Biochemical modulation of fluorouracil: comparison of methotrexate, folinic acid, and fluorouracil versus folinic acid and fluorouracil in advanced colorectal cancer: a randomized trial

Recent advances in biochemical pharmacology have revealed the basis for the biological modulation of 5-fluorouracil (5-FU) by methotrexate (MTX) and folinic acid (FA). Sequential use of MTX given 24 h prior to 5-FU has resulted in enhanced cell kill in vitro and in vivo. In addition, administration of FA prior to 5-FU has led to potentiation of 5-FU action by stabilization of the ternary complex of thymidine synthase. In the present randomized study, two groups of patients with advanced colorectal cancer were treated as follows: 43 patients (pts) in group A received 5-FU + FA, whereas 45 pts in group B received 5-FU + FA + MTX. The dosage was as follows: group A received FA i. v. at 300 mg/m2 per day, prior to i. v. 5-FU at 500 mg/m2 per day on days 1 – 4; group B was given MTX i. v. at 130 mg/m2 per day on day 0, followed 24 h later by FA at 15 mg q6h × 6, and 5-FU + FA was started on day 1 and given at the same doses and schedule described for group A. Objective responses were achieved by 8/43 pts in group A (1 complete response and 7 partial responses) and by 18/45 pts in group B (3 complete and 15 partial responses), all occurring in the liver. There was no significant difference in the median time to progression (group A 6.1 months, group B 6.8 months) or the median survival (group A 9.2 months, group B 10.3 months). Toxicity was significantly greater in group B [grade 2 – 3 mucositis 20% versus only 2% in group A (P <0.0001); grade 3 diarrhea in group B 15% versus 3% in group A (P <0.001)]. According to our results, double biological modulation of 5-FU with MTX + FA led to an enhanced response rate with increased toxicity as compared with the 5-FU + FA regimen given at less than its maximally tolerated dose.