A patient is seeing you in follow- up for his mCPRC including metastasis to the lungs, liver, and spine. He recently had radiographic progression of disease on abiraterone and prednisone after 9 months of therapy. The patient asks about changing to enzalutamide but is also open to other therapies. Which of the following should you tell him?
A 65- year- old male with mCRPC including metastasis to the pelvis, spine, and ribs has recently started treatment with enzalutamide. His initial PSA on therapy was 46.7 ng/ dl. Over the next 6 months the patient’s PSA declined to 4.7 ng/ dl. After completing 9 months of therapy, his PSA is 16.2 ng/ dl. Repeat imaging demonstrates no new areas of disease. He is tolerating the treatment well with some mild fatigue and has no symptoms related to his prostate cancer. What is the most appropriate next step for this patient’s treatment regimen based on Prostate Cancer Working Group 3 recommendations?