New drug to fight against localized high-risk prostate tumors

Men with prostate cancer could significantly benefit from a recently approved hormone-depleting drug, according to results from a phase II clinical trial. The drug - abiraterone acetate (Zytiga(R)) - can help eliminate or almost eliminate tumors in many prostate cancer patients whose cancer has not yet metastasized. The study, conducted by researchers at Dana-Farber Cancer Institute in collaboration with other research centers, will be presented at the annual meeting of the American Society of Clinical Oncology (ASCO), June 1-5, in Chicago. In order to examine the effects of (Zytiga(R)) in combination with prednisone and surgery, the researchers enrolled 58 men with high-risk prostate cancer isolated to the prostate gland to participate in the study. Study participants were assigned to receive the combination therapy for either three or six months, in addition to surgery to remove the prostate. After completing the treatment regimen, the researchers found that one-third of the men had either little or no tumor tissue left. Mary-Ellen Taplin, M.D., of Dana-Farber, and lead author of the study, said: "Very high-risk cancers localized to the prostate are rarely cured by prostatectomy alone. 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." The male hormone androgen powers prostate cancer growth, and although standard treatments target the production of this hormone in the adrenal glands and testes, they do not target androgen within the tumor itself. However, abiraterone acetate has the ability to inhibit the production of androgen in all three sites. In addition to abiraterone acetate, study participants also received 5mg daily of prednisone (a steroid). Conventionally, prednisone is administered with abiraterone acetate in a 10mg dose. However, the researchers believed that the lower dose would reduce the adverse effects of prednisone while maintaining its benefits. According to the researchers, the 5mg dose is adequate for the majority of patients. Taplin explained: "Most of the patients in this study had large tumors, high grade prostate cancers and were at high risk for cancer spread. 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."