This is the first time that a drug intended to slow the progression of the disease has received full regulatory approval, as other approved drugs only target the symptoms. Leqembi, made by Japanese drugmaker Eisai and US drugmaker Biogen, targets a type of protein in the brain called beta-amyloid, which scientists have long believed to be a root cause of Alzheimer’s disease.
In a Phase 3 clinical trial of 1,795 patients with mild cognitive impairment or early-stage disease, disease progression was slowed by 27% over 18 months. Dr. Ronald Petersen, a neurologist at the Mayo Clinic in Rochester, Minnesota, said by email that a Leqembi is not a cure and does not stop the disease.
“This is the first step to hopefully more therapeutic agents in the future,” Petersen said, adding that the drug appeared to slow the decline of the patients’ condition by about five months.
The treatment “may give people in the early stages of Alzheimer’s more time to maintain their independence and do the things they love,” Joanne Pike, president and CEO of the Alzheimer’s Association, said in a statement. “This gives people several months to recognize their spouses, children and grandchildren,” Pike said.
In the Phase 3 clinical trial, researchers measured cognitive decline using a scale that focused on how well patients did in six categories: memory, orientation, judgment and problem solving, community affairs, home and hobbies, and personal care.
Serious side effects have also been experienced
According to Dr. Alberto Espay, a neurologist at the University of Cincinnati College of Medicine, a 27% slowdown in disease progression does not reach the threshold that would be “noticeable” to the patient.
“The chances of brain swelling and stroke are far greater than any actual improvement,” said Espay, who launched a petition in June demanding that the Alzheimer’s treatment not be given full approval. In the approval, the FDA attached the strongest warning label — the so-called boxed warning — about these particular side effects, noting that they can lead to seizures and death. In addition, before starting the drug, patients should undergo genetic testing to better understand the risk of such side effects.
In the study, about 12.6% of patients receiving Leqembit developed brain swelling, compared to 1.7% of patients in the placebo group. About 17% of the Leqembi group had a stroke, compared to 9% of the placebo group. The side effect is also seen with another Alzheimer’s drug, Biogen Aduhelm, which also targets amyloid in the brain. During clinical trials, three deaths were also linked to the drug.
Regarding the side effects, Ronald Petersen said that in about 75% of the patients, the brain side effects that were detected in the MRI scans did not cause symptoms. According to the recommendation of the Alzheimer’s expert roundtable, patients regularly undergo brain scans to monitor the side effects.
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