Combining BET protein inhibitors with radiation in HPV oropharyngeal cancer

项目摘要/摘要： 在过去的十年里，口咽癌超过了宫颈癌，成为最常见的癌症。 由人乳头瘤病毒(HPV)引起。近2万名男性被诊断为口咽癌 以及美国每年的女性人数。尽管长期生存有利，但目前无针对性 顺铂/放射治疗方案会导致严重的治疗毒性。通过以下方式降低辐射剂量 替代靶向疗法对于限制与治疗相关的毒性和改善患者状况至关重要 生活质量。为了解决这个问题，我们建议减少病毒基因的转录输出和dna损伤。 反应(DDR)，通过减少对转录共调节蛋白BRD4， 在口咽组织中表达。我们认为，第二代可以导致DDR缺陷 人乳头瘤病毒口咽部肿瘤中的溴域特异性化学抑制物。这种化学诱导的DDR缺乏 状态延迟DNA修复的动力学，从而导致基因组不稳定。肿瘤处于这种脆弱的状态， 给予最佳辐射剂量将导致基因组灾难，从而根除肿瘤。我们 确定了优先针对BRD4的溴结构域Bd1和BD2的第一代抑制剂 含有被破坏的病毒基因组的HPV肿瘤亚群的病毒和DDR基因表达降低 不受干扰的病毒基因组。然而，PAN-BD结构域的抑制可以引起多效性效应。我们 使用于2020年在HPV肿瘤细胞系上推出的第二代区域特异性抑制剂来提炼PAN- BD抑制法。我们观察到了优先的结构域特异性转录调控。而BD2域 抑制阻断的病毒肿瘤的DDR反应，BD1上调抗病毒基因的表达 未中断的病毒肿瘤。这些结果引导我们假设患者预先选择了被破坏的病毒 基因组可以匹配BD区域特异性抑制剂和降级放射治疗。我们将在 体外和体内方法，以解决a)BD结构域特异性抑制物产生DDR- 通过测量病毒基因表达和量化DDR反应动力学来检测其缺陷状态，并检测其靶向 对BRD4基因敲除和BD1和BD2区域特异性缺失的肿瘤细胞的疗效，b)优化剂量 辐射足以维持患者来源的异种移植小鼠BD结构域特异性抑制的有效性 对存活率、肿瘤体积增长、细胞凋亡、全血细胞计数进行次级终点分析的模型 毒性小组和增殖和DNA修复蛋白的免疫组织化学。

PROJECT SUMMARY/ABSTRACT: During the past decade, oropharyngeal cancer surpassed cervical cancer, becoming the most common cancer caused by human papillomavirus (HPV). Nearly 20,000 oropharyngeal cancer cases are diagnosed among men and women in the United States annually. Despite favorable long-term survival, current non-targeted cisplatin/radiation treatment protocols lead to significant treatment toxicities. De-escalating radiation doses with alternative targeted therapies would be critical for limiting treatment-related toxicities and improving patient quality of life. To address this, we propose to reduce the transcriptional output of viral genes and DNA damage response (DDR) by reducing its dependence on a transcriptional co-regulator bromodomain protein, BRD4, expressed in the oropharyngeal tissue. We propose that DDR deficiencies can be induced by second-generation bromodomain-specific chemical inhibitors in HPV oropharyngeal tumors. This chemically induced DDR deficient state delays the kinetics of DNA repair, thereby causing genomic instability. With tumors in this fragile state, administering optimal radiation doses will result in genomic catastrophe leading to eradicating tumors. We established that a first-generation inhibitor that targets both bromodomains BD1 and BD2 of BRD4 preferentially reduced viral and DDR gene expression of a subset of HPV tumors, which harbored disrupted viral genomes over non-disrupted viral genomes. However, pan-BD domain inhibition could give rise to pleiotropic effects. We used second-generation domain-specific inhibitors introduced in 2020 on HPV tumor cell lines to refine the pan- BD inhibition approach. We observed preferential domain-specific transcriptional regulation. While BD2 domain inhibition downregulated DDR response in disrupted viral tumors, BD1 upregulated anti-viral gene expression in non-disrupted viral tumors. These results guide us to postulate that patients selected upfront for disrupted viral genomes can be matched for BD domain-specific inhibitor and de-escalated radiation treatments. We will use in vitro and in vivo approaches to address a) efficacy of BD domain-specific inhibitors towards creating a DDR- deficient state by measuring viral gene expression and quantifying DDR response kinetics, and test its on-target efficacy in BRD4 knockdown and BD1 and BD2 domain-specific deleted tumor cells, b) Optimize the dose of radiation sufficiently to preserve the efficacy of BD domain-specific inhibition in patient-derived xenograft mice models with secondary endpoint analyses of survival, tumor volume growth, apoptosis, complete blood count panel for toxicity and immunohistochemistry for proliferation and DNA repair proteins.