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News Note: Addition of Experimental Drug to Standard Chemotherapy for Advanced Prostate Cancer Shows No Benefit in Phase 3 Clinical Trial

Prostate cancer patients in a phase 3 trial who were non-responsive to hormone therapy and received the investigational agent atrasentan in addition to a standard chemotherapy regimen, did not have longer survival or longer progression-free survival compared to the patients on the same chemotherapy regimen and a placebo. This determination was made by the trial’s Data and Safety Monitoring Committee (DSMC) based on a planned interim analysis of the trial. Atrasentan belongs to a class of compounds known as selective endothelin-A receptor antagonists, or SERAs. SERAs antagonize the effect of endothelin, a protein thought to be involved in the stimulation of the spread of cancer cells. A receptor antagonist does not provoke a biological response itself upon binding to a receptor, but blocks or dampens antagonist-mediated responses.

The study (S0421: Phase III Study of Docetaxel and Atrasentan Versus Docetaxel and Placebo for Patients with Advanced Hormone Refractory Prostate Cancer) was supported by the National Cancer Institute (NCI), part of the National Institutes of Health, and was conducted by SWOG (formerly the Southwest Oncology Group) with the participation of several other NCI-supported Cooperative Groups. Atrasentan for the trial was provided under an agreement with Abbott Laboratories, Abbott Park, Ill., and was distributed by the Department of Veterans Affairs Cooperative Studies Program Clinical Research Pharmacy Coordinating Center.

Posted: April 2011