Abiraterone acetate in metastatic hormone-resistant prostate cancer

The authors determined the safety and effectiveness of abiraterone acetate (Zytiga) in patients with metastatic hormone-resistant prostate cancer. 

Hormone therapy is a common treatment used in prostate cancer. It targets the male sex hormones active in prostate cancer, such as testosterone. Some patients can develop a resistance to hormone therapy and will need alternative treatments. This is known as hormone-resistant prostate cancer. Hormone resistance can occur in some metastatic prostate cancers (cancer that has spread outside of the prostate to other organs). Abiraterone acetate has shown promising results in improving overall survival (patients who are still alive following treatment) in patients with metastatic hormone-resistant prostate cancer.

Further studies are needed to determine the safety and effectiveness of abiraterone acetate in metastatic hormone-resistant prostate cancer. 

The authors aimed to determine the safety and effectiveness of abiraterone acetate in treating metastatic hormone-resistant prostate cancer.

306 patients were analyzed in this study with a follow up of 3 years. All patients had received chemotherapy before receiving abiraterone acetate.

69% of patients received more than 3 months of treatment. 31% received less than 3 months of treatment. Overall survival from the beginning of chemotherapy was 37.1 months. Overall survival from the beginning of abiraterone acetate treatment was 14.6 months. Overall survival was significantly associated with the length of abiraterone acetate treatment received. Prostate specific antigen (PSA – protein elevated in the blood indicating the presence of prostate cancer) levels were significantly decreased in patients treated with abiraterone acetate for more than 3 months. This was compared to patients treated for less than 3 months.

Patients with multiple tumor sites, previous hormone treatment of less than 70 months and abiraterone acetate treatment of less than 3 months were more at risk of experiencing a reduced overall survival.

The most common treatment-related side effects were low potassium levels, high blood pressure and liver dysfunction. 89.5% of patients discontinued treatment due to disease progression. Among them, 9% of patients died from prostate cancer.

The authors concluded that abiraterone acetate reduced PSA levels in prostate cancer patients. They also determined that the length of treatment time could be decided based on the PSA response analyzed after 3 months of treatment.