Clinical efficacy and safety of sunitinib after imatinib failure in Japanese patients with gastrointestinal stromal tumor

Background: Imatinib used to be the only effective treatment for advanced gastrointestinal stromal tumor. However, early clinical reports have shown that sunitinib has substantial anticancer activity in patients with advanced gastrointestinal stromal tumor after failure of imatinib. Methods: Eighteen Japanese patients with advanced gastrointestinal stromal tumor who were resistant or intolerant to previous treatment with imatinib were entered into this study. These patients were given sunitinib orally, once daily at a 50-mg starting dose, in 6-week cycles with 4 weeks on and 2 weeks off treatment. Tumor response and drug safety were then evaluated. Results: Median time-to-treatment failure was 207 days. Overall, 5.6% (1/18) of patients achieved partial response, 38.9% (7/18) had stable disease and 44.4% (8/18) had progressive disease. The common adverse events were hand-foot syndrome, liver dysfunction, fatigue, anorexia and hypertension. Mild anemia, leukocytopenia and neutropenia were also noted. Nine patients required dose reduction or cessation because of adverse events. Conclusions: This study demonstrates that sunitinib may be an effective agent for advanced gastrointestinal stromal tumor after failure of imatinib in clinical practice.