Docetaxel-ifosfamide combination chemotherapy in patients with metastatic hormone-refractory prostate cancer: a phase I pharmacokinetic study.

Abstract

This phase I study was designed to evaluate the activity toxicity and pharmacokinetics of docetaxel combined with ifosfamide in the treatment of hormone-refractory prostate cancer. Ten patients received a median of 4.6 treatment cycles. Docetaxel was administered at a dose of 40 mg/m2 in a 1-hour infusion followed by ifosfamide 3,000 mg/m2 in a 24-hour infusion every 3 weeks. The optimal sequence of chemotherapeutic agents was investigated by reversing the order of administration in the second cycle and by collecting a total of six pharmacokinetic blood samples per cycle from all patients during the first and second cycles. The sequence of administration did not influence the pharmacokinetics of docetaxel. Prostate-specific antigen (PSA) responses were observed in four out of nine patients, with a PSA response rate of 44.4% (complete response + partial response). The treatment was well tolerated. No grade IV toxicities were recorded and grade III leucopenia resulted in dose-reductions in 6 cycles (13.3%). The pharmacokinetic parameters of docetaxel were similar in both sequences. Our recommendation for further phase II studies is ifosfamide followed by low-dose docetaxel. Further phase II efficacy studies are warranted.