Therapeutic strategies for targeting PARP1 in small cell lung cancer

项目摘要/摘要 虽然癌症基因组学和靶向治疗改善了部分非小细胞肺癌的预后 癌症患者(例如，EGFR突变、ALK融合)，小细胞肺癌(SCLC)的治疗 基本保持不变。大多数患者在完成一线治疗后的几个月内复发。 而且无法从现有的二线治疗中受益，因此迫切需要新的有效治疗方法。 我们先前发现，PARP1在小细胞肺癌中高水平表达，并且PARP抑制剂是活性的 在临床前模型中。基于这项工作，我们启动了针对小细胞肺癌患者的PARP抑制剂的临床试验 初步结果首次证实了小细胞肺癌患者亚群中的单药活性。基于我们的 初步数据，我们假设(1)小细胞肺癌对PARP抑制剂的敏感性由存在的 DNA修复缺陷(例如，ATM丢失)、SLFN11的过度表达以及PARP-DNA捕获的程度 (造成细胞毒性)；(2)抵抗力由代偿途径的激活(例如，G2检查点)驱动 激酶Chk1、Wee1、ATR)±下调PARP1；和(3)DNA损伤修复(DDR)抑制剂 在阻止DNA修复的同时取消G2细胞周期的治疗组合 Checkpoint可能对这种p53突变的癌症有效。我们将从以下几个方面研究这些假设 目标。在目标1中，我们将通过a)测试对PARP抑制剂的贡献来确定PARP抑制剂的敏感性机制 DDR缺陷、SLFN11和PARP捕获对PARP抑制反应的分子表征 人和GEMM来源的细胞系和PDX；b)直接检测ATM、SLFN11和其他标记 有助于应答；以及c)在II期临床试验中测试患者肿瘤的预测性生物标志物 替莫唑胺±PARP抑制剂维利帕利布和单药PARP抑制剂他唑帕利布的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)调节关键的肿瘤过程和研究对PARP抑制剂的耐药机制 用过表达和敲除方法研究PARP1在小细胞肺癌中的催化活性 体外和体内模型；b)确定PARP抑制剂耐药的机制，包括逃避PARP G2检查点激酶的捕获和激活。最后，在目标3中，我们将开发合成致命方法 通过DDR抑制剂组合通过a)确定DDR的有效性来提高PARP抑制剂的活性 使用药物的抑制剂组合(例如，PARP Chk1、PARP Wee1、PARP ATM、PARP ATR) 细胞系和小鼠模型中的基因敲除方法和b)识别基因组和蛋白质组机制 以及利用已建立的分子图谱和配对的前/后标记对DDR组合的响应 治疗侧写。我在研究小细胞肺癌和确定生物标记物方面有很高的工作效率 靶向治疗，并组建了一支在DDR生物学/靶向、转化性肺方面具有专业知识的团队 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.