Once a clinical trial has been completed, especially when the trial is positive, researchers will “data mine” the published information. The published results provide additional opportunities to evaluate the data in different ways than the trial was originally designed. This new data can be very interesting and informative, however it also needs to be considered somewhat suspect since the trial was not initially designed to answer these additional questions.
We do know that prostate cancer disproportionately affects older men and a man’s age should affect treatment decisions. So, it is important to understand the efficacy and tolerability of the therapies used to treat advanced prostate cancer in elderly men. In a look back study of the phase III PREVAIL trial (used to obtain the FDA approval of enzalutamide) researchers decided to perform an analysis of the efficacy and safety outcomes in men aged over 75 years who received enzalutamide
The PREVAIL trial was a randomized, double-blind, multinational study of oral enzalutamide 160 mg/day (N=872) versus placebo (N=845) in chemotherapy-naive men with metastatic castration-resistant prostate cancer. The trial evaluated the overall survival (OS) and radiographic progression-free survival (rPFS) of men with castrate resistant advanced prostate cancer. In the look back researchers performed a subgroup analysis of the men older (elderly) and younger than 75 years.
They found that in the elderly subgroup, OS was greater with enzalutamide than with placebo, as was rPFS (not yet reached when the trial was halted
They also found that irrespective of treatment the incidence of AEs was similar between the two age groups, except for an overall higher incidence of falls among elderly men than younger men.
They concluded that elderly men benefited from treatment with enzalutamide in terms of both OS and rPFS. They also concluded that Enzalutamide was well tolerated in both subgroups. However, they did find that age and enzalutamide treatment were associated with a higher incidence of falls.