Immunotherapy for Chronic Myelogenous Leukemia

描述（由申请人提供）：目前的申请是竞争性续期，旨在继续研究慢性粒细胞白血病（CML）的新疗法，特别是癌症疫苗的开发。此次更新将重点关注BCR-ABL酪氨酸激酶抑制剂甲磺酸伊马替尼（STI-571或GleevecTM）的免疫调节作用及其在CML化学免疫治疗方法中的应用。伊马替尼已成为CML患者的治疗选择，但出现耐伊马替尼白血病仍然是一个主要挑战。这促使了新的酪氨酸激酶抑制剂如达沙替尼或舒尼替尼的评估，以及化疗免疫治疗等联合治疗的研究。肿瘤免疫学领域最近取得了重大突破，其中之一是CD4+CD25+调节性T细胞（Treg）的出现，它在癌症诱导耐受的建立和持续中起着关键作用。在我们目前的资助周期中，我们报告了甲磺酸伊马替尼可以有效地与我们实验室开发的富含伴侣蛋白的细胞裂解物疫苗（CRCL）联合治疗已建立的BCR-ABL+白血病。为了阐明甲酸伊马替尼对免疫细胞的作用机制，我们获得了重要的数据，表明该药物可能负向调节CD4+CD25+调节性T细胞（Treg）的抑制功能。这是一个尚未被探索的新概念。因此，本提案需要验证的中心假设是甲磺酸伊马替尼不仅可以直接作用于BCR-ABL+白血病细胞，还可以通过下调Treg抑制活性使免疫细胞对肿瘤疫苗敏感。为了解决这一假设，我们提出以下具体目标：1。研究BCR-ABL酪氨酸激酶抑制剂对Treg的负调节作用。我们将(1)研究BCR-ABL酪氨酸激酶抑制剂如何在体内和体外影响Treg和非Treg淋巴细胞的免疫生物学，(2)确定这些药物是否影响CD4+CD25- T细胞向CD4+CD25+FoxP3+ Treg的转化。确定BCR-ABL酪氨酸激酶抑制剂抑制Treg的分子机制。在Treg和常规T细胞中，BCR-ABL酪氨酸激酶抑制剂对特定细胞信号转导通路的调节和关键转录因子的调节将被检查。3. 优化Treg消除或灭活与特异性肿瘤疫苗相结合的化学免疫治疗策略。为了验证伊马替尼在化学免疫治疗方法中的应用，我们提出(1)评估BCR-ABL酪氨酸激酶抑制剂的差异效率和目前使用的体内消耗/灭活Treg的策略，以及(2)进一步优化使用BCR-ABL抑制剂和肿瘤特异性疫苗治疗小鼠BCR-ABL+或BCR-ABL-白血病的化学免疫治疗方法。4. 评价BCR-ABL酪氨酸激酶抑制剂对CML患者Treg数量、表型和功能的影响。为了验证甲磺酸伊马替尼作为一种潜在的Treg抑制剂在人类化学免疫治疗策略中的应用，该提案的这一部分至关重要。将在甲磺酸伊马替尼治疗前和治疗期间对CML患者进行Treg频率、表型和抑制活性分析。这些研究基于一个新颖的概念，有令人信服的初步数据支持，即使用FDA批准的药物消耗/灭活肿瘤诱导耐受性的主要细胞成分。这不仅将揭示BCR-ABL酪氨酸激酶抑制剂的作用机制，而且可能会进一步改善白血病的化学免疫治疗。因此，我们的建议是及时的，高度相关的和重要的发展改进治疗CML。公共卫生相关性：该建议基于治疗慢性粒细胞白血病的两个临床相关挑战：白血病对甲氨替尼的耐药性，以及以调节性T细胞为可能贡献者的白血病诱导免疫耐受的建立。拟开展的研究将探讨BCR-ABL酪氨酸激酶抑制剂如何更有效地抑制调节性T淋巴细胞的抑制功能，促进抗肿瘤T细胞的功能，从而与基于白血病的疫苗接种协同作用。这些研究的结果将有助于阐明如何改进化疗免疫治疗方法，不仅针对CML，也针对其他（BCR-ABL-）癌症。

DESCRIPTION (provided by applicant): The current application is a competing renewal designed to pursue our studies on the development of novel therapies, specifically cancer vaccines, for chronic myelogenous leukemia (CML). This renewal will focus on the immunomodulatory role of the BCR-ABL tyrosine kinase inhibitor imatinib mesylate (STI-571 or GleevecTM) and its application in chemoimmunotherapy approaches for CML. This drug has become the therapy of choice for patients with CML, but the emergence of imatinib resistant leukemia remains a major challenge. This has prompted the evaluation of newer tyrosine kinase inhibitors such as dasatinib or sunitinib, and the examination of combination treatments such as chemoimmunotherapy. The field of tumor immunology has recently seen major breakthroughs, one of which is the emergence of CD4+CD25+ regulatory T cells (Treg) as critical contributors in the establishment and persistence of cancer- induced tolerance. During our current grant cycle we have reported that imatinib mesylate can be efficiently combined with a chaperone rich cell lysate vaccine (CRCL), developed in our laboratory, to treat established BCR-ABL+ leukemia. In an attempt to elucidate the mechanism of action of imatinib mesylate on immune cells, we have generated significant data indicating that this agent may negatively modulate the suppressive function of CD4+CD25+ regulatory T cells (Treg). This is a novel yet unexplored concept. Therefore, the central hypothesis to be tested in this proposal is that imatinib