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

描述（由申请人提供）：本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）的集体资源和各种相关支持机制（即R01， P01， N01和SPORE）进行基于机制的组蛋白去乙酰化酶抑制剂（HDACI） belinostat （PXD-101）和蛋白酶体抑制剂（PI） bortezomib在难治性AML，高风险MDS， CML-blast危像和ALL患者中的I期试验。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记物方法的充分性，这些标记物可能预测疾病反应性，并有助于确定未来基于疗效的试验（例如，II期）中对该方案的耐药机制。我们实验室先前的研究证实了HDACIs和pi在恶性造血细胞（包括人类白血病细胞）中的协同作用。协同作用的机制可能是多因素的，包括pi介导的hdaci诱导的NF-:B活化的抑制，NF-:B依赖性抗凋亡蛋白（Bcl-xL， XIAP）的下调，hdaci介导的Bim上调以及聚合体功能的破坏。此外，有证据表明，hdac破坏蛋白酶体功能，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，我们实验室最近的临床前证据表明，极低浓度（例如nM）的belinostat和硼替佐米在培养的和原代AML细胞中以高度协同的方式相互作用，诱导细胞凋亡，这与核p65/RelA定位减少、NF-: b依赖性蛋白（Bcl-xL和XIAP）下调和Bim上调有关。尽管有这些临床前证据，hdac与pi联合治疗AML、MDS和相关急性白血病的策略尚未得到评估。该提案的具体目标#1是进行一项为期3周的I期试验，将belinostat给予IVP的第1-5天和第8-12天与硼替佐米联合给予IVP的每周两次x两周，并确定RPTD（推荐的II期剂量）用于未来的II期试验。次要目的是确定该方案的剂量限制性毒性，并初步了解该策略的潜在治疗效果。本提案的具体目标#2是测试在使用贝利诺他/硼替佐米治疗前和治疗后24小时监测白血病母细胞候选相关药效学决定因素方法的充分性，重点关注临床前研究中体外观察到的事件，例如通过数字化荧光显微镜观察到的p65/RelA核定位降低；Western blot分析Bcl-xL/XIAP下调、Bim上调；抑制20S蛋白酶体活性。这项试验的成功实施和相关实验室研究的表现可以作为NCI、学术界和制药行业之间未来合作伙伴关系的原型，以开发涉及两种或更多研究药物的新型、基于机制的抗癌治疗策略。

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.