New Alzheimer drug lecanemab brings modest benefits and high risks

Canada recently approved lecanemab to treat early Alzheimer disease, but the clinical benefits are modest, it carries a risk of serious adverse effects, and treatment is complex. An article in CMAJ (Canadian Medical Association Journal) https://www.cmaj.ca/lookup/doi/10.1503/cmaj.260193 provides an overview of the medication and advises health care professionals to engage in shared decision-making with patients and caregivers to help them understand potential risks and benefits.

"The interpretation of benefits from lecanemab may be influenced by the limited availability of therapies for and the personal and societal burdens of Alzheimer disease. Clinical benefits are modest at best, with uncertain impacts on quality of life, independence, and caregiver burden," writes Dr. Sharon Straus, a geriatrician at Unity Health Toronto and professor, University of Toronto, Toronto, Ontario, with coauthors.

Although lecanemab is approved in Canada, it is expensive - about $35 000 to $40 000 per year per patient - and it is not publicly funded. Most provinces and territories remain uncertain about whether they will cover it with health insurance.

Lecanemab treatment is resource intensive, requiring specialized diagnostics, regular intravenous doses, and frequent monitoring with MRI scans. Patients with early Alzheimer disease and confirmed amyloid in the brain are eligible, with confirmation via a PET scan or a lumbar puncture with cerebrospinal fluid analysis. Brain swelling and small brain bleeds can occur as the drug tries to clear amyloid, the protein that may build up in the brain with Alzheimer disease.

The authors recommend shared decision-making and provide a tool to help clinicians engage with patients and caregivers.

"Given the uncertain clinical benefit, risks of adverse events, and resource and financial implications, the decision to initiate lecanemab should be individualized. Some patients who place a high value on small potential delays in disease progression may choose to proceed and accept the risks, monitoring requirements, and out-of-pocket costs. In some cases, deferring treatment pending further evidence may be a reasonable approach," the authors conclude.