Clinical Development of Therapies for Charcot-Marie-Tooth Disease: Recommendations for Trial Design, Endpoints, and Regulatory Pathways.

Charcot-Marie-Tooth disease (CMT) encompasses a heterogeneous group of inherited peripheral neuropathies. Despite being the most common genetic neurological condition, individual CMT subtypes are rare, presenting unique challenges for therapeutic development. The Together Patients Industry Clinicians versus CMT (ToPIC: CMT) Advocacy Group was formed with a diverse group of patient advocacy groups, clinician-scientists who treat patients with CMT, and pharmaceutical industry representatives to develop a common guidance on development of new treatments for CMT with clear expectations for meaningful patient outcomes and objective assessments of improvement. The ToPIC: CMT Group developed recommendations for clinical development of drugs and biological products for treating CMT, addressing trial design considerations for this rare progressive disease. Key challenges in CMT include small patient populations, variable disease progression, and the need for sensitive outcome measures. Recommendations emphasize flexible trial designs including adaptive designs, external controls, and single-participant designs when scientifically justified. Where possible, broad inclusion criteria based on clinical phenotype rather than genetic subtype alone are recommended. Disease-specific, validated outcome measures should assess function across ages and disease stages. Biomarkers reflecting peripheral nervous system health may serve as surrogate endpoints to support accelerated approval pathways. Patient and care partner perspectives are essential throughout development, particularly regarding treatment goals, risk tolerance, and meaningful endpoints. Successful therapeutic development for CMT and related neuropathies requires innovative approaches that balance rigorous scientific standards with the realities of rare disease research. Regulatory flexibility, informed by patient input and natural history data, can facilitate efficient development while maintaining assurance of safety and effectiveness.