Health

Alzheimer’s drug breakthrough slows cognitive decline - but with side-effects

Lecanemab was associated with a dangerous type of brain swelling in nearly 13 per cent of patients in trial

In Alzheimer’s disease, it is thought the brain’s ability to remove amyloid beta becomes impaired. Photograph: iStock
In Alzheimer’s disease, it is thought the brain’s ability to remove amyloid beta becomes impaired. Photograph: iStock
Wed Nov 30 2022 - 06:47

The first major breakthrough in 30 years of Alzheimer’s research is providing momentum for clinical trials of treatments targeting the proteins associated with the mind-robbing disease.

An experimental Alzheimer’s drug from Eisai and Biogen slowed cognitive decline in a closely watched trial but may carry a risk of serious side effects for certain patients, according to detailed data presented on Tuesday.

The drug, lecanemab, was associated with a dangerous type of brain swelling in nearly 13 per cent of patients in the trial that spanned 18 months and enrolled nearly 1,800 participants with early-stage Alzheimer’s.

Some patients also experienced bleeding in the brain, with five suffering macrohemorrhages and 14 per cent suffering microhemorrhages – a symptom linked to two deaths of people receiving the drug in a follow-on study.

READ SOME MORE

[ Alzheimer Society of Ireland welcomes ‘hope’ of new groundbreaking research ]

The companies said in September that lecanemab – an antibody designed to remove sticky deposits of a protein called amyloid beta – reduced the rate of cognitive decline on a clinical dementia scale (CDR-SB) by 27 per cent compared to a placebo.

“All of these amyloid-lowering drugs carry a risk for increased brain haemorrhage,” said Dr Ronald Petersen of the Mayo Clinic in Rochester, Minnesota. “I think the primary outcomes, the secondary outcomes, the amyloid-lowering is pretty impressive.”

The Alzheimer’s Association said the data confirms the drug “can meaningfully change the course of the disease,” and called on US regulators to approve the company’s application for accelerated approval.

[ Dementia Diary: When you have Alzheimer’s disease there is no past or future, only the here and now  ]

The full data showed that some patients with a genetic risk of developing the mind-wasting disease did not benefit from lecanemab based on the CDR-SB measure.

They did, however, show improvement for the trial’s secondary goals, including other measures of cognition and daily function. Overall, lecanemab patients benefited by 23 per cent to 37 per cent compared with a placebo on these secondary trial goals

“I believe it’s an important benefit that will justify full approval. But of course, we want a bigger benefit,” said Dr Paul Aisen, director of the University of Southern California Alzheimer’s Therapeutic Research Institute and a co-author of the study published in the New England Journal of Medicine.

[  How big a factor is lifestyle in Alzheimer’s disease? ]

He said lecanemab is likely to provide greater benefit if given earlier in the disease, “before you’ve accumulated enough irreversible damage to be causing symptoms”.

Detailed data from the study were presented at the Clinical Trials on Alzheimer's disease meeting in San Francisco.

Eisai believes the trial results prove a long-standing theory that removing amyloid beta from the brains of people with early Alzheimer's can delay advance of the disease.

At 18 months, 68 per cent of trial participants treated with lecanemab had amyloid clearance, Eisai said. The drug also lowered levels of tau, a different protein that forms toxic tangles inside brain cells.

The two deaths from brain haemorrhages that were reported in the follow-on study were a 65-year-old woman who received a type of medicine known as tissue plasminogen activator to clear blood clots after suffering a stroke and an 87-year-old who was on the blood thinner Eliquis.

Eisai said it believes the deaths “cannot be attributed to lecanemab”. – Reuters