The Efficacy and Safety of a Low Relative Dose Intensity of Cabazitaxel in Patients With Metastatic Castration-resistant Prostate Cancer

Background/aim: Clinical trials have shown that the efficacy of a reduced dose of cabazitaxel (20 mg/m² every 3 weeks) was not inferior to that of the standard dose (25 mg/m² every 3 weeks). However, the efficacy of even lower relative dose intensities, such as 20 mg/m² every 4 weeks, have not been evaluated conclusively. The aim of this study was to investigate the efficacy and safety of a low relative dose intensity of cabazitaxel in patients with metastatic castration-resistant prostate cancer in the real world.

Patients and methods: We retrospectively analyzed 101 consecutive patients treated with cabazitaxel for docetaxel-refractory metastatic castration-resistant prostate cancer. The progression-free and overall survival after introduction of cabazitaxel and prostate-specific antigen response rate were assessed as oncological outcome measures.

Results: The patients were divided into two groups (relative dose intensity >60%, n=74 and ≤60%, n=27). Both progression-free and overall survivals were significantly better in the >60% group than in the ≤60% group (median 5 and 2 months, p<0.01, and 15 and 6 months, p<0.01, respectively). In multivariate analyses, visceral metastasis and relative dose intensity ≤60% were prognostic factors for shorter progression-free and overall survivals (p=0.04, p<0.01, respectively). The incidence of adverse events was not significantly different between groups.

Conclusion: The cabazitaxel relative dose intensity ≤60% group had significantly shorter progression-free and overall survivals than the >60% group, whereas the incidence of adverse events was not significantly different. The results suggested that reducing the relative dose intensity of cabazitaxel to ≤60% may not be recommended.