Hypoxia-Activated O6-Benzylguanine Prodrugs

缺氧激活的 O6-苄基鸟嘌呤前药

• 批准号: 8080493
• 负责人: ALAN CLAYTON SARTORELLI
• 金额: $ 28.5万
• 依托单位: YALE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-07-01 至 2013-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8080493
• 关键词: Active Sites; Alkylating Agents; Alkylation; Animals; Antineoplastic Agents; Area; Binding; Biochemical; Cancer Patient; Carmustine; Cell Fraction; Cells; Chemicals; Clinical; Clinical Trials; Cysteine; Cytosine; DNA; DNA lesion; Dacarbazine; Development; Diffusion; Dose; Drug Formulations; Drug-sensitive; Employment; Enzymes; Ethane; Evaluation; Experimental Neoplasms; FDA approved; Guanine; Human; Hydrazine; Hypoxia; In Vitro; Laboratories; Lead; Lomustine; Malignant Neoplasms; Measurement; Measures; Methodology; Mus; Myelosuppression; Neoplasms; Nitroreductases; Nitrosourea Compounds; Normal tissue morphology; O(6)-Methylguanine-DNA Methyltransferase; O(6)-benzylguanine; Oxygen; Patients; Pharmaceutical Preparations; Positioning Attribute; Procarbazine; Prodrugs; Proteins; Reaction; Relative (related person); Resistance; Site; Solid Neoplasm; Specificity; Staging; Streptozocin; System; Therapeutic; Tissues; Transplantation; Tumor Tissue; Water; adduct; alkyl group; analog; base; crosslink; cyclohexylchloroethylnitrosourea; cytotoxic; design; dosage; expectation; in vivo; inhibitor/antagonist; lead series; methyl group; neoplastic cell; nucleophilic substitution; public health relevance; repaired; resistance mechanism; temozolomide; tumor

DESCRIPTION (provided by applicant): Alkylating agent prodrugs that chloroethylate the O-6 position of DNA guanine include onrigin (cloretazine), an agent designed and synthesized in our laboratory, currently in late stage clinical trial; carmustine (BCNU) and temozolomide (TMZ), an FDA approved clinically used nitrosourea and methylating agent, respectively, and KS119, a sulfonylhydrazine prodrug selectively activated in hypoxic cells of solid tumors will be employed. The DNA lesion, produced by the cholorethylating agents, an alkylation of the O6-position of DNA guanine which leads to a G-C crosslink, is susceptible to repair by O6-alkylguanine-DNA alkyltransferase (AGT), a protein that transfers alkyl and methyl groups from the O-6 position of guanine to the AGT molecule. This action represents the primary mechanism of tumor and host tissue resistance to onrigin, KS119, BCNU, and TMZ. Non-toxic doses of systemic O6-BG have been shown in cancer patients to deplete the AGT content of tumors; this action also depletes AGT in normal tissue, sensitizing both tumor host tissues to BCNU used in combination. The depletion of AGT necessitates an 80% decrease in dosage of BCNU because of myelosuppression, leading to an ineffective antineoplastic level of this nitrosourea. The Specific Aims of this application are (a) the design and synthesis of formulatable O6-BG prodrugs containing a p-nitrobenzylcarbonyl trigger/linker activated selectively/preferentially by reducing enzymes in oxygen-deficient cells of solid tumors, thereby selectively depleting tumors of AGT while sparing oxygenated normal tissue; (b) evaluation of pretreatment of hypoxic and oxygenated tumor cells with O6-BG prodrugs in vitro followed by onrigin, KS119, BCNU, and TMZ; (c) evaluation in vivo of combinations of these agents with synthesized AGT inhibitors against a variety of transplanted human and murine tumors containing varied levels of AGT and (d) biochemical studies of the mechanism of action of the synthesized prodrugs The expectation is that solid tumors, resistant to the cytotoxic actions of O6-DNA guanine targeting agents because of constitutively high levels of AGT, will be selectively/preferentially depleted of the resistance inducing protein AGT by pretreatment with the O6-BG prodrug, leading to the conversion of chloroethylating/methylating agent resistant neoplasms to drug sensitive ones, thereby increasing the spectrum of malignancies that may derive benefit from onrigin, KS119, BCNU and TMZ. PUBLIC HEALTH RELEVANCE: The selective activation of AGT inhibitory prodrugs in oxygen-deficient tumor tissue enhance the antitumor potential of alkylating and methylating drugs that chloroethylate and methylate the O6-position of DNA guanine, as well as reverse the primary mechanism of resistance of this class of agents (i.e., alkylating agents targeting the O6-position of DNA guanine). The design, synthesis and characterization of new AGT inhibitory agents in concert with the continued development of specific known DNA O6-guanine targeting agents to use in combination may well prove to yield unique new treatments for a variety of currently non-responsive tumors.

