Real world treatment patterns of gastrointestinal stromal tumor patients

e15602 Background: Imatinib is accepted as the standard first-line therapy to treat gastrointestinal stromal tumor (GIST) in patients with unresectable or metastatic disease. In the case of disease progression, physicians may consider increasing imatinib dose or switching to another second-line agent, such as sunitinib. The aim of this study was to analyze the real-world long term treatment patterns of GIST patients. Methods: Two large claims databases from 01/1999 to 03/2008 were combined (MarketScan and Ingenix Impact) to extract patients diagnosed with GIST who initiated on imatinib ≥400 mg/day. Patients were followed from the first observed imatinib prescription to the end of data availability. Patients who dose increased during the study period were defined as dose escalators, while patients who later switched to sunitinib with or without dose escalation were defined as switchers. Kaplan Meier analyses were used to estimate the rate of treatment changes over time including imatinib discontinuation, d...