Effective combination therapy for MTAP-deficient bladder carcinoma by targeting metabolic vulnerability and modulating tumor immune microenvironment

项目概要/摘要 该项目的长期目标是确定免疫治疗抵抗的机制，并开发 转移性膀胱癌（BC）患者的有效疗法。本建议的总体目标是 为患有转移性BC的特定基因组亚群的患者建立成功的联合疗法 携带染色体上甲硫腺苷磷酸化酶（MTAP）基因的纯合缺失 9 p21区。尽管新型免疫检查点疗法（ICT），包括抗PD 1/PD-L1，提供了实质性的治疗效果， 对于转移性BC患者，缓解率通常为15%至25%。这部分是因为 这种生物学上异质的癌症在临床上仍然作为统一的疾病来治疗。因此，识别 赋予对ICT不敏感性的BC的特定基因组亚型可能提供新的机会来改善 临床反应。我们已经证实，约1/4的BC含有MTAP（MTAPdef）的纯合缺失， 9 p21区域。MTAP基因编码催化甲硫腺苷（MTA）的必需酶， 腺嘌呤合成的补救途径。肿瘤MTAPdef导致免疫和代谢 后果在免疫学上，肿瘤MTAPdef导致其底物MTA的积累，其通过以下途径起作用： 腺苷2B受体（A2 BR）抑制IFN信号传导和T细胞功能。因此，MTAPdef BC可以促进 一个“冷”的肿瘤免疫微环境（TIME）不利于ICT。在代谢上，肿瘤MTAPdef导致 缺乏补救途径腺嘌呤合成;因此，MTAPdef BC应对 抗叶酸剂（例如，培美曲塞），其有效抑制腺嘌呤从头合成。这个概念 通过将提供的临床前和临床数据证实。重要的是，我们的数据还表明培美曲塞 增加肿瘤免疫细胞浸润和PD-L1表达，因此可能使BC对ICT敏感。基于 根据这些数据，我们假设，通过靶向MTAPdef BC的代谢脆弱性， 其肿瘤免疫微环境，可以为MTAPdef BC建立有效的联合疗法。测试 基于这一假设，我们提出了两个具体的目标：（1）明确MTAPdef在BC中的免疫学后果; (2)确定专门针对MTAPdef BC的成功联合治疗。患者源性BC组织，基因 敲除和“拯救”小鼠BC模型，以及来自IRB批准的临床试验的样品将用于 实现这些目标。在完成时，我们预计将确定MTAPdef的贡献和/或相邻 基因如CDKN 2A在9 p21区域的BC时间。此外，我们将确定时间的范围 培美曲塞+/- avelumab（抗PD-L1）的调节作用与其在以下患者中的疗效相关 转移性BC。此外，我们将确定三联治疗的临床前治疗益处 与培美曲塞、抗PD-L1和A2 RB抑制剂联合应用对小鼠MTAPdef BC的影响。这些发现对于 建立新的、生物标志物指导的、高效的联合疗法， 审判这些数据可以外推到9 p21区域中含有MTAPdef的所有癌症的14%。

PROJECT SUMMARY/ABSTRACT The long-term goals of this project are to define the mechanisms of resistance to immunotherapy and to develop effective therapies for patients with metastatic bladder cancer (BC). The overall objective of this proposal is to establish successful combination therapies for patients with a specific genomic subset of metastatic BC harboring homozygous deletion of the methylthioadenosine phosphorylase (MTAP) gene from the chromosome 9p21 region. Although novel immune checkpoint therapy (ICT), including anti-PD1/PD-L1, provides substantial benefits to patients with metastatic BC, response rates are usually modest at 15% to 25%. This is partly because this biologically heterogeneous cancer is still treated clinically as a uniform disease. Therefore, identification of specific genomic subtypes of BC that confer insensitivity to ICT may provide novel opportunities to improve clinical responses. We have confirmed that ~1/4 of BC contain homozygous deletion of MTAP (MTAPdef) from the 9p21region. The MTAP gene encodes for an essential enzyme to catalyze methylthioadenosine (MTA) in the salvage pathway for adenine synthesis. Tumor MTAPdef leads to both immunologic and metabolic consequences. Immunologically, tumor MTAPdef results in accumulation of its substrate MTA, which acts through the adenosine 2B receptor (A2BR) to inhibit IFN signaling and T cell function. Therefore, MTAPdef BC may foster a “cold” tumor immune microenvironment (TIME) unfavorable to ICT. Metabolically, tumor MTAPdef results in a lack of salvage pathway adenine synthesis; thus, MTAPdef BC should be very sensitive to the cytotoxic effects of anti-folate agents (e.g., pemetrexed), which effectively inhibit de novo adenine synthesis. This concept is confirmed by pre-clinical and clinical data to be presented. Importantly, our data also indicate that pemetrexed increases tumor immune cell infiltration and PD-L1 expression and thus may sensitize BC to ICT. Based on these data, we hypothesize that, by targeting the metabolic vulnerability of MTAPdef BC and directly modulating its tumor immune microenvironment, effective combination therapies can be established for MTAPdef BC. To test this hypothesis, we proposed two Specific Aims: (1) Define the immunological consequences of MTAPdef in BC; (2) Identify successful combination therapies specifically targeting MTAPdef BC. Patient-derived BC tissues, gene knockout and “rescue” mouse BC models, and samples from an IRB-approved clinical trial will be used to address these goals. At completion, we expect to establish the contribution of MTAPdef and/or loss of adjacent genes such as CDKN2A in the 9p21 region to the BC TIME. In addition, we will determine the extent of TIME modulation by pemetrexed +/- avelumab (anti-PD-L1) in relation to their therapeutic efficacy in patients with metastatic BC. Furthermore, we will define the preclinical therapeutic benefits of triple combination treatment with pemetrexed, anti-PD-L1, and A2RB inhibitor on mouse MTAPdef BC. These findings are important for the establishment of novel, biomarker-guided, highly effective combination therapies that can be tested in clinical trials. These data could be extrapolated to 14% of all cancers containing MTAPdef in the 9p21 region.