Hypoxia-Activated O6-Benzylguanine Prodrugs

缺氧激活的 O6-苄基鸟嘌呤前药

• 批准号: 7247982
• 负责人: ALAN CLAYTON SARTORELLI
• 金额: $ 28.52万
• 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 2009-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7247982
• 关键词: Active Sites; Alkylating Agents; Alkylation; Biochemical; Carmustine; Cells; Clinical; Cysteine; Cytosine; DNA; DNA lesion; Development; Dose; Drug-sensitive; Enzymes; Ethane; Evaluation; Guanine; Human; Hydrazine; Hydrazines; Hypoxia; In Vitro; Lesion; Malignant Neoplasms; Mammalian Cell; Myelosuppression; Neoplasms; Nitrosourea Compounds; Normal tissue morphology; Numbers; O(6)-Methylguanine-DNA Methyltransferase; O(6)-benzylguanine; Patients; Phase III Clinical Trials; Positioning Attribute; Prodrugs; Property; Proteins; Reaction; Resistance; Solid Neoplasm; Therapeutic; Tissues; Toxic effect; Transplantation; United States Food and Drug Administration; Water; alkyl group; base; crosslink; cytotoxic; design; dosage; expectation; in vivo; inhibitor/antagonist; inorganic phosphate; neoplastic cell; nucleophilic substitution; repaired; tumor

DESCRIPTION (provided by applicant): Alkylating agent prodrugs that chloroethylate the O-6 position of DNA guanine include Cloretazine, an agent currently in Phase III clinical trial; BCNU, an FDA approved clinically used nitrosourea; and KS119W, a water-soluble sulfonyl hydrazine prodrug selectively activated in hypoxic cells of solid tumors. This DNA lesion is susceptible to repair by O6-alkylguanine-DNA alkyltransferase (ACT), a protein that transfers alkyl groups from the O-6 position of guanine to the ACT molecule. This action represents the primary mechanism of tumor and host tissue resistance to Cloretazine, BCNU, and KS119W. One of the most potent known inhibitors of ACT is O6-benzylguanine (06-BG), which reacts with ACT to form S- benzylcysteine in the active site of the protein. As a result, O6-BG depletes ACT and increases the sensitivity of tumor and host cells to Cloretazine, BCNU and KS119W. Non-toxic doses of systemic O6-BG have been shown in patients to deplete the ACT content of tumors. This action, however, also sensitizes host tissues to BCNU used in combination, necessitating an 80% decrease in the dosage of this agent because of myelosuppression, leading to an ineffective level of BCNU. The Specific Aims of this application are the (a) design and synthesis of O6-BG prodrugs activated selectively by reducing enzymes in hypoxic cells of solid tumors, thereby selectively depleting tumors of AGT while sparing oxygenated normal tissues; (b) evaluation of pretreatment of hypoxic and oxygenated tumor cells with O6-BG prodrugs in vitro followed by Cloretazine, BCNU, and KS119W; (c) evaluation in vivo of these combinations against a variety of transplanted human tumors containing high levels of AGT activity; and (d) pharmacological and biochemical studies of the mechanism of action of synthesized prodrugs. The primary overall objective is the selection of an O6-BG prodrug for clinical development to use in combination with BCNU, Cloretazine and KS119W. The O6-BG prodrug selected should deplete AGT selectively in solid tumors, thereby permitting use in sequential combination at close to full therapeutic dosage of a chloroethylating agent without increased myelosuppression or toxicities to other normal tissues. The expectation is that solid tumors, resistant to the cytotoxic actions of Cloretazine, KS119W and BCNU because of constitutively high levels of AGT, will be selectively depleted of the resistance inducing protein by pretreatment with the O6-BG prodrug, resulting in conversion of chloroethylating agent resistant neoplasms to drug sensitive ones, thereby increasing the spectrum of malignancies that may benefit from Cloretazine, KS119W, and BCNU.

描述（申请人提供）：将DNA鸟嘌呤O-6位氯乙基化的烷基化剂前药包括氯雷他嗪，目前处于III期临床试验中； BCNU，FDA批准临床使用的亚硝基脲； KS119W是一种水溶性磺酰肼前药，在实体瘤的缺氧细胞中选择性激活。这种 DNA 损伤很容易被 O6-烷基鸟嘌呤-DNA 烷基转移酶 (ACT) 修复，ACT 是一种将烷基从鸟嘌呤的 O-6 位转移到 ACT 分子的蛋白质。这一作用代表了肿瘤和宿主组织对氯雷他嗪、BCNU 和 KS119W 耐药的主要机制。 O6-苄基鸟嘌呤 (06-BG) 是已知最有效的 ACT 抑制剂之一，它与 ACT 反应，在蛋白质的活性位点形成 S- 苄基半胱氨酸。因此，O6-BG 会消耗 ACT，并增加肿瘤和宿主细胞对氯雷他嗪、BCNU 和 KS119W 的敏感性。已证明患者全身使用无毒剂量的 O6-BG 可以消耗肿瘤的 ACT 含量。然而，这种作用也会使宿主组织对联合使用的 BCNU 敏感，由于骨髓抑制，因此需要减少 80% 的剂量，从而导致 BCNU 水平无效。该申请的具体目标是（a）设计和合成O6-BG前药，通过减少实体瘤缺氧细胞中的酶来选择性激活，从而选择性地消耗肿瘤​​的AGT，同时保留含氧的正常组织； (b) 在体外用 O6-BG 前药随后用氯雷他嗪、BCNU 和 KS119W 预处理缺氧和含氧肿瘤细胞的评估； (c) 体内评估这些组合针对含有高水平 AGT 活性的多种移植人类肿瘤的作用； (d)合成前药作用机制的药理学和生物化学研究。主要总体目标是选择 O6-BG 前药进行临床开发，与 BCNU、氯雷他嗪和 KS119W 联合使用。所选择的O6-BG前药应在实体瘤中选择性地耗尽AGT，从而允许以接近完全治疗剂量的氯乙基化剂顺序组合使用，而不增加骨髓抑制或对其他正常组织的毒性。预计由于 AGT 水平较高而对氯雷他嗪、KS119W 和 BCNU 的细胞毒性作用具有抗性的实体瘤，将通过 O6-BG 前药预处理选择性地耗尽抗性诱导蛋白，从而导致氯乙基化剂的转化抗药性肿瘤对药物敏感的肿瘤，从而增加了可能受益于氯雷他嗪、KS119W 和 BCNU 的恶性肿瘤谱。