Cabazitaxel 20 mg/m2 (C20) is noninferior to cabazitaxel 25 mg/m2 (C25) for the treatment of post-docetaxel patients with metastatic castration-resistant prostate cancer (mCRPC), according to a study published in the Journal of Clinical Oncology.

Although the current standard C25 demonstrates significant clinical benefit in patients with mCRPC, previously conducted trials suggested investigating the efficacy of C20 as lower doses may reduce the rates of toxicity.

For the phase III PROSELICA study (ClinicalTrials.gov identifier: NCT01308580), researchers randomly assigned more than 1200 patients with mCRPC to receive C20 or C25. The primary outcome measured was overall survival (OS). Baseline characteristics were well balanced among all patients.

The median OS for patients receiving C20 was 13.4 months vs 14.5 months for C25 (hazard ratio [HR], 1.024), demonstrating noninferiority of C20.

Prostate-specific antigen (PSA) response rate was superior in the C25 group (42.9%) vs the C20 group (29.5%; nominal P <.001).

Median time to PSA progression was superior in the C25 group at 6.8 months vs 5.7 months in the C20 group (HR for C20 vs C25, 1.195; 95% CI, 1.025-1.393).

The safety profiles of both cabazitaxel doses were consistent with those demonstrated in previous studies. Frequency of grade 3 to 4 adverse events (AEs) was 39.7% in patients receiving C20 vs 54.5% for patients receiving C25.

The researchers conclude saying “that patients can achieve a similar clinical benefit from cabazitaxel at both the 20 and 25 mg/m2 starting doses and that dose reductions may be implemented in patients who require them without significant detriment to outcome.”

Reference

Eisenberger M, Hardy-Bessard A, Kim CS, et al. Phase III study comparing a reduced dose of cabazitaxel (20 mg/m2) and the currently approved dose (25 mg/m2) in postdocetaxel patients with metastatic castration-resistant prostate cancer-PROSELICA [published online August 15, 2017]. J Clin Oncol. doi: 10.1200/JCO.2016.72.1076