Esophageal adenocarcinoma (EAC) is a leading cause of cancer-related mortality. Sitravatinib is a novel multi-gene tyrosine kinase inhibitor (TKI) that targets tumor-associated macrophage (TAM) receptors, VEGF, PDGF, and c-Kit. Currently, sitravatinib is actively being studied in clinical trials across solid tumors and other TKIs have shown efficacy in combination with immune checkpoint inhibitors (ICI) in cancer models. In this study, we investigated the antitumor activity of sitravatinib alone and in combination with PD-1 blockade in an EAC rat model. Treatment response was evaluated by mortality, pre- and post-treatment MRI, gene expression, immunofluorescence and immunohistochemistry. Our results demonstrated adequate safety and significant tumor shrinkage in animals treated with sitravatinib, and more profoundly, sitravatinib and PD-1 inhibitor, AUNP-12 (P < 0.01). Suppression of TAM receptors resulted in increased gene expression of pro-inflammatory cytokines and decreased expression of anti-inflammatory cytokines, enhanced infiltration of CD8+ T cells, and M2 to M1 macrophage phenotype repolarization in the tumor microenvironment of treated animals (P < 0.01). Moreover, endpoint immunohistochemistry staining corroborated the anti-tumor activity by downregulation of Ki67 and upregulation of Caspase-3 in the treated animals. Additionally, pre-treatment gene expression of TAM receptors and PD-L1 were significantly higher in major responders compared to the non-responders, in animals that received sitravatinib and AUNP-12 (P < 0.02), confirming that TAM suppression enhances the efficacy of PD-1 blockade. In conclusion, this study proposes a promising immunomodulatory strategy using a multi-gene TKI to overcome developed resistance to an ICI in EAC, establishing rationale for future clinical development.

中文翻译：

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Sitravatinib 联合 PD1 阻断可增强食管腺癌中 M2 至 M1 肿瘤巨噬细胞复极化的细胞毒性 T 细胞浸润。

食管腺癌（EAC）是癌症相关死亡的主要原因。Sitravatinib 是一种新型多基因酪氨酸激酶抑制剂 (TKI)，靶向肿瘤相关巨噬细胞 (TAM) 受体、VEGF、PDGF 和 c-Kit。目前，sitravatinib 正在实体瘤临床试验中积极研究，其他 TKI 已在癌症模型中显示出与免疫检查点抑制剂 (ICI) 联合使用的功效。在这项研究中，我们在 EAC 大鼠模型中研究了 Sitravatinib 单独使用以及与 PD-1 阻断联合使用的抗肿瘤活性。通过死亡率、治疗前和治疗后 MRI、基因表达、免疫荧光和免疫组织化学来评估治疗反应。我们的结果表明，使用西曲替尼治疗的动物具有足够的安全性和显着的肿瘤缩小，更深入地说，西曲替尼和 PD-1 抑制剂 AUNP-12 治疗的动物具有足够的安全性和显着的肿瘤缩小（P < 0.01）。抑制 TAM 受体导致治疗动物肿瘤微环境中促炎细胞因子基因表达增加、抗炎细胞因子表达减少、CD8+ T 细胞浸润增强以及 M2 至 M1 巨噬细胞表型复极化（P < 0.01）。此外，终点免疫组织化学染色证实了治疗动物中 Ki67 下调和 Caspase-3 上调的抗肿瘤活性。此外，在接受 Sitravatinib 和 AUNP-12 的动物中，主要反应者中 TAM 受体和 PD-L1 的治疗前基因表达显着高于无反应者（P < 0.02），证实 TAM 抑制增强了 TAM 的疗效。 PD-1阻断。总之，本研究提出了一种有前途的免疫调节策略，使用多基因 TKI 来克服 EAC 中对 ICI 产生的耐药性，为未来的临床开发奠定了基础。