描述（申请人提供）：对DNA鸟嘌呤O-6位进行氯乙基化的烷基化剂前药包括Onrigin（氯雷他嗪），这是我们实验室设计和合成的药物，目前处于后期临床试验阶段；将使用卡莫司汀（BCNU）和替莫唑胺（TMZ）（分别是FDA批准的临床使用的亚硝基脲和甲基化剂）以及KS119（一种在实体瘤缺氧细胞中选择性激活的磺酰肼前药）。由氯乙基化剂产生的 DNA 损伤，即 DNA 鸟嘌呤 O6 位的烷基化，导致 G-C 交联，容易被 O6-烷基鸟嘌呤-DNA 烷基转移酶 (AGT) 修复，AGT 是一种转移烷基和甲基的蛋白质从鸟嘌呤的O-6位置到AGT分子。这一作用代表了肿瘤和宿主组织对 Onrigin、KS119、BCNU 和 TMZ 耐药的主要机制。在癌症患者中，全身性无毒剂量的 O6-BG 已被证明可以消耗肿瘤中的 AGT 含量；这一作用还会消耗正常组织中的 AGT，使两种肿瘤宿主组织对联合使用的 BCNU 敏感。由于骨髓抑制，AGT 的耗尽需要 BCNU 剂量减少 80%，从而导致亚硝基脲的抗肿瘤水平无效。本申请的具体目标是（a）设计和合成可配制的O6-BG前药，其含有通过减少实体瘤缺氧细胞中的酶选择性/优先激活的对硝基苄基羰基触发剂/连接剂，从而选择性耗尽肿瘤的AGT同时保留含氧的正常组织； (b) 体外用 O6-BG 前药随后用 Onrigin、KS119、BCNU 和 TMZ 预处理缺氧和含氧肿瘤细胞的评估； (c) 体内评估这些药物与合成 AGT 抑制剂的组合对含有不同水平 AGT 的各种移植人类和小鼠肿瘤的作用，以及 (d) 合成前药作用机制的生化研究由于 AGT 水平较高，对 O6-DNA 鸟嘌呤靶向剂的细胞毒性作用具有抵抗力，因此，通过用O6-BG 前药，导致对氯乙基化/甲基化剂耐药的肿瘤转化为药物敏感的肿瘤，从而增加可能受益于 Onrigin、KS119、BCNU 和 TMZ 的恶性肿瘤谱。 公共健康相关性：AGT 抑制性前药在缺氧肿瘤组织中的选择性激活增强了烷基化和甲基化药物的抗肿瘤潜力，这些药物使 DNA 鸟嘌呤的 O6 位氯乙基化和甲基化，并逆转此类药物的主要耐药机制试剂（即靶向 DNA 鸟嘌呤 O6 位的烷化剂）。新型 AGT 抑制剂的设计、合成和表征，与特定已知 DNA O6-鸟嘌呤靶向剂的持续开发相结合，可能会很好地证明可以为多种目前无反应的肿瘤提供独特的新疗法。