A phase 3 randomized study of a new medication indicated that the drug was effective in slowing the spread of metastatic prostate cancer while also helping patients to maintain their quality of life. Because of its favorable results, the study was unblinded midway to enable patients receiving the placebo to take the drug (abiraterone acetate, marketed as Zytiga [Janssen Biotech, Inc, Horsham, Pa.]). According to Charles Ryan, MD, associate professor of clinical medicine at the University of California at San Francisco (UCSF) Helen Diller Family Comprehensive Cancer Center, abiraterone acetate extended patients' lives while also delaying the development of pain and the deterioration of patients' overall conditions.
Results have indicated that the drug may be able to be used at an earlier stage of prostate cancer, thereby extending its benefits to a wider population, Dr. Ryan says. He and Eric Small, MD, chief of hematology and oncology at UCSF, have collaborated on researching this class of medication for approximately 9 years. Last year, the US Food and Drug Administration approved abiraterone acetate for men whose disease had spread, who were resistant to standard hormonal therapy, and who had received chemotherapy with docetaxel. That approval was based on a clinical trial that demonstrated the effectiveness of the medication in postchemotherapy patients with advanced disease.
In this trial, the patients' cancer had metastasized and become resistant to initial hormone therapy but the patients were not exhibiting extensive symptoms and had not yet received chemotherapy. The study included 1088 men who had been diagnosed with prostate cancer an average of 5 years prior.
The trial participants received abiraterone acetate in combination with low-dose prednisone, and the trial was unblinded in March after researchers determined it delayed the need for chemotherapy and pain medications and improved survival and quality of life. Results demonstrated that the drug slowed the spread of cancer from an average of 8 months in the placebo group to approximately 16 months in the treatment group. Consequently, an independent monitoring committee recommended that patients receiving the placebo be allowed to receive the active drug.
Abiraterone acetate targets prostate cancer by blocking the production of hormones that can stimulate tumor growth. The manufacturer warns that it should be used with caution in patients who have a history of cardiovascular disease, high blood pressure, low blood potassium, and fluid retention.