Pemetrexed Continuation Maintenance in Patients with Nonsquamous Non-small Cell Lung Cancer: Review of Two East Asian Trials in Reference to PARAMOUNT

Purpose A recent phase III study (PARAMOUNT) demonstrated that pemetrexed continuation maintenance therapy is a new treatment paradigm for advanced nonsquamous non-small cell lung cancer (NSCLC). The majority of patients enrolled in PARAMOUNT were Caucasian (94%). We reviewed efficacy and safety data from two clinical trials, which enrolled East Asian (EA) patients, to supplement data from PARAMOUNT on pemetrexed continuation maintenance therapy in patients with nonsquamous NSCLC. Materials and Methods Study S110 was a phase II, multicenter, randomized, controlled, open-label trial in never-smoker, chemonaive, EA patients (n=31) with locally advanced or metastatic nonsquamous NSCLC (n=27). Study JMII was a multicenter, open-label, single-arm, post-marketing, clinical trial in Japanese patients (n=109) with advanced nonsquamous NSCLC. PARAMOUNT was a multicenter, randomized, double-blind, placebo-controlled trial in patients with advanced nonsquamous NSCLC. Results In EA patients with nonsquamous NSCLC, the median progression-free survival (PFS) for pemetrexed continuation maintenance therapy was 4.04 months (95% confidence interval [CI], 3.22 to 5.29 months) in study S110 and 3.9 months (95% CI, 3.2 to 5.2 months) in study JMII. The median PFS for pemetrexed continuation maintenance therapy in PARAMOUNT was 4.1 months (95% CI, 3.2 to 4.6 months). Pemetrexed continuation maintenance therapy in EA patients in studies S110 and JMII did not lead to any unexpected safety events, and was consistent with PARAMOUNT's safety profile. Conclusion The efficacy and safety data in the EA trials were similar to those in PARAMOUNT despite differences in patient populations and study designs. These data represent consistent evidence for pemetrexed continuation maintenance therapy in EA patients with advanced nonsquamous NSCLC.