Background: Accumulating data shows that exon 19 deletions and L858R, both activating epidermal growth factor receptor mutations in non-small-cell lung cancers (NSCLCs), are just two different entities in terms of prognosis and treatment response to tyrosine kinase inhibitors (TKIs).
Methods: A systematic review and meta-analysis of randomized controlled trials comparing TKIs with conventional chemotherapy was performed. Eight trials of 1498 patients and five trials of 1279 patients with either exon 19 deletions or L858R were included in the meta-analysis.
Results: TKI treatment demonstrated progression-free survival benefit in patients with exon 19 deletions (hazard ratio (HR): 0.27, 95% confidence interval (CI): 0.21-0.35) and L858R (HR: 0.45, 95% CI: 0.35-0.58). Patients with exon 19 deletions had significant overall survival (OS) benefit under TKI treatment (HR: 0.72, 95% CI: 0.60-0.88). Subgroup analyses showed that irreversible TKIs, but not reversible TKIs, had statistically significant OS benefit in these patients (irreversible TKIs, HR: 0.59, 95% CI: 0.47-0.73; reversible TKIs, HR: 0.84, 95% CI: 0.69-1.02). Patients with L858R demonstrated no OS benefit under first-line TKI use (HR: 1.15, 95% CI: 0.95-1.39).
Conclusions: In patients with advanced NSCLC harbouring exon 19 deletions, TKIs are associated with better OS compared with conventional chemotherapy. Future clinical trials should take exon 19 deletions and L858R as distinct disease entities and evaluate the treatment efficacy separately.