A hormone-depleting drug can help eliminate or nearly eliminate aggressive, nonmetastatic prostate cancer tumors, according to a clinical study.
The phase 2 clinical trial involved 58 men with high-risk prostate cancer isolated to the prostate gland. Researchers studied the use of the drug abiraterone acetate (Zytiga®) in combination with prednisone and surgery. Participants received either 3 or 6 months of the 2-drug regimen prior to surgery to remove the prostate. After treatments concluded, pathology exams showed that 1/3 of the participants had no or almost no tumor tissue remaining.
“Very high-risk cancers localized to the prostate are rarely cured by prostatectomy alone,” says the study’s lead author, Mary-Ellen Taplin, MD, of Dana-Farber. “Therapies that combine surgery with older androgen-inhibiting drugs have not historically improved outcomes. This unmet need has given rise to efforts to develop new drugs capable of more completely reducing androgen levels within the prostate tumors.”
Unlike conventional prostate cancer therapies, abiraterone acetate is capable of blocking androgen production in 3 sites: the testes, the adrenal glands, and the tumor itself. Furthermore, in this study, half the standard dose of prednisone was given along with abiraterone acetate. Researchers hoped the lower prednisone dosage would reduce the side effects associated with steroids while maintaining its benefits of protecting particular steroid imbalances associated with abiraterone. Because there were no increases in side effects from abiraterone, the researchers believe the lower dose of prednisone (5 mg daily) is adequate for most patients.
“Most of the patients in this study had large tumors, high-grade prostate cancers and were at high risk for cancer spread,” Taplin remarks. “We’re very encouraged by the results and have begun another phase II study investigating another novel androgen signaling inhibitor, MDV3100, in the neoadjuvant setting for high-risk prostate cancer. We are also developing a clinical trial program investigating the addition of the investigational drug ARN509 to abiraterone. To prove the overall benefit of intensive androgen deprivation treatment in conjunction with prostatectomy, a large randomized clinical trial will need to be done.”
Source: Dana-Farber Cancer Institute.