Phase II study of pulse 5-fluoro-2'-deoxyuridine and leucovorin in advanced colorectal cancer patients previously treated with chemotherapy.

Because of possibly better activity against colorectal cancer of 5-fluoro-2'-deoxyuridine [floxuridine (FUdR)] compared to 5-fluorouracil (5-FU), and because of improved therapeutic results of leucovorin (LV) modulation of 5-FU, we carried out a phase II study of systemic FUdR and LV in 5-FU-treated patients with metastatic colorectal cancer. Weekly regimens consisted of a 4-hour infusion of LV, 200 mg/m2, and at 2 hours, a 2-hour infusion of FUdR, 30 mg/kg, with weekly dose escalation, as tolerated, to a maximum of 60 mg/kg. Twenty-nine patients were treated; they had a median age of 66, most had good performance status, and all had measurable disease. All had received 5-FU, although three had received it as adjuvant therapy only. Two patients had partial responses (6.9% response rate, 95% confidence interval, 1.9-21.9%) lasting 29 and 19 weeks, and five had stable disease. Median time to progression was 8 weeks and median survival was 36.5 weeks. The median number of courses was 6.5; escalation of FUdR was carried out in 27 patients. Hematologic toxicity was minimal and gastrointestinal toxicity was most frequent, although mild. This regimen, although well tolerated, is minimally effective in previously 5-FU-treated patients with metastatic colorectal cancer.