Genomic profiling reveals non-small cell lung cancer with common mutations of EGFR exon 20 and exon 21: a case report

Epidermal growth factor receptor (EGFR) gene is one of the most common driver genes for non-small cell lung cancer (NSCLC). The PIONEER study showed that 51.4% of unselected Asian patients with advanced lung adenocarcinoma have EGFR-sensitive mutations. EGFR mutations mainly occur in the first four [18-21] exons of the intracellular tyrosine kinase (TK) region. At present, there are more than 30 types of mutations in the TK region, including exon 19 deletion mutation (19Del) and exon 21 L858R mutation (L858R) which are the most common types of sensitive mutations, accounting for more than 90% of all EGFR mutations. About 10% of NSCLC patients with EGFR mutations are rare mutation types, including exon 18 point mutation (G719X), exon 20 point mutation (S768I), exon 19 point mutation (L747S), exon 21 point mutation (L833V), etc. About 1% of NSCLC patients have primary double mutations of EGFR.In this present study, we identified a 59-year-old female patient with no smoking history had double mutations in EGFR exon 20 R776S mutation and exon 21 L858R mutation by next-generation sequencing (NGS).This observation may explore a new mechanism study for EGFR-TKIs and provide a new direction for clinical treatment of NSCLC.