The Biotechnology Innovation Organization (BIO) submitted written comments supporting the FDA’s proposed “Plausible Mechanism Framework” for individualized or disease-targeted therapies when traditional large randomized trials are not feasible. BIO said the framework is a meaningful regulatory-science advance but urged the FDA to add operational clarity. BIO recommended broadening applicability beyond individualized products and making guidance modality-agnostic where appropriate. It also called for clearer definitions with references to existing FDA guidance, expanded flexibilities for chemistry, manufacturing, and controls (CMC) expectations, and more explicit instructions on using prior knowledge and platform technologies across the product lifecycle. For biotech sponsors pursuing small-population indications—particularly rare diseases—the comment letter signals how developers want the FDA’s alternative evidence pathway to translate into predictable submission requirements.