Prospective phase II study of cisplatin plus pemetrexed with maintenance of pemetrexed for advanced non-squamous cell non-small cell lung cancer in Japan

Background: A previous study showed a survival benefit with maintenance therapy with pemetrexed in patients with advanced non-small cell lung cancer (NSCLC). However, it remains unclear whether continuation maintenance therapy with pemetrexed is beneficial in Japanese patients. Here, we present our phase II study that assessed the efficacy and safety of cisplatin plus pemetrexed as induction chemotherapy, followed by maintenance therapy with pemetrexed in advanced NSCLC patients in Japan. Methods: Chemotherapy-nave patients received 500 mg/m(2) pemetrexed and 75 mg/m(2) cisplatin on day one every three weeks for four cycles. In patients who responded to therapy or achieved stable disease, pemetrexed was continued until disease progression. The primary endpoint of this study was the progression-free survival rate at six months (PFS-6). Results: Of the 35 patients initially enrolled in the study, 18 (51%) received maintenance chemotherapy with pemetrexed. The median PFS was 6.7 months, and the PFS-6 was 60% (95% confidence interval [CI], 42-76%). Median overall survival(OS) was 15.5 months(95% CI, 8.3-22.7 months). The median PFS and OS in patients who received maintenance chemotherapy with pemetrexed were 9.5 months and 25.3 months, respectively. The most frequently noted severe toxicity during induction chemotherapy was neutropenia, which occurred in seven patients. Two patients discontinued maintenance therapy owing to prolonged grade 2 edemain one patient and grade 3 neutropenia in another. Conclusion: Continuation maintenance chemotherapy with pemetrexed is associated with a survival benefit in patients who have completed induction chemotherapy for non-squamous NSCLC.