5-fluorouracil administered as a 48-hour chronomodulated infusion in combination with leucovorin and cisplatin: a randomized phase II study in metastatic colorectal cancer

Abstract

Objective: The primary objective of this trial was to determine the objective response of two regimens with CDDP administered every 2 weeks immediately before or after an 'optimal' 48-hour chronomodulated infusion of 5-fluorouracil (5-FU) modulated with leucovorin (LV) in metastatic colorectal cancer patients. Secondary endpoints were toxicity, 5-FU and its metabolites, plasma pharmacokinetics and progression-free and overall survival.

Methods: Metastatic colorectal cancer patients with measurable disease who were chemotherapy-naive or pretreated only with a 5-FU-bolus-based chemotherapy were eligible for this study. The study was designed as a randomized phase II clinical trial.

Results: Eighty-three patients were entered into the study. Forty-two were randomized to CDDP given before 5-FU and 41 to CDDP given after 5-FU. Patient characteristics were similar among the two groups. Toxicities were also similar among the two arms and the most frequent WHO grade III-IV toxicities were stomatitis (14%) and neutropenia (39-50%). Plasma pharmacokinetic profiles of 5-FU and 5-FUH2 were not significantly affected by the sequence of CDDP and 5-FU administration. Antitumor activity was similar in the two arms and was very promising both in pretreated patients (response rate 29%; 95% confidence interval 15-46%) and in chemotherapy-naive patients (response rate 56%, complete response 9%, 95% confidence interval 40-71%). Median survival of the patients with and without pretreatment was 12 and 16 months, respectively.

Conclusions: These results do not suggest a sequence dependence of the synergism between CDDP and 5-FU. However, they challenge the need of oxaliplatin to improve 5-FU/LV activity in advanced colorectal cancer. In fact, our results with an 'optimal' 5-FU dose and scheduling are very similar to those obtained with oxaliplatin plus 5-FU/LV. However, only a randomized phase III study will be able to give an answer to the hypotheses raised by this study.