Efficacy and safety of cisplatin/pemetrexed versus cisplatin/gemcitabine as first-line treatment in East Asian patients with advanced non-small cell lung cancer: results of an exploratory subgroup analysis of a phase III trial.

Introduction: We conducted an exploratory, post hoc, subgroup analysis of the East Asian (EA) patients in a multinational phase III trial to determine whether the efficacy results for this subgroup were consistent with those observed for the entire study population.
Methods: Thousand seven hundred twenty-five patients with advanced non-small cell lung cancer (NSCLC), including 126 EA patients (7.3%) from Taiwan and Korea, were enrolled in the trial and randomly assigned first-line chemotherapy with cisplatin and pemetrexed (CP; n = 862) or cisplatin and gemcitabine (CG; n = 863). Adjusted Cox proportional hazards models were used to compare overall survival and progression-free survival between the treatment arms in the EA subgroup. Median time-to-event data were estimated with the Kaplan-Meier method.
Results: Consistent with the results for the entire study population, survival in the EA subgroup trended in favor of CP over CG in patients with non-squamous histology, despite the more frequent use of post discontinuation targeted therapy in the CG arm. The opposite trend was noted for patients with squamous tumors. A higher proportion of patients in the EA subgroup were never smokers compared with the entire study population. A trend toward improved survival with CP compared with CG was seen regardless of smoking status, particularly in non-squamous patients.
Conclusions: The key finding of this subgroup analysis was that the NSCLC histology effect on treatment outcomes for pemetrexed-treated patients seen in the entire study population was also apparent in the EA subgroup. The potential prognostic influence of race, histology subtype, and smoking status should be assessed in future NSCLC studies.