5-FLUOROURACIL AND HIGH-DOSE FOLINIC ACID IN HORMONE-REFRACTORY METASTATIC PROSTATE-CANCER - A PHASE-II STUDY

Background: The response of hormone-refractory metastatic prostate cancer to chemotherapy is poor. The antitumour activity of single agent 5-fluorouracil (5-FU) is approximately 15%. Folinic acid is a reduced folate which when combined with 5-FU augments the activity of 5-FU by stabilizing the ternary complex of 5-deoxyuridine monophosphate-thymidylate synthetase-5,10 methylene tetrahydrofolate, resulting in increased DNA inhibition and in increased cytotoxicity of 5-FU. Patients and methods: We used the combination of 5-FU at 300-370 mg/m2 and folinic acid at 200 mg/m2 daily for five days in 16 patients with hormone-refractory metastatic prostate cancer. Results: A total of 15 evaluable patients were treated. There were no complete or partial responses. Seven patients had stable disease. Diarrhea constituted the most common non-hematologic toxicities (67%). Four patients experienced grade 3 and 4 neutrophil toxicity. There was one treatment-related death from an acute enterocolitis and peritonitis in a patient with grade 4 neutropenia. Conclusion: High dose folinic acid did not increase the cytotoxicity of 5-FU in hormone-refractory metastatic prostate cancer.