Dose Escalation of Imatinib After Failure of Standard Dose in Korean Patients with Metastatic or Unresectable Gastrointestinal Stromal Tumor

We evaluated the results of imatinib dose escalation in patients with advanced gastrointestinal stromal tumors (GISTs) after disease progression on standard-dose imatinib. Clinical data from patients with metastatic or unresectable GISTs whose dose of imatinib was increased after disease progression on imatinib 400 mg/day were retrospectively reviewed. The 24 patients studied had a median age of 52 years. Imatinib dosing was escalated to 600 mg/day in 12 patients, then to 800 mg/day in four patients. The other 12 patients had dose escalation directly to 800 mg/day. Two patients (8.3%) achieved a partial response, and seven (29.2%) had stable disease. Six-month progression-free and overall survival rates were 33.3 and 70.7%, respectively. Dose escalation to 600 or 800 mg/day was generally well tolerated. Imatinib dose escalation is feasible and well tolerated in patients with advanced GIST who progress on standard-dose therapy, producing clinical benefit in similar to 37% of patients.