CT-2106, a camptothecin (CPT) conjugate, is a new generation of topoisomerase I inhibitors designed to deliver higher, more effective chemotherapy to tumor tissue with less toxicity to normal tissues. The objective of this study is to determine the dose limiting toxicities, safety profile and antitumor activity of CT-2016 in combination with 5-FU and folic acid for the treatment of colorectal cancer.

Inclusion Criteria:

• Histologically proven metastatic colorectal adenocarcinoma, failing one prior treatment containing oxaliplatin plus 5-FU/FA
• At least one measurable lesion according to RECIST criteria for both Phase I and II
• ECOG performance status 0 or 1
• Adequate hematologic, renal and hepatic function
• Wash out period of at least 4 weeks from surgery, 4 weeks from radiotherapy

Exclusion Criteria:

• Past or concurrent history of neoplasm other than colorectal adenocarcinoma, except curatively treated non melanoma skin cancer or in situ carcinoma of the cervix.
• Pregnant or lactating patients
• Prior treatment with camptothecins
• Presence or history of CNS metastasis or carcinomatous leptomeningitis
• Current active infection per investigator assessment
• Unresolved bowel obstruction or partial obstruction, uncontrolled Crohn's disease or ulcerative colitis
• Current history of chronic diarrhea greater than or equal to grade 1 (CTCAE version 3)