Introduction: The IRESSA Survival Evaluation in Lung Cancer (ISEL) phase III study compared the efficacy of gefitinib (IRESSA) versus placebo in patients with refractory advanced non-small cell lung cancer (NSCLC). Although a statistically significant difference in survival was not seen between gefitinib and placebo in the overall ISEL population, preplanned subset analyses demonstrated a significant survival benefit in patients who had never smoked and in patients of Asian origin.
Methods: In ISEL, 1692 patients who were refractory to or intolerant of their latest chemotherapy were randomized to receive either gefitinib (250 mg/day) or placebo, plus best supportive care. Preplanned subgroup analyses included an assessment of patients who were of Asian origin (n = 342).
Results: Two hundred thirty-five patients of Asian origin received gefitinib, and 107 received placebo. In these patients, treatment with gefitinib significantly improved survival compared with placebo (hazard ratio [HR], 0.66; 95% confidence interval [CI], 0.48, 0.91; p = 0.010; median survival, 9.5 versus 5.5 months). Patients of Asian origin also experienced statistically significant improvements in time to treatment failure with gefitinib compared with placebo (HR, 0.69; 95% CI, 0.52, 0.91; p = 0.0084; 4.4 versus 2.2 months), and objective response rates were higher with gefitinib than with placebo (12 versus 2%). Gefitinib was generally well tolerated in patients of Asian origin, with rash and diarrhea being the most common adverse events. No unexpected adverse events were observed.
Conclusions: Treatment with gefitinib was associated with a significant improvement in survival in a subgroup of patients of Asian origin with previously treated refractory advanced NSCLC.