Alzheimer's Drug Lecanemab Hailed As Momentous Breakthrough

An anonymous reader quotes a report from the BBC: The first drug to slow the destruction of the brain in Alzheimer's has been heralded as momentous and historic. The research breakthrough ends decades of failure and shows a new era of drugs to treat Alzheimer's -- the most common form of dementia -- is possible. Yet the medicine, lecanemab, has only a small effect and its impact on people's daily lives is debated. And the drug works in the early stages of the disease, so most would miss out without a revolution in spotting it. Lecanemab is an antibody -- like those the body makes to attack viruses or bacteria -- that has been engineered to tell the immune system to clear amyloid from the brain. Amyloid is a protein that clumps together in the spaces between neurons in the brain and forms distinctive plaques that are one of the hallmarks of Alzheimer's.

The large-scale trial involved 1,795 volunteers with early stage Alzheimer's. Infusions of lecanemab were given every fortnight. The results, presented at the Clinical Trials on Alzheimer's Disease conference in San Francisco and published in the New England Journal of Medicine, are not a miracle cure. The disease continued to rob people of their brain power, but that decline was slowed by around a quarter over the course of the 18 months of treatment. The data is already being assessed by regulators in the US who will soon decide whether lecanemab can be approved for wider use. The developers -- the pharmaceutical companies Eisai and Biogen -- plan to begin the approval process in other countries next year.

There is debate among scientists and doctors about the 'real world' impact of lecanemab. The slower decline with the drug was noticed using ratings of a person's symptoms. It's an 18-point scale, ranging from normal through to severe dementia. Those getting the drug were 0.45 points better off. [Prof Tara Spires-Jones, from the University of Edinburgh] said that was a 'small effect' on the disease, but 'even though it is not dramatic, I would take it.' Dr Susan Kohlhaas, from Alzheimer's Research UK, said it was a 'modest effect... but it gives us a little bit of a foothold' and the next generation of drugs would be better. There are also risks. Brain scans showed a risk of brain bleeds (17% of participants) and brain swelling (13%). Overall, 7% of people given the drug had to stop because of side effects. A crucial question is what happens after the 18 months of the trial, and the answers are still speculation. [Dr Elizabeth Coulthard, who treats patients at North Bristol NHS Trust] says that people have, on average, six years of living independently once mild cognitive impairment starts. Slow that decline by a quarter and it could equate to an extra 19 months of independent life, 'but we don't know that yet', she says. It is even scientifically plausible that the effectiveness could be greater in longer trials.

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