The big news today is that the FDA has acted on aducanumab, approving it for use as a treatment for Alzheimer's disease. (It will be marketed as "Aduhelm.") The approval comes by way of the FDA's "accelerated approval pathway," which allows a drug to be approved even if it has not been shown to be effective.
These provisional approvals are for cases where a treatment has been shown to be effective against a surrogate endpoint in way indicating that it likely also hits the true endpoint. In this case, the true endpoint is slowing the loss of cognition, while the surrogate endpoint is removal of amyloid plaques in the brain. What trials have so far failed to prove to the satisfaction of some key players is that removing the amyloid plaques this way leads to at least slowing the decline of cognition. Under this approval system, people with Alzheimer's can receive treatment with Aduhelm/aducanumab, but Biogen must continue work to prove that it is effective against the primary endpoint. If they are unable to do so, the FDA may withdraw approval and take everyone off the treatment.
Aduhelm has some enthusiastic supporters. OK, but there are some things to keep in mind when considering prospects that the treatment provides dramatic changes in the course of the disease. It has been noted that the monoclonal antibody can slow progress of the disease in a limited population, but it has not been shown to either stop decline or improve cognition. It can also cause micro-hemorrhages in the brain, necessitating periodic MRIs during treatment. It is not a pill, but rather a monthly infusion requiring a medical visit each time.
The limited population on which it has been tested includes those -- like me -- with MCI as well as some with early dementia. Those who read Beating the Dementia Monster understand the progress of Alzheimer's disease from MCI to dementia.
Not surprisingly, Biogen's stock price jumped sharply on the announcement. It had been pretty flat over the past year. But what does the future hold?
The hope is that, while this is not a cure, it opens a pathway for future research that will lead to increasingly more effective treatments. It assumes the amyloid hypothesis is correct (which we discussed in Beating the Dementia Monster), although some researchers doubt the credibility of the amyloid hypothesis. So, it could turn out to be a dead end that distracts from pursuing more effective approaches.
In all probability, some families will want to begin the treatment for their loved ones as soon as it is available. Hopefully, they will have accepted the both the risks and uncertainty associated with it.
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