The Alliance for mRNA Medicines (AMM) submitted comments to the U.S. Food and Drug Administration on April 27, 2026, responding to FDA’s draft guidance on Considerations for the Use of the Plausible Mechanism Framework To Develop Individualized Therapies That Target Specific Genetic Conditions With Known Biological Cause (docket FDA-2026-D-1256).
In its filing, AMM applauded FDA for publishing the draft guidance and offered recommendations to help ensure the framework can be applied successfully across modalities and patient populations. The filing highlighted the role of mRNA in the recent individualized gene editing therapy for KJ Muldoon (“Baby KJ”).
AMM’s comments focus on the scope of the framework, manufacturing expectations, feasibility in small patient populations, and regulatory mechanisms for approval. On scope, AMM suggested that the guidance not be limited to genome editing and instead apply to therapies that address a specific genetic, cellular, or molecular abnormality, including modalities such as mRNA protein replacement. AMM also urged FDA to consider applying the framework to “N of 1/N of few” disorders, where platform-based development could support licensure based on data from a very small number of patients with different diseases, provided the same product modality is used to correct the underlying genetic mutation.
On manufacturing, AMM said current Chemistry, Manufacturing, and Controls expectations do not reflect the lifecycle realities of individualized medicine and urged FDA to incorporate the flexibility principles from its January 2026 statement on cell and gene therapy manufacturing. AMM also recommended that FDA clarify what constitutes “robust” natural history data, define what post marketing evidence generation is feasible for very rare disorders, and outline how approval under an NDA or BLA would be operationalized using this framework.
The filing emphasized that regulatory clarity and predictability across therapies will be essential for the framework to succeed, and called for public workshops and follow-on guidance to support transparent and predictable implementation as the framework is applied to specific technologies and case studies.
See comments here.