Genetically engineered mouse models (GEMMs) harboring YVMA and G776>VC insertions, allograft (Ba/F3-YVMA insertion) and PDX (NSCLC YVMA insertion) were utilized for the drug testing in vivo....mobocertinib showed strong inhibitory activity in HER2 exon 20YVMA allograft and PDX models....mobocertinib showed a robust inhibitory activity against HER2 exon 20 insertion mutations both in vitro and in vivo.