FDA Aproves Zytiga (abiraterone acetate) for Late-Stage Prostate Cancer
PCF's Take: The Prostate Cancer Foundation (PCF) applauds the approval of Zytiga (abiraterone acetate), a once-daily oral agent, for the treatment of castration-resistant, metastatic prostate cancer following docetaxel chemotherapy. This represents a clinical breakthrough for patients who previously had few good clinical therapies available to them.
Zytiga represents a new class of medication that suppresses androgen (testosterone) synthesis in a very new way. The agent targets an enzyme, Cyp17 lyase, which is involved in the complex conversion of cholesterol to testosterone. The ability of this agent to reduce intratumoral testosterone levels far below the levels achieved with current androgen suppressive medications resulted in a profound survival advantage for patients in a large, randomized Phase III clinical trial. Clinicians will now have a new, powerful, and relatively safe, life-prolonging treatment for advanced prostate cancer patients. Clinical practice will be changed in a positive way for these patients.
Where do we go from here? A second, large Phase III clinical trial is underway to assess the efficacy of Zytiga in castration-resistant prostate cancer patients with minimal symptoms prior to chemotherapy. This trial has been fully accrued and we await the outcomes analysis. If positive, once again, clinical practice will be changed for a much larger group of patients.
PCF is pleased to have funded over $8 million for competitive research awards centered on Zytiga. This resource helped to determine the mechanism of action of the agent, the execution of Phase II clinical trials, and continues to fund a determination of mechanisms of patient resistance to the agent. The PCF-DoD Clinical Trials Consortium, along with funded investigators at the Royal Marsden Hospital in London, were instrumental in designing the pivotal Phase III clinical trial that supported the FDA decision to approve the agent.
This is just the beginning, the very first approval, for new agents that modulate testosterone-driven progression of prostate cancer. Many more are on the horizon. PCF will be the knowledge exchange for determining the most intelligent sequencing of the agents as they become approved. The approval of Zytiga is a great day for prostate cancer patients seeking life-prolonging therapy for advanced disease. The future is even brighter.