Using Insights from EGFRvIII to Improve EGFR Directed Therapy in Human Gliomas

描述（由申请人提供）：EGF受体已成为合理治疗药物设计的关键靶点。超过60%的胶质母细胞瘤肿瘤表达高水平，并且细胞质外缺失变体EGFRvIII经常存在。现在有三种FDA批准的针对该受体的治疗剂：两种是酪氨酸激酶抑制剂（TKI），吉非替尼和厄洛替尼，第三种是单克隆抗体，西妥昔单抗（C225）。然而，所有这些药物的反应率仅为8- 15%。创造更有效地靶向EGFR的药物是下一个挑战。我们对EGFRvIII的研究已经强调了关于活化和致癌性的两个关键特征，其可以潜在地用于靶向EGFR和EGFRvIII。在具体目标#1中，我们将鉴定EGFRvIII中存在的独特二聚化基序。最近解决的EGF受体的晶体结构揭示了受体二聚化的一种机制，但这在EGFRvIII中被删除。鉴定EGFRvIII通过其二聚化的基序也将提示使所有EGFR家族二聚体失能的策略。对于特定目标#2，我们将确定高尔基体定位对EGFRvIII和wtEGFR的致癌特性的贡献。Ras的致癌信号来源于高尔基体定位蛋白，表明这种定位是关键的。我们将通过将受体引导至高尔基体，然后测试各种下游信号传导分子和与肿瘤相关的参数，来测试高尔基体EGFRvIII和EGFR的定位如何有助于它们的致癌性。我们还将使用细胞分级分离研究和共聚焦显微镜观察吉非替尼和厄洛替尼是否对基于高尔基体的受体具有任何不同的敏感性。在具体目标#3中，我们将综合这些信息以创建更有效地靶向胶质瘤中的EGFRvIII和wtEGFR的疗法。首先，我们将产生一个单克隆抗体的二聚化基序，并确定其在各种生物测定。将分析该单克隆抗体对肿瘤生长的影响，并与西妥昔单抗进行比较，以确认其更有效。将使用每种TKI进行单克隆抗体的联合治疗，以证明任何协同作用。动物模型的研究将探索TKI是否能更有效地抑制高尔基体受体。这项工作将揭示对EGFR和EGFRvIII特性的新见解，并将产生可用于创建胶质母细胞瘤肿瘤新药和疗法的信息。

DESCRIPTION (provided by applicant): The EGF receptor has emerged as a key target for rational therapeutic drug design. Over 60% of glioblastoma tumors express high levels and the extracytoplasmic deletion variant EGFRvlll is frequently present. There are now three FDA approved therapeutics against the receptor: two are tyrosine kinase inhibitors (TKIs), gefitinib and erlotinib, and the third is a monoclonal antibody, cetuximab (C225). However, the response rates for all of these drugs ranges from only 8-15%. Creating drugs that will more effectively target the EGFR is the next challenge. Our studies on EGFRvlll have highlighted two critical features regarding activation and oncogenicity that can potentially be exploited for targeting both EGFR and EGFRvlll. In Specific Aim #1, we will identify the unique dimerization motif present in EGFRvlll. The recently solved crystal structure of the EGF receptor has revealed one mechanism for receptor dimerization but this is deleted in EGFRvlll. Identifying the motif by which EGFRvlll dimerizes will also suggests a strategy for disabling all EGFR family dimers. For Specific Aim #2, we will determine the contribution of Golgi localization to the oncogenic properties of EGFRvlll and wtEGFR. The oncogenic signals of Ras originate from Golgi localized protein indicating that this localization is critical. We will test Golgi how the localization of EGFRvlll and EGFR contributes to their oncogenicity by directing receptor to the Golgi and then testing various downstream signaling molecules and parameters related to transfomation. We will also see if gefitinib and erlotinib have any differential sensitivity towards Golgi based receptor using cell fractionation studies and confocal microscopy. In Specific Aim #3, we will synthesize this information to create therapies that will more effectively target EGFRvlll and wtEGFR in gliomas. First, we will generate a monoclonal antibody to the dimerization motif and determine its in various biologic assays. The effect of this monoclonal on tumor growth will be analyzed in comparison with cetuximab to confirm that it is more effective. Combination therapy with the monoclonal antibody will be performed with each TKI to demonstrate any synergy. Work on animal models will explore if a TKI is more effective at inhibiting Golgi based receptor. This work will reveal new insights into the properties of EGFR and EGFRvlll and will yield information that can be applied to the creation of new drugs and therapies for glioblastoma tumors.