P16.13 MenImmune: Evaluation of immune-related and prognostic biomarkers in meningioma

Abstract

Abstract BACKGROUND Meningiomas are the most common group of adult central nervous system primary tumor. The major known predictors for meningioma recurrence are extent of surgical resection and histological grade. Although grading system is the actual standard for risk classification, there are several exceptions in the clinical behavior. Recent studies have shown that meningiomas can express PD-L1, a known therapeutic target for checkpoint inhibitors. Tumor microenvironment and hormonal setting are known to influence the immune system response. The only standard therapeutic strategies nowadays are surgery and radiotherapy. Meningiomas microenvironment needs to be further studied looking for new therapeutic targets. New prognostic tools combining histological and radiological features (RF) are needed to better address the treatment strategy. ELIGIBILITY CRITERIA Patients diagnosed with meningioma who underwent surgery at the Department of Neurosurgery of the IRCCS Ospedale Policlinico San Martino of Genoa from 1998. - Availability of magnetic resonance imaging (MRI) at diagnosis. - Availability of histological samples. OBJECTIVES Identification and prevalence of immune-related biomarkers and their correlation with morphological and hormonal features. - Survival analyses in the study population and according to the different characteristics analyzed. - The identification of specific clinical, histological and RF of meningiomas and their inclusion in a prognostic signature. STUDY DESIGN This is a retrospective-prospective monocentric study designed to analyze clinical, radiological and histological features of meningioma patients. - Clinical data will be collected from the electronic patient records. - Analyses will be conducted on a cohort of patients enriched with higher grade meningioma to balance the proportion between high and low grade histologies. - Histological specimen will be blindly reviewed and reclassified according to histological type, morphological features and WHO 2016 criteria. - The MRI features will be analyzed at diagnosis. STUDY ANALYSIS We retrospectively enrolled 50 patients with available radiological, histological and clinical data.- All histopathological specimens will be examined with slides obtained from material fixed in 10% neutral buffered formalin, included in kerosene, sectioned at 3 µm and stained with hematoxylin-eosin. - We will look for the presence of estrogens and progesterone receptors. - Concerning immune-related biomarkers we will further assess PD-L1 positivity (cut-off: positive 1%, negative <1%), MSI status and the inflammatory infiltrate with immunohistochemistry, in particular TILs (CD45, CD3, CD4, CD8, FOXP3, CTLA4), B cell (CD20), TAM (CD68). - All histological and radiological data will be analyzed and correlated with the clinical characteristics of meningioma patients and their outcomes.