Exploiting CTLA-4, PD-1 and PD-L1 to reactivate the host immune response against cancer

The past few years have witnessed something of a renaissance in the field of cancer immunotherapy, relating largely to the clinical advances that have been associated with the development of monoclonal antibodies targeting the immune inhibitory co-receptors CTLA-4 and PD-1 and to the pursuit of genetically modified antigen-redirected adoptive T-cell therapies. These advances are based on a more substantial understanding of the factors restricting effective immune therapies that has been derived from the study of pre-clinical models of tumour growth in immune competent mice. Just as the recognition of the importance of positive co-stimulatory signaling has been instrumental to recent advances in the development of genetically modified antigen-specific adoptive cellular therapies, an increasing awareness of the ability of tumours to subvert multiple immune inhibitory pathways, effectively blunting the development or expansion of any anti-tumour immunity, is fostering the development of novel therapies that appear active as monotherapies but may achieve their greatest impact in combinatorial regimens. This mini-review will focus on attempts to target co-inhibitory members of the immunoglobulin superfamily.     

PD-1/PD-L1抑制剂联合治疗在癌症免疫治疗中的研究进展

程序性死亡蛋白-1(programmed cell death-1,PD-1)是一种免疫检查点的负性调控因子,通过与其配体PD-L1/PD-L2结合,抑制T细胞的免疫功能,而PD-1抑制剂则可恢复免疫系统的抗肿瘤作用。较其他治疗手段而言,PD-1抑制剂有显著的临床疗效,然而其仍然存在不足,即目前仍有很大一部分癌症患者对PD-1抑制剂治疗是无效的。研究表明联合治疗可改善PD-1抑制剂单药治疗的有效率。联合治疗包括联合免疫检查点抑制剂、放疗、化疗、癌症疫苗和其他癌症治疗方法。FDA已批准了PD-1抑制剂联合CTLA-4阻断剂治疗,其抗肿瘤效率与肿瘤微环境以及免疫相关因子有关,但关于免疫系统,特别是T细胞对肿瘤阳性响应率的潜在作用机制研究甚少。本文将综述免疫检查点PD-1抑制剂的临床疗效以及其影响因素、作用机制以及PD-1抑制剂联合其他治疗的研究现状。     

Intratumoral CD8+ T cells with a tissue-resident memory phenotype mediate local immunity and immune checkpoint responses in breast cancer

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基于靶点人源化小鼠的PD-1/CTLA-4双特异性抗体及其IgG1亚型的抗癌活性评价

目的：构建基于靶点人源化小鼠的程序性死亡受体-1(PD-1)/细胞毒性T淋巴细胞抗原-4(CTLA-4)双特异性抗体（BsAb）并对BsAb及其IgG1亚型进行抗癌活性评价和探讨其潜在的作用机制。方法：构建和扩增并纯化不同结构及抗体亚型的PD-1/CTLA-4抗体BsAb1、BsAb2和BsAb3,对纯化BsAb进行靶点亲和力检测,采用荧光素酶报告基因实验和FCM检测抗体的生物学活性。基于B-hPD-1-hPD-L1-h CTLA-4人源化小鼠的MC38-hPD-L1结肠癌细胞移植瘤模型对BsAb进行体内药效评估,并通过移植瘤组织中肿瘤浸润淋巴细胞（TIL）分析PD-1/CTLA-4抗体的作用机制。结果：成功制备的BsAb1、BsAb2及BsAb3对靶点PD-1和CTLA-4均有较强的特异性亲和力、对靶点通路均有不同程度的阻滞活性,均明显抑制移植瘤的生长（P<0.05或P<0.01）。IgG1亚型BsAb体内药效更优（P<0.01）,TIL分析发现BsAb2-IgG1明显增加了CTL百分率（P<0.05）,显著降低了肿瘤浸润Treg细胞百分率（P<0.01...     

LAG-3 及其抑制剂在肿瘤免疫治疗中应用的研究进展

[摘要] 淋巴细胞活化基因3（lymphocyte-activation gene 3,LAG-3）又称CD223,是一种由LAG-3 基因编码的含有498 个氨基酸的I 型穿膜蛋白,由胞外区、穿膜区和胞内区三部分组成。LAG-3 主要通过胞外区与配体结合,负向调控T淋巴细胞,避免T细胞过度激活引发自身免疫。与程序性死亡蛋白-1（programmed cell death 1,PD-1）和细胞毒性T淋巴细胞抗原4（cytotoxic T lymphocyte antigen 4,CTLA-4）一样,LAG-3 是体内重要的免疫检查点,对人体免疫系统起到平衡调控作用。肿瘤细胞通过高表达LAG-3 配体逃避机体免疫系统的监视。随着免疫检查点的研究逐渐深入,LAG-3 成为继PD-1 和CTLA-4 之后新一代的免疫治疗靶点。本文主要对LAG-3的结构、功能及其抑制剂在肿瘤免疫治疗中的应用进行综述,以期为LAG-3 的进一步研究提供参考。     

Assessment of the expression of the immune checkpoint molecules PD-1, CTLA4, TIM-3 and LAG-3 across different cancers in relation to treatment response,tumor-infiltrating immune cells and survival

Immune checkpoint molecules have been identified as crucial regulators of the immune response, which motivated the emergence of immune checkpoint-targeting therapeutic strategies. However, the prognostic significance of the immune checkpoint molecules PD-1, CTLA4, TIM-3 and LAG-3 remains controversial. The aim of our study was to conduct a systematic assessment of the expression of these immune checkpoint molecules across different cancers in relation to treatment response, tumor-infiltrating immune cells and survival. Oncomine and PrognoScan database analyses were used to investigate the expression levels and prognostic values of these immune checkpoint molecule genes across various cancers. Then, we used Kaplan–Meier plotter to validate the associations between the checkpoint molecules and cancer survival identified in the PrognoScan analysis. TIMER analysis was used to evaluate immune cell infiltration data from The Cancer Genome Atlas. Finally, we used Gene Expression Profiling Interactive Analysis to investigate the prognostic value of these four checkpoint molecules and assess the correlations between these four checkpoint molecules and genetic markers. These immune checkpoint molecules may potentially serve as prognostic factors and therapeutic targets in breast cancer, ovarian cancer and lung cancer. The prognostic roles of these checkpoint molecules varied greatly across cancers, which implied a noteworthy amount of heterogeneity among tumors, even within the same molecular subtype. In addition, the expression patterns of these checkpoint molecules were closely associated with treatment response and provided some useful direction when choosing chemotherapeutic drugs. These findings enhance our understanding of these checkpoints in cancer treatment and identify strategies to promote synergistic activities in the context of other immunotherapies.     

Remodeling of the immune and stromal cell compartment by PD-1 blockade in mismatch repair-deficient colorectal cancer

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