Characteristics of diffuse hemispheric gliomas, H3 G34-mutant in adults

• Published in: Neuro-oncology advances Vol. 3; no. 1; p. vdab061
• Main Authors: Picart, Thiébaud, Barritault, Marc, Poncet, Delphine, Berner, Lise-Prune, Izquierdo, Cristina, Tabouret, Emeline, Figarella-Branger, Dominique, Idbaïh, Ahmed, Bielle, Franck, Bourg, Véronique, Vandenbos, Fanny Burel, Moyal, Elizabeth Cohen-Jonathan, Uro-Coste, Emmanelle, Guyotat, Jacques, Honnorat, Jérôme, Gabut, Mathieu, Meyronet, David, Ducray, François
• Format: Journal Article
• Language: English
• Published: US Oxford University Press 01.01.2021; Society for NeuroOncology (SNO); the European Association of Neuro-Oncology(EANO); and Oxford University Press
• Subjects: Cancer; Clinical Investigations; Life Sciences; Neurobiology; Neurons and Cognition; PNET; diffuse hemispheric glioma; H3.3 G34R/V mutation; H3.3 K27M mutation; survival; Survival; Diffuse Hemispheric Glioma
• ISSN: 2632-2498; 2632-2498
• DOI: 10.1093/noajnl/vdab061

Abstract Background Diffuse hemispheric gliomas, H3 G34-mutant (DHG H3G34-mutant) constitute a distinct type of aggressive brain tumors. Although initially described in children, they can also affect adults. The aims of this study were to describe the characteristics of DHG H3G34-mutant in adults and to compare them to those of established types of adult WHO grade IV gliomas. Methods The characteristics of 17 adult DHG H3G34-mutant, 32 H3.3 K27M-mutant diffuse midline gliomas (DMG), 100 IDH-wildtype, and 36 IDH-mutant glioblastomas were retrospectively analyzed. Results Median age at diagnosis in adult DHG H3G34-mutant was 25 years (range: 19–33). All tumors were hemispheric. For 9 patients (56%), absent or faint contrast enhancement initially suggested another diagnosis than a high-grade glioma, and diffusion-weighted imaging seemed retrospectively more helpful to suspect an aggressive tumor than MR-spectroscopy and perfusion MRI. All cases were IDH-wildtype. Most cases were immunonegative for ATRX (93%) and Olig2 (100%) and exhibited MGMT promoter methylation (82%). The clinical and radiological presentations of adult DHG H3G34-mutant were different from those of established types of adult grade IV gliomas. Median overall survival of adult DHG H3G34-mutant was 12.4 months compared to 19.6 months (P = .56), 11.7 months (P = .45), and 50.5 months (P = .006) in H3.3 K27M-mutant DMG, IDH-wildtype, and IDH-mutant glioblastomas, respectively. Conclusions Adult DHG H3G34-mutant are associated with distinct characteristics compared to those of established types of adult WHO grade IV gliomas. This study supports considering these tumors as a new type of WHO grade IV glioma in future classifications.