Phosphatase activation as therapeutic strategy for Chronic lymphocyic leukemia

 描述（由申请人提供）：尽管随着慢性淋巴细胞白血病（CLL）新疗法的引入，无进展生存期延长，但目前可用的疗法并不能治愈所有患者，复发患者的反应通常较差。鉴定在耐药患者中起作用的新药剂是研究的主要焦点。与延长存活和缺陷性凋亡相关的蛋白质的组成性磷酸化是CLL和其他癌症中反复出现的主题。虽然激酶的抑制被积极追求，但蛋白磷酸酶的药理学激活较少探索，并且代表了CLL中异常磷酸化蛋白的潜在治疗调节的范式转变。我们已经鉴定了FDA批准的免疫抑制剂FTY 720，其通过蛋白磷酸酶2A（PP 2A）活化依赖性机制介导CLL中的细胞毒性。尽管FTY 720在多种血红素恶性肿瘤（包括CLL、套细胞淋巴瘤、慢性髓性白血病和急性淋巴细胞白血病）中具有有效的临床前活性，但FTY 720的免疫抑制性质阻碍了其在血红素恶性肿瘤中临床应用的进一步开发。因此，我们开发了一种非免疫抑制FTY 720衍生物，OSU-2S，具有强大的细胞毒活性。该提案将追求OSU-2S在B细胞恶性肿瘤中的机制、药理学和转化开发。具体而言，在目的1中，我们提出鉴定OSU-2S的直接靶点并确定OSU-2S诱导细胞凋亡的机制基础，重点是CLL中的磷酸酶。为了克服OSU-2S在体内的潜在脱靶效应，我们产生了CLL肿瘤抗原（ROR 1）靶向免疫脂质体递送制剂（2A 2-OSU-2S-ILP）和在白血病B细胞上表达人ROR 1抗原的CLL小鼠模型。在目的2中，我们提出通过a）确定2A 2-OSU-2S-ILP在人ROR 1 + Tcl 1 CLL小鼠中的最大耐受剂量和暴露; B）表征Eµ-ROR 1-Tcl 1小鼠中骨髓、脾脏、循环WBC和其它组织中pSHP 1的2A 2-OSU-2S-ILP药代动力学和药效学（PK/PD）调节之间的体内关系，和c）使用PK/PD建模和模拟来设计2A 2-OSU-2S-ILP的最佳剂量方案，其使pSHP 1诱导最大化，同时使非患病组织中的剂量水平和OSU-2S暴露最小化。我们将在目标3中验证人ROR 1靶向OSU-2S制剂在我们的人ROR 1 + CLL小鼠模型中的体内治疗功效。本项目完成后，我们将获得足够的OSU-2S的机制和药理学数据，以证明其过渡到CLL的早期临床试验。我们准备通过我们的专利OSU-2S，新型CLL靶向给药制剂和独特的动物模型来实现这一目标，这些模型是专门为满足我们进行全面临床前评估的需求而开发的。为了实现这一目标，我们组建了一个高度互动的团队，他们拥有蛋白质组学、转化医学、药物开发、小鼠建模、药物递送以及PK/PD建模和模拟方面的专业知识。

 DESCRIPTION (provided by applicant): Despite prolonged progression free survival with the introduction of novel therapies for Chronic lymphocytic leukemia (CLL) currently available therapies are not curative in all patients and patients who relapse generally respond poorly. Identification of new agents that work in resistant patients represents a major focus of investigation. Constitutive phosphorylation of proteins associated with prolonged survival and defective apoptosis is a recurrent theme in CLL and other cancers. While inhibition of kinases is actively pursued, pharmacological activation of protein phosphatases is less explored and represents a paradigm shift for potential therapeutic modulation of aberrantly phosphorylated proteins in CLL. We have identified FTY720, an FDA approved immunosuppressant, to mediate cytotoxicity through a protein phosphatase 2A (PP2A) activation dependent mechanism in CLL. Despite its potent pre-clinical activity in multiple heme-malignancies including CLL, mantle cell lymphoma, chronic myeloid leukemia and acute lymphoid leukemia, the immunosuppressive property of FTY720 precluded its further development for clinical application in heme-malignancies. We therefore developed a non-immunosuppressive FTY720 derivative, OSU-2S, with potent cytotoxic activity. This proposal will pursue mechanistic, pharmacological and translational development of OSU-2S in B cell malignancies. Specifically, in Aim 1 we propose to identify the direct target of OSU-2S and determine the mechanistic basis of OSU-2S induced apoptosis with emphasis on phosphatases in CLL. To overcome potential off target effects of OSU-2S in-vivo, we generated CLL tumor antigen (ROR1) targeted immunoliposomal delivery formulations (2A2-OSU-2S-ILP) and CLL mouse models expressing human ROR1 antigen on leukemic B cells. In Aim 2, we propose to maximize the therapeutic index of 2A2-OSU-2S-ILP by a) determining maximum tolerable doses and exposures of 2A2-OSU-2S-ILP in human ROR1+Tcl1 CLL mice; b) characterizing the in-vivo relationships between 2A2-OSU-2S-ILP pharmacokinetics and pharmacodynamic (PK/PD) modulation of pSHP1 in bone marrow, spleen, circulating WBCs and other tissues in Eµ-ROR1-Tcl1 mice, and c) using PK/PD modeling and simulation to design optimal dose regimens of 2A2-OSU-2S-ILP that maximize pSHP1 induction while minimizing dose levels and OSU-2S exposure in non-diseased tissues. We will validate the in-vivo therapeutic efficacy of the human ROR1 targeted OSU-2S formulations in our human ROR1+ CLL mouse model in Aim 3. At completion of this project we will have generated sufficient mechanistic and pharmacological data with OSU-2S to justify its transition to early clinical trials for CLL. We are poised to accomplish this through our patented OSU-2S, novel CLL targeted delivery formulation and unique animal models exclusively developed to meet our needs to perform a comprehensive pre-clinical evaluation. To accomplish this goal we have assembled a highly interactive team with expertise in proteomics, translational medicine, drug development, mouse modeling, drug delivery, and PK/PD modeling and simulation.