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Xtandi Approved for Metastatic Castration-Sensitive Prostate Cancer

This week, the United States Food and Drug Administration (US FDA) expanded the use of Xtandi (enzalutamide). Xtandi is now indicated for metastatic castration-sensitive prostate cancer. Castration-sensitive prostate cancer is a type of prostate cancer that responds to hormone therapy or orchiectomy (removal of the testicles). Castration-resistant prostate cancer does not respond to these treatments. Xtandi has already been approved for use in castration-resistant prostate cancer.

How does Xtandi work?

Xtandi is an androgen receptor inhibitor. These drugs block the action of testosterone and other androgens in the body. Prostate cancer tumors often grow in response to these hormones. By turning off the body’s ability to respond to testosterone or other androgens, tumor growth may be slowed or stopped. Androgen receptor inhibitors are also called anti-androgens.

Xtandi in clinical trials

This new FDA approval is based on results from the ARCHES Phase III clinical trial. Over 1100 men with metastatic castration-sensitive prostate cancer participated. Half of the men received Xtandi and the other half received a placebo (non-active drug). All participants also received a hormone therapy called a GnRH analog or previously had an orchiectomy.

The researchers measured radiographic progression-free survival (rPFS). rPFS is the amount of time between starting Xtandi and cancer progression. Cancer progression was defined as seeing two or more new bone lesions on a bone scan or cancer newly affecting the soft tissues. Death within 24 weeks after stopping Xtandi was also factored into rPFS.

Overall, the risk of cancer progression was reduced by 61 percent for the Xtandi group when compared to placebo. This suggests that Xtandi may lengthen the time before prostate cancer progression in some cases.

The trial also looked at PSA progression and time until a new cancer treatment was needed. Xtandi delayed the time until a new cancer drug was started by 72 percent. It also delayed the time until PSA progression by 81 percent. This suggests that Xtandi may slow down rising PSA levels and that some cancers may respond to Xtandi for a longer amount of time.

The trial is relatively new, and information on overall survival has not yet been determined. More follow-up is needed to determine the longer-term effects of Xtandi.1

What are the side effects of Xtandi?

The most common side effects of Xtandi include:

Things to know about Xtandi

Some drugs can impact the way Xtandi is broken down in the body. Tell your doctor about any other medications or supplements you are taking before starting Xtandi. Xtandi can very rarely increase the risk of certain complications including:

  • Seizures
  • Headaches
  • Confusion
  • Inflammation around the brain
  • Heart disease
  • Falls and fractures

Your doctor will help determine if the benefits of taking Xtandi outweigh the rare risks.

Xtandi can harm a developing fetus and lead to pregnancy loss. Men taking Xtandi who are sexually active with women who could become pregnant should use contraception.

Read the prescribing information to learn more about Xtandi.

This article represents the opinions, thoughts, and experiences of the author; none of this content has been paid for by any advertiser. The ProstateCancer.net team does not recommend or endorse any products or treatments discussed herein. Learn more about how we maintain editorial integrity here.

  1. FDA Approves Enzalutamide for Metastatic Castration-Sensitive Prostate Cancer. United States Food and Drug Administration. Available at: https://www.fda.gov/drugs/resources-information-approved-drugs/fda-approves-enzalutamide-metastatic-castration-sensitive-prostate-cancer. Accessed 12/19/2019.

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