FDA Approves Leqembi IV Maintenance Dosing

LBC83

Today, Eisai issued a press release announcing that the FDA has approved their application for a once every 4 week infusion of Leqembi IV for maintenance dosing. After the initial 18 months of once every two weeks dosing in what they now call the "initiation phase", "a transition to the maintenance dosing regimen of 10 mg/kg once every 4 weeks may be considered or the regimen of 10mg/kg once every two weeks may be continued." I take this to mean it is up to you and your Dr to decide whether to switch to once a month dosing or keep with the once every 2 week dosing schedule.

The press release notes that Eisa's application to the FDA for maintenance dosing was based on analytical modeling of observed data from the Phase 2 study with Leqembi and the long-term extension as well as the Phase 3 study and its long-term extension. "Modeling simulations prediction that transitioning to once every 4 weeks maintenance dosing after 18 months of once every two weeks treatment will maintain clinical and biomarker benefits of therapy."

The press release repeats the Eisai standard mantra about Leqembi & AD: "AD is a progressive, relentless disease caused by a continuous underlying neuro toxicprocess that begins before and continues after plaque removal. Only Leqembi works to fight AD in two ways: continuously clearing protofibrils and rapidly clearing plaque [side note: Kisunla doesn't clear protofibrils]. This is important because with continuous administration, Leqembi clears highly toxic protofibrils which can continue to cause neural injury even after the amyloid-beta plaque has been cleared from the brain."

The press release goes on to explain the importance of ongoing treatment:

Data from a previous off-treatment period in the Phase 2 core study and the long-term extension showed that a discontinuation of treatment resulted in the reaccumulation of amyloid PET and plasma CSF biomarkers, and reversion to the placebo rate of clinical decline.

For maintenance treatment, once every 4 weeks dosing regimen may be easier than once every 2weeks dosing for patients and care partners to continue treatment for early AD

Ongoing treatment can slow disease progression and prolong the benefit of therapy, with the goal of helping patients maintain who they are for longer.

Over 3 years of treatment in the Phase 3 clinical trial and the long-term extension, Leqembi reduced cognitive decline on the Clinical Dementia Rating - Sum of Boxes(CDR-SB) by -0.95 relative to a matched natural history cohort - showing clinically meaningful benefit for early AD patients. The press release notes that "A change from 0.5 to 1 on the CDR-SB score domains of Memory, Community Affairs and Home/Hobbies is the difference between slight impairment and loss of independence, such as people's ability to be left alone, remember recent events, participate in daily activities, complete household chores, function independently and engage in hobbies and intellectual interests."

https://www.eisai.com/news/2025/news202506.html