Regorafenib in GIST With Secondary C-KIT Exon 17 Mutation

Inclusion Criteria: An eligible subject must fulfill all of the following inclusion criteria: * Signed informed consent (IC) obtained before any study specific procedure. Patients must be able to understand and willing to sign the written IC. * Pathologically confirmed gastrointestinal stromal tumours. * All patients had received imatinib or sunitinib. * Pathological confirmed c-kit exon 17 mutation. * At least one measurable lesion in a non-irradiated area or allowed to be tracked whether there are circumstances recurrence by computed tomography (CT) or magnetic resonance imaging (MRI). * Aged \> 20 years old. * Eastern Cooperative Oncology Group (ECOG) performance status 0 or 1. * Life expectancy greater than 12 weeks. * Adequate bone marrow function: 1) Absolutely neutrophil count \>= 1.5 x10\^9/L or white blood cell count (WBC) \>= 4x10\^9/L; 2) Hemoglobin \>= 9 g/dL; 3) Platelet count \>= 100x10\^9/L. * Adequate liver function: 1) Total bilirubin \<= 1.5x the upper limit of normal (ULN); 2) Alanine Aminotransferase (ALT) \& Aspartate Aminotransferase (AST) \<= 2.5x ULN if without liver metastasis or \<= 5x ULN if with hepatic metastasis; 3) Alkaline phosphatase \<= 2.5x ULN if without liver metastasis or \<= 5x ULN if with hepatic metastasis or bone metastasis; 4) Bilirubin \< 2x ULN. * Adequate renal function: creatinine \<1.5x ULN. * Patients must be accessible for treatment and follow-up in the participating centers. Exclusion Criteria: Subject will not meet any of the following exclusion criteria: * Major surgery within four weeks prior to entering the study. * Patients with central nervous system (CNS) metastasis, including clinical suspicion. * Patients who are under active or uncontrolled infections. * Patients who with unstable angina (angina symptoms at rest, new-onset angina (begun within the last 3 months) or myocardial infarction history 6 months before entry. * Cardiac arrhythmia requiring anti-arrhythmic therapy (beta blockers or digoxin are permitted). * Congestive heart failure New York Heart Association (NYHA) class 2. * Uncontrolled hypertension (systolic blood pressure \[BP\] \> 150 mmHg or diastolic pressure \> 90 mmHg despite optimal medical management. * Arterial or venous thrombotic or embolic events such as cerebrovascular accident (including transient ischemic attacks), deep vein thrombosis or pulmonary embolism within 6 months before the start of study medication. * Patients who are pregnant or with breast feeding. * Other concomitant or previously malignancy within 5 years except for in situ cervix cancer or squamous cell carcinoma of the skin treated by surgery only. * Mental status is not fit for clinical trial. * Cannot take study medication orally. * Fertile men and women unless using a reliable and appropriate contraceptive method. * Patients with evidence or history of any bleeding diathesis, irrespective of severity. * Any hemorrhage or bleeding event \>= Common Terminology Criteria for Adverse Events (CTCAE) Grade 3 within 4 weeks prior to the start of study medication. * Non-healing wound, ulcer, or bone fracture. * Renal failure requiring hemo-or peritoneal dialysis.