I’ve had a few days to think about this and still have a difficult time understanding the Advisory Committee vote. I admit that I didn’t see this coming. Maybe I should have. After all, this committee (with different members) gave a thumbs up to CONTRAVE. And what happened with CONTRAVE? The FDA went back to the basics of the drug approval process, the basics of benefit risk, and determined that the sponsor had not satisfied the regulatory requirements.
Will the same thing happen with QNEXA? I don’t know what the FDA will do, but I do know what they should do. Efficacy doesn’t seem to be an issue although there doesn’t seem to be any additional weight loss after 1 year of treatment. With the unanswered, it seems likely that if approved, use beyond one year will be limited.
But let’s look at the safety issues. The two biggies are sitting right out there – cardiovascular risk and teratogenic potential in women of child bearing potential. Both of these are unknowns at this time and both can be answered. The question for the FDA is whether the answers should come before approval or after approval.
Teratogenic risk: QNEXA is a teratogen. The population at risk has a high percentage of women of child bearing potential. The component responsible for the teratogenic risk is already available for the treatment or migraines and epilepsy in a population that contains women of child bearing potential. The issue here is not the approvability of the drug but rather the adequacy of the REMS program and the labeling. Can the FDA and the sponsor work this out before the PDUFA Date?
Cardiovascular risk. The FDA has raised this issue in both of their Briefing Documents. The previous Advisory Committee had this as one of the major outstanding issues they used to support its 6-10 vote against recommending approval. The FDA is concerned enough about cardiovascular risk with obesity drugs to call for another Advisory Committee meeting with this as the sole topic for discussion next month. Now, the interesting thing is that the upcoming Advisory Committee meeting is going to be another meeting of the Endocrine Metabolic Drugs panel, the same panel that just recommended approval for QNEXA. The FDA will probably invite a lot of cardiologists, more than were at the QNEXA meeting. The cardiologist vote for QNEXA was split, one for, one against approval. The negative vote was very negative. It is unlikely the FDA will make any decision about resolving the cardiovascular risk associated with QNEXA until after the March Advisory Committee. If the Committee continues to support the current FDA reequirement that studies that rule out cardiovascular risk must be completed before approval then the decision to be made by the FDA is obvious. If however, the Committee recommends that in some circumstances these studies can be conducted post approval, the question then becomes whether the FDA and the sponsor can work this out before the PDUFA Date. They would have to agree to the protocol for such a study and agree on labeling that identifies the absence of information that defines the population at risk.
I’m of a view now that QNEXA will be approved for the treatment of obesity. The questions of when and with what kind of a label still remain. It is unlikely it will be approved at its PDUFA Date. How long after the PDUFA Date is a question that can only be answered after the March Advisory Committee meeting. A point to keep in mind – while we are focusing on the approval of QNEXA, the FDA is also thinking about the precedent it will set for other drugs in the review/development pipeline.