Conditional approval
FDA approves new drug for Alzheimer's disease
Polina Loseva, N+1
American Food and Drug Administration (FDA) approved aducanumab– a Biogen development for Alzheimer's disease. The previous drug for this disease, which received FDA approval, entered the market 18 years ago. The new drug is aimed at destroying amyloid plaques in the brain, but how well it copes with the disease is still unclear. The developers will have to prove that aducanumab really improves the cognitive functions of patients – otherwise the FDA may withdraw its approval back.
Until recently, there were five drugs in the world for the treatment of Alzheimer's disease. Four of them are approved in the USA and around the world, but they do not actually cure patients – because they do not fight the cause of the disease, but only mitigate the manifestation of some symptoms.
The fifth drug was approved in 2019 in China. It was created on the basis of an algae extract: the developers expected that the components of the plant cell wall would feed the "right" bacteria in the human intestine, and those, in turn, would suppress inflammation in the nervous tissue. However, many questions immediately arose about this medicine – and so far it has not received worldwide recognition.
At the same time, the American company Biogen was developing its own drug, aducanumab. These are monoclonal antibodies that should attack and destroy aggregates of beta-amyloid – one of the main signs of Alzheimer's disease. Until now, none of the therapies directed against beta-amyloid have worked in clinical trials, and many scientists suspected that amyloid was not the cause, but a side effect of the disease. In March 2019, Biogen also failed: she stopped her clinical trials, explaining that the drug did not show the desired effect – amyloid plaques in the brain become smaller, but aducanumab does not always affect cognitive abilities.
Nevertheless, in the fall of 2019, Biogen announced that it had revised the data - and came to new conclusions. According to the developers of the drug, the samples of the subjects turned out to be heterogeneous: one of the branches of the trials probably included more people whose disease developed faster than average. If they were excluded from the analysis, then the medicine looked effective. With this formulation, Biogen submitted documents for consideration to the FDA.
The expert commission at the department dealt with the situation for about a year, and in the fall of 2020 issued a verdict: the data of different branches of the test can be considered independently of each other. It sounded like a recommendation to approve the medicine – as long as failure in one of the branches does not detract from success in the other. After that, a panel of external experts, having studied the report of the FDA experts, issued the opposite verdict: it did not recommend approving the drug, with ten votes "against" against one "for".
And six months later, the FDA published its decision: the drug (it was named Aduhelm) was approved, but provisionally. In its statement, the agency clarifies that such a procedure is used when "there are expectations of clinical benefit, despite the doubts that remain about this benefit." The FDA expects that, since amyloid plaques in the brains of patients have become smaller in all branches of the trials, it can be expected that the drug will still manifest itself against external signs of the disease.
Nevertheless, the developers will have to conduct the fourth, post-registration phase of trials and confirm that aducanumab really improves cognitive functions in patients. If this cannot be proved, the FDA reserves the right to revoke its authorization.
Earlier we talked about a mutation that protected a resident of Colombia from a hereditary form of Alzheimer's disease. In addition, the researchers tried to treat this disease with ionizing radiation – and got the first positive results.
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