti-leukaemia drug, Omapro (omacetaxine mepesuccinate) to be approved.

Omapro is a second-line targeted treatment for chronic myeloid leukaemia who have the T315I mutation and no long respond to the first-line treatment, imatinib.

The FDA acknowledged the need for Omapro, but expressed concern over the lack of a validated diagnostic to determine whether a potential patient has the T315I mutation.

During the trials of Omapro, at least two different diagnostics were used with differing performance characterisitcs, which introduces the possibility of variability in diagnosis. Furthermore, one third of trial patients did not have the presence of the T315I mutation validated by the central laboratories at the time of enrolment.

A letter sent to ChemGenex yesterday from the FDA Oncologic Drugs Advisory Committee did not request any new studies.

In response to the letter, ChemGenex CEO, Greg Collier, wrote: “The complete response letter from the FDA provides the initial guidance towards our endeavor to bring a new therapy to CML patients who harbour the T315I mutation and currently have very limited or unsatisfactory treatment options.

"Because the principal issues raised by the FDA were similar to those discussed during the 22 March meeting of the Oncology Drug Advisory Committee (ODAC), and based upon our interpretation of the scientific requirements underpinning the complete response letter, we are confident that we can work in a positive manner with the FDA to address the outstanding matters.

"We appreciate the constructive comments made by the agency in the response letter and ChemGenex will seek a meeting with the FDA to discuss and find agreeable solutions for each of the FDA’s requests.”

ChemGenex (ASX:CXS) stock has bumped by 8% to 47c since the issuing of the letter, although this is still over 30% down from its value prior to the ODAC ruling.