Dubai, United Arab Emirates (CNN) — A monoclonal antibody treatment for Alzheimer’s disease that seemed promising in a phase 3 clinical trial may have contributed to the death of one of the study participants, according to an adverse event report published by digital health platform Stat.
In a statement to CNN Friday, Esai, which makes the experimental drug lecanemab, said that to protect patient issues, it cannot provide specific information about patients or comment on information from other sources.
The stat platform reported that one of the study’s investigators told Esai about the death, and that it was caused by a brain hemorrhage. The investigator concluded that the cause of the bleeding was related to the drug, but the company pointed to other possible factors.
The company told Stat that there was a “reasonable possibility that lecanemab may have contributed” to the bleeding. And that there may be other factors related to the participant in the experiments, such as “the participant’s frequent falls, heart attacks, respiratory infections, and mini-stroke-like accidents,” according to Stat. The participant in question was also taking blood thinners due to his heart condition, according to the adverse events report that Stat reported to have reviewed. It was reported on the Stat platform that the causes of death are still under investigation.
“What Stat published is generally accurate in terms of how difficult it is to know the exact cause of a patient’s death, especially when the patient is elderly and has multiple medical problems,” Isai said in a statement.
The company explained that it has adopted a strict safety monitoring process to ensure the safety of participants, including the formation of an independent data integrity monitoring committee composed of external experts, and added that it sent safety information to investigators, regulators and participants immediately.
And the company added, that in the second phase of clinical trials, the death rate among participants who received the drug was “common” compared to those who received a placebo.
“The well-being of patients enrolled in our clinical studies has always been a top priority for Isai,” the statement also said.
Dixie Ecklund, president-elect of the Association for Clinical Trials, which is not affiliated with Eisai, and is not involved in clinical trials, acknowledged that the possibility of death is certainly in the context of testing a new drug, but believes that clinical trials are essential “because with scientific rigor, you can design trials well, get answers, and then make a difference in society.”
She also noted the importance of having an external panel to monitor data integrity in this experiment, as these boards are “very strict about scientific rigour”.
“There are a lot of checks and balances built into the US clinical trial industry between the FDA, the National Institutes of Health, and peer review, all of which may give an individual the ability to make a responsible evaluation.”
In September, Esai reported preliminary results of a trial that found the treatment slowed the progression of cognitive decline by 27% compared to a placebo.
They also met all secondary endpoints, and showed “target adherence” with lower levels of amyloid, a protein that is a hallmark of Alzheimer’s disease, and positive effects on cognition and the ability to perceive and perform daily tasks when compared with placebo.
The company said at the time that it believed that the results of the study “provide the amyloid hypothesis, in terms of the abnormal accumulation of amyloid-beta protein in the brain, one of the main causes of Alzheimer’s disease.”
Dr. Richard Isaacson, director of the Alzheimer’s Prevention Clinic in the Center for Brain Health at Florida Atlantic University’s Schmidt School of Medicine, told CNN in September that this was not evidence in itself but the trial was significant.
“In the past, lower brain amyloid levels were not always associated with cognitive improvement, or any meaningful clinical improvement. And in this study, every positive end point was the result. This is something we haven’t seen before,” he explained.
Preliminary results showed that about 2.8% of the trial participants who took the drug had a side effect called ARIA-E, or swelling in the brain, but this was not the case in those who took the placebo.
The rate of symptomatic ARIA-H, brain hemorrhage, and tissue iron accumulation was 0.7% in the drug group and 0.2% in the placebo group. Isai will present the drug trial results at the Alzheimer’s Clinical Trials Conference in late November.
Eisai, who works with Biogen, said it plans to publish the results in a journal after undergoing peer review and approval from US regulatory authorities by the end of March.