The BRAF Status May Predict Response to Sorafenib in Gastrointestinal Stromal Tumors Resistant to Imatinib, Sunitinib, and Regorafenib: Case Series and Review of the Literature

BACKGROUND: Sorafenib has shown efficacy in patients with imatinib-, sunitinib-, and regorafenib-resistant gastrointestinal stromal tumors (GISTs). No biomarker is currently available for predicting response to sorafenib in patients with GIST. METHODS: We herein report 3 patients with imatinib-, sunitinib-, and regorafenib-resistant metastasized GISTs, who were treated with sorafenib. Besides receptor tyrosine kinase KIT and platelet-derived growth factor receptor α, also BRAF was tested for mutations. RESULTS: Sorafenib therapy induced a long-term disease control in 2 out of 3 patients over a period of 49 and 19 months, respectively. Sorafenib-responsive GISTs were BRAF wild-type, whereas the sorafenib-resistant GIST carried a BRAF V600E mutation. CONCLUSION: We confirm sorafenib as an effective therapeutic option in patients with imatinib-, sunitinib-, and regorafenib-resistant GISTs. Larger studies are required to corroborate whether BRAF mutation may predict sorafenib resistance in GISTs.