On September 26, 2008, the U. S. Food and Drug Administration (FDA) approved pemetrexed injection (Alimta Injection, Eli Lilly and Company) for use in combination with cisplatin therapy for the initial treatment of patients with locally advanced or metastatic non-squamous non-small cell lung cancer (NSCLC). Pemetrexed is not indicated for treatment of patients with squamous cell lung carcinoma.
A multicenter, randomized, open-label study in 1725 patients with stage IIIb/IV NSCLC who had not received prior chemotherapy was conducted to compare overall survival following treatment with pemetrexed plus cisplatin (AC) to gemcitabine plus cisplatin (GC). The median survival was 10.3 months in the AC arm and 10.3 months in the GC arm [adjusted hazard ratio 0.94 (95% CI: 0.84, 1.05)]. The median progression-free survival was 4.8 and 5.1 months for the AC and GC arms, respectively [adjusted hazard ratio 1.04 (95% CI: 0.94, 1.15)]. The overall response rates were 27.1% and 24.7% for the AC and GC arms, respectively.
A pre-specified analysis of the impact of NSCLC histology on overall survival was conducted in this trial. Clinically relevant differences in survival according to histology were observed. In the non-squamous cell NSCLC subgroup the median survival was 11.0 and 10.1 months in the AC and GC groups, respectively [unadjusted hazard ratio 0.84 (95% CI: 0.74, 0.96)]. However, in the squamous cell histology subgroup the median survival was 9.4 versus 10.8 months in the AC and GC groups, respectively [unadjusted hazard ratio 1.22 (95% CI: 0.99, 1.50)]. This unfavorable effect on overall survival associated with squamous cell histology observed with pemetrexed was also noted in a retrospective analysis of the single-agent trial of pemetrexed versus docetaxel in patients with stage III/ IV NSCLC after prior chemotherapy. Single-agent pemetrexed was approved in 2004 for this more heavily treated lung cancer population. Current product labeling has been revised to recommend that Alimta is also not indicated in patients with squamous cell lung cancer after prior chemotherapy.