Pathogenetic Mechanism and Clinical Targeting of CSF3R-Driven Cancer

申请者描述(申请人提供)：本申请地址为PA-11-260研究项目资助(家长R01)。慢性中性粒细胞白血病(CNL)和不典型(BCR-ABL1阴性)慢性髓系白血病(ACML)都是血液系统的恶性肿瘤，历史上都是基于粒细胞肿瘤性扩张和排除其他骨髓增生性肿瘤(MPN)中已知的基因驱动因素而诊断的。缺乏对遗传损伤的定义使这些疾病的诊断具有挑战性，并导致患者缺乏有效的治疗选择。我最近在约60%的CNL和aCML患者的肿瘤细胞中发现了功能获得CSF3R突变(1)。这些CSF3R突变诱导下游的激酶信号通路激活，导致CSF3R突变细胞对FDA批准的小分子激酶抑制剂高度敏感。一些携带CSF3R突变的患者已经作为单药接受了这些激酶抑制剂的治疗，并表现出戏剧性和持久的临床反应。这些发现导致了一些重要的新问题和项目方向。我的长期目标是建立CSF3R靶向疗法，作为CNL/aCML患者有效长期疾病管理的支柱。我的近期目标是全面了解CSF3R驱动白血病发生的分子机制，定义可以控制CSF3R驱动的疾病的联合治疗方案，并在没有CSF3R突变的病例中确定替代驱动因素。基于CSF3R和相关通路是CNL和aCML发病机制的核心假设，我预测靶向这些通路将彻底改变CNL/aCML患者的临床治疗和预后。为了实现这些目标，将解决几个具体问题：1)CSF3R突变导致受体激活的分子机制是什么？CSF3R突变根据蛋白质内的空间位置分为两类，初步数据表明，这两类CSF3R突变表现出不同的激活机制和药物敏感性模式。充分阐明这些表型背后的分子机制将是重要的。2)涉及CSF3R的组合突变的后果是什么？我最近公布的数据表明，相当大比例的CSF3R突变病例在CSF3R的相同等位基因内或在SETBP1等次级基因内也存在继发性突变。我将在体外和体内的单一药物和联合治疗方案的背景下，研究这些组合突变对信号和药物敏感性的影响。3)无CSF3R突变的CNL/aCML病例的遗传驱动因素是什么？我已经对无CSF3R突变的CNL/aCML病例进行了深度测序，并在每个病例中确定了CSF3R通路或相关通路中的候选突变。我将验证这些候选致癌基因的转化能力和药物敏感性。总而言之，我预计这些创新的分析将对我们对CNL/aCML生物学的理解和这些疾病的成功临床治疗产生重大影响。

DESCRIPTION (provided by applicant): This application addresses PA-11-260 Research Project Grant (Parent R01). Chronic neutrophilic leukemia (CNL) and atypical (BCR-ABL1-negative) chronic myeloid leukemia (aCML) are both hematologic malignancies that have historically been diagnosed based on neoplastic expansion of granulocytic cells and exclusion of genetic drivers known to occur in other myeloproliferative neoplasms (MPN). The absence of defining genetic lesions has made diagnosis of these diseases challenging, and resulted in a dearth of effective therapeutic options for patients. I have recently identified gain-of-function CSF3R mutations in neoplastic cells from ~60% of CNL and aCML patients(1). These CSF3R mutations induce activation of downstream kinase signaling pathways resulting in hypersensitivity of CSF3R-mutant cells to FDA-approved small-molecule kinase inhibitors. Several patients harboring CSF3R mutations have been treated with these kinase inhibitors as single-agents and have exhibited dramatic and durable clinical responses. These findings lead to a number of important new questions and project directions. My long-term goal is to establish CSF3R targeted therapies as a pillar of effective long-term disease management for CNL/aCML patients. My immediate goals are to comprehensively understand the molecular mechanisms by which CSF3R drives leukemogenesis, to define the combinatorial therapeutic regimens that can control CSF3R- driven disease, and to identify alternative drivers in cases without CSF3R mutation. Based on the central hypothesis that CSF3R and related pathways are onco-requisite for the pathogenesis of CNL and aCML, I predict that targeting these pathways will revolutionize clinical care and outcomes for CNL/aCML patients. To accomplish these goals, several specific questions will be addressed: 1) What are the molecular mechanisms by which CSF3R mutation leads to receptor activation? CSF3R mutations fall into two categories based on spatial location within the protein, and preliminary data indicate these two classes of CSF3R mutations exhibit distinct mechanisms of activation and drug sensitivity patterns. It will be important to fully elucidate the molecular mechanisms underlying these phenotypes. 2) What are the consequences of combinatorial mutations involving CSF3R? My recently published data indicate that a substantial proportion of CSF3R mutant cases also harbor secondary mutations within the same allele of CSF3R or within secondary genes such as SETBP1. I will examine the effects on signaling and drug sensitivity of these combinatorial mutations in the context of single-agent and combination therapeutic regimens, both in vitro and in vivo. 3) What are the genetic drivers in CNL/aCML cases without CSF3R mutation? I have performed deep sequencing on CNL/aCML cases without CSF3R mutation, and have identified candidate mutations within the CSF3R pathway or related pathways in each case. I will validate the transformative capacity and drug sensitivity of each of these candidate driver oncogenes. Cumulatively, I expect these innovative analyses to have a major impact on our understanding of CNL/aCML biology and successful clinical management of these diseases.