PATH-61. IMMUNOHISTOCHEMICAL PHENOTYPING AND SURVIVAL ANALYSIS OF WHO GRADE II-IV GLIOMAS

Abstract

Abstract INTRODUCTION Specific genetic mutations are linked to clinical prognosis in gliomas. There has been increasing demand to understand the association between tissue biomarker expression and survival. Using patient-derived samples, WHO grade II-IV gliomas were evaluated by the protein-staining pattern of molecular markers of interest across tumor grade, and the association between their expression and survival was investigated. METHODS Tissue microarrays (TMA) containing duplicate 1 mm cores were generated from 78 gliomas (WHO grade II-IV) using an automated TMA system. Immunohistochemistry was performed per the manufactures recommendation to evaluate expression of: Wilms tumor 1 (WT1), platelet endothelial cell adhesion molecule (CD31), adhesion G protein-coupled receptor E5 (CD97), complement decay-accelerating factor (CD55), hypoxia inducible factor 1 subunit alpha (HIF1α), EGF-like module-containing mucin-like hormone receptor-like 3 (EMR3), integrin, and isocitrate dehydrogenase 1 (IDH1). Samples with moderate (+1) or intense (+2) staining to WT1, CD31, CD97, CD55, or HIF1α, or any staining to EMR3 or IDH1 mutation, were considered positive. RESULTS Of the 78 tumor samples, there were 11 (14%) WHO grade II, 22 (28%) grade III, and 45 (59%) grade IV gliomas. Across grade III gliomas, anaplastic astrocytomas had significantly higher positive WT1 (p=0.04), CD31 (p=0.002) and IDH1 wild-type (p< 0.0001) staining. High-grade (III & IV) gliomas had significantly higher positive staining for WT1 (p=0.013), CD31 (0.024), integrin (p=0.021), and IDH1 wild type (p=0.044). In all gliomas, positive staining for WT1 (p< 0.0001), CD31 (p=0.009), CD97 (p=0.024), EMR3 (p=0.036), and IDH1 wild type (p=0.0006) were associated with worse overall survival. After adjusting for patient age, positive staining for WT1 (p=0.003) was associated with worse overall survival. CONCLUSION Using immunohistochemistry, unique biomarker staining patterns were identified for WHO grade III anaplastic astrocytomas and for high-grade gliomas. Irrespective of grade, staining for WT1, CD97, CD31, EMR3, and IDH1 wild-type were associated with worse overall survival.