IDH-Mutant Diffuse Glioma: From Metabolic Origins to Targeted Therapy

Background/Objectives: Isocitrate Dehydrogenase (IDH)1/2-mutant diffuse gliomas represent a biologically distinct subgroup of adult brain tumors in which eary metabolic reprogramming and accumulation of the oncometabolite D-2-hydroxyglutarate (D-2HG) drive epigenetic, immunologic, and clinical characteristics, including a high burden of glioma-associated epilepsy. This review summarizes the molecular and metabolic consequences of IDH mutations, their role in glioma-associated epilepsy, and the evolving impact of mutant IDH-targeted therapies in contemporary neuro-oncology. Methods: We conducted a narrative review of key molecular, translational, imaging, and clinical studies on IDH-mutant diffuse gliomas. The literature included the 2021 (World Health Organization) WHO Classification of Tumours of the Central Nervous System, studies investigating D-2HG biology and glioma-associated epilepsy, and prospective clinical trials and real-world evidence evaluating IDH-targeted therapies and contemporary antiseizure management. Particular emphasis was placed on vorasidenib, advanced metabolic imaging, and emerging liquid biopsy approaches. Results: IDH mutations are early driver events that promote D-2HG accumulation, resulting in widespread epigenetic reprogramming, metabolic dysregulation, and an immunosuppressive tumor microenvironment. D-2HG has also been implicated in the development of glioma-associated epilepsy, although the underlying mechanisms remain incompletely understood. Advances in integrated histomolecular diagnostics, magnetic resonance spectroscopy, amino acid positron emission tomography, and cerebrospinal fluid liquid biopsy have improved disease classification and treatment monitoring. Mutant IDH inhibitors, particularly vorasidenib, prolong progression-free survival, delay the need for subsequent treatment, and reduce intratumoral D-2HG concentrations, and have shown encouraging early signals of improved seizure control and preserved health-related quality of life in patients with grade 2 IDH-mutant gliomas, although this evidence remains preliminary and requires confirmation in larger prospective studies. Conclusions: IDH-mutant diffuse gliomas exemplify precision neuro-oncology, in which a single metabolic alteration informs diagnosis, disease monitoring, and targeted therapeutic approach. Additionally, ongoing studies are expected to further define the role of IDH inhibition across different disease stages and in combination with immunotherapy and standard treatments. Lastly, future clinical trials should systematically incorporate seizure outcomes, neurocognitive function, patient-reported outcomes, and immunologic endpoints to optimize both tumor control and quality of life.