The immune checkpoint blockade (ICB) immunotherapy has prolonged overall survival for cancer patients but the response rates are low. The resistance to ICB is likely due to compensatory upregulation of additional immune inhibitory molecules. In this study, we first systematically examined Tim-3 expression in immune cells in mouse tumors and found that Tim-3 was specifically up-regulated in a large number of Treg, conventional CD4+, CD8+ T cells, dendritic cell 1 (DC1), and macrophage 1 (M1) in the tumor microenvironment (TME). Interestingly, Tim-3+ T cells in the TME were phenotypically effector but not "exhausted" T cells because Tim-3+ PD-1+ CD8+ T cells had a higher number of mitochondria, greater levels of glycolysis, and higher tumor-specific cytolytic activities compared to Tim-3- PD-1- CD8+ T cells. The combination treatment with Tim-3 and PD-1 mAbs resulted in a synergistic antitumor activity but also increased the expression of Lag-3 and GITR in TIL, demonstrating cross-regulation between multiple checkpoint molecules. Furthermore, we found that the antitumor efficacy with triple combination of Tim-3, PD-1, and Lag3 mAbs was much greater than any two antibodies. Mechanistically, we demonstrated that simultaneous targeting of Tim-3, PD-1, and Lag-3 cooperatively increased the levels of granzyme B and tumor-specific cytolytic activities of CD8+ TIL. Our data indicate that multiple checkpoint molecules are coordinately upregulated to inhibit the function of hyperactivated T cells in the TME and requirement for the simultaneous blockade of PD-1, Tim-3 and Lag3 for cancer treatment.

中文翻译：

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检查点分子在肿瘤微环境中协同抑制过度活化的效应T细胞。

免疫检查点封锁（ICB）免疫疗法已延长了癌症患者的总体生存期，但反应率很低。对ICB的耐药性可能是由于其他免疫抑制分子的补偿性上调所致。在这项研究中，我们首先系统地检查了小鼠肿瘤免疫细胞中Tim-3的表达，发现Tim-3在大量Treg，常规CD4 +，CD8 + T细胞，树突状细胞1（DC1），肿瘤微环境（TME）中的巨噬细胞1（M1）。有趣的是，TME中的Tim-3 + T细胞是表型效应者，而不是“力竭” T细胞，因为Tim-3 + PD-1 + CD8 + T细胞的线粒体数量更多，糖酵解水平更高，肿瘤特异性更高。与Tim-3-PD-1-CD8 + T细胞相比，细胞溶解活性更高。Tim-3和PD-1 mAb的联合治疗产生协同的抗肿瘤活性，但同时也提高了TIL中Lag-3和GITR的表达，证明了多个检查点分子之间的交叉调节。此外，我们发现Tim-3，PD-1和Lag3 mAb的三联组合的抗肿瘤功效远大于任何两种抗体。从机制上讲，我们证明同时靶向Tim-3，PD-1和Lag-3可以协同增加颗粒酶B的水平和CD8 + TIL的肿瘤特异性细胞溶解活性。我们的数据表明，多个检查点分子被协同上调以抑制TME中超活化T细胞的功能，并要求同时阻断PD-1，Tim-3和Lag3进行癌症治疗。