Arsenic Trioxide, Fluorouracil, and Leucovorin in Treating Patients With Stage IV Colorectal Cancer That Has Relapsed or Not Responded to Treatment

ATO will be administered at dose levels determined by the dose escalation scheme (section 4.2). Intra-venous (IV) infusion of ATO (mg/kg body weight) over 1-4 hours will be administered for 5 consecutive days (day 1 to day 5) during the first week, twice a week on weeks 2 and 3 (days 8, 11, 15, and 18), and only one day (day 22) of week 4. Treatment will continue for a maximum of 8 cycles, provided that the patient tolerates treatment and there is evidence of clinical benefit.

Escalate 5-FU, starting at dose 1600 mg/m2. On day 8, 15, and 22 the assigned dose of 5 FU plus 500 mg/m2 of leucovorin will be administered over 24 hours intravenous infusion following the administration of arsenic trioxide. Treatment will continue for a maximum of 8 cycles, provided that the patient tolerates treatment and there is evidence of clinical benefit.

On day 8, 15, and 22 the assigned dose of 5 FU plus 500 mg/m2 of leucovorin will be administered over 24 hours intravenous infusion following the administration of arsenic trioxide. Treatment will continue for a maximum of 8 cycles, provided that the patient tolerates treatment and there is evidence of clinical benefit.

Pre-Treatment and and one hour post ATO on days 1, 5, 8, 11,15, 18, and 22

Peripheral blood samples (PAXgene Blood RNA tube, Qiagen, USA) will be obtained up to 2 weeks prior to start of treatment (same day as the first FNA) and one hour post ATO on days 1, 5, 8, 11,15, 18, and 22. Along with FNA an additional blood sample will be obtained on day 23 of every odd treatment cycle.

Pre-Treatment, Day 23 of Cycles 1, 3, 5, 7