WASHINGTON, July 14 — For the millions of American families watching a loved one slowly lose their memories, the arrival of lecanemab has felt like the first real glimmer of something the field has never had: a treatment that actually slows the disease, not just manages its symptoms. The drug, developed by the Japanese pharmaceutical company Eisai in partnership with Biogen, targets the sticky amyloid beta plaques that build up in the brains of people with Alzheimer’s.
In plain terms, it’s trying to address one of the root causes of the disease, rather than just papering over the effects. The evidence comes from a Phase 3 clinical trial called Clarity AD, which enrolled 1,795 participants with early-stage Alzheimer’s across multiple countries.
Results published in the New England Journal of Medicine in November 2022 showed that lecanemab reduced cognitive decline by 27% over 18 months compared to a placebo. That was measured using a standard tool called the Clinical Dementia Rating-Sum of Boxes, or CDR-SB. Here’s what that 27% figure means in practical terms: patients on the drug declined more slowly than those who got the placebo.
It’s not a cure — no one is claiming that — but it’s the first time any therapy has demonstrated a statistically significant slowing of cognitive decline in a late-stage trial. That’s a big deal for a field that has seen more failures than successes.
The U.S. Food and Drug Administration granted lecanemab accelerated approval in January 2023 under the brand name Leqembi, with a decision on traditional approval expected in July 2023.
Side effects and costs
No drug comes without trade-offs. The most common side effects included infusion-related reactions and a condition called amyloid-related imaging abnormalities, or ARIA. That occurred in about 12.5% of treated patients.
ARIA involves temporary swelling or small bleeds in the brain, visible on MRI scans, and it’s something doctors monitor closely during treatment. The annual list price was set at $26,500.
That pricing figure has been a point of discussion, especially given the controversy that surrounded Biogen’s earlier Alzheimer’s drug, aducanumab, which received FDA approval in 2021 amid significant scrutiny over its efficacy and cost. Lecanemab enters a landscape shaped by that debate.
The bigger picture
Alzheimer’s disease is a progressive neurodegenerative disorder affecting an estimated 6.5 million Americans aged 65 and older, according to the Alzheimer’s Association. That number is only expected to grow as the population ages. The practical upshot of lecanemab’s arrival is that for the first time, patients diagnosed early enough have a treatment option that might buy them meaningful extra time at a higher functional level.
The drug is not a simple pill — it’s administered as an intravenous infusion, which means patients need to visit a clinic regularly. That logistical reality is something families and healthcare systems are still working through.
What to watch next: the FDA’s decision on traditional approval, expected this month, and how Medicare and insurers handle coverage. Those decisions will determine how many of those 6.5 million Americans actually get access to the drug. Consult your doctor for medical advice.
