Uncommon mutations account for 10-15% of epidermal growth factor receptor (EGFR) mutations in patients with non-small-cell lung cancer. Afatinib is currently the most efficient EGFR-tyrosine kinase inhibitor (TKI) against uncommon EGFR mutations. Here we report a 56-year-old woman presenting with persistent cough for one month. She was diagnosed with stage IV lung adenocarcinoma by bronchoscopic biopsy to the left lower lung tumour and serial image modalities. A rare H773L/V774M compound mutation in exon 20 was detected by gene sequencing. The patient received first-line afatinib but primary resistance was noted with rapid left lower lung tumour progression. Second-line chemotherapy combined with bevacizumab, pemetrexed, and cisplatin demonstrated more durable response. Our case suggests that H773L/V774M may be one of the EGFR-TKI-resistant uncommon EGFR mutations.
Keywords: Afatinib; H773L/V774M; epidermal growth factor receptor; non‐small‐cell lung cancer; uncommon mutations.