Lecanemab Approved for Alzheimer’s Treatment

January 9, 2023

The US Food and Drug Administration (FDA) has approved lecanemab, a monoclonal antibody developed by Eisai and Biogen, for the treatment of Alzheimer’s disease. Lecanemab is the second drug to receive approval for the treatment of Alzheimer’s and the first to slow cognitive decline in a clinical trial. However, the approval process has been controversial, with patient deaths and accusations that the FDA acted improperly when approving the first such drug, aducanumab, last year.

Alzheimer’s Disease

Alzheimer’s disease is a progressive neurological disorder characterized by the accumulation of amyloid beta protein in the brain, leading to the formation of amyloid plaques and neurofibrillary tangles. These abnormalities cause damage and death to brain cells, leading to memory loss, cognitive decline, and behavioral changes. There is currently no cure for Alzheimer’s, and treatment options are limited to therapies that aim to slow the progression of the disease and improve symptoms.

Lecanemab

Lecanemab is a monoclonal antibody that targets amyloid beta protein. By binding to and neutralizing this protein, lecanemab aims to reduce the formation of amyloid plaques and neurofibrillary tangles in the brain. In a clinical trial involving 1,800 patients with early-stage Alzheimer’s, lecanemab slowed cognitive decline by 27% over 18 months of treatment. The drug is administered intravenously and is intended to be used in the early stages of Alzheimer’s to allow individuals to “have more time to participate in daily life and live independently,” according to Joanne Pike, President and CEO of the Alzheimer’s Association in Washington DC.

Approval Process

Lecanemab received approval through the FDA’s “accelerated approval” pathway, which is reserved for therapies for diseases with few treatment options and does not require phase III clinical trial data. However, lecanemab was granted approval on the basis of phase II data, rather than the more comprehensive phase III data, which were published in November 2021. The phase III data showed that lecanemab slowed cognitive decline by 27% in a clinical trial involving 1,800 patients with early-stage Alzheimer’s. The phase II data showed that lecanemab reduced plaques in the brains of 856 patients, but did not assess the effect on cognitive abilities.

Controversy

The approval of lecanemab has been controversial, with some questioning the decision to grant approval on the basis of phase II data and concerns about patient deaths. Three patients enrolled in the lecanemab phase III trial died during the extended phase of the trial, when patients receiving placebo can ask to be given the drug. The deaths were attributed to complications involving brain bleeding and seizures, and researchers suspect that the antibody may have weakened blood vessels in the brain as it attacked amyloid plaques. All of the patients were taking anticoagulant drugs at the time of their deaths, and the FDA has stated that lecanemab should not be used in patients taking these medications.

Additionally, the approval process for lecanemab has been compared to that of aducanumab, the first Alzheimer’s treatment to receive FDA approval. Both drugs were granted approval through the accelerated approval pathway on the basis of phase II data, and there have been accusations that the FDA acted improperly in approving aducanumab.

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