ChemGenex will need a validated T315i mutation test for omacetaxine in CML
Yesterday afternoon, the FDA and ODAC met for a second time in the day to review the application for omacetaxine from ChemGenix. The drug was tested in limited trials in people with chronic myeloid leukemia (CML) for whom tyrosine kinase (TKI) therapy with drugs such as imatinib, dasatinib or nilotinib had failed or who had the T315i mutation.
My previous analysis from last month is here. Unlike the concerns in the morning with safety and efficacy associated with pixantrone in NHL, this time the FDA were clearly concerned about the validity of commercially available assays to detect the T315i mutation.
I did a search to see what was out there for testing T315i and found two:
- Quest Diagnostics are advertising one here.
- DxS Diagnostics are advertising one here.
Interestingly, the DxS one clearly states that it is for research purposes only, not for diagnosis. I'm not sure if the Quest test has been approved commercially, but it would seem odd of the FDA to make a song and dance about a widely available test if there is one available, so it is possible that both are only available for research purposes so far and as such, not approved for commercial use. Or it may be that the Quest one is approved but has not yet been validated with omacetaxine. It isn't overly clear from the information we have so far.
Either way, Kerri Wachter was on the scene at the meeting and tweeted the vote succinctly:
This isn't really surprising: if you are claiming to target a particular marker or target, then you need a validated companion diagnostic test to be commercially available once the drug is approved. I think what the FDA is saying to ChemGenex is that they need to do a small study comparing and validating the data between commercial assays and the ones used more commonly in hospital Path labs for research purposes and clinical trials. It's not a big deal, but it does need to be done.
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4 Responses to “ChemGenex will need a validated T315i mutation test for omacetaxine in CML”
Hi Sally,
This is “off topic” but, why would Oncothyreon and MerckAG suspend their trials of Stimuvax in breast and NSCLC based on a smaller Phase 2 exploratory study in multiple myeloma; in the Phase 2 study one patient developed encephalitis. This is one patient out of nearly 1,000 patients which have been dosed over the years in much broader and longer studies.
Doesn’t make much sense as to why suspend a study based on one single event.
Thanks
Craig, I don’t know… may be other factors we don’t yet know about.
Encephalitis is irritation and swelling (inflammation) of the brain, usually due to infections. It’s not a side effect that anyone would want and is potentially life threatening, so possibly the companies are being cautious and taking a look at the safety data overall before deciding whether to proceed or not.
I’d rather they take a sensible approach like this and evaluate the data than risk more people being exposed to the drug if there is a real rather than spurious risk.
This approach does not preclude the studies re-starting again if it is deemed sensible.
Hi Sally
Do you think the FDA are not concerned about safety and efficacy for omacetaxine or are they doing this in a step process and these questions will come later, prehaps to a second ODAC meeting?
thanks
Brett, ah now that is the $64M question!
I have no idea, really not sure what to expect here except to say that no current TKI therapies work against the T315i mutation. The data I saw presented at ASH suggests omacetaxine has some biologic activity there.
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