Clinical Meaningfulness in Alzheimer's Disease Clinical Trials. A Report from the EU-US CTAD Task Force.

Recent positive results of three phase III anti-amyloid monoclonal antibody trials are transforming the landscape of disease-modifying therapeutics for Alzheimer's disease, following several decades of failures. Indeed, all three trials have met their primary endpoints. However, the absolute size of the benefit measured in these trials has generated a debate on whether the change scores observed on clinical outcome assessments represent a clinically meaningful benefit to patients. An evidence-based conclusion is urgently required to inform decision-making related to the approval, reimbursement, and ultimately, the management of emerging therapies in clinical practice. The EU-US CTAD Task Force met in Boston to address this important question. The current state-of-the-art knowledge for interpreting clinical meaningfulness of AD clinical trial results, including the point of view of patients and study partners on what is clinically meaningful, was discussed and is summarized here. A combination of methodologies to address the challenges emerged. There remain gaps in the understanding of clinical meaningfulness that only long-term longitudinal studies will be able to address.