Serum and hematologic responses after three cycles of cabazitaxel therapy as predictors of survival in castration-resistant prostate cancer.

Abstract

In this study, we investigated the association between the early response of serum and hematological variables and the outcome of cabazitaxel therapy. The medical records of 59 consecutive patients who had previously received docetaxel chemotherapy for the treatment of metastatic castration-resistant prostate cancer (CRPC) and who received cabazitaxel at our hospital between January 2011 and March 2020 were retrospectively reviewed and statistically analyzed. The median follow-up period after cabazitaxel initiation was 15.2months. The 30% prostate-specific antigen (PSA) response rate, median PSA progression-free survival period, and overall survival (OS) period were 45.8%, 4.3months, and 22.6months, respectively. Within 1 to 2 cycles of cabazitaxel, we were unable to identify hematological or serum kinetics that had a relationship with OS. Analysis of the variables after 3 cycles of cabazitaxel, however, revealed two factors, PSA decline > 30% (p = 0.016) and neutrophil-lymphocyte ratio (NLR) decline > 30% (p = 0.044), as the predictors of favorable outcome for OS. We established a prognostic model for predicting the OS period composed of these two factors, which exhibited distinctly separated OS curves (p = 0.004). The C-index of a model incorporating these two factors was 0.703. This is the first study to demonstrate that PSA and NLR decline 3 cycles after the initiation of cabazitaxel were associated with favorable outcome in patients with CRPC. Also, 3 cycles of cabazitaxel might be necessary to assess the efficacy of cabazitaxel therapy.