Severe Persistent Urinary Retention Following Treatment With Intravenous Lecanemab.

Lecanemab is an amyloid-targeted antibody indicated for treating patients with amyloid-confirmed early Alzheimer's Disease in mild dementia or mild cognitive impairment stages. We report here a case of a subject with early stage of Alzheimer's Disease dementia, amyloid positive, who developed severe acute urinary retention following his first dose of intravenous lecanemab. His urinary retention resolved after a week but recurred following the second intravenous dose 2 weeks later. Lecanemab was discontinued, but the urinary retention has persisted for 8 months indicating possible permanent adverse impact on the bladder. The Naranjo causality probability score was 6. The incidence of urinary retention with intravenous lecanemab is not known but given that elderly patients with dementia may have multiple risks for bladder dysfunction, clinicians should remain vigilant. It is hoped that newer formulations, such as subcutaneous lecanemab, may prove safer in such patients.