CLINICAL TRAILS IN MYELOID MALIGANANCIES WITH MOLECULARLY TARGETED THERAPIES

FLT3的激活突变导致了大约30%的AMI病例的病理生理。内部串联重复突变与不良预后有关，特别是在细胞遗传学正常的亚群中。该项目前期的研究表明，在小鼠骨髓移植模型中，激活FLT3的突变可使白血病细胞系产生不依赖因子的生长，并导致致命的骨髓增生性综合征。FLT3酪氨酸激酶的药理学抑制剂特异性杀死这种转化的细胞系，并延长患有这种模型肿瘤的小鼠的存活时间。通过与制药公司的合作以及与实验室同事的密切合作，达纳-法伯癌症研究所的成人白血病项目率先开发了用于急性髓性白血病临床应用的FLT3抑制剂。我们确定PKC412和MLN518作为单一药物在AML患者中耐受，并在大多数记录有FLT3突变的白血病患者中产生外周白血病细胞计数减少。然而，迄今为止所有FLT3抑制剂的经验表明，它们作为单一药物的效用将受到限制，部分原因是药理学方面的考虑，但也由于AML中其他遗传群体的相关性。有必要将FLT3抑制剂与增强靶抑制或干扰关键途径的药物联合使用。我们已经领导了两项研究，其中FLT3抑制剂联合化疗治疗新诊断的AML患者。我们建议通过领导一项标准化疗+/- PKC412的明确III期研究来扩展FLT3抑制剂加化疗（特异性Aim 1）的研究，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（Specific Aim 1b）基线FLT3自磷酸化和下游信号对结果的影响，（Specific Aim 1c）与诊断相比，复发时FLT3突变模式变化的频率。我们将在项目1中与Griffin博士密切合作，他将评估通过FLT3抑制剂和其他途径/细胞过程抑制剂的组合在体外杀死人类白血病细胞。然后，我们将进行（Specific aim 2）临床试验，在突变型FLT3 AML患者中测试有希望的组合。第一个这样的试验，基于项目1的临床前实验，将是PKC412和mTOR抑制剂RAD001的I期研究。辅助研究将确定酪氨酸激酶抑制与下游信号抑制的结合是否可行，是否可以抑制预期的靶点。基于这个项目和其他项目的临床前开发

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.