Phase II trial of carboplatin and pemetrexed as first-line chemotherapy for non-squamous non-small cell lung cancer, and correlation between the efficacy/toxicity and genetic polymorphisms associated with pemetrexed metabolism: Hokkaido Lung Cancer Clinical Study Group Trial (HOT) 0902

This phase II study evaluated the response rate (RR) and safety of combination therapy with carboplatin (CBDCA) and pemetrexed (PEM) in Japanese patients with non-squamous non-small cell lung cancer (non-sq NSCLC). Further, the relationship between therapy efficacy/toxicity and genetic polymorphisms associated with PEM metabolism was analyzed. Forty-one patients received CBDCA at a dose targeting an area under the concentration-time curve of 5 mg/mL x min and PEM of 500 mg/m(2) on day 1 every 3 weeks. Single-nucleotide polymorphisms of the thymidylate synthase (TYMS) coding gene, the variable number of tandem repeat (VNTR) in the TYMS, and the methylenetetrahydrofolate reductase (MTHFR) coding gene were analyzed. The overall RR was 36.6 %. Median progression-free survival and median survival time were 4.7 months [95 % confidence interval (CI) 3.9-5.6 months] and 16.2 months (95 % CI 6.1-26.2 months), respectively. Epidermal growth factor receptor gene mutations were detected in 6 patients (14.6 %). The VNTR in the TYMS significantly correlated with anemia (p = 0.047) and thrombocytopenia (p = 0.038). This combination therapy was effective and tolerable in patients with advanced non-sq NSCLC. The VNTR in the TYMS appears to be a predictive factor for anemia and thrombocytopenia in patients treated with this regimen.