CLINICAL TRIALS IN MYELOID MALIGANANCIES WITH MOLECULARLY TARGETED THERAPIES

大约30%的急性心肌梗死患者的病理生理与Flt3基因的激活突变有关。内部串联复制突变与不良预后相关，特别是在细胞遗传学正常的亚组中。该应用的前一个资助期的工作表明，在小鼠骨髓移植模型中，激活Flt3突变可以在白血病细胞系中实现非因子依赖性生长，并导致致命的骨髓增殖性综合征。Flt3酪氨酸激酶的药物抑制剂可以特异性地杀死这种转化的细胞系，并延长带有这种模型肿瘤的小鼠的生存时间。在与制药公司的合作以及与我们实验室同事的密切合作下，Dana-Farber癌症研究所的成人白血病项目已经率先开发出用于AML临床使用的Flt3抑制剂。我们证实，在AML患者中，PKC412和MLN518作为单一药物是被耐受的，并且在大多数白血病被证明具有Flt3突变的患者中，PKC412和MLN518导致外周血白血病原始细胞计数减少。然而，到目前为止，所有Flt3抑制剂的经验表明，它们作为单一药物的用途将受到限制，部分原因是药理学考虑，但也是由于AML中其他基因军团的相关性。有必要将Flt3抑制剂与增强靶向抑制或干扰关键途径的药物结合起来。我们已经领导了两项研究，在这两项研究中，Flt3抑制剂与新诊断的AML患者的化疗相结合。我们建议通过领导标准化疗+/-PKC412的第三阶段最终研究来扩展Flt3抑制剂加化疗的研究(特定目标1)，并进行辅助研究以确定Flt3耐药的潜在机制。与这项美国组间III期试验相关的辅助研究将包括(特定目标1b)基线Flt3自动磷酸化和下游信号对结果的影响，以及(特定目标1c)与确诊相比复发时Flt3突变模式改变的频率。我们将在项目1中与Griffin博士密切合作，他将评估Flt3抑制剂和其他途径/细胞过程抑制剂的组合在体外对人类白血病细胞的杀伤作用。然后，我们将进行(特定目标2)临床试验，以测试在突变的Flt3 AML患者中有希望的组合。[第一个这样的试验基于项目1中的临床前实验，将是PKC412和mTOR抑制剂RAD001的I期研究。辅助研究将确定这种酪氨酸激酶抑制和下游信号抑制的组合是否可行，是否能够抑制预期的目标。]基于这个项目和这个项目中的其他项目的临床前发展 格兰特说，我们期待能够为这种预后不良的急性髓细胞白血病患者设计出新的、潜在有效的治疗方法。

Activation mutations of FLT3 contribute to the pathophysiology of approximately 30% of AMI cases. Internal tandem duplication mutations are associated with an adverse prognosis especially in the subgroup with normal cytogenetics. Work from the prior funding period of this application showed that activating mutations of FLT3 confer factor-independent growth in leukemic cell lines and lead to a fatal myeloproliferative syndrome in a murine bone marrow transplant model. Pharmacological inhibitors of the FLT3 tyrosine kinase specifically kill such transformed cell lines and prolong the survival of mice with this model neoplasm. In partnership with pharmaceutical companies and in close collaboration with our laboratory-based colleagues, the adult leukemia program at the Dana-Farber Cancer Institute has taken the lead in developing FLT3 inhibitors for clinical use in AML. We established that PKC412 and MLN518 were tolerated as single agents in patients with AML and produced a reduction in peripheral leukemic blast count in most patients whose leukemia was documented to have a FLT3 mutation. However, the experience with all the FLT3 inhibitors to date suggests that their utility as single agents will be limited, due in part to pharmacological considerations but also due to the relevance of other genetic legions in AML. It will be necessary to combine FLT3 inhibitors with agents which either enhance target inhibition or interfere with critical pathways. We have led two studies in which a FLT3 inhibitor is combined with chemotherapy in patients with newly diagnosed AML. We propose to extend the studies with FLT3 inhibitors plus chemotherapy (specific Aim 1) by leading a definitive phase III study of standard chemotherapy +/- PKC412 and to perform ancillary studies to determine the potential mechanisms of FLT3 resistance. Ancillary studies associated with this U.S. Intergroup phase III trial will include (Specific Aim 1b) the impact of baseline FLT3 autophosphorylation and downstream signaling on outcome and (Specific Aim 1c) the frequency of changes in FLT3 mutational patterns at relapse compared with diagnosis. We will work closely with Dr. Griffin in Project 1 who will assess killing of human leukemic cells in vitro by combinations of FLT3 inhibitors and inhibitors of other pathways/cellular processes. We will then perform (Specific aim 2) clinical trials to test promising combinations in patients with mutant FLT3 AML. [The first such trial, based on preclinical experiments in Project 1, will be a phase I study of PKC412 and the mTOR inhibitor RAD001. Ancillary studies will determine if this combination of tyrosine kinase inhibition with downstream signaling inhibition is feasible and can inhibit the expected targets.] Based on pre-clinical development in this and the other projects in this grant we anticipate being able to devise new and potentially effective therapies for patients with this type of poor prognosis AML.