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

项目摘要/摘要 该项目的长期目标是确定免疫疗法的耐药机制，并开发 转移性膀胱癌(BC)患者的有效治疗。这项提议的总体目标是 为转移性BC特定基因组亚群患者建立成功的联合治疗 染色体上存在甲硫腺苷磷酸化酶(MTAP)基因的纯合子缺失 9p21区。尽管新的免疫检查点疗法(ICT)，包括抗PD1/PD-L1，提供了实质性的 对于转移性结直肠癌患者，有效率通常在15%至25%之间。这部分是因为 这种生物学上的异质性癌症在临床上仍被视为一种统一的疾病。因此，身份识别 对ICT不敏感的BC特定基因组亚型可能提供新的改进机会 临床反应。我们已经证实~1/4的BC含有MTAP(MTAPdef)的纯合缺失 9p21区域。MTAP基因编码一种催化甲硫腺苷(MTA)的关键酶。 腺嘌呤合成的挽救途径。肿瘤MTAPdef导致免疫和代谢 后果。在免疫学上，肿瘤MTAPdef会导致其底物MTA的积聚，MTA通过 腺苷2B受体(A2BR)抑制干扰素信号转导和T细胞功能。因此，MTAPdef BC可能会促进 “冷”的肿瘤免疫微环境(时间)不利于ICT。在代谢方面，肿瘤MTAPdef会导致 缺乏挽救途径的腺嘌呤合成；因此，MTAPdef BC应该对 抗叶酸剂(如培美曲塞)，可有效抑制从头合成腺嘌呤。这个概念是 经临床前和即将提交的临床数据证实。重要的是，我们的数据还表明培美曲塞 增加肿瘤免疫细胞的浸润和PD-L1的表达，从而可能使BC对ICT敏感。基于 这些数据，我们假设，通过靶向MTAPdef BC的代谢脆弱性并直接调节 其肿瘤免疫微环境，可为MTAPdef BC建立有效的联合治疗方案。为了测试 在这一假设下，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)确定针对MTAPdef BC的成功联合疗法。患者来源的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本将用于 实现这些目标。完成后，我们希望确定MTAPdef的贡献和/或相邻设备的损失 CDKN2A等基因在9p21区至BC时间。此外，我们将确定时间范围 培美曲塞+/-阿维卢单抗(抗PD-L1)对慢性粒细胞白血病患者疗效的影响 转移的卑诗省。此外，我们还将确定三联疗法的临床前治疗益处。 培美曲塞、抗PD-L1和A2RB抑制剂对小鼠MTAPdef BC的影响。这些发现对于 建立可在临床上测试的新型、生物标记物引导的高效联合疗法 审判。这些数据可以外推到所有在9p21区域含有MTAPdef的癌症中的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.