グエン, ナ チ 徳島大学大学院医学研究科（医学専攻）
香西, 博之 Tokushima University
Afroj, Tania Tokushima University
軒原, 浩 Tokushima University
immune checkpoint inhibitor
myeloid-derived suppressor cells
Myeloid-derived suppressor cells (MDSCs) have been known to play a pivotal role in the induction of immune tolerance, which limits the benefits of immune checkpoint inhibitors (ICIs). Recent studies revealed that several chemotherapeutic agents decreased tumor-infiltrating MDSCs. Therefore, combination therapy with cytotoxic chemotherapeutic agents and ICIs was approved for first-line treatment for lung cancer. However, the impact of chemotherapeutic agents on MDSCs and an optimal partner of ICIs has not been fully investigated in thoracic tumors, including lung cancer and malignant pleural mesothelioma. In the present study, we found that treatment with 5-FU and its oral formulation, S-1, suppressed tumor progression and inhibited the accumulation of MDSCs in thoracic tumor-bearing mice. Tumor-infiltrating T cells and dendritic cells were significantly expanded in S-1-treated mice. 5-FU suppressed the ability of tumor cells to recruit MDSCs, while it did not suppress the survival and differentiation of mouse MDSCs in vitro. We also revealed that 5-FU or S-1 significantly downregulated the expression of tumor-derived Bv8 and S100A8. The knockdown of Bv8 or S100A8 in tumor cells suppressed tumor growth and MDSC recruitment in vivo. Furthermore, in comparison with pemetrexed, administration of S-1 improved the synergistic therapeutic efficacy of anti-PD-1 antibodies with or without carboplatin. Our findings revealed a novel mechanism wherein S-1 primed a favorable tumor microenvironment to provide the rationale for combination therapy with S-1 and ICIs as the optimal therapy for thoracic cancer.
Japanese Cancer Association|John Wiley & Sons
本論文は，著者Na T. Nguyenの学位論文として提出され，学位審査・授与の対象となっている。
This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License (https://creativecommons.org/licenses/by-nc-nd/4.0/), which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made.
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