EPCO-40. INFRATENTORIAL NF2 MUTANT SPORADIC MENINGIOMAS DIFFER FROM THOSE IN SUPRATENTORIAL LOCATIONS AND ARE MORE BENIGN

Abstract

Abstract INTRODUCTION Approximately 50% of sporadic meningiomas, which originate throughout the neuroaxis, harbor bi-alleic NF2 loss. We sought to determine whether NF2 mutant meningiomas originating from different intracranial locations relative to the tentorium differ with regards to their genomic profile and clinical behavior. METHODS Clinical and whole exome sequencing data (WES) for all patients who underwent resection of NF2 mutant meningiomas and consented to WES were reviewed and analyzed. RESULTS 258 NF2 mutant meningiomas were included and subdivided into supra- (sNF2) versus infra-tentorial (iNF2) groups (230 versus 28, respectively). Supratentorial location was significantly associated with genomically unstable tumors (percent genome altered median 12% vs. 1%, p< 0.001) and were more likely to harbor the more aggressive feature of chromosome 1p deletion (31.4% vs. 8.3%, p= 0.036). These malignant genomic features correlated with an increased incidence of high risk clinical features, including higher-grade (i.e. WHO Grade II/III) (48.9% vs. 7.14%, p < 0.001) and elevated Ki-67 (58.9% vs. 16.6%, p< 0.01), as well as larger volume (median 26.21 cm3 vs. 9.84 cm3, p< 0.001) and edema (65.8% vs. 25.9%, p= 0.001) in sNF2 meningiomas as compared with iNF2 tumors, respectively. Not surprisingly, although there was no difference in extent of resection between the groups (gross total resection (GTR), 96.26% vs. 96.15%, p= 0.45), patients with sNF2 tumors had more associated deaths (14.6% vs. 0%, p= 0.03) and a marginally shorter overall survival (p= 0.061). GTR was associated with longer progression-free survival (p= 0.037). CONCLUSION Within the homogeneous group of somatic NF2 mutated meningiomas, infratentorial tumors are seemingly more benign in their genomic make-up and clinical manifestation as compared to ones located in the supratentorial location. While GTR is useful to both groups in preventing recurrence, this benefit may be especially important in the clinically and genomically higher risk sNF2 tumors.