A phase II study of oral eniluracil/fluorouracil in patients with anthracycline-refractory or anthracycline- and taxane-refractory advanced breast cancer

Background: Eniluracil is an effective inactivator of dihydropyrimidine deh ydrogenase, the initial and rate limiting enzyme in the catabolism of fluor ouracil. The current study was done to determine the objective tumour respo nse of a 28-day oral regimen of eniluracil-fluorouracil in patients with ad vanced breast cancer. Patients and methods: This was a multicentre, phase II study in patients wi th anthracycline-refractory (AR) or anthracycline- and taxane-refractory (A TR) advanced breast cancer. Oral eniluracil (10 mg/m(2)) and fluorouracil ( 1 mg/m(2)) were taken twice daily for 28 days of each 35-day treatment cour se. Results: In this study, 106 patients received treatment: 62 patients in the AR stratum and 44 patients in the ATR stratum. The objective tumour respon se rate in the intent-to-treat population was 18% (95% confidence intervals (CI): 11%-27%), including three complete responses. The response rate was similar in both strata: 19% in the AR and 16% in the ATR stratum. The overa ll median duration of response was 23.6 weeks. The treatment was well toler ated with a low incidence of grade 3 or 4 toxicities that were considered a ttributable to study medication. Conclusion: Treatment with oral eniluracil-fluorouracil was well tolerated by patients with advanced breast cancer. The efficacy data were comparable with those of other published studies in this group of refractory patients.