Therapeutic strategies for targeting PARP1 in small cell lung cancer

项目概要/摘要 虽然癌症基因组学和靶向治疗改善了一部分非小细胞肺癌患者的预后， 癌症患者（例如，EGFR突变，ALK融合），小细胞肺癌（SCLC）的治疗具有 基本保持不变。大多数患者在完成一线治疗后数月内复发 并且不能从现有的二线治疗中获益，因此迫切需要新的有效疗法。 我们先前发现PARP 1在SCLC中高水平表达，并且PARP抑制剂是活性的， 在临床前模型中。基于这项工作，我们启动了针对SCLC患者的PARP抑制剂的临床试验， 初步结果首次证实了单药在小细胞肺癌患者中的活性。基于我们 根据初步数据，我们假设（1）SCLC对PARP抑制剂的敏感性取决于 DNA修复缺陷（例如，ATM丢失）、SLFN 11过表达和PARP-DNA捕获程度 （引起细胞毒性）;（2）抗性由代偿途径的激活驱动（例如，G2关卡 激酶Chk 1、Wee 1、ATR）± PARP 1下调;和（3）DNA损伤修复（DDR）抑制剂 阻止DNA修复同时消除G2细胞周期的治疗组合 检查点可能对这种p53突变的癌症有效。我们将在下文中研究这些假设 目标。在目标1中，我们将通过以下方式确定对PARP抑制剂敏感性的机制：a）测试以下物质的贡献： DDR缺陷、SLFN 11和PARP捕获对PARP抑制剂反应的分子特征 人和GEMM衍生的细胞系和PDX; B）测试ATM、SLFN 11和其它标志物是否直接 有助于响应;和c）测试来自II期临床试验的患者的肿瘤中的预测性生物标志物 替莫唑胺± PARP抑制剂维利帕尼的I期研究和单药PARP抑制剂talazoparib的I期研究 并与临床结果相关。在目标2中，我们将研究PARP 1在DDR和转录调控中的作用。 调节关键的肿瘤学过程并检查对PARP抑制剂的抗性机制， 使用过表达和敲低方法研究PARP 1在SCLC中的催化活性， 体外和体内模型; B）鉴定PARP抑制剂抗性的机制，包括从PARP逃逸 捕获和激活G2检查点激酶。最后，在目标3中，我们将开发合成致命方法， 通过DDR抑制剂组合增强PARP抑制剂活性， 抑制剂组合（例如，PARP+Chk1、PARP+Wee1、PARP+ATM、PARP+ATR）， 在细胞系和小鼠模型中的敲低方法和B）鉴定基因组和蛋白质组学机制 以及使用已建立的分子谱和配对的前/后- 治疗概况。我在研究小细胞肺癌和确定生物标志物方面有着良好的记录。 靶向治疗，并组建了一支在DDR生物学/靶向、转化肺 癌症研究、生物信息学、遗传小鼠模型和肺癌病理学。

Project summary/abstract While cancer genomics and targeted therapies have improved outcomes for a subset of non-small cell lung cancer patients (e.g., EGFR mutations, ALK fusions), the treatment for small cell lung cancer (SCLC) has remained largely unchanged. The majority of patients relapse within months of completing frontline treatment and do not benefit from available second-line treatment, so there is an urgent need for new effective therapies. We previously discovered that PARP1 is expressed at high levels in SCLC and that PARP inhibitors are active in preclinical models. Based on this work, we initiated clinical trials of PARP inhibitors for SCLC patients and preliminary results confirm--for the first time--single-agent activity in a subset of SCLC patients. Based on our preliminary data, we hypothesize that (1) sensitivity to PARP inhibitors in SCLC is determined by the presence of DNA repair deficiencies (e.g., ATM loss), overexpression of SLFN11, and the degree of PARP-DNA trapping (causing cytotoxicity); (2) resistance is driven by activation of compensatory pathways (e.g., the G2 checkpoint kinases Chk1, Wee1, ATR) ± downregulation of PARP1; and (3) DNA damage repair (DDR) inhibitor therapeutic combinations which prevent DNA repair while simultaneously abrogating the G2 cell cycle checkpoint may be effective in this p53-mutated cancer. We will investigate these hypotheses in the following aims. In Aim 1, we will determine mechanisms of sensitivity to PARP inhibitors by a) testing the contribution of DDR deficiencies, SLFN11, and PARP trapping to PARP inhibitor response in molecularly characterized human and GEMM-derived cell lines and PDXs; b) testing whether ATM, SLFN11, and other markers directly contribute to response; and c) testing predictive biomarkers in tumors from patients on a Phase II clinical trial of temozolomide ± the PARP inhibitor veliparib and a Phase I study of single-agent PARP inhibitor talazoparib and correlate with clinical outcomes. In Aim 2, we will investigate the role of PARP1 in DDR and transcriptional regulation of key oncologic processes and examine mechanisms of resistance to PARP inhibitors by a) investigating the catalytic activity of PARP1 in SCLC using overexpression and knockdown approaches in in vitro and in vivo models; b) identifying mechanisms of PARP inhibitor resistance, including escape from PARP trapping and activation of G2 checkpoint kinases. Finally, in Aim 3, we will develop synthetic lethal approaches to enhance PARP inhibitor activity through DDR inhibitor combinations by a) determining efficacy of DDR inhibitor combinations (e.g., PARP+Chk1, PARP+Wee1, PARP+ATM, PARP+ATR) using pharmacologic and knockdown approaches in cell lines and mouse models and b) identifying genomic and proteomic mechanisms and markers of response to DDR combinations using established molecular profiles and paired pre/post- treatment profiling. I have a track record of productivity in studying SCLC and identifying biomarkers for targeted therapy and have assembled a team with expertise in DDR biology/ targeting, translational lung cancer research, bioinformatics, genetic mouse models, and lung cancer pathology.