Biochemical and Objective Response to Abiraterone Acetate Withdrawal: Incidence and Clinical Relevance of a New Scenario for Castration-resistant Prostate Cancer.

OBJECTIVE:
To describe the incidence and clinical relevance of biochemical and objective responses to abiraterone acetate (AA) withdrawal (AAWD) in patients with castration-resistant prostate cancer (CRPC).
MATERIALS AND METHODS:
Twenty-six patients with progressive CRPC treated with first-line docetaxel-based chemotherapy were administered with AA at the standard dose of 1000 mg/day in combination with prednisone until progression. The patients were regularly followed up during treatment and after AAWD.
RESULTS:
Nineteen of the 26 patients discontinued AA because of progression. Three of the patients undergoing AAWD experienced a biochemical response, which was accompanied by a metabolic and radiological response as revealed by choline positron emission tomography in 2 cases.
CONCLUSION:
Regardless of the underlying molecular bases, AAWD response does not occur rarely. It is sometimes long-lasting and accompanied by a metabolic and radiographic improvement. AAWD response should be taken into account when further therapeutic strategies are planned in patients with CRPC with progressive disease during abiraterone therapy.