No additional benefit of adding ifosfamide to docetaxel in castration-resistant metastatic prostate cancer

In the treatment of many types of cancer, combination chemotherapy has been shown to be better than single-agent chemotherapy. The aim of our phase I-II clinical trial was to assess the efficacy and toxicity of docetaxel-ifosfamide combination chemotherapy in patients with castration-resistant metastatic prostate cancer (CRPC).

A total of 31 patients were enrolled to receive first-line chemotherapy consisting of 40-60 mg/m(2) docetaxel followed by 3.0 g/m(2) ifosfamide with mesna. All drugs were administered intravenously. The maximum duration of the chemotherapy was six cycles. The median age of the patients was 70 (range 58-82) years. Prostate specific antigen (PSA) responses were determined according to the PSA working group guidelines and all toxicities, time-to-progression and overall survival were determined according to the WHO criteria.

The objective PSA response rate was 32% in 11/31 patients. The mean PSA value at baseline was 300 (range 2.5-1577) μg/l. The overall median survival was 14.1 months; 15 patients were alive at a median follow-up time of 18 months. The observed side-effects were as expected, with grade 3-4 neutropenia developing in 38% of the cycles, whereas febrile neutropenia occurred in only 12% of the patients. The median number of administered cycles was 4.8. No acute hypersensitivity reactions were observed. Transient renal insufficiency developed in two patients, thus necessitating dose reductions.

The combination of docetaxel and ifosfamide seems to be well-tolerated and has some activity in patients with CRPC. However, newer docetaxel-based combination chemotherapy regimens need to be further developed in other to provide more efficacious and well-tolerated treatment options for earlier phases of CRPC.