Dissecting the function of PI3K/mTOR pathway activation in ROS1 fusion-mediated oncogenesis and resistance to targeted therapy

项目总结/摘要 最近发现ROS 1融合是所有非小细胞肺癌的1-2%的致癌驱动因素 （NSCLC）。虽然靶向的ROS 1激酶抑制剂如克唑替尼在临床上取得了初步成功， 大多数患者具有不完全的反应，并且一些患者根本没有反应（即，对以下药物具有新的耐药性 治疗）。到目前为止，还没有新的耐药的例子已经公布，没有这种前期机制 已经发现了耐药性，并且获得性耐药性的唯一已发表机制是靶向 ROS 1激酶结构域中阻止药物结合的突变。阐明下游途径驱动 ROS 1融合介导的肿瘤并导致对靶向治疗的耐药性对于开发 合理的综合治疗，以改善患者的反应和生存。我们实验室的初步研究，基于 来自2例对克唑替尼表现出新发耐药的ROS 1融合阳性患者和1例对克唑替尼表现出新发耐药的患者的数据- 耐药患者来源的ROS 1融合阳性NSCLC细胞系，表明 PI 3 K/mTOR通路不仅与ROS 1融合蛋白协同作用，促进肿瘤的发生，而且还可能促进肿瘤的发生。 对靶向激酶抑制的前期抗性。在这些ROS 1融合阳性病例中，我们发现了两个 我们怀疑PI 3 K/mTOR通路中的新突变导致mTOR信号转导过度激活。在这 研究中，我建议功能和生化表征这些PI 3 K/mTOR突变，并确定 该途径的激活如何促进ROS 1融合介导的肿瘤发生（目的1）。另外，我将 确定mTOR通路激活是否是必要的，并足以驱动抵抗ROS 1靶向 ROS 1融合驱动的NSCLC中的治疗，以及ROS 1和mTOR的组合抑制是否增强 体内肿瘤细胞收缩和死亡（目的2）。

Project Summary/Abstract ROS1 fusions have recently been found to be oncogenic drivers of 1-2% of all non-small cell lung cancers (NSCLC). While targeted ROS1 kinase inhibitors like crizotinib have shown some initial success in the clinic, most patients have incomplete responses, and some do not respond at all (i.e., are de novo resistant to therapy). Thus far, no examples of de novo resistance have been published, no mechanisms for this upfront resistance have been discovered, and the only published mechanism for acquired resistance is an on-target mutation in the ROS1 kinase domain that prevents drug binding. Elucidating what downstream pathways drive ROS1 fusion-mediated tumors and contribute to resistance to targeted therapies is critical for development of rational polytherapies to improve patient response and survival. Preliminary studies from our lab, based on data from two ROS1 fusion-positive patients exhibiting de novo resistance to crizotinib and a crizotinib- resistant patient-derived ROS1 fusion-positive NSCLC cell line, suggest that genetic activation of the PI3K/mTOR pathway may not only cooperate with ROS1 fusions in driving oncogenesis, but also contribute to upfront resistance to targeted kinase inhibition. In these ROS1 fusion-positive cases, we have discovered two novel mutations in the PI3K/mTOR pathway that we suspect cause hyperactivation of mTOR signaling. In this study, I propose to functionally and biochemically characterize these PI3K/mTOR mutations and determine how activation of this pathway contributes to ROS1 fusion-mediated oncogenesis (Aim 1). Additionally, I will determine whether mTOR pathway activation is necessary and sufficient to drive resistance to ROS1-targeted therapy in ROS1 fusion-driven NSCLC, and whether combinatorial inhibition of ROS1 and mTOR enhances tumor cell shrinkage and death in vivo (Aim 2).