Background: The third‐generation EGFR tyrosine kinase inhibitor osimertinib has been approved in many countries to treat advanced NSCLC in patients with the EGFR T790M mutation. As the development of acquired resistance is inevitable, it is urgent that the mechanisms of such resistance be clarified. Methods: DNA samples from a cohort of 340 patients with lung adenocarcinoma who were taking osimertinib were subjected to next‐generation sequencing and screened in terms of the frequencies of the L792H and G796R mutations. Ba/F3 cells stably expressing the EGFR L858R/T790M mutations (in cis) with either the L792H or G796R mutation were created to investigate the impact of the two novel mutations on EGFR tyrosine kinase inhibitors and other potential drug combinations in vitro. Structural analyses were performed by using Schrödinger/Maestro software (version 11.1.012, Schrödinger LLC, Cambridge, MA). Results: L792H and G796R were detected in 1.76% (six of 340) and 0.56% (two of 340) patients with lung adenocarcinoma treated with osimertinib, respectively. The introduction of L792H or G796R mutations against an L858R/T790M background caused dramatic reductions in osimertinib sensitivity. Structural modeling showed that mutations in cis with T790M either forced the ligand (osimertinib) to rotate out (breaking the binding) or pulled the hinge loop (breaking the hinge). Various other drug combinations. including cetuximab with EAI045, failed to inhibit either cis mutant effectively. Conclusions: The EGFR L858R/T790M/L792H and L858R/T790M/G796R mutations conferred resistance to osimertinib both in vitro and in silico. For patients in whom the two resistance mutations occur at low frequency, more precise treatment strategies and additional combinational approaches are required.

中文翻译：

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EGFR L792H 和 G796R：介导对第三代表皮生长因子受体酪氨酸激酶抑制剂奥希替尼耐药的两种新突变

背景：第三代EGFR酪氨酸激酶抑制剂奥希替尼已在许多国家被批准用于治疗EGFR T790M突变的晚期NSCLC患者。由于获得性耐药性的发展是不可避免的，因此迫切需要阐明这种耐药性的机制。方法：对 340 名服用奥希替尼的肺腺癌患者的 DNA 样本进行二代测序，并根据 L792H 和 G796R 突变的频率进行筛选。创建了稳定表达具有 L792H 或 G796R 突变的 EGFR L858R/T790M 突变（顺式）的 Ba/F3 细胞，以研究这两种新突变对体外 EGFR 酪氨酸激酶抑制剂和其他潜在药物组合的影响。使用 Schrödinger/Maestro 软件（版本 11.1.012，Schrödinger LLC，Cambridge，MA）进行结构分析。结果：分别在 1.76%（340 名中的 6 名）和 0.56%（340 名中的 2 名）接受奥希替尼治疗的肺腺癌患者中检测到 L792H 和 G796R。针对 L858R/T790M 背景引入 L792H 或 G796R 突变导致奥希替尼敏感性显着降低。结构模型显示，T790M 的顺式突变要么迫使配体（奥希替尼）旋转（打破结合），要么拉动铰链环（打破铰链）。各种其他药物组合。包括带有 EAI045 的西妥昔单抗，未能有效抑制任一顺式突变体。结论： EGFR L858R/T790M/L792H 和 L858R/T790M/G796R 突变赋予对奥希替尼的体外和计算机抗性。