URO ONCO

Welcome, this website is intended for all international healthcare professionals in uro-oncology. By clicking the link below you are declaring and confirming that you are a healthcare professional.

You are here

Efficacy of Enzalutamide Following Abiraterone Acetate in Chemotherapy-naive Metastatic Castration-resistant Prostate Cancer Patients

European Urology 2015 Jan;67(1):23-9

Abstract

Background

The activity of enzalutamide after prior treatment with both abiraterone acetate (abiraterone) and docetaxel has been examined in several retrospective studies. However, limited data are available on the efficacy of enzalutamide following abiraterone in chemotherapy-naive patients with metastatic castration-resistant prostate cancer (mCRPC).

Objective

To compare the activity of enzalutamide after abiraterone in docetaxel-experienced and docetaxel-naive mCRPC patients.

Design, setting, and participants

The British Columbia Cancer Agency Cancer Registry was searched for mCRPC patients who received enzalutamide after prior abiraterone. Clinicopathologic characteristics, confirmed prostate-specific antigen (PSA) response rates (PSA decline ≥50% confirmed ≥3 wk later), and survival data were collected.

Outcome measurements and statistical analysis

Outcomes on enzalutamide were compared between docetaxel-experienced and docetaxel-naive patients using chi-square for PSA response and log-rank test for time to PSA progression and overall survival (OS). Univariate analysis was performed to identify variables associated with confirmed PSA response on enzalutamide, using either chi-square for categorical variables or logistic regression for continuous variables.

Results and limitations

A total of 115 patients received enzalutamide after abiraterone: 68 had received prior docetaxel and 47 were docetaxel naive. Median time on enzalutamide was 4.1 mo. Confirmed PSA response rates (22% vs 26%;p = 0.8), median time to radiologic/clinical progression (4.6 mo vs 6.6 mo;p = 0.6), and median OS (10.6 mo vs 8.6 mo;p = 0.2) did not differ significantly between docetaxel-experienced and docetaxel-naive patients. No clinical variables (including prior response to abiraterone) were found to associate significantly with confirmed PSA response to enzalutamide.

Conclusions

Antitumour activity of enzalutamide following abiraterone was limited in mCRPC patients irrespective of prior docetaxel use. Identifying clinical and molecular factors predictive of response to enzalutamide remains a high priority for future research.

Patient summary

We looked at the effectiveness of enzalutamide after abiraterone acetate for treatment of advanced prostate cancer. We found that patients who had received docetaxel chemotherapy before abiraterone gained similar benefit from enzalutamide compared with patients who had not received docetaxel. These results suggest that earlier treatment with docetaxel does not have a large impact on the activity of enzalutamide after abiraterone.

Take Home Message

In a cohort of 115 patients with metastatic castration-resistant prostate cancer (mCRPC), we found that outcomes on enzalutamide following abiraterone are comparable in docetaxel-experienced and docetaxel-naive mCRPC patients. These data indicate that prior treatment with docetaxel does not contribute to cross-resistance between abiraterone and enzalutamide.

Keywords: Enzalutamide, Abiraterone acetate, Abiraterone, Docetaxel, Castration-resistant prostate cancer.

Footnotes

Department of Medical Oncology, British Columbia Cancer Agency, Vancouver, British Columbia, Canada

lowast Corresponding author. Department of Medical Oncology, British Columbia Cancer Agency, 600 West 10th Avenue, Vancouver, BC, V5Z 4E6, Canada. Tel.: +1 604 877 6000; Fax: +1 604 877 0585.