263MO - Enzalutamide versus abiraterone plus prednisolone for Japanese non-metastatic castration-resistant prostate cancer patients: Sub-analysis from ENABLE for PCa, a multicenter, randomized controlled trial

Background

Enzalutamide (ENZ) and abiraterone plus prednisolone (ABI) demonstrated survival improvement for castration-resistant prostate cancer (CRPC). However, which agent is better for non-metastatic CRPC patients remains quite unclear.

Methods

To evaluate which agent is better for CRPC patients as a first-line treatment, an investigator-initiated, multicenter, randomized controlled trial (ENABLE study for PCa) including both metastatic and non-metastatic CRPC was conducted in Japan. We additionally analyzed such as prostate-specific antigen (PSA) response rate (≥50% decline from baseline), overall survival, and safety assessment in non-metastatic CRPC patients.

Results

In 92 patients in each arm treated and analyzed, the number of non-metastatic patients in the ENZ and the ABI arm was 15 and 26, respectively. There was no significant difference in PSA response rate between the ENZ and the ABI arms (80% and 64%, respectively; P = 0.30). There was no significant difference in overall survival between arms (median, not reached and 33.7 months in the ENZ and the ABI arm, respectively; hazard ratio, 1.47; 95% CI, 0.47–4.62; P = 0.53). Furthermore, no significant differences were observed in radiographic progression-free survival and cancer-specific survival between arms (P = 0.61 and P = 0.64, respectively). The number of grade ≥3 of adverse events in the ENZ and the ABI arm were only 4 and 6, respectively.

Conclusions

ABI showed a similar efficacy to ENZ with a similar safety profile in non-metastatic CRPC patients.

Clinical trial identification

UMIN000015529;1 November 2014.

Editorial acknowledgement

Legal entity responsible for the study

The authors.

Funding

Japanese Foundation for Multidisciplinary Treatment of Cancer.

Disclosure

K. Izumi: Financial Interests, Personal, Invited Speaker: Astellas Pharma; Financial Interests, Personal and Institutional, Invited Speaker: Janssen Pharmaceutical. A. Mizokami: Financial Interests, Personal, Invited Speaker: Astellas Pharma, Janssen Pharmaceutical. All other authors have declared no conflicts of interest.