To detect the mutation abundance and sites of epidermal growth factor receptor (EGFR), and to investigate their influence on the therapeutic efficacy of EGFR-tyrosine kinase inhibitors (EGFR-TKIs) in patients with advanced non-small cell lung carcinoma (NSCLC).
A total of 2,417 NSCLC patients with EGFR gene mutations were retrospectively analyzed using an amplification refractory mutation system (ARMS). Of 861 patients, 407 patients had exon 19 deletions and 454 patients had exon 21 (L858R) site mutations of the EGFR gene. Next we analyzed the mutation abundance of lung adenocarcinoma patients who received EGFR-TKI therapy and complete follow up. 194 patients diagnosed with stage IIIB or stage IV lung adenocarcinoma with an ECOG score of 0-3 were enrolled. The primary endpoint was to determine associations between progression-free survival (PFS) and mutation abundance or mutation sites after EGFR-TKI therapy. The secondary endpoint was to evaluate the objective response rate and effects when EGFR-TKI was administered as the first-line treatment, as well as risk factor analysis for PFS.
Of the 194 enrolled patients, the median PFS was 9.3 months (95% CI, 8.2–10.8 months). The PFS was significantly different with EGFR gene mutation abundance after EGFR-TKI therapy (P = 0.014). The median PFS was significantly longer when the cut-off value of EGFR mutation abundance of exon 19 or exon 21, exon19 was > 26.7% and 61.8%, respectively. For patients who received EGFR-TKI as first-line treatment, the median PFS was significantly longer in the high mutation abundance group than in the low mutation abundance group (12.7 m vs 8.7 m, P = 0.002). However, there was no significant correlation with gender, age or smoking status and PFS.
The PFS benefits were greater in patients with a higher abundance of exon 19 mutations in the EGFR gene after EGFR-TKI treatment.
Clinical trial identification
Legal entity responsible for the study
All authors have declared no conflicts of interest.