Clinical evaluation of medicines for patients with mild cognitive impairment and mild dementia due to Alzheimer's disease in Japan

Lecanemab and donanemab were approved in Japan for early Alzheimer's disease in 2023 and 2024, respectively.Drug efficacy was considered clinically meaningful after comprehensive evaluation.Biomarker evaluation, including amyloid beta (Aβ), is crucial to support the intended mechanism of action.Aβ reduction did not correlate with the suppression of clinical symptom progression in individual cases.No biomarker is validated as a surrogate, and minimal clinically important difference cannot be inferred from Aβ reduction.