Targeting dual functions of PD-L1 for cancer therapy

摘要 以封闭抗体为靶向的免疫检查点信号在治疗黑色素瘤中达到了限制 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‘S与T细胞上PD-1受体的胞外相互作用及PD-L1和PD-L1的潜在适应性上调 它从细胞内室到细胞表面的循环可能会影响它们的功效。重要的是， 发现PD-L1‘S具有促进癌细胞存活和代谢的细胞内功能 还突出显示 肿瘤细胞对细胞毒治疗产生抵抗力的机制 呼吁制定新的战略来瞄准 PD-L1。 因此，迫切需要设计、测试和翻译能够 同时抑制 PD-L1‘S的胞外和胞内功能。 这项应用将利用一种新的PD-L1抗体(克隆H1a) 通过破坏PD-L1与CMTM6的结合而减少肿瘤细胞中PD-L1的表达 (一种可以稳定PD-L1循环和表达的分子)，随后引导PD-L1降解。 H1a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的相互作用，因此 去除T细胞中PD-1‘S抑制信号的同时，也扰乱了PD-L1’S细胞在肿瘤细胞内的内在功能 和髓系细胞，从而降低肿瘤对化疗的抵抗力，释放免疫刺激 髓系细胞的功能。因此，H1a抗体可能是一个很好的靶向PD-L1双重功能的候选抗体 用于癌症治疗。根据初步数据，这一建议的中心假设是细胞内信号 通过PD-L1导致肿瘤对细胞毒化疗的抵抗并限制免疫刺激功能 髓系细胞。因此，导致PD-L1降解并消除其细胞内的靶向药物 信号传递能力代表了一种新的治疗策略，它将与化疗协同作用，并改善 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H1a如何 抗体与化疗协同克服肿瘤耐药性；(2)确定H1a抗体如何 促进增强的T细胞对攻击肿瘤的反应。为了进一步评估H1a抗体未来的临床应用， 已经产生了完全人源化版本的H1a和人源化PD-1和PD-L1小鼠，这将使 评估甲型H1a病毒单独或联合化疗和探查的疗效 H1a在体内的新作用机制。拟议研究的总体影响很高，因为它将 提供一种能够靶向PD-L1双重功能的新治疗剂，从而改善 细胞毒化疗的疗效和增强的免疫反应。这一战略代表着一个重要的 在未来临床如何靶向PD-L1等免疫检查点分子方面，该领域内的范式转变 申请。

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.