[High-dose leucovorin and 5-FU].
Leucovorin (LV), given intravenously the orally becomes 5, 10-methylene tetrahydrofolate in both cancer and normal cells. FdUMP which is an active metabolite of 5-FU binds tightly to thymidylate synthase in the presence of the cofactor 5, 10-methylene tetrahydrofolate. This interaction leads to potentiate the cytotoxic effect of 5-FU by prolonged inhibition of thymidylate synthase. Clinically, the combination of LV and 5-FU is given parenterally by two schedules; 5 consecutive days schedule and weekly schedule. Five 5 consecutive days-schedule is divided into 2 methods. One is a 200 mg/m2/day of LV by Machover, and the other is 20 mg/m2/day of LV by O'Connell. The weekly schedule is a 2-hour infusion of dl-LV (500 mg/m2) and iv bolus of 5-FU (600 mg/m2), given 1 hour after the beginning of LV infusion by Petrelli. A multicenter cooperative study in Japan was conducted to evaluate the clinical efficacy of LV and 5-FU using the weekly schedule by Petrelli. Response rates were 31.5% and 41.2% against advanced gastric and colorectal cancer respectively. Then, we carried out a randomized early phase II study using 250 mg/m2 of l-LV weekly (similar to the schedule of Petrelli's, armA) and 100 mg/m2 (similar to the schedule of Machover's, arm B) or 10 mg/m2 (similar to the schedule of O'Connell's, arm C) of l-LV for 5 consecutive days against gastric cancer. The response rate was 33.3% in arm A, 24.1% in arm B and no response in arm C. Toxicity was within acceptable limits, Toxic effects included diarrhea, stomatitis, anorexia and myelohypoplasia. Our data suggests that high-dose LV and 5-FU seems to be a very promising combination but, there was no responder using low dose (10 mg/m2) of l-LV schedule against gastric cancer patients.
Sasaki
T
T
Department of Chemotherapy, Tokyo Metropolitan Komagome Hospital, Japan.
D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use*; D015179:Colorectal Neoplasms / Q000188:drug therapy; D004341:Drug Evaluation; D005468:Fluorodeoxyuridylate / Q000378:metabolism; D005472:Fluorouracil / Q000008:administration & dosage / Q000378:metabolism; D006801:Humans; D002955:Leucovorin / Q000008:administration & dosage / Q000493:pharmacokinetics; D013274:Stomach Neoplasms / Q000188:drug therapy*; D013940:Thymidylate Synthase / Q000737:chemistry / Q000378:metabolism
D005468:Fluorodeoxyuridylate; D013940:Thymidylate Synthase; D002955:Leucovorin; D005472:Fluorouracil