EXTH-83. BIRC3 AS A PREDICTOR OF OUTCOME AND A NEW THERAPEUTIC TARGET IN TMZ RESISTANT GLIOBLASTOMA TUMORS

Abstract

Abstract Glioblastoma (GBM) is an incurable malignant brain tumor, with a highly unfavorable prognosis. Apart from MGMT promoter methylation and TMZ response, molecular biomarkers associated with therapeutic response or survival prognosis are still lacking in GBM. Previously, using NAD(P)H-fluorescence lifetime imaging, a new drug screening precision medicine ex-vivo approach, we perturbed patients-derived vital GBM tumor explants (GB-EXPs) by TMZ treatment and obtained a stratification in TMZ responder (Res) and non-responder (Non-Resp) tumors, identifying several genes differentially expressed between the two groups. To validate the approach we enlarged our glioblastoma case study. Transcriptome analysis was performed to characterize TMZ Res and Non-Resp cases. In-silico and functional cellular investigations were carried on to explore the biomarker's efficiency. The majority of the genes found dysregulated in the previous study, showed the same directional regulation of expression and we confirmed, in TMZ-resistant samples the statistically significant upregulation of BIRC3, a strong inhibitor of apoptosis. The TCGA dataset provided an opportunity to fully assess the BIRC3 mRNA expression complementarity with the MGMT status as a predictor of outcome. BIRC3 was validated as a prognostic factor of survival also in large French and Italian glioblastoma cohorts. Most importantly, AZD5582 drug, which is a specific antagonist of BIRC3, combined with TMZ treatment, is able to reverse the TMZ resistance, in glioblastoma cell lines, by restoring apoptosis, and in GB-EXPs that were resistant to TMZ treatment. BIRC3 represents a potential biomarker of prognosis and a predictor of TMZ treatment response in GBM and complements MGMT status as an outcome predictor. The level of BIRC3 expression could stratify patients who will benefit from AZD5582 or its combination with TMZ. Our study provides a potentially new treatment approach and valuable leads to determine whether functional precision medicine combined with BIRC3 expression assessment become a standard tool in glioblastoma clinical oncology.