A novel weekday-on/weekend-off UFT schedule

In a step toward a clinical trial, the tumor response and survival of a weekday-on/weekend-off schedule of UFT was compared with its conventional daily schedule in a cancer-bearing rat model. The dose-intensive schedule--600 mg of UFT for 5 days followed by 2 drug-free days--amounts to a weekly dose similar to the conventional schedule of 400 mg/day. The weekday-on/weekend-off schedule provided increased survival and significantly greater antitumor activity than the conventional daily schedule, with no difference in adverse reactions. A study was also conducted in human subjects to measure fluorouracil (5-FU) concentrations that identified the pharmacokinetic activity during the 2 drug-free days of the weekday-on/weekend-off schedule. The plasma 5-FU concentration declined markedly after 24 hours, but the concentration in the tumor remained at a relatively high level after 2 days off the drug. A one-year clinical study evaluated the compliance and toxicity of the weekday-on/weekend-off UFT schedule as adjuvant chemotherapy for colorectal cancer. Based on the findings of all these studies, the weekday-on/weekend-off schedule for UFT as adjuvant chemotherapy for colorectal cancer can be recommended for a clinical trial.