Patient 4 was a 65 year-old female never-smoker who was diagnosed with advanced lung adenocarcinoma...Then she received nivolumab immunotherapy as the second-line treatment and confirmed progressive disease (PD) after eight cycles with new onset of bone and brain metastases...The result of NGS of re-biopsy tissue revealed HER2 exon 20 insertion mutation (p.G778_S779insCPG)...