A man’s prostate gland is part of his reproductive system. It is located below the bladder and around the urethra, and its main function is to produce a fluid that combines with sperm and makes semen more liquid. When a man develops prostate cancer, the cells in the gland start to grow out of control, compared to healthy cells, which normally divide and die. Due to the location of the gland, prostate cancer affects both the reproductive and urinary systems.
Symptoms of prostate cancer include a slow or weak urinary stream or the need to urinate more often, especially at night; blood in the urine; erectile dysfunction; and pain if the cancer has spread to the bones or other organs. There is currently no cure for the disease.
How Zytiga works
Zytiga (abiraterone acetate) is a type of hormone therapy classified as an adrenal inhibitor. It is used in combination with prednisone to treat metastatic castration-resistant prostate cancer in men who have already received chemotherapy containing Taxotere (docetaxel).
“The male body naturally produces hormones called androgens. The most well known androgen in men is testosterone. For men with [metastatic castration-resistant prostate cancer], androgens play a role in fueling the tumor,” states Janssen Biotech, which commercializes the brand-name therapy.
“While not the only source, androgen is produced primarily in the testes and some is also produced by the adrenal glands, which are located above the kidneys. We know now that the tumor itself is also a source of androgen production. While there are other key factors that contribute to the disease, androgen is one such factor. Reducing the production of androgen is key in helping you and your doctor manage your illness,” Janssen says on its website.
The U.S. Food and Drug Administration (FDA) approved the use of Zytiga in combination with prednisone in 2011 and expanded its use in 2012.
Zytiga to treat prostate cancer
According to a Phase 3 trial of Zytiga, overall survival was longer in the abiraterone acetate-prednisone group than in the placebo-prednisone group after a median follow-up of 12.8 months (14.8 months vs. 10.9 months). The clinical trial included 1,195 patients from 13 countries whose metastatic prostate cancer had previously been treated with one of two chemotherapy regimens that included Taxotere. Treatment with Zytiga improved PSA progression, progression-free survival, and PSA response rate, according to the study.
Over time, most prostate cancers become resistant to treatment. Zytiga works by blocking the production of androgen in the testes, adrenal glands, and prostate cancer tumors themselves. The group of 797 patients randomly assigned to receive Zytiga plus prednisone reported a median overall survival of 14.8 months, four months longer than patients treated with prednisone plus a placebo.
According to the FDA, “The recommended dose and schedule for abiraterone acetate is 1000 mg administered orally once daily in combination with prednisone 5 mg administered orally twice daily. Abiraterone acetate must be taken on an empty stomach.”
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