Prostate cancers initially need the male hormone testosterone for growth. Hormone therapies that lower the level of testosterone are among the most effective treatments for prostate cancers that have spread to other organs (metastasized). The benefits of hormone treatments do not last, however. Over time, many prostate cancers continue to grow despite hormonal therapies (and are called “castration-resistant” prostate cancer, or CRPC).
Enzalutamide and abiraterone acetate are drugs used to treat CRPC. They work in different ways to block the hormones that prostate cancer needs to grow. Enzalutamide is approved for treating men with metastatic CRPC who have already received chemotherapy; in this study, it will be assessed in men who have not yet had chemotherapy for metastatic CRPC. Abiraterone, which is given with prednisone, is approved for treating men with metastatic CRPC when given before or after chemotherapy. However, the three drugs have never been evaluated together.
In this study, patients with metastatic CRPC will be randomly assigned to receive one of two treatment regimens: enzalutamide alone, or enzalutamide with abiraterone and prednisone. Researchers will see how the two groups fare to determine if one regimen in more effective than the other. All three drugs are taken orally (by mouth).