Leqembi, or lecanemab-irmb, is Eisai's amyloid beta-directed antibody for adults with mild cognitive impairment or mild dementia due to Alzheimer's disease. The FDA converted it to traditional approval after the CLARITY AD trial showed slower clinical decline than placebo in patients with confirmed amyloid pathology.

The therapy reduces amyloid plaques that form in the brain and is offered with intravenous initiation plus later maintenance dosing options. It is a marketed disease-modifying Alzheimer's treatment rather than a sphingolipid-pathway inhibitor.