Immunomodulatory Effects of Targeting DNA Repair with Novel Temozolomide Combinations in Colorectal Cancer

摘要 DNA修复在几乎所有癌症类型的发病机制中发挥着重要作用，并识别 异常DNA修复通路已经确定了靶向治疗的预测性和预后生物标志物。为 例如，O6-甲基鸟嘌呤DNA甲基转移酶(MGMT)启动子的表观遗传超甲基化 预测多种癌症的患者存活率更高，对替莫唑胺(TMZ)的敏感性增加， 包括结直肠癌(CRC)。TMZ是一种单功能烷化剂，TMZ对DNA的损伤是 主要由MGMT修复，而MGMT由启动子超甲基化沉默。碱基切除修复(BER) 途径也是修复TMZ DNA损伤的关键途径。临床前，同时抑制 息肉ADP核糖聚合酶(PARP)抑制剂的BER进一步增加MGMT缺陷肿瘤对TMZ的敏感性。 然而，我们的初步发现揭示了另一种平行的机制：TMZ损伤导致急性 复制应激和叉状塌陷导致共济失调毛细血管扩张症和Rad3相关(ATR)依赖 检查点激酶1(Chk1)的磷酸化。我们利用了这些发现，并在体内进行了额外的 实验，通过两项由研究人员发起的临床试验，将新的TMZ组合推向临床 MGMT使CRC沉默：1)TMZ+olaparib(PARP抑制剂)和TMZ+AZD 6738(ATR抑制剂)。注册将 在耶鲁·斯米洛癌症医院继续前进，未来有机会通过我们的 中国铁建抗癌(SU2C)梦之队。此外，我们的目标是开发新的生物标志物分析方法。 包括评估MGMT异质性的生物标记物，以确定对TMZ联合最敏感的肿瘤， 并进行基因组图谱分析。利用DNA损伤还代表了一种潜在的工具，可以刺激 免疫反应，并通过辅助研究和使用从我们的试验获得的样本，我们将研究 TMZ联合用药对免疫微环境的影响为增加免疫治疗提供支持 在未来。我是一名内科肿瘤学家，专注于晚期胃肠道(GI)癌症的治疗 重点是结直肠癌的创新疗法。这个奖项将促进我作为一名医生的发展- 有能力设计和实施由研究人员发起的早期临床试验的科学家 有关DNA修复和免疫疗法的临床前证据。我的训练将包括授课课程 肿瘤免疫学，临床试验实施的实践经验，生物标记物的正式指导 技巧。为了实现这些目标，我组建了一个由我的主要负责人领导的多学科指导团队 导师，Patricia LoRusso博士，她有成功指导初级教员和 在研究人员发起的临床试验方面拥有丰富的专业知识。在这个奖项结束时，我将获得 临床研究基础的宝贵技能，特别是临床试验设计， 以及DNA修复和免疫学的生物标记物识别。这个奖项将有助于确立我作为一名 为结直肠癌和其他胃肠道癌症进行早期临床试验的独立调查者。

ABSTRACT DNA repair plays an important role in the pathogenesis of virtually all cancer types, and the identification of aberrant DNA repair pathways has identified predictive and prognostic biomarkers to targeted therapies. For example, epigenetic hypermethylation of the promoter of O6-methylguanine DNA methyltransferase (MGMT) predicts for better patient survival and increased sensitivity to temozolomide (TMZ) in multiple cancers, including colorectal cancer (CRC). TMZ is a monofunctional alkylator, and the DNA damage caused by TMZ is principally repaired by MGMT, which is silenced by promoter hypermethylation. The base excision repair (BER) pathway also serves as a critical pathway to repair TMZ DNA damage. Preclinically, the simultaneous inhibition of BER with polyp ADP ribose polymerase (PARP) inhibitors further sensitizes MGMT deficient tumors to TMZ. However, our preliminary findings reveal an alternative and parallel mechanism: TMZ damage causes acute replication stress and fork collapse leading to Ataxia Telangiectasia and Rad3 related (ATR) dependent phosphorylation of Checkpoint Kinase 1 (Chk1). We have leveraged these findings, and additional in vivo experiments, to advance novel TMZ combinations into the clinic with two investigator-initiated clinical trials for MGMT silenced CRC: 1) TMZ + olaparib (PARP inhibitor) and TMZ + AZD 6738 (ATR inhibitor). Enrollment will proceed at Yale Smilow Cancer Hospital with future opportunities expand to collaborating sites through our CRC Stand up to Cancer (SU2C) Dream Team. Furthermore, we aim to develop new biomarker assays including a biomarker assessing MGMT heterogeneity to identify tumors most sensitive to TMZ combinations, and perform genomic profiling. Leveraging DNA damage additionally represents a potential tool to stimulate an immune response, and through ancillary studies and using specimens obtained from our trials we will study the effects TMZ combinations on the immune microenvironment to lend support to the addition of immunotherapy in the future. I am a medical oncologist focusing on the treatment of advanced gastrointestinal (GI) cancers with an emphasis on innovative therapies for CRC. This award will facilitate my development as a physician- scientist equipped to design and conduct investigator-initiated early phase clinical trials based on innovative preclinical evidence regarding DNA repair and immunotherapies. My training will include didactic coursework for tumor immunology, practical experience of clinical trial implementation, and formal instruction in biomarker techniques. To achieve these goals, I have assembled a multidisciplinary mentorship team led by my primary mentor, Dr. Patricia LoRusso who has a proven track record of successfully mentoring junior faculty and extensive expertise in investigator-initiated clinical trials. At the conclusion of this award, I will have gained valuable skills into the underpinnings of clinical research generically, and specifically for clinical trial design, and biomarker identification for DNA repair and immunology. This award will help establish me as an independent investigator conducting early phase clinical trials for CRC and other GI cancers.