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

描述（由申请人提供）：该GO RC 2申请的中心目标是利用三个机构（VCU/梅西癌症中心，MD安德森癌症中心，H。Lee Moffitt癌症中心）和各种相关的支持机制（即，R 01、P01、N 01和SPORE）进行一项基于机制的I期试验，研究组蛋白脱乙酰酶抑制剂（HDACI）贝利司他（PXD-101）和蛋白酶体抑制剂（PI）硼替佐米在难治性AML、高危MDS、CML-母细胞危象和ALL患者中的作用。第二个目标是进行相关的实验室研究，以测试用于监测候选替代标志物的方法的充分性，所述候选替代标志物可以预测疾病反应性并有助于在未来基于疗效的试验中确定对该方案的耐药机制（例如，第二阶段）。我们实验室以前的研究记录了HDACIs和PI在恶性造血细胞（包括人白血病细胞）中的显著协同作用。负责协同相互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的上调以及攻击体功能的破坏。此外，有证据表明HDACIs破坏蛋白酶体功能，提高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，非常低的（例如，nM）浓度的贝利司他和硼替佐米在培养的和原代AML母细胞中以高度协同的方式相互作用，以诱导与减少的核p65/RelA定位、NF-：B依赖性蛋白（Bcl-xL和XIAP）的下调和Bim的上调相关的细胞凋亡。尽管有这些临床前证据，但HDACI与PI联合治疗的策略尚未在AML、MDS和相关急性白血病中进行评估。本提案的具体目标#1是进行贝利司他（在3周时间表的第1-5天和第8-12天给予IVP）联合硼替佐米（每周两次给予IVP）× 2周的I期试验，并确定未来II期试验的RPTD（推荐II期剂量）。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是检测贝利司他/硼替佐米治疗前和治疗后24小时监测白血病原始细胞中候选相关药效学决定因素的方法的适当性，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减少p65/RelA核定位;通过Western印迹分析Bcl-xL/XIAP下调和Bim上调;和抑制20 S蛋白酶体活性。这项试验的成功进行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，用于开发涉及两种或多种研究药物的新型，基于机制的抗癌治疗策略。 公共卫生相关性：急性髓细胞性白血病和相关疾病（骨髓增生异常综合征、急性淋巴细胞性白血病、慢性髓细胞性白血病急变）是导致显著发病率和死亡率的原因。如果成功的话，目前的提议可能会导致为这些疾病开发一种新的和潜在的更有效的治疗策略，也可能有助于确定实验室相关性，这些相关性可能预测个体患者的疾病反应性。

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.