How does Xtandi treat advanced prostate cancer?

In up to 40 percent of men who are diagnosed with prostate cancer and undergo therapy, the disease spreads (metastasizes) and develops into advanced prostate cancer.

For those who have tried and failed to respond to androgen-deprivation therapy (also known as failure to respond to castration-resistant prostate cancer), there are other treatment options, including Xtandi (enzalutamide).

How does Xtandi treat advanced prostate cancer?

What is Xtandi?

Xtandi is an FDA-approved drug for the treatment of men with metastatic castration-resistant prostate cancer. It is in a drug class known as androgen receptor inhibitors, which means it blocks the androgen receptor signaling pathway in tumor cells. It does this in several ways. For example, preclinical research has shown that the drug can inhibit androgens from attaching to androgen receptors, block androgen receptor nuclear translocation, and interfere with interactions between androgen receptors with DNA.

How does Xtandi work?

Testosterone is known to stimulate the growth of prostate cancer, which is why one treatment approach is to block the formation of testosterone. This is the goal of hormone therapy for prostate cancer, aka androgen deprivation therapy. For some men, however, this therapeutic approach fails to stop the progression of the disease.

When that occurs, one option is Xtandi, which works by interfering with the connection between androgens and their receptors. The interaction of androgens and androgen receptors can cause prostate cancer cells to grow. Use of Xtandi can reduce how often androgens connect with receptors, which in turn can help slow the growth and spread of prostate cancer.

In a recent study, scientists compared the effects of enalutamide and bicalutamide (Casodex), an anti-androgen drug that is used to treat advanced (metastasized) prostate cancer. Typically bicalutamide is used along with another type of drug — a luteinizing hormone-releasing hormone agonist — but it was not in this study. A total of 396 men whose cancer continued to progress after failing androgen-deprivation therapy were treated with either enzalutamide or bicalutamide. At the end of the study:

Men who had received enzalutamide had a 76 percent reduced risk of prostate cancer progression or death when compared with men who had taken bicalutamide.

Median time from start of therapy to progression of prostate cancer among men who survived was 19.4 months for men who took enzalutamide compared with 5.7 months for men who received bicalutamide

Cost of Xtandi

The cost of Xtandi (enzalutamide) may be one factor that men might use to compare medications or make medical decisions for late-stage prostate cancer. Xtandi is a drug used to treat hormone-resistant prostate cancer that has metastasized, or spread to other areas of the body.

Xtandi costs $7,450 per month. The average treatment course is eight months, so the cost of Xtandi is usually about $60,000 for a full course of treatment. Additional costs for doctor visits, co-pays, deductibles, parking fees, and travel expenses are not included in this amount.

Xtandi is an oral medication taken at home. It is an androgen receptor inhibitor that works against prostate cancer by causing cell death and decreasing tumor size. Studies show that Xtandi works by interfering with the testosterone and dihydrotestosterone receptors on prostate cancer cells. The drug also stops the hormone receptors from exchanging messages with prostate cancer cells, and this stops cancer growth.

Assistance with the Cost of Xtandi

Medicare and most insurance companies have patient cost-sharing obligations that are similar to other oral anti-cancer treatment. Coverage for Medicare Part D and Medicaid patients varies widely. Many insurance plans consider Xtandi to be a specialty drug, so cost of Xtandi may be higher than co-pays for other drugs. Your doctor can help you determine what your cost of Xtandi would be. The manufacturer has programs for both insured and uninsured patients. Xtandi Access Services helps providers and patients understand costs and addresses financial barriers to using Xtandi.

Patients with private insurance can take advantage of the Patient Savings Program. The Xtandi Patient Savings Program is for patients who have private health insurance but who may have trouble paying their out-of-pocket costs. Patients in this program may pay about $20 out-of-pocket each time they fill a prescription for Xtandi. The program covers the remaining cost-sharing obligation up to $12,000 in prescription costs per calendar year. Patients who are insured by government-sponsored insurance, such as Medicare, Medicaid, and TRICARE, are not eligible to use this program. Call Access Services at 1-855-8XTANDI to find out more about reimbursement services or the Patient Savings Program.

Uninsured patients may be eligible for the Astellas Access Program if they meet certain criteria:

• They have been prescribed XTANDI for an FDA-approved indication.
• They are uninsured, awaiting public assistance (such as Medicaid), or have a health insurance plan that has denied coverage for XTANDI.
• They have an annual household adjusted gross income of less than $100,000 per year.
• They have a verifiable shipping address within the United States.

Patients and doctors who feel that Xtandi is the right treatment for prostate cancer should be able to find an affordable way to get the medication through a combination of Medicare, private insurance, or a patient assistance program offered through the manufacturer. These factors should help with the cost of Xtandi.

Source: Penson D et al. Enzalutamide versus bicalutamide in castration-resistance prostate cancer: the STRIVE Trial. Journal of Clinical Oncology 2016 Jan 25