Does Addition of Abiraterone to Enzalutamide Therapy Benefit Men With Prostate Cancer?
Posted: Monday, September 17, 2018
The addition of abiraterone to ongoing enzalutamide versus abiraterone alone did not seem to benefit men with metastatic castration-resistant prostate cancer and rising levels of prostate-specific antigen (PSA). The investigators of the PLATO trial, led by Gerhardt Attard, MD, of The University College London Cancer Institute, observed no improvement in progression-free survival nor any advantage in terms of toxicity. The results, published in the Journal of Clinical Oncology, suggest that enzalutamide plus abiraterone should not be continued after PSA progression during enzalutamide monotherapy.
The trial, which consisted of two consecutive periods of open-label enzalutamide treatment once daily (period one) followed by randomized, double-blind treatment (period two), included 509 patients. Patients who did not show increases in PSA level at weeks 13 and 21 continued treatment until PSA progression; then they were randomized to receive abiraterone plus prednisone with either enzalutamide (n = 126) or placebo (n = 125; control group).
Differences in progression-free survival between the two groups were negligible. For patients receiving the combination therapy, the median progression-free survival was 5.7 months, versus 5.6 months among those in the control group. Reduction of 50% or more in the baseline PSA level was reported in 1% versus 2% of patients, respectively.
As for toxicity, 45% of the combination group compared with 37% of the control group reported grade ≥ 3 adverse events. No differences were observed between the two groups in the rate of pain progression, objective response rate, or time to first use of subsequent antineoplastic therapy. Hypertension and elevated liver enzymes occurred more often with the combination therapy, the authors reported.
