At a glance
| Brand | Firmagon |
|---|---|
| Approved use | Advanced prostate cancer |
| Target | Pituitary GnRH receptor |
| Hormonal effect | Lowers LH, FSH and testosterone |
| Delivery | Subcutaneous depot |
| Important distinction | Antagonist; no initial testosterone flare |
Overview
Degarelix is supplied as Firmagon, a prescription injection that forms a depot after subcutaneous administration. Lowering testosterone can slow the growth of prostate cancers that remain dependent on androgen signaling. The choice of androgen-deprivation treatment depends on disease stage, other anticancer medicines, symptoms and the individual patient’s health. Degarelix is not chemotherapy and does not remove the need for further cancer-directed treatment when indicated. Testosterone and prostate-specific antigen measurements help assess its biological effect, while clinical evaluation and imaging address the broader course of the cancer.
How it works
Degarelix binds directly to pituitary GnRH receptors as an antagonist. Blocking the receptor suppresses release of LH and FSH, and reduced LH stimulation lowers testosterone production by testicular Leydig cells. Receptor blockade acts without the initial stimulation produced by GnRH agonists. The drug therefore avoids an agonist-induced testosterone flare, although the longer-term consequences of androgen deprivation still apply.
How does it fit into prostate-cancer care?
The FDA indication is advanced prostate cancer. Degarelix provides the androgen-deprivation component of treatment; clinicians may combine this with other therapies according to the cancer’s characteristics. It is not a curative claim for all stages, and a falling PSA alone does not describe every aspect of response.
Supporting sources [1]
What did the pivotal comparison establish?
A randomized, open-label study enrolled 610 patients and compared degarelix with leuprolide over one year. Degarelix was noninferior for maintaining low testosterone and produced faster initial testosterone and PSA suppression. This endocrine endpoint should not be rewritten as a demonstrated survival advantage over leuprolide.
Supporting sources [2]
What needs monitoring?
Injection-site reactions and hot flushes are common. Hypersensitivity can be serious, and androgen-deprivation therapy can prolong the QT interval. The broader effects of sustained low testosterone include sexual and metabolic changes and loss of bone health, making clinical monitoring important beyond the injection itself.
Supporting sources [1]
Does avoiding flare mean there are no hormone-related risks?
No. Avoiding the initial testosterone rise is one difference from GnRH agonists. Degarelix still deliberately produces profound androgen deprivation, with associated symptoms and monitoring needs. Its approved oncology use does not support unsupervised use to adjust hormone levels or prevent disease in otherwise healthy people.
Reading this profile
Jurisdiction: United States; indications and availability vary by formulation and country.. Molecular class: Synthetic decapeptide GnRH receptor antagonist.
This profile was written with AI-assisted research and checked against the linked sources. It has not been represented as a clinician’s review. Evidence summaries describe the cited studies and products; they do not establish that a separately purchased preparation is equivalent.
Sources & references
Follow the original material. Product labels define specific formulations and uses; trial registration describes a study and does not by itself establish benefit.
- Firmagon — current US prescribing information ↗Regulatory source · Checked 2026-10-27
- The efficacy and safety of degarelix: a 12-month, comparative, randomized, open-label, parallel-group phase III study in patients with prostate cancer. ↗Original research · Checked 2026-10-27