Lung Adenocarcinoma Harboring Triple Rare EGFR Exon 18 Mutations Rapidly Developed Resistance to Multiple Therapies.

There is no standard therapy for nonsmall-cell lung cancer harboring rare coexistent EGFR mutations. Here, we report a female patient who was diagnosed as lung adenocarcinoma with three mutations of G724S, E709K, and V689I in exon 18. The patient responded to, but also showed rapid development of resistance to multiple therapies, including a second-generation EGFR-TKI of afatinib, a platinum-based doublet chemotherapy, and a multiple target TKI of anlotinib. As such, she ended up with a short overall survival time. Further research is required to understand the resistance mechanism(s) of these complex gene mutations.