EAU15: Latest data from two trials with enzalutamide show its efficacy

The latest results of the Phase III PREVAIL and Phase II TERRAIN studies on enzalutamide in early metastatic castrations-resistant prostate cancer (mCPRC) were presented and critiqued during the late breaking news session.

Prof. Bertrand Tombal (BE) presented an updated analysis of the overall survival data from the PREVAIL trial, which compared enzalutamide to placebo in men with mCRPC with progression after androgen deprivation therapy (ADT). The studied population represented a traditional early CRPC patient group and the updated data confirmed a robust benefit of enzalutamide over placebo in overall survival.

Tombal demonstrated that the PREVAIL study confirms the value and anti-tumour efficacy of enzalutamide. It also shows delayed need for treatment with chemotherapy, an objective response rate of 59%, and a quality of life response rate of 40%.

Tombal concluded: “Enzalutamide is profoundly changing the early mCRPC landscape and by starting treatment in asymptomatic patients there is a significant delay in symptomatic disease and an overall survival benefit.”

Prof. Maria De Santis (DE) commented on this by raising the issue of resistance and the urgent need for biomarkers to identify patients with primary resistance. Adverse events of enzalutamide are also a cause of concern as almost 50% of patients suffer from fatigue as a result of the treatment. Tombal recognised that these are important research topics for the future.

Prof. Axel Heidenreich (DE) presented the latest data of the TERRAIN study, which compared enzalutamide with bicalutamide in early mCRPC. He resonated Tombal’s conclusion that enzalutamide is transforming the treatment for this disease because of its benefits for progression-free survival and delayed PSA progression.

Dr. Alberto Briganti (IT) criticised this conclusion and pointed to the adverse events of enzalutamide, which are more prominent than those of bicalutamide, and the considerable costs of the former drug. He further argued that the results of this study were to be expected because it has been shown that the mechanism of enzalutamide is much more effective in managing mCRPC. “This trial is an easy way to demonstrate the efficacy of one drug over another,” Briganti said.

Heidenreich responded by saying that there was never any evidence that bicalutamide was effective in mCRPC; with enzalutamide there now is an effective alternative to treat patients. A final issue raised by Briganti and acknowledged by Heidenreich is that in some countries the decision to treat with enzalutamide is not in the hands of urologists but in those of medical oncologists. This is a political problem that requires more attention.