Novel therapeutics for the targeted eradication of DDR-defective tumors

靶向根除 DDR 缺陷肿瘤的新疗法

• 批准号: 10734414
• 负责人: Ranjit Bindra
• 金额: $ 65.42万
• 依托单位: YALE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-07-25 至 2028-06-30
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10734414
• 关键词: Address; Alkylating Agents; Alkylation; Apoptosis; Biological Availability; Cells; Central Nervous System Agents; Chemicals; Clinic; Colon Carcinoma; Cyclization; Cytosine; DNA; DNA Alkylation; DNA Damage; DNA Interstrand Crosslinking; DNA Repair; DNA Repair Disorder; DNA Repair Gene; Data; Dealkylation; Development; Drug resistance; Excision; Futile Cycling; Genes; Genetic; Genome; Genomics; Glioblastoma; Glioma; Goals; Grant; Guanosine; Human; Hypermethylation; Ions; Kinetics; Lesion; MGMT gene; Malignant Neoplasms; Malignant neoplasm of lung; Mediating; Methyltransferase; Mismatch Repair; Modeling; Modification; Mutagens; Non-Small-Cell Lung Carcinoma; Oligonucleotides; Oral; Pathway interactions; Patients; Penetration; Pharmaceutical Preparations; Phenotype; Polymerase; Prodrugs; Proliferating; Radiation therapy; Reaction; Research; Resected; Resistance; Structure; Testing; Therapeutic; Therapeutic Index; Thymine; Time; Tissues; Toxic effect; Transferase; Translating; Translations; Work; adduct; bench to bedside; chemotherapy; clinically significant; crosslink; cytotoxicity; design; efficacy evaluation; experience; functional loss; improved; in vivo; ineffective therapies; inhibitor; mouse model; new therapeutic target; novel; novel strategies; promoter; repaired; response; small cell lung carcinoma; standard of care; synergism; systemic toxicity; targeted agent; temozolomide; tissue culture; treatment strategy; trial design; tumor; tumor specificity

PROJECT SUMMARY/ABSTRACT. O6-Methylguanine methyltransferase (MGMT) reverts O6-alkylguanosine residues to guanosine via dealkylation by SN2 displacement. MGMT is ubiquitously expressed in healthy tissue but is silenced (referred to as “MGMT– “) in ~50% of glioblastomas (GBMs), most gliomas, and in up to 40% of colon cancers, 35% of small cell lung cancers, and 25% of non-small cell lung cancers. MGMT– tumors are sensitized to DNA alkylation agents, such as temozolomide (TMZ). This sensitization creates a therapeutic index (TI). TMZ prolongs survival of patients with MGMT– GBM by ~8 mo. The cytotoxicity of TMZ relies on an intact DNA mismatch repair (MMR) pathway. MMR silencing (referred to as “MMR–”) is the primary mechanism of acquired TMZ resistance, and second-line therapies are ineffective. Despite >20 y of research, efforts to overcome MMR silencing-based resistance have not been successful. Herein, we present 2-fluoroethylating agents (FEtAs) as novel, orally bioavailable com- pounds that selectively eradicate MGMT–/MMR– GBM in vivo, without systemic toxicity. Our data indicate FEtAs induce DNA interstrand cross-links (ICLs) only in MGMT– tumors by formation of O6-(2-fluoroethyl)guanosine (O6FEtG), slow cyclization to an N1,O6-ethanoguanine (EG) intermediate, and ring-opening by the adjacent cytosine. The slow rates of EG formation provide time for MGMT to reverse the initial alkylation in healthy (e.g., MGMT+) cells, leading to a high TI. In contrast, chloroethylation agents, such as mitozolomide, generate O6-(2- chloroethyl)guanosine (O6ClEtG), which cyclizes to EG competitively with MGMT reversal. This leads to the formation of ICLs or toxic DNA–MGMT cross-links, via opening of EG by MGMT, in healthy cells. Additionally, the chloroethylsulfide formed on MGMT reversal of O6ClEtG converts to a reactive episulfonium ion, which also cross-links MGMT to DNA, while MGMT reversal of O6FEtG creates a stable fluoroethylsulfide. Together, these differences lend a higher MGMT TI to FEtAs suggesting they are likely to display improved tolerability in humans. Since ICL toxicity is MMR-independent, FEtAs retain activity in TMZ-resistant, MMR– tumors. Here we will study the amount of O6FEtG formed from FEtAs and the rate of its reversal by MGMT. We will characterize the structure and reaction kinetics of the ICLs using oligonucleotides containing a single O6FEtG. We will conduct studies to improve FEtA CNS penetration. We will probe for synergy between FEtAs and DDR inhibitors, other DNA repair deficiencies, and radiotherapy. Completion of this research will lead to the identification of novel chemotherapies with high CNS penetration that operate by a novel, MMR-independent mechanism, thereby addressing acquired TMZ resistance. As FEtAs are structurally-related to TMZ, we expect rapid translation to the clinic. MGMT is silenced in a range of tumor types; this work will set the stage to evaluate FEtAs as treatments for other MGMT– tumors, alone or in combination regimes. Finally, to the best of our knowledge, the relative rates of DNA chemical modification and repair have not previously been exploited to obtain tumor specificity; we believe this “kinetic lethal” strategy may constitute the first iteration of a new approach to targeted chemotherapeutic design.

