CFTR gene correction via targeted exon replacement

PROJECT SUMMARY Cystic fibrosis (CF) is a life-threatening genetic disorder that affects >120,000 individuals worldwide. Mutations in the CFTR gene cause CF, with 10% of people with CF (pwCF) having two copies of mutations that are unre- sponsive to FDA-approved CFTR modulators. Exon 12 contains the most common modulator-ineligible mutations, affecting nearly one in five pwCF who are not able to receive modulator therapies. This subpopulation of pwCF urgently needs a corrective gene editing therapy to restore CFTR function. Gene editing the endogenous CFTR presents a promising path to cure CF by correcting the pathogenic mutations. However, current approaches face significant limitations: they target only one or few mutations at a time, demonstrate low efficiency and risk unintended off-target effects. To overcome these barriers, this proposal aims to develop a new gene editing strategy that replaces the entire exon 12 without a DNA break, termed retron editing. Successful completion of the proposed aims will establish a retron editor that can safely and efficiently replace CFTR exon 12. More broadly, successful retron-mediated exon replacement will transform the lives of pwCF and those with other rare monogenic diseases.