Phase II trial of 5-fluorouracil, high-dose leucovorin calcium, and dipyridamole in advanced prostate cancer.

To examine the effect of altering intracellular folate pools on the efficacy of 5-fluorouracil (FUra) in the treatment of advanced prostate cancer, we performed a phase II trial of FUra (300-370 mg m-2 day-1 x 5 as an i.v. bolus) combined with high-dose folinic acid (500 mg m-2 day-1 x 5.5 days by continuous i.v. infusion) and dipyridamole (75 mg p.o. every 6 h x 5.5 days) administered on a 28-day schedule in patients with stage D2 disease. A group of 13 patients have been treated. The median age was 68 years (range 48-78 years); the performance status ranged from 50% to 90%. Among 12 evaluable patients, there were no objective responders; the median time to progression was 1.9 months. Median survival after entry on this trial was 8.6 months. Treatment with FUra, high-dose folinic acid and dipyridamole was well tolerated. Only one episode each of grade 3 leukopenia, granulocytopenia, and thrombocytopenia was observed. These results suggest that, despite previous trials demonstrating activity for FUra in stage D2 prostate cancer, this disease may be relatively resistant to fluoropyrimidines and, thus, less amenable to biochemical modulation with high-dose folinic acid and dipyridamole.