在这项研究中，我们研究了局部放疗 (RT) 和抗糖皮质激素诱导的肿瘤坏死因子受体 (GITR) 激动剂是否可以提高 PD-L1 阻断的疗效。我们分析了乳腺癌分子分类学中的乳腺癌数据集国际联盟 (METABRIC) 致力于确定 GITR 在乳腺癌中的作用。我们使用 4T1 小鼠 TNBC 模型（原发性和继发性肿瘤）来研究 PD-L1 阻断、局部 RT、抗 GITR 激动剂及其组合的疗效。我们通过肿瘤体积测量、体内生物发光成像和转移性肺结节计数来评估肿瘤生长，以评估这些治疗的效果。流式细胞术和免疫组织化学测定了肿瘤和脾脏中 CD8 T 细胞和调节性 T 细胞 (Treg) 的比例和表型。通过酶联免疫吸附测定法测量血浆细胞因子水平。在 METABRIC 队列中，编码 GITR 的 TNFRSF18 高表达的患者比低表达的患者有明显更好的生存率。与单独的 PD-L1 阻断相比，在 PD-L1 阻断中添加局部 RT 或抗 GITR 激动剂并没有显着提高疗效；然而，将两者添加到 PD-L1 阻断中可显着减少肿瘤生长和肺转移。三联疗法的好处还包括肿瘤微环境和脾脏中 CD8 T 细胞的增加和 Tregs 的减少。局部 RT 与抗 GITR 激动剂的组合显着增强了 PD-L1 阻断诱导的抗肿瘤免疫反应。这些结果为联合治疗提供了临床前依据。版权所有 © 2023 Elsevier B.V. 保留所有权利。

In this study, we investigated whether local radiotherapy (RT) and an anti-glucocorticoid-induced tumor necrosis factor receptor (GITR) agonist could increase the efficacy of PD-L1 blockade.We analyzed a breast cancer dataset from the Molecular Taxonomy of Breast Cancer International Consortium (METABRIC) to determine the role of GITR in breast cancer. We used the 4T1 murine TNBC model (primary and secondary tumors) to investigate the efficacy of PD-L1 blockade, local RT, anti-GITR agonist, and their combinations. We assessed tumor growth by tumor volume measurements, in vivo bioluminescence imaging, and metastatic lung nodule counts to evaluate the effects of these treatments. Flow cytometry and immunohistochemistry determined the proportions and phenotypes of CD8+ T-cells and regulatory T-cells (Tregs) in the tumors and spleen. Plasma cytokine levels were measured by enzyme-linked immunosorbent assay.In the METABRIC cohort, patients with high expression of TNFRSF18, which encodes GITR, had significantly better survival than those with low expression. Adding local RT or anti-GITR agonist to PD-L1 blockade did not significantly augment efficacy compared to PD-L1 blockade alone; however, adding both to PD-L1 blockade significantly reduced tumor growth and lung metastasis. The benefits of triple combination were accompanied by increased CD8+ T-cells and decreased Tregs in the tumor microenvironment and spleen.The combination of local RT and an anti-GITR agonist significantly enhanced the anti-tumor immune responses induced by PD-L1 blockade. These results provide the preclinical rationale for the combination of therapy.Copyright © 2023 Elsevier B.V. All rights reserved.