Metastatic Castration-Resistant Prostate Cancer: Two Case Reports of Dramatic Response with Abiraterone Acetate in Patients Heavily Pretreated with Chemotherapy

Metastatic castration-resistant prostate cancer (mCRPC) with visceral involvement requires new, effective and safe treatments after chemotherapy failure. The CYP17A1 inhibitor abiraterone acetate has been approved as a treatment for mCRPC, both after docetaxel chemotherapy and more recently for patients who are not responding to chemotherapy. In published studies, most patients previously treated with docetaxel had received a limited number of lines of chemotherapy and a small proportion of these patients presented with visceral metastases. We report two mCRPC patients with extensive visceral disease, who were heavily pretreated with chemotherapy. They experienced major responses to treatment with abiraterone acetate. For both patients, responses to abiraterone were noticeable within 1 month, encompassing a marked regression of visceral metastases and a decrease in prostate-specific antigen. The clinical benefit of abiraterone was maintained for at least 6 months and the treatment was well tolerated.