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

Background: In this study, we investigated the association between the early response of serum and hematological variables and the outcome of cabazitaxel therapy.

Patients And Methods: 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.

Results: The median follow-up period after cabazitaxel initiation was 15.2 months. The 30% prostate-specific antigen (PSA) response rate, median PSA progression-free survival period, and overall survival (OS) period were 45.8%, 4.3 months, and 22.6 months, 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.

Conclusions: 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.