Experts have received comprehensive data showing an experimental drug can slow cognitive decline in Alzheimer’s patients, but cautioned that the improvements were comparatively small and said it was unclear what difference it might make to people’s lives.
Japanese drugmaker Eisai and its American partner Biogen announced in September that preliminary data from a trial of lecanemab found that it slowed cognitive decline by 27 percent over an 18-month period.
The companies on Tuesday provided the full results of the study on nearly 1,800 people in the early stages of the disease, the most common cause of dementia among older adults.
Every two weeks for 18 months, study participants received lecanemab intravenously or a placebo. The researchers tracked them using an 18-point scale that measures cognitive and functional ability.
Those who received lecanemab declined more slowly, a difference of less than half a point on that scale, the research team led by Christopher van Dyck at Yale University concluded.
That’s a hard change to understand, but measured in another way, lecanemab delayed worsening in patients by about five months over the course of the study, Eisai’s Dr. Michael Irizarry told The Associated Press (AP) news agency. . In addition, lecanemab recipients were 31 percent less likely to progress to the next stage of the disease during the study.
“That translates to more time in the early stages” when people function best, Irizarry said.
But doctors are divided on the difference those changes can make for patients and their families.
“Individual patients are unlikely to notice the small difference reported in this trial,” said Madhav Thambisetty of the National Institute on Aging, who told the AP he was not speaking on behalf of the government agency.
He said many researchers believe significant improvement would require at least a full point difference on that 18-point scale.
But Ron Petersen, an Alzheimer’s expert at the Mayo Clinic, said the drug’s effect was “modest, but I think it’s clinically significant,” because even a few months’ delay in progression could give someone a little more time when it is working independently. .
The trial is important because it shows that a drug that targets a sticky protein called amyloid, considered one of several Alzheimer’s culprits, can slow the progression of the disease, said Maria Carrillo, chief scientific officer for the Alzheimer’s Association.
“We all understand that this is not a cure and we are all trying to really understand what it means to delay Alzheimer’s, because this is the first time,” Carrillo said.
But any delay in early cognitive decline could be significant for “how much time we have with loved ones at a stage of the disease where we can still enjoy family and going out, vacations, bucket lists,” he said.
Drugs that target amyloid can cause side effects including swelling and bleeding in the brain, and lecanemab did too. One type of this swelling was seen in about 13 percent of the recipients. Eisai said most were mild or asymptomatic.
In addition, two deaths among lecanemab users who were also taking blood-thinning medications for other health problems were publicly reported. Eisai said Tuesday that the deaths cannot be attributed to the Alzheimer’s drug.
But Mayo’s Petersen said that if lecanemab is approved for use in the United States, he would avoid prescribing it to people taking blood thinners, at least initially.
And Thambisetty said the reports of death raise concerns about how the drug may be tolerated outside of research studies “where patients are likely to be sicker and have many other medical conditions.
Speaking to Al Jazeera on Wednesday, Bart de Strooper, director of the UK’s Dementia Research Institute, said the risk of side effects “has to be assessed on a patient-to-patient basis.”
“Most of the side effects are barely noticed by the patient, so there are some rare cases where this can be life-threatening…this needs to be investigated further,” de Strooper said.
“I wouldn’t expect a drug without side effects; I don’t think that really exists. So it’s a balance between risk and how much you want to avoid Alzheimer’s.”
The Food and Drug Administration (FDA) is considering approving lecanemab under its fast track program, with a decision expected in early January. If approved, it would be the second anti-amyloid drug on the market.
Almost all of the treatments available for people with Alzheimer’s only temporarily relieve symptoms. Scientists still don’t know exactly how Alzheimer’s forms, but one theory is that a buildup of sticky amyloid plays a key role, even though one drug after another that targets it has failed.
In a controversial move last year, the FDA approved the first amyloid-targeting drug, Biogen’s Aduhelm, despite a lack of evidence for better patient outcomes. Insurers and many doctors have been hesitant to prescribe the expensive drug, another reason experts have eagerly awaited news about how well the new lecanemab might work.
