Favorable clinical outcomes of pemetrexed treatment in anaplastic lymphoma kinase positive non-small-cell lung cancer

Introduction: The development of anaplastic lymphoma kinase (ALK) inhibitor has just followed the recent discovery of ALK rearrangement in lung cancer, therefore not much is yet known about the clinical course and treatment outcomes to chemotherapy in ALK-positive patients. The purpose of this study was to investigate the clinical characteristics and treatment outcomes in patients with ALK-positive NSCLC treated with conventional chemotherapy during pre-ALK inhibitor period. Patients and Methods: We retrospectively screened 381 consecutive NSCLC patients without known epidermal growth factor receptor (EGFR) or KRAS mutation who were diagnosed between 2007 and 2008 at a single center, and identified ALK rearrangements by fluorescence in situ hybridization. Additional 44 ALK-positive patients who were identified since 2009 by central lab for participation on clinical trial were included for the analysis of clinical outcomes. Results: Of the 381 tumors screened, 21 (5.6%) showed ALK rearrangements, with twenty adenocarcinomas and one pleomorphic carcinoma. Of 65 ALK-positive patients including additional 44 ALK-positive patients, 32 patients received pemetrexed as a second- or further-line therapy, in whom the response rate was 34.4% (11/32), median progression-free survival (PFS) was 4.0 months (range: 0-22.0 months) and median overall survival (OS) was 50.8 months (95% confidence interval [CI]: 38.7-62.8). Conclusions: The prevalence of ALK rearrangement was 5.6% among EGFR and/or KRAS wild-type/unknown NSCLC population. Pemetrexed, given as a second- or further-line therapy, showed favorable clinical outcomes in ALK-positive NSCLC patients.