Abstract
Alzheimer's disease (AD) impacts more than half a million people worldwide, with no cure available. The regulatory approval of three anti-amyloid monoclonal antibodies (mAbs), including aducanumab, lecanemab, and donanemab, has established immunotherapy as a therapeutic approach to modify disease progression. Its multifactorial pathology, which involves amyloid-β (Aβ) plaques, tau neurofibrillary tangles, neuroinflammation, and cerebrovascular dysfunction, limits the efficacy of single-target therapies. The restricted blood-brain barrier (BBB) penetration and amyloid-related imaging abnormalities (ARIA), together with small treatment effects, demonstrate the necessity for advanced biologic therapies. Protein engineering advancements have created bispecific antibodies that bind to pathological proteins (e.g., Aβ, tau) and BBB shuttle receptors to boost brain delivery and dual therapeutic effects. This review combines existing information about antibody-based therapy in AD by focusing on bispecific antibody formats and their preclinical and clinical development, as well as biomarker-based patient selection and upcoming combination strategies. The combination of rationally designed bispecific antibodies with fluid and imaging biomarkers could show potential for overcoming existing therapeutic challenges and delivering significant clinical advantages.