The FDA proposed a faster 'plausible mechanism' framework aimed at accelerating personalized genomic and ultrarare disease drug development by accepting mechanistic evidence in lieu of large trials. The draft seeks to clarify evidentiary pathways for highly individualized therapies but leaves open questions about global alignment and post‑market requirements. That regulatory shift came as senators and patient advocates publicly criticized FDA consistency in rare‑disease reviews during a congressional hearing, citing cases where companies and clinicians say the agency reversed prior suggestions. The combined pressure on policy and oversight suggests regulators will face intensified scrutiny while sponsors reassess global development strategies.