Efficacy analysis of tyrosine kinase inhibitors on rare non-small cell lung cancer patients harboring complex EGFR mutations

The efficacy of epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKI) in patients with non-small cell lung cancer (NSCLC) is related to EGFR mutations. Although the p.L858R point mutation in exon 21 and the in-frame deletion mutation in exon 19 are well known, efficacy of EGFR-TKI in patients with more than one EGFR mutation is not well understood. 799 NSCLC patients were screened for EGFR mutations. Of the 799 patients, 443 (55.4%) had mutations, out of which 22 (2.75%) had multiple complex mutations. Most multiple mutations (20/22) harbored common mutations such as the p.L858R point mutation in exon 21 and the in-frame deletion mutation in exon 19. 11 out of 22 patients who had multiple EGFR mutations underwent TKI therapy and primary end-points of progression free and overall survival were determined. Our analysis revealed that cases with multiple mutations had similar end-point outcomes as single mutation to TKI therapy. Report of these cases will be helpful in decision making for treatment of NSCLC patients harboring multiple EGFR mutations.