From Target Engagement to Treatment Governance: The Evolving Role of Amyloid PET in Anti-Amyloid Therapy.

The introduction of anti-amyloid monoclonal antibodies has shifted Alzheimer's disease care from diagnostic clarification alone to the problem of treatment governance. While lecanemab and donanemab have demonstrated amyloid reduction at the group level, routine clinical care raises a different question: how should treatment exposure be managed in individual patients within constrained healthcare systems? We suggest that amyloid positron emission tomography (PET) may support this task by providing a quantitative baseline reference for target engagement and by informing decisions on treatment continuation, switching, or discontinuation during follow-up. However, amyloid reduction on PET should not be equated with proven individual-level clinical benefit, and the potential role of longitudinal PET must be considered alongside unresolved questions regarding safety, treatment burden, feasibility, and health-system capacity. Drawing on real-world experience from a high-volume European memory clinic, we argue that amyloid PET may have an increasingly relevant role within structured anti-amyloid treatment pathways.