Complete response of gastrointestinal stromal tumor liver metastases to regorafenib

Imatinib, sunitinib, and regorafenib show high disease control rates for metastatic or unresectable gastrointestinal stromal tumor. However, partial response rates are low, and complete response to regorafenib had not been reported. Our case was an 81-year-old woman who underwent partial gastrectomy for an extremely large high risk gastrointestinal stromal tumor. Adjuvant imatinib caused intolerable adverse effects. One year after the surgery, local recurrence was diagnosed and sunitinib was started. Sunitinib also caused severe adverse effects. However, long-term disease control for 39 months was achieved with adequate dose reduction. After that period, the local recurrence started to grow rapidly, and the patient underwent total gastrectomy and distal pancreatectomy with excisions of nearby seeding nodules. Six months after the second operation, two liver metastasis nodules and one peritoneal metastasis nodule were found. We started regorafenib at standard dose. One month after the start of regorafenib treatment, the dose was reduced as follows: 2 weeks administration of 80 mg per day followed by 2 weeks drug holiday, due to intolerable adverse effects. The evaluation computed tomography and 18F-Fluorode-oxyglucose positron emission tomography could confirm complete response of her liver metastases. Even low dose regorafenib could maintain complete response for 10 months with only mild adverse effect. We report the first case of clinical complete response by regorafenib against liver metastases of gastrointestinal stromal tumor with intolerance to imatinib and refractory to sunitinib.