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非小细胞肺子集的结果 癌症患者（例如 EGFR 突变、ALK 融合），小细胞肺癌 (SCLC) 的治疗已 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受益，因此迫切需要新的有效疗法。 我们之前发现 PARP1 在 SCLC 中高水平表达，并且 PARP 抑制剂具有活性 在临床前模型中。基于这项工作，我们启动了针对 SCLC 患者和 PARP 抑制剂的临床试验 初步结果首次证实了单药在 SCLC 患者亚群中的活性。基于我们的 根据初步数据，我们假设 (1) SCLC 对 PARP 抑制剂的敏感性取决于 PARP 抑制剂的存在 DNA 修复缺陷（例如 ATM 丢失）、SLFN11 过度表达以及 PARP-DNA 捕获程度 （引起细胞毒性）； (2) 抵抗是由补偿通路（例如 G2 检查点）的激活驱动的 激酶 Chk1、Wee1、ATR) ± PARP1 下调； (3)DNA损伤修复(DDR)抑制剂 阻止 DNA 修复同时废除 G2 细胞周期的治疗组合 检查点可能对这种 p53 突变癌症有效。我们将在下面研究这些假设 目标。在目标 1 中，我们将通过以下方式确定 PARP 抑制剂的敏感性机制：a) 测试 分子表征中 DDR 缺陷、SLFN11 和 PARP 捕获对 PARP 抑制剂反应的影响 人类和 GEMM 衍生的细胞系和 PDX； b) 测试是否可以直接使用ATM、SLFN11等标记 为应对做出贡献； c) 在 II 期临床试验中测试患者肿瘤中的预测生物标志物 替莫唑胺 ± PARP 抑制剂 veliparib 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 PARP1 在 DDR 和转录中的作用 通过 a) 调节关键肿瘤过程并检查 PARP 抑制剂的耐药机制 使用过表达和敲低方法研究 PARP1 在 SCLC 中的催化活性 体外和体内模型； b) 识别 PARP 抑制剂耐药机制，包括逃离 PARP G2 检查点激酶的捕获和激活。最后，在目标 3 中，我们将开发合成致死方法 通过 DDR 抑制剂组合增强 PARP 抑制剂活性，方法是：a) 确定 DDR 的功效 使用药理和抑制剂组合（例如 PARP Chk1、PARP Wee1、PARP ATM、PARP ATR） 细胞系和小鼠模型中的敲低方法，b) 识别基因组和蛋白质组机制 以及使用已建立的分子谱和配对的前/后对 DDR 组合的反应标记 治疗概况。我在研究 SCLC 和识别生物标志物方面拥有出色的记录 靶向治疗，并组建了一支具有 DDR 生物学/靶向、转化肺专业知识的团队 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.