On February 23, 2026, the Food and Drug Administration (FDA) released a draft guidance entitled “Considerations for the Use of the Plausible Mechanism Framework to Develop Individualized Therapies that Target Specific Genetic Conditions with Known Biological Cause.” This guidance is designed for targeted, individualized therapies for which randomized controlled trials are not practical due to a small patient population, and was previewed by the Commissioner in several public forums. The guidance describes considerations for generating substantial evidence of effectiveness and evidence of safety for individualized therapies based on a plausible mechanism framework.