IMMUNOLOGICAL ANALYSIS OF THE TUMOR MICROENVIRONMENT IN GLIOBLASTOMA - PhD day 2026 oral presentation

IMMUNOLOGICAL ANALYSIS OF THE TUMOR MICROENVIRONMENT IN GLIOBLASTOMA Sara Gualdi Phd student and my tutors: Giulia Romagnoli, Irene Canini, Simona Donati, Caterina La Penta, Gabriella Rainaldi and supervisor Lucia Gabriele Department of Oncology and Molecular Medicine, Tumor Immunology Unit, National Institute of Health (Istituto Superiore di Sanità, ISS), Rome Despite advances in oncology, the standard treatment for isocitrate dehydrogenase (IDH)-wildtype glioblastoma (GB) has not changed in over fifteen years, with median survival still below fifteen months, underscoring the urgent need for novel strategies to extend survival and quality of life (QoL). GB shows extensive heterogeneity within and across patients, grows in a diffusely invasive manner resisting complete surgical removal, and recurs in nearly all cases. This aggressiveness relates to a microenvironment that reduces anti-tumour immunity, favouring tumour expansion over immune clearance. The lack of reliable biomarkers further limits clinical benefits and hinders immunotherapy strategies, which benefit only a limited number of patients. My doctoral work, within the European IPerGlio project, characterizes the immune landscape of the tumor microenvironment (TME) in GBM patients to identify patient-specific biomarkers predictive of immunotherapy response. Business Intelligence (BI) approaches integrate multidimensional datasets, including lifestyle (LE) data, and Artificial Intelligence algorithms identify clinically relevant biomarker signatures. Blood and tumor samples are collected from GB patients at Fondazione Policlinico Universitario Agostino Gemelli IRCCS following signed informed consent. Blood is processed to isolate peripheral blood mononuclear cells (PBMCs) and serum; tumor samples yield viable cells and paraffin-embedded tissue blocks. For a subset of patients, bulk RNA-seq was performed on tumor samples and a 78-plex immune Bioplex assay on serum. RNA-seq data were deconvoluted using three independent methods (EPIC, ssGSEA and GBMdeconvoluteR), consistently showing myeloid/tumour-associated macrophage predominance linked to inflammatory signaling. Patients were classified according to the molecular subtypes (classical, mesenchymal or proneural), revealing distinct cell distributions linked to stratification. The Bioplex analysis identified 30 of 78 serum analytes significantly elevated in patients versus healthy donors (FDR<0.05). As a complementary functional approach, co-cultures of patient-derived tumor cells and amplified autologous tumor-infiltrating lymphocytes (TILs) were established. Patient-derived 3D cultures investigated tumour–immune interactions directly, showing TIL homing to the tumor only in selected patients. Overall, these data represent a crucial advancement towards personalized immunotherapy, identifying patient-specific biomarkers to guide treatment selection. This project has received funding from the European Union's Horizon 2020 research and innovation programme under Grant Agreement ERAPERMED2022-245.