According to the results of a clinical trial of an experimental Alzheimer's drug, the treatment slowed cognitive decline for people in the early stages of the disease but also caused some patients to experience brain swelling or brain bleeding.
The first detailed look at the effects of lecanemab was released Tuesday evening, two months after the manufacturers of the drug announced positive results.
The new information gave reason for optimism and caution.
A co-director of the University of Pennsylvania's Penn Memory Center was not involved in the research.
According to a report published in the New England Journal of Medicine, lecanemab resulted in less decline in cognitive function in patients compared to placebo. The study concluded that more trials are needed to determine the efficacy and safety of lecanemab in early Alzheimer's disease.
The field of Alzheimer's drug development has been marked by years of failures, and the companies' initial announcement sent their stock prices soaring.
It followed months of controversy over the Food and Drug Administration's decision to approve another Alzheimer's drug, Aduhelm, despite studies that did not prove the treatment worked and showed it carried significant safety risks. The expensive drug Aduhelm was removed from the market after Medicare decided to limit its coverage.
Similar to Aduhelm, lecanemab is given as an injection every two weeks and is meant to be used in patients with Alzheimer's. Years of trials of various anti-amyloid compounds have not shown that they can help patients. The gantenerumab made by Genentech failed to show any benefit to the brain.
The first time that attacking amyloid has correlation with a slower rate of cognitive decline is in the lecanemab trial. Doctors who treat Alzheimer's wondered if the effect would be noticeable to patients or their families because the rate was not dramatically slower.
Patients receiving lecanemab declined 27 percent slower after 18 months than they did before, according to a clinical trial.
A professor of neurology and Psychiatry at the University of California, San Francisco was not involved in the study. What will be a high financial cost and how do we balance that with significant safety risks are some of the questions she asked.
It is exciting that an experimental treatment targeting brain amyloid in Alzheimer's disease appears to slow cognitive decline.
The difference between lecanemab and placebo is not considered to be a clinically meaningful treatment effect.
The number of people with Alzheimer's is expected to double by the year 2020. Patients with mild cognitive impairment or early-stage Alzheimer's have higher-than-normal levels of amyloid in their brains.
Aduhelm was granted accelerated approval by the F.D.A., which means it can be given to drugs with uncertain benefit if they are for serious diseases. If the drug works, further trials are required to prove it.
If the January decision is favorable, the company will use the new data to try to get approval early next year.
Dr. Sam Gandy, director of the Mount Sinai Center for Cognitive Health, was not involved in the study.
Concerns about the safety of lecanemab have been fueled by news reports of the deaths of two patients who experienced brain swelling and brain bleeding. Anti-amyloid drugs can causeSwelling and Bleeding. Tens of thousands of patients could be excluded if lecanemab is deemed unsafe for blood thinners.
There were at least six deaths among the lecanemab patients and seven deaths among the placebo patients. There were no deaths that were related to lecanemab, according to the authors.
The deaths of the trial participants are not included in the study because they happened after the randomized portion of the trial ended. Both patients decided to take part in an open-label extension study after 18 months.
The patients who were reported by the journal had other medical problems. A 65-year-old woman died a few days after she received a standard treatment for stroke-related blood clot problems. Lecanemab weakened the woman's blood vessels and made them vulnerable to bursting when she received the blood-clotting treatment, according to a neuropathologist who conducted an autopsy at the request of the woman's husband.
A man in his 80s who was taking a blood thinner for a heart condition and had also experienced falls and ministroke-like events shortly before his death was the other case.
The deaths cannot be attributed to lecanemab, according to the statement. In the trial, the rate of deaths with major brain bleeds was 0.1 percent in the lecanemab and placebo groups.
Two deaths add to questions about lecanemab's safety issues in real world clinical practice where patients are likely to be sicker and have multiple other medical conditions.
The data on lecanemab showed that it was less likely to cause swelling and bleeding than Aduhelm was.
More than 13 percent of patients receiving lecanemab experienced brain swelling, which was mild or moderate in most cases, while less than 2 percent of patients receiving the placebo experienced such swelling. Within a few months, most brain swelling did not cause any problems. 17 percent of lecanemab patients had brain bleeding, compared with 9 percent of placebo patients. dizziness was the most common symptom.
Fourteen percent of lecanemab patients and eleven percent of placebo recipients had serious adverse events, according to the authors. More than twice as many lecanemab patients dropped out of the trial due to negative side effects as placebo recipients. More than a quarter of the lecanemab patients had adverse reactions, including flu-like symptoms, when they received the first dose. A small number of placebo patients experienced those reactions.
The study found that lecanemab patients lost cognitive function by 1.21 points and placebo patients lost cognitive function by 1.66 points.
Patients began to show slower decline several months after starting lecanemab, and the pace slowed further during the trial.
More participants of color were included in the trial than in previous Alzheimer's trials. The study said that 25 percent of those who took part in the trial in the US were black or Hispanic. People with a variety of medical conditions were able to participate.
The implications for the general population of Alzheimer's patients can be difficult to predict because patients in trials are carefully monitored.
According to Dr. Yaffe, this one seems most clearly positive and convincing, which is good news for the field.
The effect will most likely be even less for patients with more varied Alzheimer's pathology.
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