FDA reviewers unimpressed with Gleevec-resistant CML therapy omacetaxine

The response rate among Gleevec-resistant chronic myeloid leukemia (CML) patients to ChemGenex Pharmaceuticals' omacetaxine (Omapro) appears too low even for the FDA to approve, according to the agency's reviewers in Washington DC.

The poor assessment of omacetaxine now moves on to the Oncologic Drugs Advisory Committee, which will examine data from a single trial which tested safety and efficacy, and advise the FDA on whether or not they should approve the drug.

The results from the trial (which can be seen summarized here) seem especially dismal, offering only marginal benefit to a very small percentage of trial participants. The FDA also found a variety of problems with the trial itself.

ChemGenex fought back saying omacetaxine is "an effective and durable therapy" and "an important option" for Gleevec-resistant patients.

The FDA is often criticized for approving too many marginally effective oncology drugs, but omacetaxine appears it will be one of the rare exceptions.

Omacetaxine, fast-tracked by the FDA, had been impressive when presented as an abstract at the recent ASH meeting, but a closer look at the data is not bearing out any of that early excitement.