Hydroxyurea was administered by means of two schedules designed to provide continuous 72-hour exposure of tumor cells to therapeutic drug levels. Toxicity and pharmacokinetics were determined for both an oral pulse dose schedule (every 4 hours x 18 doses) and continuous intravenous (IV) infusion for 72 hours. The maximal tolerated dose (MTD) was 800 mg/m2 every 4 hours for the oral route and 3.0 mg/m2/min x 72 hours for IV infusion. Granulocytopenia was dose-limiting for both schedules and correlated well with plasma-HU levels. Serial sampling of normal bone marrow (10 patients) and tumor tissue (3 patients) showed a modest degree of synchronization induced by continuous IV infusion of hydroxyurea. Interindividual pharmacokinetic variations severely limit the usefulness of the oral pulse schedule as a potential means of synchronizing cells. Hydroxyurea administered by continuous IV infusion may be useful as a synchronizing agent in humans.
A randomized trial was conducted by the Southwest Oncology Group (SWOG) in advanced carcinoma of the stomach and pancreas. Patients were assigned to receive monthly 5-fluorouracil 96-hour continuous infusions with either bolus mitomycin-C or oral methyl-CCNU. Mitomycin-C and methyl-CCNU were administered every eight weeks. The 5 FU-mitomycin combination produced a 14% and 22% response rate in disseminated stomach and pancreatic carcinoma, respectively. The combination of infusion 5 FU and methyl-CCNU achieved responses in 9% and 5% of stomach and pancreatic tumors, respectively. There was no significant difference in survival between limbs for either tumor. Median survival in gastric carcinoma on the 5 FU-mitomycin regimen was 25 weeks vs. 18 weeks on the 5 FU-METHYL-CCNU arm. In pancreatic carcinoma median survival on the mitomycin limb was 19 weeks as compared to 17 weeks on the methyl-CCNU program. Leukopenia was greater for the first course on the mitomycin limb. Regression analysis demonstrated that performance status was the most important pretreatment characteristic for predicting survival in both tumors. Neither 5 FU infusion combination appears to significantly alter the dismal prognosis of advanced upper gastrointestinal neoplasms.
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