Department of Pediatric Oncology and Hematology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt - Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany.
Berlin Institute of Health, Berlin, Germany.
Mol Carcinog. 2020 Jul;59(7):724-735. doi: 10.1002/mc.23202. Epub 2020 Apr 25.
The immunosuppressive microenvironment in solid tumors is thought to form a barrier to the entry and efficacy of cell-based therapies such as chimeric antigen receptor (CAR) T cells. Combining CAR T cell therapy with checkpoint inhibitors has been demonstrated to oppose immune escape mechanisms in solid tumors and augment antitumor efficacy. We evaluated PD-1/PD-L1 signaling capacity and the impact of an inhibitor of this checkpoint axis in an in vitro system for cancer cell challenge, the coculture of L1CAM-specific CAR T cells with neuroblastoma cell lines. Fluorescence-activated cell sorting-based analyses and luciferase reporter assays were used to assess PD-1/PD-L1 expression on CAR T and tumor cells as well as CAR T cell ability to kill neuroblastoma cells. Coculturing neuroblastoma cell lines with L1CAM-CAR T cells upregulated PD-L1 expression on neuroblastoma cells, confirming adaptive immune resistance. Exposure to neuroblastoma cells also upregulated the expression of the PD-1/PD-L1 axis in CAR T cells. The checkpoint inhibitor, nivolumab, enhanced L1CAM-CAR T cell-directed killing. However, nivolumab-enhanced L1CAM-CAR T cell killing did not strictly correlate with PD-L1 expression on neuroblastoma cells. In fact, checkpoint inhibitor success relied on strong PD-1/PD-L1 axis expression in the CAR T cells, which in turn depended on costimulatory domains within the CAR construct, and more importantly, on the subset of T cells selected for CAR T cell generation. Thus, T cell subset selection for CAR T cell generation and CAR T cell prescreening for PD-1/PD-L1 expression could help determine when combination therapy with checkpoint inhibitors could improve treatment efficacy.
实体瘤中的免疫抑制微环境被认为形成了细胞疗法（如嵌合抗原受体 (CAR) T 细胞）进入和疗效的障碍。CAR T 细胞疗法与检查点抑制剂联合已被证明可以对抗实体瘤中的免疫逃逸机制并增强抗肿瘤疗效。我们在体外癌症细胞挑战系统（L1CAM 特异性 CAR T 细胞与神经母细胞瘤细胞系的共培养）中评估了 PD-1/PD-L1 信号传导能力和该检查点轴抑制剂的影响。基于荧光激活细胞分选的分析和荧光素酶报告基因检测用于评估 CAR T 和肿瘤细胞上的 PD-1/PD-L1 表达以及 CAR T 细胞杀伤神经母细胞瘤细胞的能力。将神经母细胞瘤细胞系与 L1CAM-CAR T 细胞共培养会上调神经母细胞瘤细胞上的 PD-L1 表达，证实了适应性免疫抵抗。暴露于神经母细胞瘤细胞也会上调 CAR T 细胞中 PD-1/PD-L1 轴的表达。检查点抑制剂nivolumab 增强了 L1CAM-CAR T 细胞定向杀伤。然而，nivolumab 增强的 L1CAM-CAR T 细胞杀伤与神经母细胞瘤细胞上的 PD-L1 表达并不严格相关。事实上，检查点抑制剂的成功依赖于 CAR T 细胞中 PD-1/PD-L1 轴的强烈表达，这反过来又依赖于 CAR 构建体中的共刺激结构域，更重要的是，依赖于 CAR T 细胞生成中选择的 T 细胞亚群。因此，CAR T 细胞生成的 T 细胞亚群选择和 CAR T 细胞的 PD-1/PD-L1 表达预筛选可以帮助确定何时联合检查点抑制剂治疗可以提高治疗效果。
