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.