西妥昔单抗可在约 13% 的头颈鳞状细胞癌 (HNSCC) 中诱导反应。我们描述了西妥昔单抗获得性耐药的分子机制，可以通过改用不同的抗 EGFR 抗体来克服。在三个不同的时间点收集活检：西妥昔单抗开始使用前 (PRE-cetux)、西妥昔单抗获得性耐药时 (AR-cetux) 和杜利戈珠单抗获得性耐药时 (AR-duligo)。使用肿瘤和正常全外显子组测序、RNASeq 和超深覆盖的靶向面板测序来分析活检，以生成差异突变和表达谱。 WES 和靶向测序分析在 AR-cetux 活检中发现了 EGFR p.G465R 胞外域突变。此外，RNASeq证实了该突变在肿瘤组织中的表达。该突变阻止了西妥昔单抗与 EGFR 的结合，并且在 PRE-cetux 和 AR-duligo 活检中不存在，表明西妥昔单抗获得性耐药的潜在机制。分子动力学模拟证实 duligotuzumab 可有效结合带有 p.G465R 突变的 EGFR。有趣的是，与野生型 EGFR 相比，p.G465R 突变提高了 duligotuzumab-EGFR 复合物的稳定性。这是第一份关于 EGFR ECD 突变与西妥昔单抗获得性耐药相关的报告，需要进一步验证。我们建议对最初具有西妥昔单抗获益的特定患者应考虑进行适当的连续突变分析来识别 ECD 突变。© 2024。作者获得 Springer Nature America, Inc. 的独家许可。

Cetuximab induces responses in about 13% of head and neck squamous cell carcinomas (HNSCC). We describe the molecular mechanism of acquired resistance to cetuximab, which could be overcome by switching to a different anti-EGFR antibody. Biopsies were collected at three different time points: before the start of cetuximab (PRE-cetux), at acquired resistance to cetuximab (AR-cetux), and at acquired resistance to duligotuzumab (AR-duligo). Biopsies were analyzed using tumor and normal whole-exome sequencing, RNASeq, and targeted panel sequencing with ultra-deep coverage to generate differential mutation and expression profiles. WES and targeted sequencing analysis identified an EGFR p.G465R extracellular domain mutation in AR-cetux biopsy. Furthermore, RNASeq confirmed the expression of this mutation in the tumor tissue. This mutation prevented the binding of cetuximab to EGFR and was not present in PRE-cetux and AR-duligo biopsies, suggesting a potential mechanism of acquired resistance to cetuximab. Molecular dynamic simulations confirmed that duligotuzumab effectively binds EGFR with a p.G465R mutation. Interestingly, the p.G465R mutation improved the stability of the duligotuzumab-EGFR complex as compared to the wild-type EGFR. This is the first report of an EGFR ECD mutation associated with acquired resistance to cetuximab, posing a need for further validation. We suggest appropriate serial mutational profiling to identify ECD mutations should be considered for select patients with initial cetuximab benefit.© 2024. The Author(s), under exclusive licence to Springer Nature America, Inc.