非小细胞肺癌（NSCLC）表皮生长因子受体（EGFR）基因中大约10%的突变为外显子20（X20）内框插入。这些肿瘤通常不对常规EGFR酪氨酸激酶抑制剂（TKIs）起反应。包括最近被美国食品药品监督管理局（FDA）批准的mobocertinib在内，临床开发了几种针对X20插入的新型EGFR-TKIs。然而，在使用这些TKIs治疗期间仍存在后期获得性耐药性，就像早期一代的EGFR-TKIs一样。我们长期暴露了五种最常见的X20插入突变（A763_Y764insFQEA、V769_D770insASV、D770_N771insSVD、H773_V774insNPH和H773_V774insH）转导的Ba/F3细胞，将其与N-乙基-N-亚硝胺一起用于mobocertinib，并寻找次级EGFR突变。我们评估了几种EGFR X20插入抑制剂（包括zipalertinib和sunvozertinib）对带有获得性耐药突变的细胞的疗效。所有导致获得性mobocertinib耐药性的次级突变均仅为insFQEA和insSVD的C797S。然而，在其他X20插入（insASV、insNPH和insH）中，T790M或C797S次级突变对mobocertinib的耐药性起到作用。T790M的出现在药物浓度较低的细胞中更为频繁。Sunvozertinib对带有T790M的耐药细胞表现了良好的活性。C797S的细胞对所有EGFR-TKIs均无效，除了对带有C797的insFQEA有效的erlotinib。根据初始X20插入突变的情况，T790M或C797S可导致对mobocertinib的获得性耐药性。基于T790M的mobocertinib耐药性，Sunvozertinib可能是治疗选择。 版权所有©2023国际肺癌研究学会，由Elsevier Inc.出版。保留所有权利。

Approximately 10% of mutations in the epidermal growth factor receptor (EGFR) gene in non-small cell lung cancer (NSCLC) are in-frame insertions in exon 20 (X20ins). These tumors usually do not respond to conventional EGFR-tyrosine kinase inhibitors (TKIs). Several novel EGFR-TKIs active for X20ins are in clinical development, including mobocertinib, which was recently approved by the US FDA. However, acquired resistance during treatment with these TKIs still occurs as in the case of EGFR-TKIs of earlier generations.We chronically exposed Ba/F3 cells transduced with five most common X20ins (A763_Y764insFQEA, V769_D770insASV, D770_N771insSVD, H773_V774insNPH and H773_V774insH) to mobocertinib in the presence of N-ethyl-N-nitrosourea and searched for secondary EGFR mutations. We evaluated the efficacies of several EGFR X20ins inhibitors, including zipalertinib and sunvozertinib, against cells with acquired resistant mutations.All secondary mutations resulting in acquired resistance to mobocertinib were exclusively C797S in insFQEA and insSVD. However, in the case of other X20ins (insASV, insNPH and insH), T790M or C797S secondary mutations contributed to acquired resistance to mobocertinib. The emergence of T790M was more frequent in cells treated with lower drug concentrations. Sunvozertinib showed good activity against resistant cells with T790M. Cells with C797S were refractory to all EGFR-TKIs, except for erlotinib, which was active for insFQEA with C797S.T790M or C797S, depending on the original X20ins mutations, conferred acquired resistance to mobocertinib. Sunvozertinib may be the treatment of choice for patients with tumors resistant to mobocertinib because of T790M.Copyright © 2023 International Association for the Study of Lung Cancer. Published by Elsevier Inc. All rights reserved.