Role of constitutive androstane receptor in cyclophosphamide-based chemotherapy

描述（由申请人提供）：环磷酰胺（CPA）是一种烷基化前药，已广泛用于治疗恶性血液病，特别是作为非霍奇金淋巴瘤和慢性淋巴细胞白血病一线治疗方案的重要组成部分。不幸的是，尽管进行了积极的化疗，但由于耐药性和/或不可耐受的毒性的发展，大量患者仍未治愈。显然需要进一步优化目前的治疗方案。本提案的总体目标是 目的是通过促进CPA经CYP 2B 6代谢转化为具有生物活性的4-羟基环磷酰胺（4-OH-CPA），而不是经CYP 3A 4代谢转化为N-二氯乙基环磷酰胺和毒性的氯乙醛，从而提高CPA化疗的疗效。为此，我们已经表明，人组成型雄烷受体（hCAR）的激活优先诱导肝脏CYP 2B 6的表达超过CYP 3A 4，并增加4-OH-CPA的形成。我们还开发了独特的人原代肝细胞（HPH）-白血病共培养模型，并证明CPA与选择性hCAR激活剂的共施用导致白血病细胞中的细胞凋亡显著增强而不增加肝毒性。在本申请中，我们假设hCAR的激活可以选择性地增强对4-OH-CPA的全身暴露，并增加基于CPA的淋巴瘤和白血病治疗的疗效：毒性比。这一中心假设将通过以下具体目标进行检验：目标1。评价hCAR在HPH和淋巴瘤/白血病细胞中CPA生物活化中的作用;目的#2。评估CPA在HPH-淋巴瘤/白血病共培养模型中的代谢和抗癌活性;以及目的#3。在hCAR转基因小鼠模型中检查hCAR活化对基于CPA的淋巴瘤/白血病治疗的影响。这些结果有望确立hCAR作为一种新的治疗靶点，促进基于CPA的造血系统恶性肿瘤化疗。对与hCAR介导的CPA抗癌活性增强相关的潜在机制的进一步理解可能最终有利于开发新的治疗策略。

DESCRIPTION (provided by applicant): Cyclophosphamide (CPA), an alkylating prodrug, has been used extensively in the treatment of hematologic malignancies, in particular, as an important component in the front-line regimens for non-Hodgkin lymphoma and chronic lymphocytic leukemia. Unfortunately, despite aggressive chemotherapy, a significant number of patients remain uncured due to development of drug resistance and/or intolerable toxicities. The need for further optimization of the current regimens is evident. The overall goal of this proposal is to improve the therapeutic efficacy of CPA-based chemotherapy by enhancing metabolic conversion of CPA to the pharmacologically active 4-hydroxylcyclophosphamide (4-OH-CPA) via CYP2B6, but not to the N- dechloroethyl-cyclophosphamide and the toxic chloroacetaldehyde by CYP3A4. Towards this end, we have shown that activation of the human constitutive androstane receptor (hCAR) preferentially induced the expression of hepatic CYP2B6 over CYP3A4 and increased the formation of 4-OH-CPA. We have also developed a unique human primary hepatocyte (HPH)-leukemia coculture model and demonstrated that co- administration of CPA with a selective hCAR activator leads to significantly enhanced apoptosis in leukemia cells without increasing hepatotoxicity. In this application, we hypothesize that activation of hCAR can selectively enhance systemic exposure to 4-OH-CPA and increase the efficacy:toxicity ratio of CPA-based treatment for lymphoma and leukemia. This central hypothesis will be tested by the following specific aims: Aim #1. Evaluate the role of hCAR in the bioactivation of CPA in HPH and lymphoma/leukemia cells; Aim #2. Assess the metabolism and anticancer activity of CPA in the HPH-lymphoma/leukemia coculture model; and Aim #3. Examine the influence of hCAR activation on CPA-based treatment of lymphoma/leukemia in an hCAR-transgenic mouse model. The outcomes are expected to establish hCAR as a novel therapeutic target facilitating the CPA-based chemotherapy for hematopoietic malignancies. Improved understanding of the underlying mechanism(s) associated with hCAR-mediated enhancement of the anticancer activity of CPA may ultimately benefit the development of new therapeutic strategies.