Development of a first-in-class mEGFR dimerization inhibitor

项目摘要/摘要 KRAS突变(MtKRAS)发生在大约25%的人类肿瘤中，并对 EGFR酪氨酸激酶抑制剂(TKI)。用药物靶向KRAS突变一直是具有挑战性的。我们是 开发DGD-1202是活化的EGFR激酶的特异性降解剂，而不是抑制剂，表现出深刻的 对mtKRAS驱动的小鼠肿瘤模型的活性。我们的数据表明，活化的EGFR的降解 在不影响mtKRAS水平的情况下，mtKRAS可能成为治疗TKI耐药mtKRAS驱动的肿瘤的一种新方法。我们 假设在这种wtEGFR/mtKRAS肿瘤类型中，EGFR的不依赖于激酶的作用对细胞至关重要 生死存亡。因此，活化的EGFR的降解足以杀死细胞，包括表达mtKRAS的细胞。 本研究的总体目标是确定DGD-1202的疗效和作用机制。因此， 这项提议的三个具体目标如下。在目标1中，我们将确定不依赖于激酶的角色 MtKRAS驱动的肿瘤中EGFR蛋白的表达。通过siRNA或shRNA消融EGFR可杀死两者驱动的EGFR 或mtKRAS表达细胞。这表明EGFR蛋白在细胞存活中起着重要的作用，而且是独立的。 它的蛋白激酶功能。我们假设，激酶死亡(KD)EGFR蛋白的表达将挽救细胞死亡 以EGFR消融的方式诱导这些细胞的增殖。在这个目标中，我们将研究死于激酶的egfr是否能促进细胞 存活和救援DGD-1202介导的细胞死亡。在目标2中，我们将阐明 DGD-1202诱导的EGFR降解克服了mtKRAS介导的TKI抵抗。EGFR蛋白的作用 重要的支架功能，其消融导致XCT和XCT等膜转运蛋白的丧失 SGLT1。这些转运蛋白的丢失分别限制了细胞对半胱氨酸和葡萄糖的摄取，从而减少了 关键自由基清除剂谷胱甘肽过氧化物酶的合成。在这一目标中，我们将调查 DGD-1202诱导mtKRAS驱动的癌细胞XCT和SGLT1上的EGFR降解及其对肿瘤细胞生长的影响 活性氧中间体的积累。根据我们的初步数据，我们假设DGD-1202 会降低wtEGFR细胞中XCT和SGLT1的蛋白水平，但对KD EGFR表达细胞的影响很小， 其中DGD-1202不降解EGFR。最后，在目标3中，我们将评估DGD-1202在 MtKRAS驱动的、抗EGFR TKI的异种移植和转基因小鼠模型。我们的预赛 数据表明，在几个mtKRAS驱动的癌症模型中，DGD-1202具有强大的单剂活性。在这个目标中， 我们将确定剂量和暴露-反应曲线。我们还将确定DGD-1202的效果 对长期生存的治疗。这种方法将针对广泛的患者，并提供一种治疗 治疗初治和EGFR-TKI耐药的mtKRAS驱动的肿瘤的选项。

Project Summary/Abstract The KRAS mutation (mtKRAS) occurs in approximately 25% of all human tumors and confers resistance to EGFR tyrosine kinase inhibitors (TKI). Targeting KRAS mutations with drugs has been challenging. We are developing DGD-1202 a specific degrader, not an inhibitor, of activated EGFR kinase that exhibits profound activity against mtKRAS-driven murine tumor models. Our data indicate that degradation of activated EGFR without affecting mtKRAS levels could be a novel therapy for TKI-resistant mtKRAS-driven tumors. We hypothesize that in such wtEGFR/mtKRAS tumor types, kinase-independent roles of EGFR are vital for cell survival. Therefore, degradation of activated EGFR is sufficient to kill cells, including mtKRAS expressing cells. The overall goal of our study is to confirm the efficacy and mechanism of action of DGD-1202. Accordingly, the three specific aims of this proposal are as follows. In Aim 1, we will determine the kinase-independent roles of EGFR protein in mtKRAS-driven tumors. The ablation of EGFR by siRNA or shRNA kills both EGFR-driven or mtKRAS expressing cells. This indicates that EGFR protein plays an essential role in cell survival, independent of its kinase functions. We hypothesize that kinase-dead (KD) EGFR protein expression will rescue cell death induced by EGFR ablation in these cells. In this aim, we will investigate if kinase-dead EGFR can promote cell survival and rescue DGD-1202 mediated cell death. In Aim 2, we will elucidate the mechanisms by which DGD-1202 induced EGFR degradation overcomes mtKRAS mediated TKI resistance. EGFR protein plays important scaffolding functions, and its ablation results in the loss of membrane transporters such as xCT and SGLT1. Loss of these transporters limits cellular uptake of cystine and glucose, respectively, thus reducing the synthesis of glutathione peroxidase, a key free radical scavenger. In this aim, we will investigate the effects of DGD-1202 induced EGFR degradation on xCT and SGLT1 in mtKRAS-driven cancer cells and its effect on the accumulation of reactive oxygen intermediates. Based on our preliminary data, we hypothesize that DGD-1202 will reduce xCT and SGLT1 protein levels in wtEGFR cells but have minimal effect in KD EGFR expressing cells, where DGD-1202 does not degrade EGFR. Finally, in Aim 3, we will assess the efficacy of DGD-1202 in a panel of mtKRAS-driven, EGFR TKI-resistant xenograft, and transgenic mouse models. Our preliminary data indicate the robust single-agent activity of DGD-1202 in several mtKRAS-driven cancer models. In this aim, we will determine the dose and exposure-response profiles. We will also determine the effect of DGD-1202 treatment on long-term survival. This approach will target a broad spectrum of patients and offer a therapeutic option for both treatment-naive and EGFR-TKI resistant mtKRAS-driven tumors.