Assessment of YB-1 Dependent Oncolytic Adenovirus-Based Glioma-Virotherapy on Cellular Immune Responses

胶质母细胞瘤(GBM)是最常见的脑部恶性肿瘤。虽然手术切除、放射治疗和化疗可延长患者的生存期至12-15个月，但仍需要新的治疗策略。溶瘤病毒疗法是一种即将问世的癌症治疗策略。各种临床前和临床试验表明，腺病毒可以作为有效的药物用于癌症的治疗。此外，最近的报道提出了强有力的证据表明，溶瘤病毒疗法在激活抗肿瘤免疫反应方面具有重要作用。关于溶瘤腺病毒(OAV)，我们已经证明YB-1是一个有效的因子，我们已经用来开发依赖于YB-1的OAV(YB-1-OAV)，在不同的小鼠移植瘤模型中显示出肿瘤选择性复制的能力和令人信服的溶瘤特性。近年来，我们致力于优化病毒的性质，以提高其免疫原性，从而诱导出强大的抗肿瘤免疫反应。我们新开发的YB-1-OAVs促进了一种高度免疫原性的细胞死亡。这是基于Adeno-WT来源的OAV的病毒治疗策略的一个优势，该策略进化地抑制免疫反应。然而，OAV介导的细胞杀伤效应及其在体内外对免疫系统的特异性影响尚不清楚。YB-1 OAVs给了我们独特的机会来研究免疫系统在诱导强大的抗肿瘤免疫反应中的作用。因此，在计划的项目中，我们想要研究基于YB-1-OAV的病毒疗法的抗肿瘤免疫激活作用，以及在人的GBM标本和体内人源化的小鼠GBM模型中对体外治疗效果的影响。病毒/免疫联合治疗GBM，即使在免疫原性YB-1-OAVs增强后，也可能尚未充分发挥其潜力。其中一个原因是，胶质瘤已经发展出一系列策略来逃避和抑制抗肿瘤免疫反应。PD-1是一种免疫检查点受体，表达在淋巴细胞上，并被认为是包括基底膜在内的多种肿瘤中免疫抑制的介质。PD-1与其配体PD-L1结合，表达在GBM细胞上，诱导肿瘤浸润性T细胞的耗竭。阻断这种相互作用已被证明增强了对GBM的免疫反应，并与放射治疗相结合，延长了GBM荷瘤小鼠的中位生存期。因此，在第二步中，计划将YB1-OAV病毒治疗与阻断PD-1/PD-L1信号通路相结合(通过应用Nivolumab或通过基于病毒的方式直接在肿瘤微环境中感染的胶质瘤细胞中表达PD-L1中和抗体)，并分析这是否将进一步增强抗GBM病毒治疗的疗效。最终目标是通过结合肿瘤病毒治疗和免疫治疗方法来开发一种治疗复发的GBM的新方法。

Glioblastoma (GBM) is the most common malignant brain tumors. Although surgical resection, radiotherapy as well as chemotherapy prolong survival to 12-15 months, new therapeutic strategies areneeded. Oncolytic virotherapy is an upcoming therapy strategy for cancer treatment. A variety of preclinical and clinical trials have shown that adenoviruses can be used as potent agents in the treatment of cancer. In addition, recent reports have presented strong evidence for a significant role of oncolytic virotherapy in the activation of anti-tumor immune responses. With regard to oncolytic adenoviruses (OAV) we have demonstrated that YB-1 is a potent factor we have used to develop YB-1-dependent OAVs (YB-1-OAV) showing the capacity of tumor-selective replication and convincing oncolytic property in different murine xenograft tumor models. In recent years we focused on the optimization of viral properties to increase its immunogenic activity to elicit a potent antitumor immune response. Our newly developed YB-1-OAVs facilitate a highly immunogenic kind of cell death. This is an advantage to virothera-peutic strategies based on Adeno-WT-derived OAV which evolutionary inhibit immune response. However, little is known about the effect of OAV mediated cell killing and its specific effects on the immune system in vitro and in vivo. YB-1 OAVs give us the unique opportunity to investigate the role of the immune system to elicit a potent antitumor immune response. Therefore, in the planned project we want to investigate the anti-tumoral immune activation by YB-1-OAV based virotherapy and ist impact on the therapeutic efficacy in vitro in human GBM specimen and in an in vivo humanized murine GBM model. Combined viro-/immunotherapy for GBM, even after enhancement by immunogenic YB-1-OAVs, might not yet achieved its full potential. One reason is that glioma have developed an array of strategies to evade and suppress antitumor immune responses. PD-1 is an immune checkpoint receptor that is expressed on lymphocytes and has been implicated to be a mediator of immune suppression in a variety of tumors, including GBM. Binding of PD-1 to its ligand PD-L1, which is expressed on GBM cells, induces exhaustion of tumor infiltrating T cells. Blocking this interaction has been shown to enhance the immune response towards GBM and to prolongate, in combination with radiotherapy, median survival of GBM bearing mice. Therefore, in a second step it is planned to combine YB1-OAV-virotherapy with the blockade of PD-1/PD-L1 signaling (by either applying Nivolumab or by virus-based expressing of a PD-L1 neutralizing anibody directly in infected glioma cells in the tumor micromilieu, and to analyze whether this will further enhance the therapeutic effects of anti-GBM virotherapy. Final goal is the development of a novel therapy for recurrent GBM by combining oncoviro- and immunoherapeutic approaches.