项目摘要/摘要。 O6-甲基鸟嘌呤甲基转移酶 (MGMT) 通过脱烷基作用将 O6-烷基鸟苷残基还原为鸟苷 通过 SN2 位移。 MGMT 在健康组织中普遍表达，但被沉默（称为“MGMT- “）约 50% 的胶质母细胞瘤 (GBM)、大多数神经胶质瘤、高达 40% 的结肠癌、35% 的小细胞肺癌 癌症和 25% 的非小细胞肺癌。 MGMT——肿瘤对 DNA 烷基化剂敏感，例如 如替莫唑胺（TMZ）。这种敏化产生了治疗指数（TI）。 TMZ 延长患者生存期 MGMT-GBM 约 8 个月。 TMZ 的细胞毒性依赖于完整的 DNA 错配修复 (MMR) 途径。 MMR沉默（简称“MMR-”）是TMZ获得性耐药的主要机制，二线药物 治疗无效。尽管进行了超过 20 年的研究，克服 MMR 沉默耐药性的努力仍然取得了进展。 没有成功。在此，我们提出 2-氟乙基化剂 (FEtAs) 作为新型口服生物可利用的药物 体内选择性根除 MGMT-/MMR- GBM，且无全身毒性。我们的数据表明 FEtAs 仅在 MGMT- 肿瘤中通过形成 O6-(2-氟乙基)鸟苷诱导 DNA 链间交联 (ICL) (O6FEtG)，缓慢环化为 N1,O6-乙醇鸟嘌呤 (EG) 中间体，并通过相邻的开环 胞嘧啶。 EG 形成的缓慢速率为 MGMT 逆转健康动物（例如， MGMT+) 细胞，导致高 TI。相反，氯乙基化剂，例如米托唑胺，产生 O6-(2- 氯乙基)鸟苷 (O6ClEtG)，与 MGMT 逆转竞争性环化为 EG。这导致 通过 MGMT 打开 EG，在健康细胞中形成 ICL 或有毒 DNA-MGMT 交联。此外， O6ClEtG 的 MGMT 反转时形成的氯乙硫醚转化为活性表锍离子，这也 MGMT 与 DNA 交联，而 O6FEtG 的 MGMT 逆转会产生稳定的氟乙基硫醚。在一起，这些 差异使 FEtAs 具有更高的 MGMT TI，表明它们可能在人类中表现出更高的耐受性。 由于 ICL 毒性与 MMR 无关，因此 FEtAs 在 TMZ 耐药、MMR 肿瘤中保留活性。在这里我们将学习 由 FEtAs 形成的 O6FEtG 的量及其被 MGMT 逆转的速率。我们将表征结构 以及使用含有单个 O6FEtG 的寡核苷酸的 ICL 的反应动力学。我们将进行研究 提高 FETA 中枢神经系统的渗透性。我们将探讨 FEtAs 和 DDR 抑制剂以及其他 DNA 修复之间的协同作用 缺陷和放射治疗。这项研究的完成将导致新型化疗药物的确定 具有高中枢神经系统渗透性，通过一种新颖的、独立于 MMR 的机制运作，从而解决获得性 替莫唑胺耐药。由于 FEtAs 在结构上与 TMZ 相关，我们期望快速转化为临床。 MGMT 是 在一系列肿瘤类型中被沉默；这项工作将为评估 FEtAs 作为其他 MGMT 的治疗方法奠定基础—— 单独或联合治疗肿瘤。最后，据我们所知，DNA 化学的相对速率 此前尚未利用修饰和修复来获得肿瘤特异性；我们相信这种“动能 “致命”策略可能构成靶向化疗设计新方法的第一次迭代。