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起着重要作用， 异常的DNA修复途径已经确定了靶向治疗的预测和预后生物标志物。为 例如，O 6-甲基鸟嘌呤DNA甲基转移酶（MGMT）启动子的表观遗传超甲基化 预测更好的患者生存率和增加敏感性替莫唑胺（TMZ）在多种癌症， 包括结肠直肠癌（CRC）。TMZ是一种单官能的烷基化剂，由TMZ引起的DNA损伤是 主要由MGMT修复，MGMT被启动子超甲基化沉默。碱基切除修复（BER） 这一途径也是修复TMZ DNA损伤的关键途径。临床前，同时抑制 BER与聚腺苷二磷酸核糖聚合酶（PARP）抑制剂的联合应用进一步使MGMT缺陷型肿瘤对TMZ敏感。 然而，我们的初步研究结果揭示了一种替代和平行的机制：TMZ损伤引起急性 复制应激和分叉塌陷导致共济失调毛细血管扩张和Rad 3相关（ATR）依赖 检查点激酶1（Chk 1）的磷酸化。我们利用这些发现，并在体内进行了额外的研究。 实验，推进新的TMZ组合进入临床，两个药物启动的临床试验， MGMT沉默CRC：1）TMZ +奥拉帕尼（PARP抑制剂）和TMZ + AZD 6738（ATR抑制剂）。招生将 继续在耶鲁Smilow癌症医院与未来的机会扩大到合作网站，通过我们的 CRC Stand Up to Cancer（SU 2C）梦之队此外，我们的目标是开发新的生物标志物检测方法， 包括评估MGMT异质性以鉴定对TMZ组合最敏感的肿瘤的生物标志物， 进行基因组分析利用DNA损伤还代表了一种潜在的工具，以刺激 免疫反应，并通过辅助研究和使用从我们的试验中获得的标本，我们将研究 TMZ组合对免疫微环境的影响，以支持添加免疫治疗 在未来我是一名医学肿瘤学家，专注于晚期胃肠道（GI）癌症的治疗 重点是CRC的创新疗法。这个奖项将促进我作为一名医生的发展- 科学家配备设计和进行制药商发起的早期临床试验的基础上，创新 关于DNA修复和免疫疗法的临床前证据。我的培训将包括教学课程 肿瘤免疫学，临床试验实施的实践经验，生物标志物的正式指导 技术.为了实现这些目标，我组建了一个多学科的导师团队， 导师，帕特里夏洛鲁索博士谁拥有成功指导初级教师和 在制药商发起的临床试验方面拥有广泛的专业知识。在这个奖项结束时，我将获得 有价值的技能到临床研究的基础一般，特别是临床试验设计， 以及用于DNA修复和免疫学的生物标志物鉴定。这个奖项将帮助我成为一个 进行CRC和其他GI癌症早期临床试验的独立研究者。

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.