Targeting dual functions of PD-L1 for cancer therapy

摘要 用阻断抗体靶向免疫检查点信号传导在治疗免疫缺陷方面已经达到了限制。 晚期癌症尽管结合程序性死亡配体1（PD-L1）的抗体在阻断PD-L1表达方面是有效的， PD-L1与T细胞上的PD-1受体的细胞外相互作用，PD-L1的潜在适应性上调和 其从细胞内区室到细胞表面的再循环可能损害它们的功效。重要的是 发现PD-L1在癌细胞中的细胞内功能，以促进其存活和代谢 还强调 肿瘤细胞可以获得对细胞毒性疗法的抗性的机制， 呼吁制定新战略， PD-L1。 因此，迫切需要设计，测试和翻译新的代理人， 同时抑制 PD-L1的细胞外和细胞内功能。 该应用将利用新的PD-L1抗体（克隆H1 A） 通过破坏PD-L1与CMTM 6的结合，降低肿瘤细胞中PD-L1的表达 （一种可以稳定PD-L1再循环和表达的分子）并随后引导PD-L1降解。 H1 A诱导的PD-L1降解不仅可能由于PD-L1的丢失而破坏PD-1/PD-L1相互作用， 去除PD-1在T细胞中的抑制信号，但也破坏了PD-L1在肿瘤细胞中的细胞内在功能 和骨髓细胞，从而降低肿瘤对化疗的抵抗力，并释放免疫刺激因子。 骨髓细胞的功能。因此，H1 A抗体可能是靶向PD-L1双重功能的良好候选物 用于癌症治疗。基于初步的数据，该提议的中心假设是细胞内信号传导 通过PD-L1导致肿瘤对细胞毒性化疗的耐药性，并限制免疫刺激功能 骨髓细胞。因此，导致PD-L1降解并消除其细胞内代谢的靶向药物 信号传导能力代表了一种新的治疗策略， 免疫反应。这一假设将通过追求两个具体目标来检验：（1）确定H1 A如何 抗体协同化疗克服肿瘤耐药性;（2）确定H1 A抗体如何与化疗协同作用， 促进增强的T细胞反应以攻击肿瘤。为了进一步评估H1 A抗体的未来临床用途， 已经产生了H1 A和人源化PD-1和PD-L1小鼠的完全人源化版本，这将允许 用于评估H1 A单独或与化疗和探索联合的治疗效果 H1 A在体内的新作用机制。拟议研究的总体影响很大，因为它将 提供一种能够靶向PD-L1双重功能的新治疗剂， 细胞毒性化疗的功效和增强的免疫应答。这一战略是一个重要的 在如何靶向免疫检查点分子如PD-L1方面，该领域内的范式转变， 应用.

Abstract Targeting immune checkpoint signaling with blocking antibodies has reached a limitation in the treatment of advanced cancers. Although antibodies that bind programmed death ligand 1 (PD-L1) are effective in blocking PD-L1's extracellular interaction with PD-1 receptor on T cells, the potential adaptive upregulation of PD-L1 and its recycling from intracellular compartment to the cell surface may compromise their efficacy. Importantly, the discovery of PD-L1's intracellular functions in cancer cells to promote thier survival and metabolism also highlight a mechanism by which tumor cells can gain resistance to cytotoxic therapy and call for a new strategy to target PD-L1. There is therefore a critical need to design, test, and translate new agents that can simultaneously inhibit PD-L1's extracellular and intracellular functions. This application will utilize a new PD-L1 antibody (clone H1A) that can reduce the expression of PD-L1 in tumor cells through disrupting the association of PD-L1 with CMTM6 (a molecule that can stabilize PD-L1 recycling and expression) and subsequently directing PD-L1 for degradation. H1A-induced degradation of PD-L1 may not only disrupt PD-1/PD-L1 interactions due to the loss of PD-L1, thus removing PD-1's suppressive signals in T cells, but also disrupt PD-L1's cell-intrinsic functions within tumor cells and myeloid cells, thereby decreasing tumor resistance to chemotherapy and releasing the immune-stimulatory function of myeloid cells. Thus, H1A antibody may be a good candidate for targeting the dual functions of PD-L1 for cancer therapy. Based on preliminary data, the central hypothesis of this proposal is that intracellular signaling through PD-L1 results in tumor resistance to cytotoxic chemotherapy and limits the immune-stimulatory function of myeloid cells. Thus, targeted agents that result in degradation of PD-L1 and elimination of its intracellular signaling ability represent a novel therapeutic strategy that will both synergize with chemotherapy and improve the immune response. This hypothesis will be tested by pursuing two specific aims: (1) Determine how H1A antibody synergizes with chemotherapy to overcome tumor resistance; (2) Determine how H1A antibody promotes an enhanced T cell response to attack tumors. To further assess the future clinical use of H1A antibody, a fully humanized version of H1A and humanized PD-1 and PD-L1 mice have been produced, which will allow for evaluation of the therapeutic effects of H1A either alone or in combination with chemotherapy and exploration of H1A's new mechanism of action in vivo. The overall impact of the proposed research is high because it will provide a new therapeutic agent that is capable of targeting the dual functions of PD-L1, resulting in improved efficacy of cytotoxic chemotherapy and an enhanced immune response. This strategy represents a significant paradigm shift within the field in terms of how to target immune checkpoint molecules like PD-L1 for future clinical applications.