Division of Cancer Immunology, Exploratory Oncology Research & Clinical Trial Center (EPOC), National Cancer Center, Chiba, Japan.
Department of Thoracic Oncology, National Cancer Center Hospital, Tokyo, Japan.
Thorac Cancer. 2021 Mar;12(5):631-642. doi: 10.1111/1759-7714.13839. Epub 2021 Jan 20.
Patients with non-small cell lung cancer (NSCLC) harboring activating EGFR mutations are sensitive to epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKIs) but inevitably develop resistance to the inhibitors mostly through acquisition of the secondary T790M mutation. Although third-generation EGFR-TKIs overcome this resistance by selectively inhibiting EGFR with EGFR-TKI-sensitizing and T790M mutations, acquired resistance to third-generation EGFR-TKIs invariably develops.
Next-generation sequencing (NGS) and fluorescence in situ hybridization (FISH) analysis were performed in an EGFR T790M-mutated NSCLC patient who had progressed after a third-generation EGFR-TKI, TAS-121. EGFR-mutated cell lines were subjected to a cell proliferation assay and western blotting analysis with EGFR-TKIs and a heat shock protein 90 (HSP90) inhibitor.
NGS and FISH analysis revealed EGFR amplification in the resistant cancer cells. While EGFR L858R/T90M-mutated cell line was sensitive to osimertinib or TAS-121 in vitro, EGFR-overexpressing cell lines displayed resistance to these EGFR-TKIs. Western blot analysis showed that EGFR phosphorylation and overexpression of EGFR in cell lines was not suppressed by third-generation EGFR-TKIs. In contrast, an HSP90 inhibitor reduced total and phosphorylated EGFR and inhibited the proliferation of resistant cell lines.
EGFR amplification confers resistance to third-generation EGFR-TKIs which can be overcome by HSP90 inhibition. The results provide a preclinical rationale for the use of HSP90 inhibitors to overcome EGFR amplification-mediated resistance.
携带激活表皮生长因子受体（EGFR）突变的非小细胞肺癌（NSCLC）患者对表皮生长因子受体酪氨酸激酶抑制剂（EGFR-TKIs）敏感，但不可避免地会因获得继发性 T790M 突变而对抑制剂产生耐药性。尽管第三代 EGFR-TKIs 通过选择性抑制 EGFR 与 EGFR-TKI 敏感和 T790M 突变来克服这种耐药性，但不可避免地会产生对第三代 EGFR-TKIs 的获得性耐药性。
对第三代 EGFR-TKI，TAS-121 治疗后进展的 EGFR T790M 突变型 NSCLC 患者进行下一代测序（NGS）和荧光原位杂交（FISH）分析。将 EGFR 突变细胞系进行细胞增殖测定和 Western blot 分析，使用 EGFR-TKIs 和热休克蛋白 90（HSP90）抑制剂。
NGS 和 FISH 分析显示耐药癌细胞中 EGFR 扩增。虽然 EGFR L858R/T90M 突变细胞系在体外对奥希替尼或 TAS-121 敏感，但 EGFR 过表达细胞系对这些 EGFR-TKIs 表现出耐药性。Western blot 分析表明，第三代 EGFR-TKIs 不能抑制细胞系中 EGFR 的磷酸化和过表达。相比之下，HSP90 抑制剂可降低总 EGFR 和磷酸化 EGFR 并抑制耐药细胞系的增殖。
EGFR 扩增赋予第三代 EGFR-TKIs 耐药性，可通过 HSP90 抑制克服。这些结果为使用 HSP90 抑制剂克服 EGFR 扩增介导的耐药性提供了临床前依据。
