Afatinib is effective in lung adenocarcinoma with an epidermal growth factor receptor exon 19 deletion-insertion (E746_A750delinsIP) detected by comprehensive genomic profiling: A case report

Among epidermal growth factor receptor (EGFR) exon 19 deletion mutations, rare deletion–insertion (“delins") variants in which one or more bases are inserted at the deletion site, have been identified. A patient with stage IIIA lung adenocarcinoma who had recurred in the mediastinal lymph nodes after chemoradiotherapy underwent immunochemotherapy. However, lymph node metastases progressed. Transbronchial needle biopsy was performed on the mediastinal lymph nodes. Comprehensive genomic profiling of the sample revealed a deletion-insertion of EGFR exon 19 ( E746_A750delinsIP ). After initiation of afatinib, the primary tumor and lymph node metastases markedly shrunk, and no recurrence was observed for 20 months.