Abiraterone in patients with metastatic castration-resistant prostate cancer progressing after docetaxel and MDV3100.

Abstract

4554 Background: Chemotherapy with docetaxel is the standard first-line treatment in patients with metastatic castration-resistant prostate cancer (mCRPC). In patients progressing after docetaxel, both abiraterone and MDV3100 have yielded improved survival for patients with mCRPC. The efficacy of abiraterone in patients pre-treated with MDV 3100 is unknown. Methods: We investigated abiraterone-prednisone in 24 patients with cancer progression after docetaxel followed by MDV3100. All patients received abiraterone 1000 mg/day plus prednisone 10mg/day. Prostate-specific antigen (PSA) response, symptom response, and time to progression were assessed. Results: Patient characteristics were as follows: median age: 74 years (53-84), median PSA: 108 ng/mL (2-2541), metastatic sites: bone: all 24 patients, liver/lung: 6 patients (25%), and lymph nodes : 9 patients (38%). Five patients (21%) had a PSA decrease on abiraterone-prednisone. Three patients (13%) achieved a PSA response, defined as a decrease of >50% in PSA, confirmed after≥ 4 weeks. The duration of PSA response was 2, 3 and 4.5 months. Six patients (29%) had a symptomatic response on the pain score and analgesic consumption was decreased. Treatment was well tolerated. Abiraterone-prednisone was discontinued in one patient due to edema and hypokaliemia. Conclusions: This study shows preliminary evidence that abiraterone-prednisone yields activity in patients with mCRPC pretreated with docetaxel and MDV3100.