Optimierung der Immuntherapie bei Glioblastomen: Synergetische Effekte von CAR-T-Zellen und Checkpoint-Inhibitoren in einem ex vivo Glioblastom Organoid Modell

Glioblastoma (GBM) represents a challenge in neurooncology due to high malignancy and limited therapeutic options. Despite advances in multimodal therapy, the prognosis remains dismal. Immunotherapies, including checkpoint inhibitors (CPIs), have shown limited efficacy, partly due to the intricate interplay with the tumor microenvironment (TME). This study aimed to explore potential synergistic effects of Chimeric Antigen Receptor (CAR) T-cells and CPIs in an ex vivo patient-derived organoid model of GBM.

Enhanced patient-derived organoids (ePDOs) from three different GBM patients were cultured in triplicates with allogeneic peripheral blood mononuclear cells (PBMCs) for 48 hours to enhance TME characteristics. ePDOs were subjected to treatment with CPIs (either anti-PD1, anti-LAG-3, anti-TIM3 or anti-CTLA4; dosage: 10 µg/ ml), CAR T-cells (effector/target: 1/4), and a combination of both treatment approaches. We used untreated ePDOs as a control. Apoptosis of tumor-associated antigen (TAA) positive cells was quantified via immunofluorescence double staining with TAA and CC3 as an apoptosis marker after 16 hours, 24 hours, and 36 hours of co-incubation. CD4+-cell proliferation was quantified via immunofluorescence double staining with CD4 and Ki67 as a proliferation marker. For statistical analysis, one-way ANOVA was performed.

Our findings revealed significant synergistic effects of combining CTLA4-CPI with CAR T-cells, resulting in increased apoptosis rates compared to individual treatments. The most pronounced effects were observed after 36 hours, correlating with the highest apoptosis rate. Remarkably, the combination of CAR T-cells and CTLA4-CPI exhibited a significantly higher apoptosis rate compared to untreated ePDOs (p=0.0152) and CTLA4-CPI treatment only (p=0.0385). Interestingly, the combination of LAG3- and PD1-CPI with CAR T-cells induced a significantly higher proliferation of CD4+ T-cells compared to untreated ePDOs (p=0.0005 and p=0.0042), respectively.

This study highlights the potential of a synergistic combination of CAR T-cells and CPIs in the treatment of GBM, analyzing TAA apoptosis and CD4+ T-cell proliferation rates. These results emphasize the promise of this approach for enhancing immunotherapeutic outcomes in GBM patients, providing a potential path toward improving the prognosis of this devastating disease.