Research Study of IV Vitamin C in Combination With Irinotecan vs Irinotecan Alone for Advanced Colorectal CA

Inclusion Criteria: * Age \> 18 years * Metastatic colorectal carcinoma (stage IV disease). * Patients must have progressed on one or more prior chemotherapy treatment regimens including at least one trial of a 5-FU/oxaliplatin based therapy (FOLFOX) in combination with bevacizumab. Patients must not have had standard chemotherapy within at least 2 weeks of beginning ascorbic acid treatment provided that they have recovered from any toxicities that they experienced. * G6PD status \> lower limit of normal * Eastern Cooperative Oncology Group (ECOG) performance status 0 to 2. * Laboratory at baseline evaluation for inclusion in the study: creatinine ≤1.5X upper limit (if the creatinine is elevated, but ≤1.5X the ULN, a 24 hour creatinine clearance will be obtained); transaminase (AST/ALT) ≤2.0X upper limit of normal; bilirubin levels ≥ 2 mg/dL; ANC ≥1,500/mm3; Hemoglobin \> 8g/dL; platelet ≥ 100,000/mm3; * Women of childbearing potential will confirm a negative pregnancy test and must practice effective contraception during the study. * Willing and able to provide informed consent and participate in the study procedures. Exclusion Criteria: * Patients with evidence of a significant current psychiatric disorder that would prevent completion of the study as determined by the PI will not be allowed to participate. * Co-morbid medical condition that would affect survival or tolerance as determined by the PI. This includes patients who have not fully recovered from toxicities ass…