San Francisco, CA (UroToday.com) Chemo-hormonal therapy has shown positive results in both the STAMPEDE and CHAARTED clinical trials and is now used for metastatic castrate sensitive prostate cancer. To date, there is no indication to combine any of the therapies currently available for castration resistant prostate cancer.
The authors of the study (NCT02522715) aimed to determine whether the potential synergistic effects between 2 newer and more effective agents could be identified an exploited for therapeutic effect in patients with metastatic castration resistant prostate cancer (mCRPC), and to obtain correlative biological information that may offer predictive and response value.
The primary objective of this study was to determine the safety and tolerability of cabazitaxel plus enzalutamide as determined by percent dose limiting toxicities (DLT), where DLT<17% is reflective of a tolerable combination. The authors also wanted to determine the efficacy of cabazitaxel plus enzalutamide in men with metastatic castrate resistant prostate cancer, as determined by the percent of subjects who achieve over 90% PSA decline following initiation of therapy. Lastly, the authors wanted to determine the effects of prior abiraterone exposure.
This was a phase I/II study to examine safety and efficacy of the combination of cabazitaxel and enzalutamide with the mandatory granulocyte-colony stimulating factor (gCSF) support in metastatic cancer resistant prostate cancer. The study design is shown in Figure 1 and patient baseline characteristics are shown in Table 1.
Figure 1 – Study Design:
Table 1 — Baseline Characteristics: 
The safety and tolerability results are shown in Table 2.
Table 2 — Results: Safety and Tolerability: 
Prior therapy with abiraterone and prednisone were associated with decreased prostate-specific antigen (PSA) response. However, subjects with prior treatment with abiraterone and prednisone also had higher pre-treatment PSA. Table 3 demonstrates the PSA response rate.
Table 3 — PSA Response Rate: 
The authors concluded that despite the advanced disease type of the subjects in this study, cabazitaxel plus enzalutamide was a tolerant combination and showed promising antitumor activity, particularly in abiraterone-naive patients. More data is needed regarding this combination therapy before any recommendations can be made.
Presented by: Julie Graff, MD, Associate Professor of Medicine, Oregon Health & Science University, Knight Cancer Institute, Portland, OR
Written by: Hanan Goldberg, MD, Urology Department, SUNY Upstate Medical University, Syracuse, NY, USA, Twitter: @GoldbergHanan, at the 2020 Genitourinary Cancers Symposium, ASCO GU #GU20, February 13-15, 2020, San Francisco, California