Introduction: In a first-line study of advanced NSCLC, pemetrexed-cisplatin was more effective among patients with adenocarcinoma and large-cell carcinoma compared with gemcitabine-cisplatin (median survival of 11.8 versus 10.4 months, P=.005), while survival with pemetrexed-cisplatin was shorter than with gemcitabine-cisplatin in patients with squamous cell carcinoma. The comparability of pemetrexed-cisplatin to other commonly used regimens within histology subgroups needs to be explored.
Methods: This retrospective analysis combined the patient-level data from three phase 3 randomized controlled trials that compared the efficacy of different third generation platinum- and non-platinum based doublets. Unadjusted median survival times and Cox covariate-adjusted treatment hazard ratio (HR) estimates were calculated. Overall results and subgroups by histological type were reported.
Results: This combined analysis consisted of 3467 patients. In the overall analysis, adjusted HRs favored pemetrexed (HR <1.0) to each of the other 5 regimens, though none of these HRs were statistically significant. Among patients with non-squamous histology, pemetrexed-cisplatin produced favorable HRs to each of the other regimens, achieving statistical significance when compared with vinorelbine-cisplatin (HR=0.67; 95% confidence intervals [CI]: 0.50, 0.91) and gemcitabine-cisplatin (HR=0.85; 95% CI: 0.75, 0.97). Among patients with squamous histology, 4 of the 5 comparison regimens produced favorable HRs (HR >1.0) when compared with pemetrexed-cisplatin, with only the comparison with gemcitabine-cisplatin achieving statistical significance (HR=1.23; 95% CI: 1.00, 1.51).
Conclusion: In the absence of randomized clinical trial data comparing pemetrexed-cisplatin to commonly used doublets in advanced NSCLC other than gemcitabine-cisplatin, this combined analysis of multiple trials provides estimates for such comparisons.
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