Department of Oncology, University of Turin Medical School, Turin, Italy. Laboratory of Translational Cancer Medicine, Candiolo Cancer Institute-FPO IRCCS, Turin, Italy.
Laboratory of Translational Cancer Medicine, Candiolo Cancer Institute-FPO IRCCS, Turin, Italy.
Clin Cancer Res. 2015 Dec 15;21(24):5519-31. doi: 10.1158/1078-0432.CCR-14-3066. Epub 2015 Aug 21.
Preclinical studies in HER2-amplified gastrointestinal cancer models have shown that cotargeting HER2 with a monoclonal antibody and a small molecule is superior to monotherapy with either inhibitor, but the underlying cooperative mechanisms remain unexplored. We investigated the molecular underpinnings of this synergy to identify key vulnerabilities susceptible to alternative therapeutic opportunities.
The phosphorylation/activation of HER2, HER3, EGFR (HER receptors), and downstream transducers was evaluated in HER2-overexpressing colorectal and gastric cancer cell lines by Western blotting and/or multiplex phosphoproteomics. The in vivo outcome of antibody-mediated HER2 blockade by trastuzumab, reversible HER2 inhibition by lapatinib, and irreversible HER2 inhibition by afatinib was assessed in patient-derived tumorgrafts and cell-line xenografts by monitoring tumor growth curves and by using antibody-based proximity assays.
Trastuzumab monotherapy reduced HER3 phosphorylation, with minor consequences on downstream transducers. Lapatinib alone acutely inhibited all HER receptors and effectors but led to delayed rephosphorylation of HER3 and EGFR and partial restoration of ERK and AKT activity. When combined with lapatinib, trastuzumab prevented HER3/EGFR reactivation and caused prolonged inhibition of ERK/AKT. Afatinib alone was also very effective in counteracting the reinstatement of HER3, EGFR, and downstream signaling activation. In vivo, the combination of trastuzumab and lapatinib-or, importantly, monotherapy with afatinib-resulted in overt tumor shrinkage.
Only prolonged inhibition of HER3 and EGFR, achievable by dual blockade with trastuzumab and lapatinib or irreversible HER2 inhibition by single-agent afatinib, led to regression of HER2-amplified gastrointestinal carcinomas. Clin Cancer Res; 21(24); 5519-31. ©2015 AACR.
在 HER2 扩增的胃肠道癌模型的临床前研究中表明，与单克隆抗体和小分子联合靶向 HER2 优于任何一种抑制剂的单药治疗，但潜在的合作机制仍未被探索。我们研究了这种协同作用的分子基础，以确定对替代治疗机会敏感的关键弱点。
通过 Western blot 和/或多磷酸化蛋白质组学评估了 HER2 过表达的结直肠和胃癌细胞系中 HER2、HER3、EGFR（HER 受体）及其下游转导物的磷酸化/激活。通过监测肿瘤生长曲线和使用基于抗体的接近测定法，评估曲妥珠单抗介导的 HER2 阻断、拉帕替尼可逆性 HER2 抑制和阿法替尼不可逆性 HER2 抑制的抗体在患者来源的肿瘤移植瘤和细胞系异种移植瘤中的体内疗效。
曲妥珠单抗单药治疗可降低 HER3 磷酸化，但对下游转导物的影响较小。拉帕替尼单独可急性抑制所有 HER 受体和效应物，但导致 HER3 和 EGFR 的重新磷酸化延迟，并部分恢复 ERK 和 AKT 活性。当与拉帕替尼联合使用时，曲妥珠单抗可防止 HER3/EGFR 重新激活，并导致 ERK/AKT 的持续抑制。阿法替尼单独使用也非常有效地对抗 HER3、EGFR 和下游信号转导激活的恢复。在体内，曲妥珠单抗和拉帕替尼的联合治疗 - 或者更重要的是，单药使用阿法替尼 - 导致 HER2 扩增的胃肠道癌明显缩小。
只有通过曲妥珠单抗和拉帕替尼的双重阻断或单药使用阿法替尼实现的 HER3 和 EGFR 的持续抑制，才能导致 HER2 扩增的胃肠道癌的消退。临床癌症研究；21(24)；5519-31. ©2015 AACR.
