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GH Axis · Reference monograph

PEGylated growth hormone receptor antagonist

Reference compound — not available from Purity Peptides. Shown for research context.

Overview

Pegvisomant is a genetically engineered analogue of human growth hormone that acts as a growth hormone receptor antagonist. Its protein backbone, a 191-amino-acid variant of GH, carries a set of amino acid substitutions, the most important being a glycine-to-lysine change at position 120, and it is conjugated to several polyethylene glycol chains. The concept arose in the late 1980s at Ohio University, where John Kopchick and Wen Chen observed that mice expressing a GH variant with an altered third helix grew smaller rather than larger.

Pegvisomant was approved in the EU in 2002 and by the FDA in 2003, marketed as Somavert, for acromegaly when other approaches are insufficient. It was the first GH receptor antagonist to reach the market and remains a key research example of rational protein engineering. Unlike somatostatin analogues, which reduce GH secretion from pituitary tumours, pegvisomant blocks GH action at its receptor, so circulating GH rises while IGF-1 falls. Research interest includes IGF-1 normalisation, liver enzyme effects, tumour volume monitoring and the biology of GH receptor activation.

Mechanism studied

  1. Pegvisomant
  2. GH receptor blockade
  3. Hepatic IGF-1 ↓
  4. IGF-1 endpoints

Growth hormone activates its receptor by binding two receptor molecules in sequence, through site 1 and then site 2, producing a conformational change in a pre-formed receptor dimer that activates JAK2 and STAT5 signalling. Pegvisomant's G120K substitution disrupts site 2, so the molecule binds the receptor but cannot induce productive activation. Additional substitutions strengthen site 1 binding, compensating for the reduced affinity caused by PEGylation. PEGylation in turn slows clearance and reduces immunogenicity. The net effect is competitive blockade of GH signalling in the liver and other tissues, lowering hepatic IGF-1 production.

Research highlights

  • 01Originated from Kopchick and Chen's observation of dwarfism in mice expressing a third-helix GH variant.
  • 02A textbook example of converting a hormone agonist into an antagonist through targeted mutagenesis.
  • 03PEGylation extends circulation time and offsets reduced receptor affinity in a carefully balanced design.
  • 04Approved in the EU in 2002 and the US in 2003 as the first GH receptor antagonist.
  • 05Open questions include long-term effects on pituitary tumour size and liver function in observational research.

Latest published research

669 papers on PubMed →

  1. Cost-effectiveness of pasireotide long-acting release in acromegaly: a systematic literature review and methodology assessment

    Gilis-Januszewska A et al. · Journal of medical economics · 2026 Dec · PMID 41518621

  2. Should radiotherapy be repositioned in the contemporary management of acromegaly?

    di Filippo L et al. · Pituitary · 2026 Oct 16 · PMID 42888334

  3. New Horizons in Pharmacotherapy for Cushing's Disease and Acromegaly

    Fleseriu M et al. · Endocrine-related cancer · 2026 Oct 15 · PMID 42878776

  4. Pegvisomant in severe, treatment-resistant thyroid eye disease: a case report

    Köröskényi L et al. · Drugs in context · 2026 · PMID 42890916

  5. Pasireotide-LAR and pegvisomant combination in resistant acromegaly: a case series of predominantly mammosomatotroph adenomas

    Mignone E et al. · Pituitary · 2026 Sep 23 · PMID 42778805

  6. Approach to the patient: precision medicine-guided evaluation and treatment of acromegaly

    Puig-Domingo M et al. · The Journal of clinical endocrinology and metabolism · 2026 Sep 16 · PMID 42314069

  7. Pegvisomant

    · 2006 · PMID 30000555

  8. Growth Hormone Receptor Antagonism Extends Lifespan

    List EO et al. · Aging cell · 2026 Sep · PMID 42701998

Live feed from PubMed (NCBI) for “Pegvisomant”, updated 2026-10-30. Listing a paper is not an endorsement of its findings.

Registered studies

41 on ClinicalTrials.gov →

From the public ClinicalTrials.gov registry for “Pegvisomant”, updated 2026-10-30. Shown for research context only; Purity Peptides products are not for human use.

Key references

  1. [1]Manufacturer's prescribing information — FDA / EMA / ANVISA
  2. [2]Trainer et al., 2000 — N Engl J Med 342:1171–1177
  3. [3]WADA — Prohibited List of Substances and Methods

FAQ

  • Pegvisomant binds the GH receptor through site 1 but carries a G120K mutation that disrupts site 2. It therefore occupies the receptor without triggering the conformational change required for JAK2 and STAT5 activation.

  • Pegvisomant acts at the receptor rather than on the pituitary, so GH secretion is not suppressed. Reduced IGF-1 feedback can increase GH release, which is why IGF-1 rather than GH serves as the main research biomarker.

  • Pegvisomant is approved by the FDA and EMA as a prescription medicine for acromegaly. Research-grade material is supplied for laboratory studies of GH receptor pharmacology and protein engineering only.

FOR RESEARCH USE ONLY.Not for human or veterinary use. Not intended to diagnose, treat, cure, or prevent any disease.

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