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Growth Hormone Receptor Antagonists (Pegvisomant)

Acromegaly is the result of growth hormone (GH) hypersecretion by a pituitary macro- or microadenoma. Presentation before puberty is rare and is the cause of pituitary gigantism.

Pathogenesis
  • Acromegaly most often occurs in adults aged 30-50 years.
  • Elevated GH levels are associated with changes in appearance, headaches, sweating and tiredness.
  • GH hypersecretion affects a number of body systems and is associated with a two-fold increase in mortality.

Pegvisomant is a genetically modified analogue of growth hormone (GH) that functions as a highly selective growth hormone receptor antagonist. Clinical trials of its use in acromegaly commenced in 1997. The drug was approved in the US in March 2003 and in Europe in November 2003.1

Indications for use

Transphenoidal surgery is the treatment of choice in most cases of acromegaly:

  • However, some patients may need medical treatment or radiotherapy after surgery to reduce GH levels:
    • High levels of GH are associated with an increase in mortality even when the patient is asymptomatic.
    • Studies have shown that pegvisomant is able to normalise circulating levels of insulin-like growth factor-1 (IGF-1), the principal mediator of GH action, in 97% of patients with active acromegaly.2,3
    • Some GH-secreting adenomas are treatable by long-term medical therapy with or without radiotherapy.
  • The consultant may offer the patient a choice between long-term medical treatment, involving injections, or surgery.

Pegvisomant should be initiated only by physicians experienced in the treatment of acromegaly. It is licensed for the treatment of acromegaly in patients with inadequate response to:

  • Surgery
  • Radiation
  • Both modalities
  • Or to treatment with somatostatin analogues e.g. octreotide

A new treatment algorithm has been proposed, in which the choice between primary medical treatment and primary surgery is individualised, depending on:4

  • Adenoma size and spread5
  • Patient factors (age, preference for therapy, contraindication for surgery)
  • Surgical experience of the centre and octreotide sensitivity of the adenoma
  • Preliminary data suggest that pegvisomant may be a particularly suitable choice of medical therapy for patients with acromegaly and coexistent diabetes mellitus2

The high cost of lifelong medical treatment, especially of pegvisomant, must be weighed against the cost of a single surgical procedure.6 The dose is initially 80 mg, then 10 mg daily, increased in steps of 5 mg daily according to response with a maximum maintenance dose of 30 mg daily. A 10 mg vial costs £50.

Contraindications and cautions

Contraindications

Cautions

  • Liver disease - liver enzymes should be monitored every 4 to 6 weeks for 6 months, or if symptoms of hepatitis develop
  • Diabetes mellitus - some adjustment of antidiabetic therapy may be necessary
  • Possible increase in female fertility

Adverse effects

Document references
  1. Biermasz NR, Romijn JA, Pereira AM, et al; Current pharmacotherapy for acromegaly: a review. Expert Opin Pharmacother. 2005 Nov;6(14):2393-405. [abstract]
  2. Paisley AN, Trainer P, Drake W; Pegvisomant: a novel pharmacotherapy for the treatment of acromegaly. Expert Opin Biol Ther. 2004 Mar;4(3):421-5. [abstract]
  3. Goldenberg N, Racine MS, Thomas P, et al; Treatment of Pituitary Gigantism with the Growth Hormone Receptor Antagonist Pegvisomant. J Clin Endocrinol Metab. 2008 May 20;. [abstract]
  4. Clemmons DR, Chihara K, Freda PU, Ho KKY et al; Optimizing Control of Acromegaly: Integrating a Growth Hormone Receptor Antagonist into the Treatment Algorithm. The Journal of Clinical Endocrinology & Metabolism 2003 Vol. 88, No. 10 4759-4767
  5. Bush ZM, Vance ML; Management of acromegaly: is there a role for primary medical therapy? Rev Endocr Metab Disord. 2008 Mar;9(1):83-94. [abstract]
  6. Drake WM, Trainer PJ; Clinical use of pegvisomant for the treatment of acromegaly. Treat Endocrinol. 2003;2(6):369-74. [abstract]
  7. Roelfsema F, Biermasz NR, Pereira AM, et al; The role of pegvisomant in the treatment of acromegaly. Expert Opin Biol Ther. 2008 May;8(5):691-704. [abstract]
  8. Hodish I, Barkan A; Long-term effects of pegvisomant in patients with acromegaly. Nat Clin Pract Endocrinol Metab. 2008 Jun;4(6):324-32. Epub 2008 Apr 22. [abstract]
Internet and further reading AcknowledgementsEMIS is grateful to Dr Hayley Willacy for writing this article. The final copy has passed scrutiny by the independent Mentor GP reviewing team. ©EMIS 2008.
DocID: 332
Document Version: 2
DocRef: bgp25178
Last Updated: 13 Jun 2008
Review Date: 13 Jun 2009
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Perhaps the biggest cause of ill health in the world is poverty. Help to Make Poverty History. For example, why not lend some of your money to disadvantaged communities to enable them to trade their way out of poverty through schemes such as Shared Interest.

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