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

项目摘要 在头颈癌（HNC）的治疗中最常用的分子靶向剂之一是 表皮生长因子受体（EGFR）靶向单克隆抗体西妥昔单抗（CTX）。西妥昔单抗是一 一线EXTREME方案的中心组成部分，并与放射治疗联合使用，是唯一 在局部晚期和复发性/转移性HNC中表现出疗效的药物。虽然许多HNC 患者在癌症治疗过程中看到CTX，过去十年的研究表明， 许多最初有反应的患者最终将变得对CTX难治。 为了鉴定HNC中CTX抗性（CTXR）的驱动因素，我们的实验室利用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外和体内模型 系统.这项工作导致了受体酪氨酸激酶（RTK）AXL作为一个中央驱动程序的鉴定。 CTXR。为了确定AXL信号传导如何导致CTXR的分子机制， 对AXL（Y 779、Y821、Y866）进行突变并定位其对CTX的敏感性。在体外和体内 分析显示：1）CTXR来自AXL的Y821通过c-Abl激酶的信号传导，2）临床前 模型（PDX）表明，CTX加伊马替尼（IMT），一种c-Abl激酶抑制剂，导致 在HNC模型中完全肿瘤消退而无复发，以及3）该应用的初步数据 这表明AXL通过Y821将c-Abl隔离在胞质溶胶中，并阻止其移动到细胞核， 由IMT诱导，促进细胞凋亡。总的来说，我们假设AXL在CTXR中起着关键作用， 将c-Abl隔离在胞质溶胶中，并且靶向c-Abl的治疗剂与CTX组合将导致 对HNC患者的反应很大。我们计划进行这个跨学科的项目，从基本的 通过以下三个目的将生物学应用于先导性临床试验：1）研究a）细胞质螯合 如果B）如果AXL和c-Abl结合是预测性生物标志物， 2）确定在CTXR PDX中同时靶向EGFR和c-Abl是否可以增强和重新靶向EGFR和c-Abl。 对CTX敏感，以及3）在以下患者中进行CTX加伊马替尼的初步机会窗研究： 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。 这些研究的成功进行有可能显着改善和完善目前的HER 通过了解Axl和Axl在HNC中作用的分子机制， c-Abl赋予CTXR。此外，该项目具有很高的意义，通过重新利用两个FDA批准的药物， 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 范例，并确定最有可能从靶向EGFR和c-Abl治疗HNC中获益的患者。

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.