The FDA unveiled draft guidance aimed at expanding access to personalized gene therapies for rare diseases with multiple mutations in the same disease gene. The proposal would allow sponsors to win initial approval for one mutation through a more traditional development path and then pursue later clearances for additional mutations using laboratory data instead of conducting a full new clinical program. Regulators said the plan would define the conditions for these staggered approvals using an “individualized feature space” included in the original application. The draft is tied to a broader FDA initiative on rare disease frameworks, intended to set clearer standards across individual conditions rather than forcing one uniform evidence package for all. Industry already sees potential fit for base-editing platforms. TD Cowen analyst Joseph Thome called the approach “plug and play” optionality, and Prime Medicine could be a key beneficiary if the framework is finalized. Company reaction underscored the significance: Prime shares rose after the draft was published, while Beam Therapeutics CEO John Evans said the concept is “completely supported by the science of base editing,” despite the guidance still being in draft form.