Backgrounds: It has been extensively proved that the efficacy of epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKIs) is superior to that of cytotoxic chemotherapy in advanced non-small cell lung cancer (NSCLC) patients harboring sensitive EGFR mutations. However, the question of whether the efficacy of EGFR-TKIs differs between exon 19 deletion and exon 21 L858R mutation has not been yet statistically answered.
Methods: Subgroup data on hazard ratio (HR) for progression-free survival (PFS) of correlative studies were extracted and synthesized based on random-effect model. Comparison of outcomes between specific mutations was estimated through indirect and direct methods, respectively.
Results: A total of 13 studies of advanced NSCLC patients with either 19 or 21 exon alteration receiving first-line EGFR-TKIs were included. Based on the data from six clinical trials for indirect meta-analysis, the pooled HRTKI/chemotherapy for PFS were 0.28 (95% CI 0.20-0.38, P<0.001) in patients with 19 exon deletion and 0.47 (95% CI 0.35-0.64, P<0.001) in those with exon 21 L858R mutation. Indirect comparison revealed that the patients with exon 19 deletion had longer PFS than those with exon 21 L858R mutation (HR19 exon deletion/exon 21 L858R mutation = 0.59, 95% CI 0.38-0.92; P = 0.019). Additionally, direct meta-analysis showed similar result (HR19 exon deletion/exon 21 L858R mutation = 0.75, 95% CI 0.65 to 0.85; P<0.001) by incorporating another seven studies.
Conclusions: For advanced NSCLC patients, exon 19 deletion might be associated with longer PFS compared to L858 mutation at exon 21 after first-line EGFR-TKIs.