Considerations for the use of the Plausible Mechanism Framework to Develop Individualized Therapies that Target Specific Genetic Conditions with Known Biological Cause; Draft Guidance for Industry

The commenter provides specific feedback on the proposed framework, advocating for the use of Activities of Daily Living (ADLs) as primary metrics and the inclusion of more diverse, impaired patient populations in trials. They also suggest clarifying guidelines for small patient populations and addressing potential inconsistencies in IRB reviews across multi-site trials.

The commenter, a family member affected by a rare genetic disease, supports the proposed Plausible Mechanism Framework because it addresses the unique needs of small populations with monogenic diseases. They specifically advocate for the inclusion of pre-symptomatic carriers in trials and request that patient and family community input be integrated into protocol design.

Chiesi USA, Inc., a pharmaceutical company specializing in rare diseases, supports the draft guidance on the Plausible Mechanism Framework. They argue for greater clarity on evidentiary expectations, the inclusion of platform-based therapeutics, and the ability to use mechanistic evidence as a substitute for natural history data in ultra-rare disease settings.

The commenter, representing researchers who have published on extracellular vesicles (EVs), supports the proposed guidance on plausible mechanism frameworks. They argue that EV-based blood assays are a critical, minimally invasive tool for characterizing drug-target interactions and monitoring treatment efficacy in individualized therapies.

The commenter, who appears to be a clinician or researcher working with rare diseases, supports the draft guidance but suggests specific improvements. They advocate for allowing multiple outcome measures in clinical trials for small populations, making autopsies the default option in consent forms, and strengthening data-sharing requirements into mandatory standards.

The commenter, an academic researcher (Jason C. Hsu), suggests that ETZ modeling with Counterfactual Uncertainty Quantification (UQ) can help address the challenges of high variability in clinical outcomes for genetic conditions like Duchenne Muscular Dystrophy. He argues that this specific statistical approach can better quantify treatment effects and reduce uncertainty compared to traditional mixed model repeated measures.

A pediatric neurologist and Director of the Center for Personalized Medicine at the University of Utah supports the Plausible Mechanism Framework, particularly for rare diseases. The commenter suggests that the FDA should consider conditional approval based on clinical outcome metrics (like mortality or hospitalizations) rather than requiring "robust" natural history data, which is often difficult to obtain.

Robert Caudill, a parent of a child with Alexander disease, supports the Plausible Mechanism Framework for developing individualized therapies for rare genetic conditions. He argues that traditional clinical trial models are impractical for ultra-rare diseases and advocates for regulatory flexibility, minimized placebo use, and clinically meaningful outcome measures.

The Cure MAPT Frontotemporal Dementia (FTD) community strongly endorses the proposed framework as it aligns with patient priorities for accelerating therapies for rare genetic conditions. They argue that the framework addresses critical needs such as mechanism-based rationales, trial flexibility for small populations, and expedited pathways for mutation-specific diseases.