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

描述(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%的胶质母细胞瘤表达高水平，胞外缺失突变体EGFRv11经常出现。目前FDA批准的针对该受体的治疗药物有三种：两种是酪氨酸激酶抑制剂(TKIs)、吉非替尼和厄洛替尼，第三种是单抗西妥昔单抗(C225)。然而，所有这些药物的应答率都只有8%-15%。创造更有效地针对EGFR的药物是下一个挑战。我们对EGFRv11的研究强调了两个关于激活和致癌的关键特征，这两个特征可能被用来靶向EGFR和EGFRv11。在特定的目标#1中，我们将确定EGFRv11中存在的独特的二聚化基序。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，但这一机制在EGFRv11中被删除。确定EGFRv11二聚化的基序也将暗示一种禁用所有EGFR家族二聚体的策略。对于特定的目标#2，我们将确定高尔基体定位对EGFRv11和wtEGFR致癌特性的贡献。RAS的致癌信号来源于高尔基体定位的蛋白，表明这种定位是关键的。我们将通过将受体定向到高尔基体，然后测试与转化相关的各种下游信号分子和参数，来测试EGFRv11和EGFR的定位对其致瘤性的影响。我们还将使用细胞分离研究和共聚焦显微镜观察吉非替尼和厄洛替尼对高尔基受体是否有区别敏感性。在特定的目标#3中，我们将综合这些信息来创造更有效地针对胶质瘤中的EGFRv11和wtEGFR的治疗方法。首先，我们将产生针对二聚化基序的单抗，并在各种生物检测中对其进行检测。该单抗对肿瘤生长的影响将与西妥昔单抗进行比较分析，以确认其更有效。将对每个TKI进行与单抗的联合治疗，以显示任何协同作用。在动物模型上的工作将探索TKI是否在抑制高尔基体受体方面更有效。这项工作将揭示对EGFR和EGFRv11特性的新见解，并将产生可应用于胶质母细胞瘤肿瘤的新药和治疗的信息。

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.