On-target off-tumor toxicity impedes the clinical application of chimeric antigen receptor-modified T cells (CAR-T cells) in the treatment of solid tumors. Previous reports proved that the combinatorial antigen recognition strategy could improve the safety profile of CAR-T cells by targeting two different tumor-associated antigens (TAAs), one as a CAR-T targeted antigen and the other as a chimeric costimulatory receptor (CCR) ligand. The programmed death-ligand 1 (PD-L1, also known as B7-H1) is preferentially overexpressed on multiple tumors, it will be highly interesting to explore the potential of PD-L1 as a universal target for designing CCR. A novel dual-targeted CAR, which is composed of first-generation CD19/HER2 CAR with CD3ζ signaling domain and PD-L1 CCR containing the CD28 costimulatory domain, was constructed and delivered into T cells by pseudotyped lentivirus. The cytokine release, cytotoxicity and proliferation of dual-targeted CAR-T cells were tested in vitro, and their safety and therapeutic efficacy were evaluated using a human tumor xenograft mouse model in vivo. The dual-targeted CAR-T cells exerted a similar cytotoxic activity against CD19/HER2+ tumor cells with or without PD-L1 in vitro, however, enhanced cytokine releases and improved proliferative capacity were only observed in the presence of both CD19/HER2 and PD-L1. Importantly, the dual-targeted CAR-T cells displayed no cytotoxicity against PD-L1+ cells alone in the absence of tumor antigen CD19/HER2. In addition, the dual-targeted CAR-T cells preferably destroyed tumor xenografts bearing both CD19/HER2 and PD-L1, but spared only antigen-positive tumor xenografts without PD-L1 in vivo. Furthermore, PD-L1 CCR also improved the antitumor efficacy of the low-affinity HER2 CAR-T cells against PD-L1+ tumors expressing high levels of HER2. Our observations demonstrated that PD-L1 could be used as a universal target antigen for designing CCR, and the dual-targeted CAR-T cells equipped with PD-L1 CCR could be used to reduce the risk of on-target off-tumor toxicity while retaining their potent antitumor efficacy in the treatment of PD-L1+ solid tumors.

中文翻译：

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PD-L1嵌合共刺激受体可提高CAR-T细胞对PD-L1阳性实体瘤的疗效，并降低体内毒性

目标上的非肿瘤毒性阻碍了嵌合抗原受体修饰的T细胞（CAR-T细胞）在实体瘤治疗中的临床应用。先前的报道证明，组合抗原识别策略可通过靶向两种不同的肿瘤相关抗原（TAA），一种作为CAR-T靶向抗原，另一种作为嵌合共刺激受体（CCR），来改善CAR-T细胞的安全性。配体。程序设计的死亡配体1（PD-L1，也称为B7-H1）优先在多种肿瘤中过表达，探索PD-L1作为设计CCR的通用靶标的潜力将非常有趣。一种新型的双靶CAR，它由具有CD3ζ信号域的第一代CD19 / HER2 CAR和包含CD28共刺激域的PD-L1 CCR组成，通过假型慢病毒将其构建并递送至T细胞。在体外测试了双重靶向CAR-T细胞的细胞因子释放，细胞毒性和增殖，并使用体内人肿瘤异种移植小鼠模型评估了它们的安全性和治疗效果。具有或不含PD-L1的双重靶向CAR-T细胞对CD19 / HER2 +肿瘤细胞具有相似的细胞毒活性，但是，只有在同时存在CD19 / HER2和PD的情况下，才能观察到细胞因子释放增强和增殖能力增强-L1。重要的是，在没有肿瘤抗原CD19 / HER2的情况下，双重靶向的CAR-T细胞对单独的PD-L1 +细胞没有细胞毒性。另外，双重靶向的CAR-T细胞最好破坏带有CD19 / HER2和PD-L1的肿瘤异种移植物，但在体内只保留了没有PD-L1的抗原阳性肿瘤异种移植物。此外，PD-L1 CCR还改善了低亲和力HER2 CAR-T细胞对表达高水平HER2的PD-L1 +肿瘤的抗肿瘤功效。我们的观察结果表明，PD-L1可用作设计CCR的通用靶标抗原，而配备PD-L1 CCR的双靶CAR-T细胞可用于降低靶标非肿瘤毒性的风险，而保留其在PD-L1 +实体瘤治疗中的有效抗肿瘤功效。