Molecular mechanism and preclinical development of BETi and PARPi combination therapy

项目总结 尽管聚(ADP-核糖)聚合酶抑制剂(PARPI)已成为治疗慢性支气管炎患者的一种有前途的药物 肿瘤、原发耐药和获得性耐药是PARPI治疗癌症的主要临床问题。几种药物 在临床前和早期临床试验中，已经设计和评估了联合策略来克服这一点 挑战。因此，在初级和获得性同源细胞中增强对PARPI反应的策略 精通重组(HR)的肿瘤将代表着癌症治疗的重大进步。溴域和 末端外结构域抑制剂(Beti)已迅速进入早期临床试验，并已显示 令人印象深刻的抗肿瘤活性。考虑到仅有Beti的临床活动可能不足以管理患者 根据最近的临床试验，需要设计Beti与其他治疗方法的组合 并进行了评估。使用将PARPI与20个特征良好的表观遗传学相结合的药物协同筛选 药物，我们确定Beti是一种在HR熟练的癌细胞中与PARPI协同作用的药物。功能性 分析表明，抑制的BET活性降低了HR，并随后增强了PARPI诱导的DNA 对癌细胞的损害。BET蛋白的化学抑制或基因耗尽会损害几个基因的转录 人力资源中的必需基因。此外，Beti治疗使临床前动物肿瘤对PARP抑制敏感 精通HR的乳腺癌和卵巢癌模型。最后，我们发现BRD4基因显著地 并在常见的成人癌症中进行焦点扩增，尽管其基因融合是一种罕见的基因组变化。 因此，我们假设Beti可能抑制HR并增强NHEJ，从而使HR熟练的癌症变得敏感 细胞对PARP的抑制作用。目的1.描述Beti协同作用的分子机制 帕尔皮。目的2.在临床前模型中评价BET和PARP抑制剂的联合治疗。目标3.定义 肿瘤微环境中对Beti和PARPI治疗的免疫反应。我们提议的研究可能 为临床应用PARPI结合Beti治疗两者提供了有力的理论依据 对PARPI治疗产生从头耐药的癌症和对获得性耐药的癌症。因此，组合 使用Beti可以极大地扩大PARP抑制对HR熟练的癌症患者的作用。

PROJECT SUMMARY Although poly (ADP-ribose) polymerase inhibitor (PARPi) has emerged as a promising drug for patients with cancer, primary and acquired resistance is a major clinical problem for PARPi in cancer treatment. Several drug combination strategies have been designed and evaluated in preclinical and early clinical trials to overcome this challenge. Therefore, strategies to enhance response to PARPi in primary and acquired homologous recombination (HR)-proficient tumors would represent a significant advance in cancer care. Bromodomains and extra-terminal domain inhibitor (BETi) has been rapidly advanced into early clinical trials and has shown impressive anti-tumor activity. Given that clinical activity of BETi alone may be insufficient to manage patients according to recent clinical trials, the combination of BETi with other treatment methods need to be designed and evaluated. Using a drug synergistic screen that combined a PARPi with 20 well-characterized epigenetic drugs, we identified BETi as a drug that acted synergistically with PARPi in HR-proficient cancer cells. Functional assays demonstrated that repressed BET activity reduces HR and subsequently enhances PARPi-induced DNA damage in cancer cells. Chemical inhibition or genetic depletion of BET proteins impairs transcription of several essential genes in HR. Moreover, BETi treatment sensitized tumors to PARP inhibition in preclinical animal models of HR-proficient breast and ovarian cancers. Finally, we showed that the BRD4 gene was significantly and focally amplified across common adult cancers, although its gene fusion was a rare genomic alteration. Thus, we hypothesize that BETi may suppress HR and enhance NHEJ, thereby sensitizing HR-proficient cancer cells to PARP inhibition. Aim 1. Characterize the molecular mechanisms by which BETi synergistically acts with PARPi. Aim 2. Evaluate the combination therapy of BET and PARP inhibitors in preclinical models. Aim 3. Define immune responses to BETi and PARPi treatment in the tumor microenvironment. Our proposed studies may provide strong rationale for clinical application of PARPi in the setting of combination with BETi to treat both cancers with de novo resistance to PARPi therapy and cancers with acquired resistance. Therefore, combination with BETi could greatly expand the utility of PARP inhibition to patients with HR-proficient cancer.