Department of Obstetrics and Gynecology, Xijing Hospital, The Fourth Military Medical University, Xi'an, China.
Department of Spine Surgery, Honghui Hospital, Xi'an Jiaotong University, Xi'an, China.
Theranostics. 2020 Aug 25;10(23):10619-10633. doi: 10.7150/thno.44871. eCollection 2020.
Great progress has been made in the field of tumor immunotherapy in the past decade. However, the therapeutic effects of immune checkpoint blockade (ICB) against ovarian cancer are still limited. Recently, an inhibitor of cyclin-dependent kinases 4 and 6 (CDK4/6i) has been reported to enhance antitumor immunity in preclinical models. The combined use of CDK4/6i and ICB may be beneficial, but the effects of CDK4/6is on the tumor immune microenvironment and whether they can synergize with ICB in treating ovarian cancer remain unknown. In this study, we first assessed the antitumor efficacy of abemaciclib, an FDA-approved CDK4/6i, in a syngeneic murine ovarian cancer model. Then, immunohistochemistry, immunofluorescence and flow cytometry were performed to evaluate the number, proportion, and activity of tumor-infiltrating lymphocytes. Cytokine and chemokine production was detected both and by PCR array analysis and cytokine antibody arrays. The treatment efficacy of combined abemaciclib and anti-PD-1 therapy was evaluated , and CD8+ and CD4+ T cell activities were analyzed using flow cytometry. Lastly, the requirement for both CD8+ T cells and B cells in combination treatment was evaluated and potential cellular mechanisms were further analyzed by flow cytometry. We observed that abemaciclib monotherapy could enhance immune infiltration, especially CD8+ T cell and B cell infiltration, in the ID8 murine ovarian cancer model. Immunophenotyping analysis showed that abemaciclib induced a proinflammatory immune response in the tumor microenvironment. PCR array analysis suggested the presence of a Th1-polarized cytokine profile in abemaciclib-treated ID8 tumors. studies showed that abemaciclib-treated ID8 cells secreted more CXCL10 and CXCL13, thus recruiting more lymphocytes than control groups. Combination treatment achieved better tumor control than monotherapy, and the activities of CD8+ and CD4+ T cells were further enhanced when compared with monotherapy. The synergistic antitumor effects of combined abemaciclib and anti-PD-1 therapy depended on both CD8+ T cells and B cells. These findings suggest that combined treatment with CDK4/6i and anti-PD-1 antibody could improve the efficacy of anti-PD-1 therapy and hold great promise for the treatment of poorly immune-infiltrated ovarian cancer.
在过去的十年中，肿瘤免疫治疗领域取得了重大进展。然而，免疫检查点阻断（ICB）对卵巢癌的治疗效果仍然有限。最近，有报道称细胞周期蛋白依赖性激酶 4 和 6（CDK4/6i）抑制剂可在临床前模型中增强抗肿瘤免疫。CDK4/6i 与 ICB 的联合使用可能是有益的，但 CDK4/6i 对肿瘤免疫微环境的影响以及它们是否能与 ICB 协同治疗卵巢癌尚不清楚。在这项研究中，我们首先评估了 FDA 批准的 CDK4/6i 药物 abemaciclib 在同源小鼠卵巢癌模型中的抗肿瘤疗效。然后，通过免疫组织化学、免疫荧光和流式细胞术评估肿瘤浸润淋巴细胞的数量、比例和活性。通过 PCR 阵列分析和细胞因子抗体阵列检测细胞因子和趋化因子的产生。评估了 abemaciclib 联合抗 PD-1 治疗的疗效，并通过流式细胞术分析 CD8+和 CD4+T 细胞的活性。最后，通过流式细胞术评估联合治疗对 CD8+T 细胞和 B 细胞的需求，并进一步分析潜在的细胞机制。我们观察到 abemaciclib 单药治疗可增强 ID8 小鼠卵巢癌模型中的免疫浸润，特别是 CD8+T 细胞和 B 细胞浸润。免疫表型分析显示 abemaciclib 诱导肿瘤微环境中促炎免疫反应。PCR 阵列分析表明，abemaciclib 处理的 ID8 肿瘤中存在 Th1 极化细胞因子谱。研究表明，abemaciclib 处理的 ID8 细胞分泌更多的 CXCL10 和 CXCL13，从而招募比对照组更多的淋巴细胞。与单药治疗相比，联合治疗可更好地控制肿瘤，且与单药治疗相比，CD8+和 CD4+T 细胞的活性进一步增强。联合 abemaciclib 和抗 PD-1 抗体的协同抗肿瘤作用依赖于 CD8+T 细胞和 B 细胞。这些发现表明，CDK4/6i 与抗 PD-1 抗体的联合治疗可能提高抗 PD-1 治疗的疗效，为治疗免疫浸润不良的卵巢癌带来希望。
