On January 6, 2023, lecanemab (trade name Leqembi), an Alzheimer's disease drug developed by Eisai and Biogen, received conditional approval from the FDA. The results of its Phase 3 clinical trial showed that the drug slowed cognitive decline in Alzheimer's disease patients by 27%. The FDA has conducted a further review of the clinical trial results to determine whether the drug can be fully approved.
On July 6, 2023, the FDA announced that lecanemab had received traditional approval. This is reportedly the first Alzheimer's disease drug to target beta-amyloid and to transition from accelerated approval to traditional approval, as well as the first new Alzheimer's disease drug to receive full FDA approval in 20 years.
The FDA's decision is of special significance because health insurers have been delaying reimbursement payments for lecanemab until it receives full FDA approval for its treatment, which costs $26,500 per year.
Lecanemab was published in the New England Journal of Medicine (NEJM) on November 29, 2022. Results from a Phase III clinical trial involving nearly 1,800 patients with early-stage Alzheimer's disease showed that the drug slowed cognitive decline in Alzheimer's disease patients by 27%.
Lecanemab is a humanized IgG1 monoclonal antibody that works by binding to beta-amyloid (Aβ).
In the clinical trial, patients with early Alzheimer's disease received intravenous lecanemab or a placebo every two weeks for 18 months. Researchers used an 18-point scale to measure their cognitive performance. The results showed that lecanemab delayed the patients' deterioration by about five months. Additionally, patients who received lecanemab were 31% less likely to progress to the next stage of the disease during the study period.
However, adverse reactions in the clinical trial results sparked controversy. 7.3% of patients treated with the drug experienced brain hemorrhage (compared to 9% in the placebo control group), and 12.6% experienced brain swelling (compared to 1.7% in the placebo control group).
Alzheimer's disease experts remain divided on the impact of these changes in the drug on patients and families. Dr. Ron Petersen, a specialist at Mayo Medical Center, believes that the drug's effect is modest but clinically meaningful. Even if it only delays disease progression for a few months, it could provide Alzheimer's patients with more time to live and work independently.
Maria Carrillo, chief scientist at the Alzheimer's Association, stated that this clinical trial is important because it demonstrates that targeting amyloid with drugs can slow the progression of Alzheimer's disease. Delaying cognitive decline in the early stages of Alzheimer's disease has significant implications, allowing patients to spend more time with loved ones, enjoy family life, travel, take vacations, and fulfill their bucket lists.
Eisai stated that drugs targeting Aβ can cause side effects, including brain swelling and brain bleeding, and lecanemab is no exception. However, most patients experience mild or no symptoms.
According to published reports, three Alzheimer's disease patients died during clinical studies of the drug, two of them from strokes caused by brain hemorrhages. Eisai mentioned that the two deaths were due to other health problems while the patients were taking blood-thinning drugs, so these deaths cannot be attributed to the Alzheimer's disease drug.
Professor Robert Alexander from the University of Arizona, chairman of the FDA Peripheral and Central Nervous System Drugs Advisory Committee, commented that based on the results of clinical trials, lecanemab has side effects, but the monitorable nature of these side effects and the benefits to patients are evident.