Phase III Study of Pemetrexed Plus Carboplatin Compared With Etoposide Plus Carboplatin in Chemotherapy-Naive Patients With Extensive-Stage Small-Cell Lung Cancer

Purpose Following a phase II trial in which pemetrexed-platinum demonstrated similar activity to that of historical etoposide-platinum controls, a phase III study was conducted to compare pemetrexed-carboplatin with etoposide-carboplatin for the treatment of extensive-stage small-cell lung cancer (ES-SCLC). Patients and Methods Chemotherapy-naive patients with ES-SCLC and an Eastern Cooperative Oncology Group performance status of zero to 2 were randomly assigned to receive pemetrexed-carboplatin (pemetrexed 500 mg/m(2) on day 1; carboplatin at area under the serum concentration-time curve [AUC] 5 on day 1) or etoposide-carboplatin (etoposide 100 mg/m(2) on days 1 through 3; carboplatin AUC 5 on day 1) every 3 weeks for up to six cycles. The primary objective of the study was noninferiority of pemetrexed-carboplatin overall survival with a 15% margin. Results Accrual was terminated with 908 of 1,820 patients enrolled after results of a planned interim analysis. In the final analysis, pemetrexed-carboplatin was inferior to etoposide-carboplatin for overall survival (median, 8.1 v 10.6 months; hazard ratio [HR], 1.56; 95% CI, 1.27 to 1.92; log-rank P < .01) and progression-free survival (median, 3.8 v 5.4 months; HR, 1.85; 95% CI, 1.58 to 2.17; log-rank P < .01). Objective response rates were also significantly lower for pemetrexed-carboplatin (31% v 52%; P < .001). Pemetrexed-carboplatin had lower grade 3 to 4 neutropenia, febrile neutropenia, and leukopenia than etoposide-carboplatin; grade 3 to 4 thrombocytopenia was comparable between arms and anemia was higher in the pemetrexed-carboplatin arm. Conclusion Pemetrexed-carboplatin is inferior for the treatment of ES-SCLC. Planned translational research and pharmacogenomic analyses of tumor and blood samples may help explain the study results and provide insight into new treatment strategies.