Afatinib as first-line treatment for advanced lung adenocarcinoma patients harboring HER2 mutation: A case report and review of the literature.

HER2 mutations are a rare group of driving genes that respond to HER2 targeted therapy, particularly afatinib. No more than 20 such cases have been reported, but afatinib was used after first-line chemotherapy. We present the case of a never-smoking female patient diagnosed with stage IV lung adenocarcinoma harboring a Her2 exon 20 inserted mutation who achieved a durable response (12 months) to first-line afatinib treatment. We review the literature concerning afatinib therapy in this rare cohort of mutated lung cancer patients.