Reduction and Escalation in the Dose of Sunitinib Were Adequately Effective against Gastrointestinal Stromal Tumor of the Small Intestine

We herein report the first case in which an escalated dose of sunitinib was effective, even after dose reduction. A 64-year-old man with gastrointestinal stromal tumor of the small intestine discontinued adjuvant imatinib because of interstitial pneumonia. After two years, peritoneal recurrence was detected. Sunitinib was started at 50 mg/day for 4 weeks every 6 weeks, after which the dosage was reduced to 37.5 mg/day because of grade 1 gastritis, stomatitis, and a fever. Four months later, computed tomography showed progressive disease. As the adverse events were well-controlled by medication, we escalated the dose to 50 mg/day and achieved a partial response.