Ionizing radiation is known to possess immune modulatory properties. However, how radiotherapy (RT) may complement with different types of immunotherapies to boost antitumor responses is unclear. In mice implanted with EO771 syngeneic tumors, NL-201 a stable, highly potent CD25-independent agonist to interleukin (IL)-2 and IL-15 receptors with enhanced affinity for IL-2Rβγ was given with or without RT. Flow analysis and Western blot analysis was performed to determine the mechanisms involved. STING (-/-) and CD11c+ knock-out mice were implanted with EO771 tumors to confirm the essential signaling and cell types required to mediate the effects seen. Combination of RT and NL-201 to enhance systemic immunotherapy with an anti-PD-1 checkpoint inhibitor was utilized to determine tumor growth inhibition and survival, along characterization of tumor microenvironment as compared to all other treatment groups. Here, we showed that RT, synergizing with NL-201 produced enhanced antitumor immune responses in murine breast cancer models. When given together, RT and NL-201 enhanced activation of the cytosolic DNA sensor cyclic GMP-AMP synthase-stimulator of interferon genes (cGAS-STING) pathway, resulting in increased type I interferon (IFN) production in dendritic cells (DCs), and consequently greater tumor infiltration and more efficient priming of antigen-specific T cells. The immune stimulatory mechanisms triggered by NL-201 and RT resulted in superior tumor growth inhibition and survival benefit in both localized and metastatic cancers. Our results support further preclinical and clinical investigation of this novel synergism regimen in locally advanced and metastatic settings.

中文翻译：

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放射与 IL-2/IL-15 刺激协同增强先天免疫激活和抗肿瘤免疫

已知电离辐射具有免疫调节特性。然而，放疗（RT）如何与不同类型的免疫疗法互补以增强抗肿瘤反应尚不清楚。在植入 EO771 同基因肿瘤的小鼠中，在有或没有放疗的情况下给予 NL-201，这是一种稳定、高效、不依赖 CD25 的白细胞介素 (IL)-2 和 IL-15 受体激动剂，对 IL-2Rβγ 具有增强的亲和力。进行流式分析和蛋白质印迹分析以确定所涉及的机制。STING (-/-) 和 CD11c+ 敲除小鼠被植入 EO771 肿瘤，以确认介导所见效果所需的基本信号传导和细胞类型。RT 和 NL-201 联合使用抗 PD-1 检查点抑制剂增强全身免疫治疗，用于确定肿瘤生长抑制和存活，以及与所有其他治疗组相比的肿瘤微环境特征。在这里，我们发现 RT 与 NL-201 协同作用在小鼠乳腺癌模型中产生增强的抗肿瘤免疫反应。当同时给予时，RT 和 NL-201 增强了胞质 DNA 传感器环 GMP-AMP 合酶-干扰素基因刺激剂 (cGAS-STING) 途径的激活，导致树突状细胞 (DC) 中 I 型干扰素 (IFN) 的产生增加，从而实现更大的肿瘤浸润和更有效地启动抗原特异性 T 细胞。NL-201 和 RT 触发的免疫刺激机制对局部癌症和转移性癌症产生了优异的肿瘤生长抑制和生存益处。我们的结果支持在局部晚期和转移性环境中对这种新型协同疗法进行进一步的临床前和临床研究。