Degarelix (Firmagon) for advanced prostate cancer

The authors evaluated the effectiveness of degarelix (Firmagon) for advanced prostate cancer.

Prostate cancer requires the androgen hormone testosterone to grow, and is described as a hormone-sensitive disease. Androgen deprivation therapy (ADT) is intended to reduce the production of androgens, or inhibit their effect on cancer cell growth. This is most often achieved using gonadotropin-releasing hormone (GnRH) receptor agonists, a type of drug that lowers the production of testosterone. However, these drugs can be associated with drawbacks such as temporary testosterone surges.

Degarelix is a drug that also works at the GnRH receptor but in a different way, and has been developed to counteract the problems associated with traditional GnRH agonists. Degarelix has been approved for patients with advanced prostate cancer.

In a phase III trial of 610 prostate cancer patients, researchers evaluated the effectiveness of degarelix. All study groups received an initial dose of 240 mg followed by once-monthly maintenance doses of 80 mg for group 1 (207 patients), 160 mg for group 2 (202 patients) and leuprolide (Eligard) 7.5 mg for group 3 (201 patients). 

After 12 months the percentage of patients whose cancer shrank or disappeared after treatment was 97.2% for group 1, 98.3% for group 2 and 96.4% for group 3. 96.1% of group 1 and 95.5% of group 2 achieved an average testosterone level of ≤0.5 ng/mL by day 3 of treatment. Most of the patients in group 3 had testosterone levels >0.5 ng/mL up to day 28 of treatment. Degarelix was not associated with testosterone surges, but the majority of leuprolide recipients experienced testosterone surges. Prostate-specific antigen (PSA) recurrences (increasing levels of PSA following treatment) occurred in 8.9% of group 1, 14.2% of group 2 and 14.1% of group 3. Analysis revealed that degarelix was associated with a 33% reduction in risk of PSA recurrence or death compared to leuprolide.

In an analysis of 5 published trials, degarelix was associated with a 29% reduced risk of PSA progression (rising PSA levels) and a 53% reduced risk of death compared to GnRH receptor agonist therapy (for example leuprolide – Eligard or goserelin – Zoladex).

One year’s treatment with degarelix was generally well tolerated with most adverse events being mild to moderate in severity. The most common adverse event was injection-site reactions (in about 40% of patients).

The authors concluded that degarelix is effective in suppressing testosterone levels without being associated with testosterone surges.