EPID-19. The International Low Grade Glioma Registry: Use of IDH-Inhibitors in the real-world

Abstract The International Low Grade Glioma Registry/OPTIMUM project (www.gliomaregistry.org) is a research study designed to learn about risk factors for and treatments associated with outcomes and quality of life for persons with lower grade glioma (LGG). After publication of the INDIGO trial results, increased use of IDH-inhibitors as treatment in this group of patients has been noted but little real world characterization of such use has been documented. During the May 2025 Brain Tumor Awareness month, the Registry developed a brief online Qualtrics survey for persons with LGG regarding knowledge and use of IDH-Inhibitors. The survey was broadly advertised via email to Registry participants as well as social media outlets (X, LinkedIn, Facebook, and Instagram). Two hundred and three persons responded with the following characteristics: 52% male, 61% aged between 30-49, and 53% with oligodendroglioma (37% astrocytoma). Patients received their care across the United States (and several in overseas locations). Seventy-five percent of respondents reported having an IDH1 mutation, 5% an IDH2 mutation and 20% reported not knowing if they had an IDH mutation. Of persons with IDH-mutated glioma, 39% reported being offered treatment with an IDH-inhibitor. Reasons for being offered this treatment included incomplete resection (27%), tumor growth after surgery (22%), contrast enhancement (10%), and development of symptoms such as seizure (7%). Agents offered included vorasidenib (77%) and isosidenib, amongst other combinations. Sixteen persons were offered an IDH-inhibitor but declined- these persons reported uncertainty re effectiveness (40%) and insurance coverage issues (13%). Of persons treated with an IDH-inhibitor, side effects included fatigue (47%), nausea (25%), and liver enzyme abnormalities (25%). Although limited by virtue of representing a convenience sample, these data provide a first glimpse at use of IDH-inhibitors in the general glioma population.