Pemetrexed and cyclophosphamide combination therapy for the treatment of non-small cell lung cancer

Lung cancer is the leading cause of cancer-related mortality. This study was undertaken to investigate the efficacy and safety of adding regulatory T cell inhibitor cyclophosphamide to pemetrexed therapy for the second-line treatment of NSCLC with wild-type epidermal growth factor receptor (EGFR). A total of 70 patients were screened between March 2011 and December 2013, out of which 62 patients were enrolled in the study. Patients were randomized to receive 500 mg/m(2) pemetrexed in combination with 20 mg/kg cyclophosphamide in a 21 day cycle (n=30) or 500 mg/m(2) pemetrexed (n=32), and followed up for 30 months. Disease progression was observed in 23 patients in the pemetrexed plus cyclophosphamide arm and 27 patients in the pemetrexed monotherapy arm. Median progression-free survival was 3.6 months (95% confidence interval [CI], 1.3 to 5.9 months) in the pemetrexed plus cyclophosphamide arm and 2.2 months (95% CI, 1.3 to 3.1 months) in the pemetrexed monotherapy arm. The 6-month PFS rates were 22% (95% CI, 10 to 34) and 14.5% (95% CI, 6 to 23) in the pemetrexed plus cyclophosphamide arm and pemetrexed monotherapy arm, respectively. Median overall survival was 9.8 months for the pemetrexed combination therapy arm and 8.8 months for the pemetrexed arm, and the 1-year survival rates were 46% and 33%, respectively. The present study showed that pemetrexed in combination with low-dose cyclophosphamide may be a better treatment approach than pemetrexed monotherapy when considering second-line treatment for wild-type EGFR NSCLC.