Clinical Evaluation - A Phase IIA Proof of Concept Study of Regorafenib (Bayer 73-4506) in Biopsy-amenable Asian Colorectal Cancer Patients

Inclusion Criteria: * Histologically or cytologically proven metastatic colorectal adenocarcinoma that is refractory to standard therapy and not amenable to surgery with curative intent. * Tumor characteristics: * At least one lesion that is suitable for a repeated biopsy; eg. subcutaneous nodule, skin lesion, rectal tumor, colonic mass easily reached by colonoscopy, peritoneal masses at least 3cm in maximum diameter that are easily assessable by image guided core biopsy. * For liver lesions, more superficially located lesions at least 3cm in maximum dimension with a rim of normal liver tissue, assessable safely by image guided core biopsy as determined by an experienced interventional radiologist. * Eastern Cooperative Oncology Group ECOG performance status of 0 or 1 (see Appendix 10.4). * Adequate bone marrow function (absolute neutrophil count =1,500/mm3; platelet count =100000/mm3; hemoglobin =9g/dl * Adequate liver and renal function as assessed by the following laboratory requirements conducted within 7 days of starting to study treatment: * Total bilirubin \< 1.5 x the upper limit of normal (ULN). * Alanine transaminase (ALT) and aspartate aminotransferase (AST) \< 2.5 x ULN (\< 5 x ULN for patients with liver involvement of their cancer). * Amylase and lipase \< 1.5 x the ULN * Serum creatinine \< 1.5 x the ULN. * Glomerular filtration rate (GFR) = 30 ml/min/1.73 m2 according to the MDRD (Modified diet in renal disease) abbreviated formula * Prothrombin time, international normalized ratio (INR) and partial thromboplastin time less than or equal to 1.2 times the ULN. * Male or female at least 21 years of age. * A female subject is eligible to enter and participate in the study if she is: * Non-childbearing potential (ie. physiologically incapable of becoming pregnant) including any women who: * Has had a hysterectomy or * Has bilateral oophorectomy (ovariectomy) or * Has bilateral tubal ligation or * Is postmenopausal (demonstrate total cessation of menses for greater than or * Childbearing potential, has a negative serum or urine pregnancy test at screening, agrees to one of the following: double barrier contraception or abstinence. * Predicted life expectancy of at least 12 weeks. * Resting oxygen saturation greater than 92% on room air. * Written informed consent. * Able to swallow and retain oral medication. * Prothrombin time (PT), International Normalized Ratio for PT (PT INR), and partial thromboplastin time (PTT) or activated partial thromboplastin time (aPTT) within normal limits. Exclusion Criteria: