The efficacy and safety of adjuvant gefitinib for patients with completely resected EGFR-mutated non-small cell lung cancer (NSCLC) versus cisplatin-based adjuvant chemotherapy are not fully known
During the ASCO World Congress 2021, IMPACT (UMIN000006252), a Japanese phase III, randomized, open-label trial comparing adjuvant treatment strategies with gefitinib versus cisplatin/vinorelbine in patients with completely resected (stages II-III) NSCLC harboring EGFR mutation (L858R or exon 19 deletion) was presented.
From September 2011 to December 2015, 234 patients were randomized to receive gefitinib (250mg/day) for 24 months or cisplatin (80mg/m² on day 1) plus vinorelbine (25mg/m2 on days 1 and 8) every three weeks for four cycles. The primary endpoint was disease-free survival (DFS) by central review in the intended-to-treat (ITT) population.
Two patients in the gefitinib arm withdrew consent and were excluded from the ITT population. No treatment-related deaths were observed in the gefitinib arm, but three treatment-related deaths were reported in the chemotherapy arm.
The average duration of follow-up was 71 months. The median DFS was numerically longer in the gefitinib arm (36 months) versus the chemotherapy arm (25.2 months). However, Kaplan-Meier curves began to overlap about five years after surgery, showing no significant difference in DFS, with a hazard ratio (HR) of 0.92 (95% CI 0.67 – 1.28; P = 0.63).
Overall survival was also not significantly different (median not achieved in either arm). The five-year survival rates for the gefitinib and cisplatin + vinorelbine arms were 78% and 74.6%, respectively, with a HR for death of 1.03 (95% CI 0.65 – 1.65; P = 0.89). Exploratory subset analysis revealed that patients > 70 years in the gefitinib arm survived longer than those in the chemotherapy arm (HR 0.31; CI 95% 0.10 – 0.98; P = 0.046).
The researchers conclude that adjuvant gefitinib apparently prevents early relapse but did not significantly prolong DFS or OS in patients with completely resected, EFGR-mutated, stage II/III NSCLC.