Degarelix (Firmagon): Uses, Mechanism, and Side Effects

Men diagnosed with advanced prostate cancer often want to understand how hormone-based therapies work before starting treatment. Degarelix, sold under the brand name Firmagon, is one option used to lower testosterone as part of managing this disease.

Key takeaways

• Degarelix is a GnRH receptor antagonist approved for advanced prostate cancer, marketed as Firmagon.
• It works by blocking pituitary GnRH receptors, which reduces gonadotropin release and lowers testosterone.
• More than 170 registered clinical trials have studied degarelix, including completed Phase 3 trials in prostate cancer.
• The most frequently reported adverse events involve injection site reactions and general symptoms like fatigue and hot flush.
• FAERS reports include deaths, but these counts reflect reporting volume, not confirmed causation.

What Degarelix Is

Degarelix belongs to a class of drugs called GnRH receptor antagonists. It binds reversibly to GnRH receptors in the pituitary gland, which reduces the release of gonadotropins. This chain of effects lowers testosterone production, a hormone that can fuel prostate cancer growth.

What Degarelix Is Approved For

Degarelix, marketed as Firmagon, is approved for treatment of patients with advanced prostate cancer. It is not indicated as a broader hormone therapy outside this cancer setting. The available labeling for this compound does not carry a boxed warning.

What the Evidence Shows

Degarelix has been studied across 174 registered clinical trials. A completed Phase 3 trial evaluated degarelix in Taiwanese patients with prostate cancer, while another completed Phase 3 trial examined its use as a neoadjuvant therapy in prostate cancer patients. Research involving degarelix continues in combination settings, including an ongoing early-phase trial pairing it with other prostate cancer treatments.

Reported Side Effects

Reported adverse events for degarelix are dominated by injection site reactions, including pain (364 reports), erythema (291), and swelling (210). General systemic effects such as fatigue (405 reports), hot flush (327), and asthenia (222) are also commonly reported. Death (209 reports) and product storage error (209) appear in the data as well. These figures represent counts of submitted reports to a safety surveillance system, not confirmed rates of incidence or proof that degarelix caused the event.