Cooperation of the TAM and Abl family kinases in therapeutic resistance in HNC

项目总结 在头颈癌(HNC)治疗中应用最多的分子靶向药物之一是 表皮生长因子受体(EGFR)靶向单抗西妥昔单抗(CTX)。西妥昔单抗是一种 一线极端疗法的中心组成部分，并与放射治疗相结合，是唯一 对局部进展期和复发/转移性HNC均有效的药物。尽管许多HNC 过去十年的研究表明，患者在癌症治疗过程中会看到环磷酰胺。 许多最初有反应的患者最终会对CTX产生耐药性。 为了确定HNC中CTX耐药(CTXR)的驱动因素，我们的实验室利用了HNC人肿瘤标本， 患者来源的异种移植物(PDX)和一系列获得性和内在耐药的体内外模型 系统。这项工作导致了受体酪氨酸激酶(RTK)Axl被确定为 CTXR。为了确定Axl信号如何导致CTXR的分子机制，三个酪氨酸残基 对AXL(Y779、Y821、Y866)进行突变定位，研究其对CTX的敏感性。无论是体外还是体内 分析表明：1)CTXR来自于AXL的Y821信号，通过c-Abl激酶，2)临床前 模型(PDX)表明，CTX与c-Abl激酶抑制剂伊马替尼(IMT)的联合使用会导致 HNC模型中肿瘤完全消退而无复发3)这一应用的初步数据 提示Axl通过Y821将c-Abl隔离在细胞质中，并阻止其移动到细胞核，这 是由IMT诱导的，促进细胞凋亡。总而言之，我们假设AXL通过以下方式在CTXR中发挥关键作用 将c-Abl隔离在胞浆中，治疗性靶向c-Abl与环磷酰胺联合将导致 HNC患者的深刻反应。我们计划进行这个跨学科的项目，从基础 生物学通过以下三个目标进行试点临床试验：1)调查a)细胞质隔离 C-Abl的表达与Ax1介导的CTXR有关，如果b)Ax1和c-Abl的关联是一个可预测的生物标志物 2)确定在CTXR PDX中同时靶向EGFR和c-Abl是否可以增强和重新 对环磷酰胺增敏，以及3)进行环磷酰胺加伊马替尼治疗慢性粒细胞白血病患者的先导性机会窗研究。 复发或转移性HNC。最终，我们的目标是改善HNC患者的治疗结果。 成功开展这些调查有可能显著改善和完善当前的HER 通过了解AXL和AXL的分子机制在HNC中以家庭为中心的治疗方法 C-Abl给予CTXR。此外，该项目通过改变FDA批准的两种药物的用途，具有很高的意义 新的癌症环境，以改善结果。总的来说，这项工作将影响未来的临床治疗。 范型和确定HNC中最有可能受益于靶向EGFR和c-Abl的患者。

PROJECT SUMMARY One of the most deployed molecular targeting agents in the treatment of head and neck cancer (HNC) is the Epidermal Growth Factor Receptor (EGFR)-targeted monoclonal antibody cetuximab (CTX). Cetuximab is a central component of the first-line EXTREME regimen and in combination with radiation therapy and is the only drug that exhibits efficacy in both locally advanced and recurrent/metastatic HNC. Although many HNC patients see CTX over the course of their cancer therapy, research over the past decade has revealed that many patients that do respond initially will eventually become refractory to CTX. To identify drivers of CTX resistance (CTXR) in HNC, our lab utilized HNC human tumor specimens, patient-derived xenografts (PDXs) and a series of acquired and intrinsically resistant in vitro and in vivo model systems. This work led to the identification of the receptor tyrosine kinase (RTK) AXL as a central driver of CTXR. To define the molecular mechanisms of how AXL signaling leads to CTXR, three tyrosine residues of AXL (Y779, Y821, Y866) were mutated and mapped for their sensitivity to CTX. Both in vitro and in vivo analysis revealed that 1) CTXR emanates from signaling from Y821 of AXL via the c-Abl kinase, 2) pre-clinical modeling (PDX) indicated that the combination of CTX plus imatinib (IMT), a c-Abl kinase inhibitor, lead to complete tumor regression without recurrence in HNC models and 3) preliminary data for this application suggests that AXL, via Y821, sequesters c-Abl in the cytosol and prevents it from moving to the nucleus, which is induced by IMT, to promote apoptosis. Collectively, we hypothesize that AXL plays a critical role in CTXR by sequestering c-Abl in the cytosol and that therapeutic targeting c-Abl in combination with CTX will lead to profound responses in HNC patients. We plan to conduct this interdisciplinary project, spanning from basic biology to a pilot clinical trial through the three following aims: 1) To investigate if a) cytoplasmic sequestration of c-Abl is responsible for AXL mediated CTXR and if b) if AXL and c-Abl association is a predictive biomarker of CTX response, 2) determine if targeting EGFR and c-Abl simultaneously in CTXR PDXs can enhance and re- sensitize to CTX, and 3) To perform a pilot window-of-opportunity study of CTX plus imatinib in patients with recurrent or metastatic HNC. Ultimately, our goal is to improve treatment outcomes for HNC patients. Successful pursuit of these investigations has the potential to significantly improve and refine current HER family-centric therapeutic approaches in HNC by understanding the molecular mechanisms of how Axl and c-Abl impart CTXR. In addition, this project has high significance by repurposing two FDA approved drugs in a new cancer setting to improve outcomes. Collectively, this work will impact future clinical treatment paradigms and identify patients most likely to benefit from targeting EGFR and c-Abl in HNC.