Xofigo Compared to Zytiga for Prostate Cancer Treatment

Xofigo compared to Zytiga means that men with prostate cancer have another treatment option to consider. The Food and Drug Administration (FDA) approved a new medication, Xofigo (radium-223 dichloride), for late stage (metastatic) castration-resistant prostate cancer on May 15, 2013.

With this new medication addition to the market, prostate cancer patients will want to ask how it compares to other available drugs they are taking or considering taking. Zytiga (abiraterone acetate) is another prescription drug for patients with late-stage castration-resistant prostate cancer. Zytiga was approved by the FDA for use in combination with a steroid, prednisone, on April 29, 2011, as a hormone therapy for patients whose prostate cancer has spread after chemotherapy.

How do Xofigo and Zytiga work?

Both medications are used for hormone-resistant prostate cancers that have metastasized, or spread to other areas of the body.

Xofigo has an anti-tumor effect. The injectable medication contains radium (a heavy metal), which delivers radiation directly to bone tumors without significantly damaging surrounding tissues. This breaks up double-strand DNA, killing the prostate cancer cell at the site of cancer-induced increased bone turnover. Therapy consists of six injections given at four-week intervals.

Zytiga is an oral medication taken once per day, but the dose is accompanied by the steroid prednisone, which is taken twice a day. Zytiga works by targeting a protein called cytochrome P450 17A1 (CYP17A1). This plays a significant role in testosterone production.

Zytiga differs from other hormone therapies for prostate cancer in that it is the only therapy able to reduce the production of testosterone from three sources: the adrenal glands, the testes, and the prostate tumor. The average length of treatment is eight months.

In studies, patients taking Zytiga had a 3.9-month survival benefit over a placebo, while Xofigo had a 3-month survival benefit over a placebo.

Xofigo compared to Zytiga: who is eligible?

Both drugs are used for advanced stages of castration-resistant prostate cancer that have spread despite hormone therapy.

Xofigo is only for cancers that have spread to the bones and not other organs. It cannot be used with chemotherapy.

Candidates for Zytiga have advanced prostate cancer that has spread or recurred after treatment with docetaxel (chemotherapy) in addition to hormone therapy.

Xofigo compared to Zytiga: side effects

Common side effects of Xofigo may include:

  • Nausea
  • Diarrhea
  • Vomiting
  • Swelling of the leg, ankle, or foot

Common side effects of Zytiga may include:

  • Cough
  • Diarrhea
  • Fluid retention
  • Heartbeat disorders
  • High blood pressure
  • Hot flashes
  • Joint swelling
  • Low potassium levels
  • Muscle aches
  • Upper respiratory tract infection
  • Upset stomach
  • Urinary frequency
  • Urinary tract infection

Prednisone is taken along with Zytiga. Steroids may be associated with weakening of the immune system, making individuals susceptible to infection.

Xofigo compared to Zytiga: cost

Xofigo costs $69,000 for the complete course of therapy. Because it is new, patients need to check with their insurance carrier for coverage. Bayer will have a patient assistant program to help with costs.

Zytiga costs $5,000 per month, and the average treatment course is eight months, so it is approximately $40,000 for a full course of treatment. Medicare and most insurance companies cover treatment. Patients may be eligible for financial assistance.

 Xofigo compared to Zytiga: which one for you?

Your physician can help you determine which medication is right for you based on your symptoms, metastases, and other treatments you are using. If your prostate cancer has spread beyond bones to other organs, then Xofigo is not the right treatment for you. If you have already had hormone therapy and chemotherapy, then Zytiga may be an option for you. You will need to weigh all the costs and benefits to make a decision that fits your situation.

Read more in our Prostate Cancer Health Center.

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