Small molecule inhibitors with a therapeutic window for EGFR signaling variants in glioblastoma

项目摘要 表皮生长因子受体(EGFR)基因在超过一半的GBM中发生突变或扩增，其 突变和局部放大与更具侵袭性的病程相关。然而，EGFR指导的 酪氨酸激酶抑制剂(TKI)未能显示出对这种疾病的疗效，这些失败不可能是 完全归因于糟糕的大脑透视率。我们假设，到目前为止，GBM的EGFR TKIs的失败反映了缺乏 一个治疗的窗口。应用EGFR抑制剂治疗非小细胞肺癌的经验教训 (非小细胞肺癌)是突变选择性是绝对必需的。无选择性，系统性抑制野生型 (WT)EGFR信号是剂量限制性毒性。在非小细胞肺癌中，激活酪氨酸激酶域的突变 与WT EGFR相比，增强了对某些EGFR TKI的敏感性，允许真正的突变选择性 抑制力。胶质母细胞瘤(GBM)中的EGFR基因异常产生结构性的、非配体依赖性的 通过结构上几乎完全是WT的信号发生域传递信号。我们的目标是创造 EGFR TKIs为GBM中异常的EGFR信号提供了治疗窗口。我们有两个具体目标。 目标1是检验具有变构作用机制的EGFR TKI将选择性地 阻断GBM中非配体依赖的EGFR信号，同时系统地保留配体激活的EGFR信号，从而 提供了一个治疗窗口，允许有效治疗EGFR驱动的基底膜。在初步研究中， 我们已经开发出能够有效抑制WT EGFR(IC50；100 NM)的小分子变构抑制剂。 生化分析)，有良好的口服小鼠PK特征，并是脑穿透。以功效为导向 在患者来源的GBM神经球和异种移植模型的研究中，我们希望确定一种适合的化合物 在第一个赠款年度用于临床开发，以便在未来几年实现临床转化。 Aim 2，利用了CM93，一种新型的第三代EGFR TKI，具有高度的脑渗透性-如此之多 它实际上显示了正的脑/血浆比率。我们将检验这样的假设，即CM93可以提供 事实上的“基于组织的”治疗窗口，允许在相对保守的情况下有效地抑制肿瘤中的EGFR 对受体的系统性研究。为此，我们将进行人类首个阶段1，剂量递增和 剂量扩张研究，以及外科“机会窗”研究，以确定最大耐受量 剂量，评价其安全性、药代动力学、药效学和临床疗效 以EGFR突变或扩增为特征的复发性胶质母细胞瘤患者的CM93。 我们的药理和基因组成像核心将促进临床材料的研究 (PGIC)。PGIC将允许我们使用MALDI MASS来量化CM93在肿瘤内的积聚 利用单细胞光谱成像和确定CM93治疗对肿瘤异质性的影响 测序。总的来说，这些研究承诺为EGFR驱动的GBM产生新的靶向疗法 提供对这些药物敏感性和耐药性决定因素的分子理解。

Project Summary The epidermal growth factor receptor (EGFR) gene is mutated or amplified in over half of GBMs, and its mutation and focal amplification correlate with a more aggressive disease course. However, EGFR-directed tyrosine kinase inhibitors (TKIs) have failed to show efficacy in this disease and these failures cannot be attributed strictly to poor brain penetrance. We posit that the failure to date of EGFR TKIs for GBM reflects lack of a therapeutic window. A lesson learned from application of EGFR inhibitors in non-small cell lung cancer (NSCLC) is that mutant-selectivity is absolutely required. Without selectivity, systemic inhibition of wild-type (WT) EGFR signaling is the dose-limiting toxicity. In NSCLC, activating mutations in the tyrosine kinase domain confer enhanced sensitivity to certain EGFR TKIs relative to WT EGFR, allowing true mutant-selective inhibition. The EGFR genetic aberrations in glioblastoma (GBM) create constitutive, ligand-independent signaling via signal generating domains that are almost exclusively WT in structure. Our objective is to create EGFR TKIs with a therapeutic window for aberrant EGFR signaling in GBM. We have two specific aims. Aim 1, is to test the hypothesis that an EGFR TKI with an allosteric mechanism of action will selectively block ligand-independent EGFR signaling in GBM while sparing ligand-activated EGFR systemically, thereby providing a therapeutic window that allows effective treatment of EGFR-driven GBMs. In preliminary studies, we have developed small-molecule allosteric inhibitors that potently inhibit WT EGFR (IC50 < 100 nM in biochemical assays) and have a good oral mouse PK profile and are brain-penetrant. Guided by efficacy studies in patient-derived GBM neurosphere and xenograft models, we expect to identify a compound suitable for clinical development in the first grant year, to enable clinical translation in the out years. Aim 2, exploits CM93, a novel third generation EGFR TKI that is highly brain-penetrant – so much so that it actually displays a positive brain/plasma ratio. We will test the hypothesis that CM93 can provide a de facto “tissue-based” therapeutic window allowing effective inhibition of EGFR in the tumor with relative sparing of the receptor systemically. Towards this end, we will conduct a first-in-human, phase 1, dose-escalation and dose-expansion study, as well as a surgical “window of opportunity” study to determine the maximum tolerated dose, evaluate the safety, pharmacokinetics, pharmacodynamics and clinical effects of orally administered CM93 in subjects with recurrent glioblastoma characterized by EGFR mutation or amplification. Studies on clinical materials will be facilitated by our Pharmacological and Genomics Imaging Core (PGIC). The PGIC will allow us to quantify intra-tumoral accumulation of CM93 using MALDI mass spectrometry imaging and to define the impact of CM93 treatment on tumor heterogeneity using single cell sequencing. Collectively, these studies promise to yield new targeted therapeutics for EGFR-driven GBMs and provide a molecular understanding of determinants of sensitivity and resistance to these agents.