FDA's 'plausible mechanism' route could cut review for personalized CRISPR therapies to ~3 months

The Food and Drug Administration in February 2026 proposed a new approval route for individualized therapies aimed at specific genetic mutations. (fda.gov) These are medicines built for one mutation, or even one patient, when a disease is too rare for a normal clinical trial. The FDA’s draft says sponsors can use a “plausible mechanism” framework to show why a therapy should work, alongside safety, manufacturing and limited clinical evidence. (fda.gov 1) (fda.gov 2) The agency released the draft guidance on February 23, 2026 through its biologics and drug centers, and labeled it nonbinding while it collects public comment. It says the goal is to generate “substantial evidence of effectiveness” and evidence of safety for individualized therapies targeting genetic conditions with a known biological cause. (fda.gov 1) (fda.gov 2) In plain terms, the pathway asks whether scientists understand the mutation, the disease process and the edit well enough that the treatment’s effect is biologically credible before large human datasets exist. That is a different standard from running a conventional randomized study across hundreds of patients. (fda.gov) (statnews.com) The policy was previewed in November 2025 by FDA Commissioner Marty Makary and Vinay Prasad, the agency’s chief medical and scientific officer and head of the Center for Biologics Evaluation and Research. STAT reported that the February guidance was the first detailed step turning that idea into agency policy. (biopharmadive.com) (statnews.com) The case that focused attention on this problem was KJ Muldoon, a baby treated with a personalized CRISPR therapy for severe carbamoyl phosphate synthetase 1 deficiency. A New England Journal of Medicine report described that patient-specific in vivo gene-editing treatment in May 2025. (nature.com) (nejm.org) Nature wrote on April 21, 2026 that the FDA’s approach could make personalized CRISPR therapies economically viable for far more patients with rare mutations. The same article said the framework could help move the field from isolated rescue cases toward a repeatable development model. (nature.com) The FDA added another piece on April 14, 2026, issuing draft guidance on how genome-editing developers should use next-generation sequencing to measure off-target edits and chromosome damage. The agency said that safety guidance is meant to support the individualized-therapy framework launched in February. (fda.gov) Companies are already organizing around the policy. BioPharma Dive reported in January that Aurora Therapeutics, co-founded by Jennifer Doudna and Fyodor Urnov and led by former Sarepta executive Ed Kaye, launched with $16 million in seed funding and said it plans to use the pathway for multiple rare-disease gene-editing programs. (biopharmadive.com) The debate has shifted from whether bespoke CRISPR can work at all to how much evidence, oversight and manufacturing consistency regulators should require before more patients get it. The FDA’s answer, for now, is a draft framework that tries to make one-patient medicine reviewable as a product category instead of a one-off exception. (statnews.com) (fda.gov)