Multiple Cerebral Hemorrhages in a Patient Receiving Lecanemab and Treated with t-PA for Stroke

The results of the phase 3 trial of the anti-amyloid-β drug lecanemab for the treatment of early Alzheimer's disease, reported in the Journal by van Dyck et al., 1 have suggested a beneficial effect on cognition scores and daily activities over a period of 18 months.An extension phase of the trial is ongoing.We report a case of numerous acute intracerebral hemorrhages that developed after treatment with intravenous tissue plasminogen activator (t-PA) for acute ischemic stroke syndrome in a patient who received three doses of intravenous lecanemab.A 65-year-old patient who was homozygous for the APOE ε4 allele and was in the early stages of cognitive decline presented to an emergency department 30 minutes after the acute onset of aphasia and left gaze preference due to an ischemic stroke.The patient had participated in the randomized phase of the trial of lecanemab, during which the treatment assignment is not known, followed by participation in the open-label phase, in which three intravenous lecanemab infusions were received (one infusion every 2 weeks), with the latest infusion administered 4 days before the stroke.Magnetic resonance imaging (MRI) of the head that had been performed 81 days before the stroke showed mild small-vessel disease, with no microhemorrhages, edema, or amyloid-related imaging abnormalities (Figs.sherry.