Leqembi® (lecanemab-irmb), a monoclonal antibody that binds with high affinity to amyloid-beta soluble protofibrils, was approved to treat Alzheimer's disease in patients with mild dementia; beta-amyloid pathology should be confirmed by PET or CSF measurements before therapy. It is given as an IV infusion once every 2 weeks, and periodic MRIs are required to monitor for amyloid-related imaging abnormalities (e.g. brain edema, microhemorrhages, superficial siderosis). In its pivotal trial (N=1795), average change from baseline in the CDR-SB score (scale
0 - 18, with higher being worse | average baseline score 3.2) was +1.21 in Leqembi-treated patients and +1.66 in placebo-treated patients after 18 months (p<0.001) [
PubMed abstract].
The effects of Leqembi were very modest, with a difference compared to placebo of 0.44 on an 18-point dementia scale, which equates to a 2.5% improvement. Alzheimer's is an dreadful disease with few options. Hopefully, longer-term use of Leqembi will show a greater benefit.