Efficacy of Icotinib, an EGFR Tyrosine Kinase Inhibitor in Non-Small Cell Lung Cancer Patients with Exon 19 Deletion and Exon 21 L858R: A Retrospective Analysis in China.

INTRODUCTION: The effect of icotinib on non-small cell lung cancer (NSCLC) patients with EGFR exon 19 deletions (19-Del) or L858R point mutation in exon 21 (21-L858R) remains inconsistent. This study aimed to evaluate the efficacy and safety of icotinib in patients with advanced NSCLC harboring these 2 EGFR mutations. METHODS: We retrospectively assessed the clinical effects of first-line icotinib on advanced NSCLC patients with 2 classic EGFR mutations. Kinase activity assays were used to reaffirm the preclinical efficacy. RESULTS: Among 2,757 patients, 2,365 (86%) harbored 19-Del (1,346/2,757, 49%) or 21-L858R (1,019/2,757, 37%) mutation. Patients with 19-Del had a higher response rate (ORR; 67.8 vs. 62.1%; p = 0.0039) and disease control rate (98.5 vs. 97.2%; p = 0.0223) than those with 21-L858R mutation. The median progression-free survival (PFS) in the 19-Del group (22.3 months, 95% confidence interval [CI]: 21.3-23.4) was significantly longer than that in the 21-L858R group (20.4 months, 95% CI: 19.5-21.7) (p = 0.004). In multivariate analysis, mutation types, clinical stage, and smoking history were significant factors for PFS. Additionally, an in vitro study indicated the 50% inhibitory concentrations (IC50) of icotinib was lower for EGFR 19-Del than 21-L858R. CONCLUSION: These results suggest that EGFR 19-Del confers superior PFS and response to the icotinib treatment compared to 21-L858R.

Differential efficacy of cisplatin plus pemetrexed between L858R and Del-19 in advanced EGFR-mutant non-squamous non-small cell lung cancer.

BACKGROUND: LUX-Lung 3 showed afatinib improved progression-free survival (PFS) compared with cisplatin plus pemetrexed in patients with epidermal growth factor receptor (EGFR) mutations. In this study, chemotherapy efficacy tended to differ between patients with Leu858Arg (L858R) point mutation and Exon 19 deletion (Del-19); PFS in L858R patients (8.1 months) was greater than in Del-19 patients (5.6 months). We investigated whether there is any difference in efficacy of cisplatin plus pemetrexed between Del-19 and L858R. METHODS: This study is a multicenter retrospective study. We reviewed medical records of patients who had received cisplatin plus pemetrexed as first line chemotherapy. Efficacies were evaluated between EGFR mutation status: Del-19 and L858R. Wild type cases were reference arm only, and not included in any statistical analysis. RESULTS: Among 304 patients, 78 (25.7%) harbored EGFR mutations: Del-19 (36/78 patients, 46.2%); and L858R (42/78, 53.8%). Median PFS of L858R group (9.4 months, 95% confidence interval [CI]: 7.0-12.6) was significantly longer than Del-19 group (5.5 months, 95% CI, 3.6-8.6) (p = 0.049). Response rate (RR) and OS presented no significant difference between L858R and Del-19. In multivariate analysis, EGFR mutation status (L858R versus Del-19) was the only significant factor for longer PFS (Hazard ratio [HR]: 0.78, 95% CI: 0.62-0.98) (p = 0.033). CONCLUSION: Our study indicated better efficacy of cisplatin plus pemetrexed in L858R than in Del-19 patients. In EGFR-mutant NSCLC, EGFR-TKIs are undoubtedly the premier therapy. However, in second line or later settings, cisplatin plus pemetrexed regimen may confer higher efficacy for L858R patients.