CTNI-40. A MULTICENTER, RETROSPECTIVE ANALYSIS OF PROGNOSTIC FACTORS IN INTRACRANIAL H3 K27M-MUTANT DIFFUSE MIDLINE GLIOMA IN ADULTS

Abstract

Abstract H3 K27M-mutant glioma were first described as a new grade IV entity in the 2016 WHO classification. Current studies have focused on its common pediatric appearance, increasing the need to better understand this entity in adults. Here we report a multicentric, retrospective analysis of 70 diffuse midline glioma in adults. We included molecularly confirmed H3K27M-mutant glioma in patients >18 years of age between 2015-2022. Clinical-, radiological- and surgical features were analyzed. Univariate and multivariate analyses were then performed to identify prognostic factors. The study was approved by the ethics committee (PV4904). Overall, 70 patients were identified, with a mean age of 36.13 years at the initial diagnosis. Median overall survival was 13.62 + 14 months. H3K27M-mutated glioma showed a midline involvement in 61.4%. Clinically, obstructive hydrocephalus was observed in almost half of the patients (46.3%). Gross total resection (GTR) was achieved in 14.5% of all patients. 30.4% had a subtotal resection (STR), and 55.1% received a biopsy. Intraoperative cryo-section resulted in low-grade glioma in 25%, high-grade glioma in 63.9% and no tumor in 11.1%. Tumors located in telencephalon/diencephalon/myelencephalon were associated with a poorer OS, while a location site in the mesencephalon/metencephalon showed a significantly longer survival (8.3 vs. 16.2 months, p = 0.009). Preoperative Karnofsky Performance Score (KPS) below 80 showed a reduced OS (6 vs. 11.24 months, p = 0.03). Patients, who received resection (GTR/STR) showed no significant survival benefit compared with biopsied patients (9.6 vs. 8 months, p = 0.4817). The present study describes surgical features of DMG with H3K27M mutation in one of the most extensive multicentric studies to date in adult patients. Our data show that location and preoperative KPS impact OS significantly in DMG. Furthermore, in our dataset resection of K27M-mutated glioma provided no significant survival benefit compared with biopsy.