Relationship of driver oncogenes to long term pemetrexed response in non-small cell lung cancer

BACKGROUND Pemetrexed is approved in the treatment of advanced stage nonsquamous non-small-cell lung cancer (NSCLC). The length of response is variable, and we thus sought to identify which clinicopathologic characteristics are associated with long-term disease control with pemetrexed. PATIENTS AND METHODS Patients with metastatic NSCLC received pemetrexed (with or without bevacizumab) for 12 months or longer, either as maintenance treatment after first-line platinum-based chemotherapy or as subsequent treatment. Clinical and pathologic characteristics were collected. RESULTS Of a total of 196 patients who received pemetrexed starting in 2007, 25 patients were identified who received pemetrexed for over 1 year. Of these, 15 patients received pemetrexed with or without bevacizumab as maintenance treatment and 10 patients received pemetrexed as subsequent treatment. Fifteen (60%) of 25 patients had an oncogenic driver mutation as follows: 5 (20%) had ROS1 gene rearrangements, 4 (16%) had ALK gene rearrangements, 3 (12%) had KRAS mutations, 2 (8%) had epidermal growth factor receptor (EGFR) mutations, and 1 (4%) had an NRAS mutation. The median overall survival was 42.2 months (95% confidence interval, 37.4-61.3) and median progression-free survival was 22.1 months (95% confidence interval, 15.1-29.1). Patients with an oncogenic driver mutation had significantly better progression-free survival (P = .006) and overall survival (P = .001). CONCLUSION Among patients with NSCLC who received pemetrexed for an extended time, those with ALK and ROS1 gene rearrangements were proportionally overrepresented compared with that anticipated in a general nonsquamous NSCLC population, and patients with oncogenic driver mutations had improved outcomes.