The U.S. Food and Drug Administration (FDA) has expanded the approved use of Zytiga® (abiraterone) to treat men with metastatic, hormone-refractory prostate cancer prior to receiving chemotherapy.
Prostate cancer is a hormonally sensitive disease that can often be controlled for long periods with androgen-deprivation therapy (ADT). When prostate cancer stops responding to this treatment, it is referred to as hormone-refractory prostate cancer. Metastatic hormone-refractory prostate cancer is a challenging form of the disease to treat because the cancer has spread to distant sites in the body and does not respond to treatment with standard hormonal therapy.
Zytiga is an oral targeted agent that blocks the production of androgens (male hormones such as testosterone) not only by the testes, but also by the adrenal glands and the tumor itself. It was initially approved in April 2011 for use in patients whose prostate cancer progressed after chemotherapy.
The expanded approval was based on data from a study that involved 1,088 men with metastatic, hormone-refractory prostate cancer who had not previously received chemotherapy. Participants were randomized to receive Zytiga or placebo in combination with prednisone. Patients who received Zytiga had a median overall survival of 35.3 months compared with 30.1 months for those receiving the placebo.
The most common side effects reported in those receiving Zytiga include fatigue, joint swelling or discomfort, swelling caused by fluid retention, hot flashes, diarrhea, vomiting, cough, high blood pressure, shortness of breath, urinary tract infection, and bruising.
The most common laboratory abnormalities included low red blood cell count; high levels of the enzyme alkaline phosphatase, which can be a sign of other serious medical problems; high levels of fatty acids, sugar, and liver enzymes in the blood; and low levels of lymphocytes, phosphorous and potassium in the blood.
Zytiga’s expanded approval was part of the FDA’s priority review program, which allows an expedited six-month review of drugs that may offer major advances in treatment.
FDA expands Zytiga’s use for late-stage prostate cancer. [FDA News Release]. U.S. Food and Drug Administration website. Available at: https://www.fda.gov/NewsEvents/Newsroom/PressAnnouncements/ucm331492.htm
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