The main purpose of this study is to examine whether regorafenib treatment can help people with gastrointestinal stromal tumours (GIST) and have gene mutation on c-kit exon 17. The safety of regorafenib treatment is also examined.

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.