Abstract
Tyrosine kinase inhibitor (TKI) therapy is one of the established standards in patients with frequent mutations in the epidermal growth factor (EGFR) gene - ie L858R point mutation and a deletions on exon 19 - generalized non-small cell lung cancer (NSCLC). However, for other (so-called rare) EGFR mutations, the situation regarding the efficacy of EGFR-TKI in NSCLC is in many cases uncertain.
Our case report of a patient with a rare short duplication of the EGFR gene at exon 19 confirms a possible positive effect of afatinib, that was reported in the previous literature. Furthermore, we describe a relatively rare cause of resistance to this treatment - a point mutation in the NRAS gene (NRAS G12D) proven by the next generation sequencing (NGS) method of circulating tumor DNA (ctDNA) from blood sampling.
Unfortunately, despite ongoing research, a reliable TKI targeting this mutation is not yet known.