Targeting the IDH1 $^{R132H}$ mutation in gliomas by CRISPR/Cas precision base editing

BACKGROUND: Gliomas, the most frequent malignant primary brain tumors, lack curative treatments. Understanding glioma-specific molecular alterations is crucial to develop novel therapies. Among them, the biological consequences of the isocitrate dehydrogenase 1 gene mutation (IDH1 $^{R132H}$) remain inconclusive despite its early occurrence and widespread expression. METHODS: We thus employed CRISPR/Cas adenine base editors, which allow precise base pair alterations with minimal undesirable effects, to correct the IDH1 $^{R132H}$ mutation. RESULTS: Successful correction of the IDH1 $^{R132H}$ mutation in primary patient-derived cell models led to reduced IDH1 $^{R132H}$ protein levels and decreased production of 2-hydroxyglutarate, but increased proliferation. A dual adeno-associated virus split intein system was used to successfully deliver the base editor in vitro and in vivo. CONCLUSIONS: Taken together, our study provides a strategy for a precise genetic intervention to target the IDH1 $^{R132H}$ mutation, enabling the development of accurate models to study its impact on glioma biology and serving as a framework for an in vivo gene therapy.