Comparison of Patient Outcomes According to Histology Among Pemetrexed-treated Patients with Stage IIIB/IV Non-small-cell Lung Cancer in Two Phase II Trials

Introduction: Recent phase III studies in advanced non-small-cell lung cancer (NSCLC) have demonstrated differential efficacy for pemetrexed according to NSCLC histology. The results of 2 phase II studies of pemetrexed and a platinum agent (carboplatin or oxaliplatin) were pooled to determine whether outcomes in the studies differed by tumor histology.

Patients And Methods: Chemotherapy-naive patients with stage IIIB/IV NSCLC received pemetrexed 500 mg/m2 plus carboplatin area under the curve of 6 (n = 89) or pemetrexed 500 mg/m2 plus oxaliplatin 120 mg/m2 (n = 41); both regimens were administered every 21 days. The primary endpoint of both trials was response rate. Treatment arms were pooled, and Cox models with main effects for squamous histology were used to assess overall survival and progression-free survival. Cofactor adjustments incorporated terms for performance status, disease stage, and sex.

Results: More than three quarters of enrolled patients had a nonsquamous histology. Mean age was 59.9 years for patients with nonsquamous histology and 63.7 years for patients with squamous histology. Response rates were 30% for patients with nonsquamous histology and 17.2% for patients with squamous histology. Overall survival was 10.5 months for patients with nonsquamous histology and 9.8 months for patients with squamous histology (hazard ratio [HR], 0.95; 95% CI, 0.52-1.74). Progression-free survival was 5.6 months for patients with nonsquamous histology and 4.7 months for patients with squamous histology (HR, 0.72; 95% CI, 0.43-1.19).

Conclusion: In patients treated with pemetrexed/ platinum doublets, nonsquamous histology was associated with better outcomes. The benefit of pemetrexed treatment among patients with nonsquamous histology is consistent with the results reported from previous studies.