Proteasome/HDAC Inhibition in Leukemia/MDS; Phase I Trial and Correlative Studies

描述(由申请人提供)：此GO RC2申请的中心目标是利用三个机构(VCU/Massey癌症中心、MD Anderson癌症中心、H.Lee Moffitt癌症中心)和各种相关支持机制(即R01、P01、N01和芽胞)的集体资源，进行一项针对组蛋白去乙酰酶抑制物(HDACi)belinostat(PXD-101)和蛋白酶体抑制物(PI)bortezomib的机制I期试验，用于治疗难治性AML、高危MDS、CML-BLAST危象和ALL。第二个目标是进行相关的实验室研究，以测试监测候选替代标志物的方法的充分性，这些替代标志物可以预测疾病的反应性，并有助于在未来的基于疗效的试验(例如，第二阶段)中确定对该方案的耐药机制。我们实验室以前的研究证明，HDACIs和PI在包括人类白血病细胞在内的恶性造血细胞中具有显著的协同作用。协同作用的机制可能是多因素的，包括PI介导的抑制HDACi诱导的NF：B激活，下调NF：B依赖的抗凋亡蛋白(BclxL，XIAP)，HDACi介导的Bim上调，以及侵袭体功能的破坏。此外，有证据表明，HDACI破坏了蛋白酶体的功能，增加了与这些药物联合治疗可能导致蛋白酶体抑制增强的可能性。值得注意的是，来自我们实验室的最新临床前证据表明，极低浓度(例如，NM)的belinostat和bortezomib在培养和原代AML母细胞中以高度协同的方式相互作用，诱导细胞凋亡，相关因素包括核p65/relA定位降低，NF：B依赖蛋白(BclXL和XIAP)下调，以及Bim上调。尽管有这些临床前证据，但HDACIs与PI相结合的策略尚未在AML、MDS和相关的急性白血病中进行评估。这项建议的具体目标1是进行倍立诺斯特的I期试验，给予静脉注射3周计划的第1-5天和第8-12天，同时给予Bortezomib每周两次×2周的静脉注射，并为未来的第二阶段试验确定RPTD(推荐的II期剂量)。次要目的是确定该方案的剂量限制毒性，并初步了解该策略的潜在治疗效果。这项建议的具体目的#2是测试在贝利诺斯特/bortezomib治疗前和治疗24小时后监测白血病原始细胞候选相关药效决定因素的方法的充分性，重点是在临床前研究中观察到的体外事件，例如，数字化荧光显微镜下的p65/relA核定位减少；Western印迹分析bclxl/xIAP下调和Bim上调；以及抑制20S蛋白酶体活性。这项试验的成功进行和相关实验室研究的执行可以作为NCI、学术界和制药业未来合作伙伴关系的原型，以开发涉及两种或更多研究试剂的基于机制的新型抗癌治疗策略。 公共卫生相关性：急性髓系白血病及其相关疾病(骨髓发育不良综合征、急性淋巴细胞白血病、急变期慢性粒细胞白血病)是导致严重发病率和死亡率的原因。如果成功，目前的建议可能导致开发一种新的、可能更有效的治疗这些疾病的策略，还可能有助于确定可能预测个别患者疾病反应性的实验室相关性。

DESCRIPTION (provided by applicant): The central goal of this GO RC2 application is to leverage the collective resources of three institutions (VCU/Massey Cancer Center, MD Anderson Cancer Center, H. Lee Moffitt Cancer Center) and various associated support mechanisms (i.e., R01, P01, N01, and SPORE) to conduct a mechanism-based Phase I trial of the histone deacetylase inhibitor (HDACI) belinostat (PXD-101) and the proteasome inhibitor (PI) bortezomib in patients with refractory AML, high-risk MDS, CML-blast crisis, and ALL. The second goal is to perform correlative laboratory studies to test the adequacy of methods for monitoring candidate surrogate markers that may predict for disease responsiveness and help to define mechanisms of resistance to this regimen in future efficacy-based trials (e.g., Phase II). Previous studies from our laboratories documented pronounced synergism between HDACIs and PIs in malignant hematopoietic cells, including human leukemia cells. Mechanisms responsible for synergistic interactions are likely to be multi-factorial, including PI-mediated inhibition of HDACI-induced NF-:B activation, down-regulation of NF-:B-dependent anti-apoptotic proteins (Bcl-xL, XIAP), HDACI-mediated up-regulation of Bim, and disruption of aggresome function. In addition, evidence suggests that HDACIs disrupt proteasome function, raising the possibility that combined treatment with these agents may result in enhanced proteasome inhibition. Notably, recent preclinical evidence from our laboratories indicates that very low (e.g., nM) concentrations of belinostat and bortezomib interact in a highly synergistic manner in cultured and primary AML blasts to induce apoptosis in association with diminished nuclear p65/RelA localization, down-regulation of NF-:B-dependent proteins (Bcl-xL and XIAP), and up- regulation of Bim. Despite this preclinical evidence, a strategy combining HDACIs with PIs has not yet been evaluated in AML, MDS, and related acute leukemias. Specific Aim #1 of this proposal is to conduct a Phase I trial of belinostat given IVP days 1-5 and 8-12 of a 3-wk schedule in conjunction with bortezomib given IVP twice weekly x two weeks and to identify the RPTD (recommended Phase II doses) for future Phase II trials. Secondary aims are to identify the dose-limiting toxicities of this regimen, and to gain preliminary insights into the potential therapeutic efficacy of this strategy. Specific Aim #2 of this proposal is to test the adequacy of methods for monitoring candidate correlative pharmacodynamic determinants in leukemic blast cells prior to and 24 hr after treatment with belinostat/bortezomib, focusing on events observed in vitro in preclinical studies e.g., diminished p65/RelA nuclear localization by digitized fluorescence microscopy; Bcl-xL/XIAP down- regulation and Bim up-regulation by Western blot analysis; and inhibition of 20S proteasome activity. The successful conduct of this trial and performance of correlative laboratory studies could serve as a prototype for future partnerships between the NCI, academia, and the pharmaceutical industry in the development of novel, mechanism-based anti-cancer therapeutic strategies involving two or more investigational agents. PUBLIC HEALTH RELEVANCE: Acute myelogenous leukemia and related diseases (myelodysplasic syndrome, acute lymphocytic leukemia, chronic myelogenous leukemia in blast crisis) are responsible for significant morbidity and mortality. If successful, the current proposal could lead to the development of a new and potentially more effective treatment strategy for these diseases, and could also help to identify laboratory correlates that might predict for disease responsiveness in individual patients.