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)