mesylate may not only act directly on BCR-ABL+ leukemia cells but may also sensitize immune cells to tumor vaccines by down-modulating Treg suppressive activity. To address this hypothesis, we propose the following specific aims: 1. Study the negative modulation of Treg by BCR-ABL tyrosine kinase inhibitors. We will (1) investigate how BCR-ABL tyrosine kinase inhibitors affect the immunobiology of Treg and non-Treg lymphocytes in vivo and in vitro, and (2) determine whether these drugs influence the conversion CD4+CD25- T cells into CD4+CD25+FoxP3+ Treg. 2. Determine the molecular mechanisms underlying BCR-ABL tyrosine kinase inhibitor suppression of Treg. The modulation of specific cell signalling transduction pathways and regulation of key transcription factors by BCR-ABL tyrosine kinase inhibitors in Treg and conventional T cells will be examined. 3. Optimize a chemoimmunotherapy strategy combining Treg elimination or inactivation with specific tumor vaccination. To validate the use of imatinib in chemo-immunotherapy approaches, we propose to (1) evaluate the differential efficiency of BCR-ABL tyrosine kinase inhibitors and the currently used strategies to deplete/inactivate Treg in vivo, and (2) further optimize a chemoimmunotherapy approach using BCR-ABL inhibitors and tumor specific vaccination to treat BCR-ABL+ or BCR-ABL- leukemia in mice. 4. Evaluate the effects of BCR-ABL tyrosine kinase inhibitors on Treg number, phenotype and function in CML patients. This part of the proposal is critical in order to validate the application of imatinib mesylate as a potential Treg inhibitory agent in human chemoimmunotherapy strategies. Analysis of Treg frequency, phenotype and suppressive activity will be performed in CML patients before and during imatinib mesylate therapy. These studies are based on a novel concept supported by convincing preliminary data to deplete/inactivate a major cellular component of tumor-induced tolerance using FDA approved agents. They will not only shed light on the mechanisms of action of BCR-ABL tyrosine kinase inhibitors, but may also lead to further improvement in chemo-immunotherapy of leukemia. Our proposal is therefore timely, highly relevant and significant for the development of improved treatments for CML. PUBLIC HEALTH RELEVANCE: This proposal is based on two clinically relevant challenges in combating chronic myelogenous leukemia: the resistance of leukemia to imatinib mesylate, and the establishment of leukemia-induced immune tolerance with regulatory T cells as the likely contributors. The proposed studies will investigate how BCR-ABL tyrosine kinase inhibitors may be used more effectively to impede the suppressive function of regulatory T lymphocytes and promote the function of anti-tumoral T cells, thereby working synergistically with leukemia- based vaccination. Results from these studies will help shed light on how to improve chemo-immunotherapic approaches not only for CML but also for other (BCR-ABL-) cancers.