Phase I clinical trial with floxuridine and high-dose continuous infusion of leucovorin calcium. Sixty-two patients with metastatic disease were treated with continuous infusion folinic acid (leucovorin calcium; Lv) and 2-deoxy-5-fluorouridine (floxuridine; FUDR). Lv was given by constant intravenous (IV) infusion at 500 mg/m2/d, days 1 to 6, while FUDR was given by IV push, days 2 to 6, at 3:00 PM daily with doses ranging from 294 to 1,214 mg/m2/d. This program was well tolerated with dose-limiting toxicities of diarrhea and stomatitis, while hematologic toxicity was minimal. Eighty-two percent of the assessable patients (46 of 56) had failed at least one chemotherapy regimen. One complete remission lasting 9 months and 10 partial remissions ranging from 5 to 10 months were observed in this heavily pretreated patient population for an overall response rate of 20%. These data suggest that the combination therapy with Lv and FUDR may have clinical use. Because of differing patient sensitivity to this drug combination, the recommended dose of FUDR for the initial therapy cycle is 500 mg/m2/d, days 2 to 6, with subsequent escalation to 900 mg/m2/d in those patients without extreme sensitivity. Phase II studies are now in progress with these doses. 