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An early GnRH antagonist for prostate cancer, later withdrawn in the US.
Also known as: Plenaxis · GnRH antagonist
Part of the Foundational & therapeutic peptides cluster
Overview
Abarelix is a synthetic decapeptide GnRH antagonist developed for advanced prostate cancer. It was introduced in the United States in 2003 but discontinued there in 2005, while remaining available in some European markets. This page is educational and is not medical advice.
Source & context
Biological / chemical source: Synthetic decapeptide analog of GnRH
Primary research or clinical context: GnRH antagonist for advanced prostate cancer; introduced in the US in 2003 but discontinued there in 2005, and remains available in some European markets
Regulatory history
Abarelix illustrates that even approved peptides can be withdrawn from a market. In the US it was discontinued in 2005 amid commercial factors and reports of allergic reactions, while it continued to be marketed in some European countries.
Mechanism
As a GnRH antagonist, abarelix produces immediate suppression of luteinizing hormone and testosterone without the testosterone flare seen early in agonist therapy. This was a key rationale for antagonist development in prostate cancer.
Sequence
One-letter sequence commonly cited for Abarelix (educational; isoforms and modifications may differ):
AFASYNLKPA
Residues plotted ~100° apart around an α-helix — clustering of one color reveals an amphipathic face.
Structure & chemistry
Molecular identity & reference confidence
Source-supported reference
Reference values are taken from the cited molecular record or curated profile. A database match is not independent laboratory verification; modifications, counter-ions, and formulations can change the measured mass.
- Molecular form
- Abarelix (source record; form not independently established)
- Species
- Not established by this molecular identity audit
- Termini (N / C)
- Not specified / Not specified
Average reference mass
Reference policy updated: 2026-10-05
- IUPHAR/BPS source snapshot · 2026-10-01
- PubChem molecular record · 2026-10-01
- Molecular formula
- C72H95ClN14O14
- Average reference mass
- ≈ 1,416.1
- Status
- Approved medicine in at least one jurisdiction (IUPHAR record)
N-terminal alanine is N-acetyl-2-naphthalenyl-alanine (Ac-Nal); residue 2 is chlorophenyalanine (Cpa); alanine residue 3 is 3-pyridinyl-alanine (Pal); tyrosine residue 5 is methylated; lysine residue 8 is 1-methylethyl-lysine; C-terminal alanine is amidated
- PubChem CID: 16131215
- IUPHAR ligand: 1188
- ChEMBL: CHEMBL1252
- DrugBank: DB00106
- CAS RN: 183552-38-7
- UNII: W486SJ5824
Chemistry values: IUPHAR/BPS Guide to Pharmacology, PubChem · fetched 2026-10-01.
Clinical development snapshot
ClinicalTrials.gov lists 5 registered studies with “Abarelix” as an intervention (snapshot 2026-10-01). A registry footprint is not evidence of efficacy or approval.
| NCT | Title | Phase | Status | Updated |
|---|---|---|---|---|
| NCT06379217 | NEPC Study: An Exploratory Safety and Efficacy Study With PSMA, SSTR2 and GRPR Targeted Radioligand Therapy in | Phase 1 | active not recruiting | 2026-09-22 |
| NCT06157528 | Diagnosis of Pelvic Endometriosis in MRI | Not applicable | not yet recruiting | 2023-12-06 |
| NCT00841113 | Abarelix Versus Goserelin Plus Bicalutamide in Patients With Advanced or Metastatic Prostate Cancer | Phase 3 | completed | 2009-02-11 |
| NCT00100243 | Study of Abarelix in Androgen-Independent Prostate Cancer Progressing After Agonist Therapy | Phase 2 | completed | 2006-09-19 |
| NCT00103623 | The Plenaxis® Experience Study | Phase 4 | suspended | 2006-09-19 |
Abarelix — reconstitution calculator
Enter how much peptide is in the vial and how much diluent (e.g. bacteriostatic water) is added. The tool returns the resulting solution concentration — and, for any amount you type, the volume it corresponds to. This is educational arithmetic, not a dosing recommendation.
Reference form: Abarelix (source record; form not independently established)Average reference mass: 1,416.1 Da
Enter an amount to see the volume it corresponds to.
Educational concentration mathematics only. This tool does not recommend a dose, amount, or protocol, and nothing here is medical advice. Many peptides are not authorized by Health Canada for human use — see our reconstitution and bacteriostatic-water guides for context.
FAQ about Abarelix
What is Abarelix?+
Abarelix is a synthetic decapeptide GnRH antagonist developed for advanced prostate cancer. It was introduced in the United States in 2003 but discontinued there in 2005, while remaining available in some European markets. This page is educational and is not medical advice.
What Canadian product status is recorded for Abarelix?+
Canadian product status for Abarelix has not been verified in this profile. No verified record here does not mean no authorization exists. Status depends on the product, formulation and use; consult Health Canada's product records.
What is the typical length of Abarelix?+
Abarelix is commonly described as approximately 10 amino acids (GnRH antagonist (decapeptide analog)).
Related peptides
References & further reading
- 1.Hogle (2004). Abarelix (plenaxis). Clin J Oncol Nurs
- 2.Doehn et al. (2000). Technology evaluation: Abarelix, Praecis pharmaceuticals. Curr Opin Mol Ther
- 3.Reddy (2004). Abarelix (Plenaxis): a gonadotropin-releasing hormone antagonist for medical castration in patients with advanced prostate cancer. Clin Prostate Cancer
- 4.Tomera et al. (2001). The gonadotropin-releasing hormone antagonist abarelix depot versus luteinizing hormone releasing hormone agonists leuprolide or goserelin: initial results of endocrinological and biochemical efficacies in patients with prostate cancer. J Urol
- 5.Debruyne et al. (2006). Abarelix for injectable suspension: first-in-class gonadotropin-releasing hormone antagonist for prostate cancer. Future Oncol
- 6.Garnick et al. (2012). New treatment paradigm for prostate cancer: abarelix initiation therapy for immediate testosterone suppression followed by a luteinizing hormone-releasing hormone agonist. BJU Int
- 7.Mongiat-Artus et al. (2004). Abarelix: the first gonadotrophin-releasing hormone antagonist for the treatment of prostate cancer. Expert Opin Pharmacother
- 8.Trachtenberg et al. (2002). A phase 3, multicenter, open label, randomized study of abarelix versus leuprolide plus daily antiandrogen in men with prostate cancer. J Urol
- 9.PubChem — compound summary for Abarelix (CID 16131215)
- 10.Wikipedia — Abarelix