Irinotecan Modulates Immune Checkpoints in Neuroblastoma

Background:Neuroblastoma (NBL) is the most common extracranial solid tumor in children, with a 50% survival rate in high-risk cases. Chemotherapy combination with immunotherapy is central to HR-NBL treatment. Aim:This study aimed to explore how Irinotecan influences the immune landscape of NBL cells, particularly focusing on the modulation of immune checkpoints relevant to future chemo-immunotherapy strategies. Methods:Two neuroblastoma cell lines, SK-N-BE(2) and SH-SY5Y, were exposed to sub-lethal doses of Irinotecan and IFN-γ. Flow cytometry assessed the expression of immune markers, including GD2, CD47, MHC I, and PD-L1. We also examined phagocytosis by macrophages and T-cell-mediated killing. In vivo studies using a neuroblastoma mouse model assessed the effects of Irinotecan and PBMC injections. Soluble CD47 was also measured in cell culture supernatants and exploratory patient plasma samples. Results:Treatment exposure was associated with modulation of several immune-related markers, including GD2, CD47, PD-L1, and MHC class I. While Irinotecan reduced macrophage-mediated phagocytosis, this effect was reversed by the addition of anti-CD47 antibodies. T-cell-mediated killing was enhanced when NBL cells were pre-treated with Irinotecan. In vivo studies showed that the combination of PBMCs and Irinotecan resulted in reduced tumor burden compared to either treatment alone. Furthermore, CD47 expression was detectable in-patient plasma, suggesting that soluble CD47 may warrant exploration in larger future cohorts. Conclusion:This pilot study suggests that irinotecan may modulate key immune checkpoints in neuroblastoma. These results supports further investigation of rational chemo-immunotherapy combinations, including GD2 and CD47-targeted combination strategies.