The FDA unveiled draft guidance that would allow a “plug and play” pathway for personalized gene therapies aimed at different mutations within the same disease-causing gene. Under the proposal, a company could win an initial approval for one mutation using a more traditional clinical approach, then seek subsequent clearances for additional mutations using laboratory data rather than running entirely new clinical programs. The FDA said the framework would define an “individualized feature space” in the original application, setting the boundaries for what can be supported by lab evidence for later approvals. The plan targets a core challenge in rare-disease medicine: many mutation-specific cohorts are too small for conventional trials. The agency is also tying the draft guidance to a broader “Rare Disease Framework Initiative,” which is intended to set standards across conditions rather than applying one-size-fits-all development assumptions. Prime Medicine and Beam Therapeutics were both cited as likely beneficiaries because their platforms could leverage the optionality in mutation-by-mutation development. Prime’s shares reportedly rose after the proposal, underscoring market interest in regulatory mechanisms that lower the development burden for ultra-rare subpopulations.