ChemGenex Pharmaceuticals announces that the US Food and Drug Administration's (FDA) Office of Oncology Drug Products has issued a complete response letter regarding the new drug application (NDA) for Omapro (omacetaxine mepesuccinate) for the treatment of adults with chronic myeloid leukaemia (CML) who have failed prior therapy with imatinib and have the Bcr-Abl T315I mutation.

The complete response letter does not contain a request for a new study, nor is there a request for enrolment of additional patients into the pivotal study on Omapro.

Commenting on the correspondence from the US FDA, Greg Collier, CEO for ChemGenex said, "The complete response letter from the US FDA provides the initial guidance towards our endeavour 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 US FDA were similar to those discussed during the meeting held on March 22 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 US 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 US FDA to discuss and find agreeable solutions for each of the US FDA's requests."

ChemGenex also met on April 9 with the US FDA's Center for Devices and Radiological Health (CDRH) to discuss a path forward for the development of a well defined diagnostic test for the T315I mutation. Both parties agreed to work together toward the validation of the T315I assay that meets the US FDA's requirements.

Omacetaxine mepesuccinate is administered subcutaneously and acts differently from TKIs.