|Inclusion Criteria:||1) Patients with histologically (or cytologically) confirmed adenocarcinoma of the colon or rectum that is recurrent or metastatic.|
2) Patients must have failed available therapy for the treatment of advanced colorectal cancer. This is defined as progressive disease during or within 6 months after fluoropyrimidine, irinotecan, oxaliplatin, bevacizumab, and for K-ras wild-type (WT) patients, anti-EGFR antibody (cetuximab or panitumumab) containing therapies, with most recent progression by RECIST criteria. Patients who had at least stable disease as best response on their prior therapies (listed above) should have received at least 2 months (approximately 60 days) of treatment. For oxaliplatin-based therapy, failure of therapy will also include patients who progressed within 12 months of adjuvant therapy and patients who had oxaliplatin stopped secondary to toxicity.
3) Patients must have K-Ras status testing results available or a tumor tissue sample available for K-Ras testing.
4) Patients must have at least one measurable lesion by RECIST criteria.
5) No prior exposure to capecitabine in the metastatic colorectal cancer setting, except limited-course radiosensitizing capecitabine (capecitabine given concurrently with radiation therapy for no more than 30 radiation treatment days), which will be allowed in the metastatic setting. Previous capecitabine use in the neo-adjuvant and/or adjuvant setting is allowed as long as 12 months elapsed between the last neo-adjuvant and/or adjuvant capecitabine dose and diagnosis of recurrent and/or metastatic disease.
6) Patient has an Eastern Cooperative Oncology Group (ECOG) performance status of 0 to 1 inclusively.
7) Patients must have adequate organ and marrow function as outlined below: ANC >/= 1500, Platelets >/= 75,000, HGB >/= 9 (with or without growth factor support), Creatinine </= 2.0 mg/dl, total, bilirubin </= 1.5x upper limit of normal, transaminase (ALT/AST) </= 2.5x upper limit of normal (</= 5x upper limit of normal in patients with liver metastases)
8) Patients must have recovered from acute toxicity or reached a new chronic stable baseline related to prior therapy excluding alopecia.
9) Patients must be able to ingest oral medications and have no known impairment of gastrointestinal function that is of the investigator's opinion would alter drug absorption.
10) Patients must be an adult (age >/= 18 years at the time of signing informed consent document or on the randomization date).
11) Patients must have ability to understand and the willingness to sign a written informed consent document.
12) Patient must be able to adhere to the study visit schedule and other protocol requirements.
13) All necessary baseline studies for determining eligibility must be obtained within 14 days prior to enrollment. (Pregnancy test must be within 72 hours for women of childbearing potential.). All patients will have a baseline evaluation that includes a chest, abdomen, and pelvic CT or MRI scan ideally within 14 days but no more than 28 days prior to starting treatment.
14) Women of child-bearing potential (WCBP), defined as a sexually mature woman who has not undergone a hysterectomy or who has not been naturally postmenopausal for at least 24 consecutive months (i.e., who has had menses any time in the preceding 24 consecutive months), must have a negative serum pregnancy test within 72 hours prior to enrollment. In addition, each sexually active WCBP and male patient must agree to use adequate contraceptive methods (oral, injectable, or implantable hormonal contraceptive; tubal ligation; intra-uterine device; barrier contraceptive with spermicide; or vasectomized partner) throughout the study for 4 weeks after the completion of treatment..