Pegvisomant

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Pegvisomant

Pegvisomant is a protein containing 191 amino acid residues to which several polyethylene glycol polymers have been covalently bound in order to slow clearance from the blood. The protein is a modified version of human growth hormone designed to bind to and block the growth hormone receptor. It is manufactured using genetically modified E. coli bacteria. The polyethylene glycol polymers are subsequently added chemically.

The FDA approved pegvisomant (Somavert Pfizer), a growth hormone receptor antagonist, for parenteral treatment of acromegaly in patients who are not candidates for or have had an inadequate response to surgery or other treatment 1).

As the only GH receptor antagonist (GHRA) available, pegvisomant has shown its effectiveness in the control of insulin like growth factor IGF-1 2).

van der Lely et al demonstrated Pegvisomant as an effective medical treatment for acromegaly, because of the patients treated for 12 months or more, 87 of 90 (97%) achieved a normal serum IGF-1 concentration 3).

It is delivered as a powder that is mixed with water and injected under the skin.

Data support a comparable QoL in patients receiving pegvisomant vs. somatostatin analogue, despite the fact that the vast majority receiving pegvisomant did not respond to or were not able to tolerate somatostatin analogs 4).

Side effects

Side effects of Pegvisomant include reactions at the injection site, swelling of the limbs, chest pain, hypoglycemia, nausea and hepatitis.

Blocking of the growth hormone’s receptor reduces feedback control of the growth hormone regulation leading to approximately doubled GH levels.

The GH receptor antagonist pegvisomant is increasingly used as therapy in acromegaly.

Combination Therapy

The combination of somatostatin analog SA and pegvisomant in patients who could not achieve IGF-1 normalization was safe and aided improved quality of life in acromegaly 5) 6) 7) 8).

Further, the combination of pegvisomant and SA could reduce the dose of SA that is required 9).

There is, however, no evidence adequate to prove the significant benefits obtained from combination 10).

In Melmed et al’s guidelines, such combination is recommended on the condition that patients are resistant to other treatments 11).

In combination with cabergoline, the combination of SA and cabergoline might provide effective treatment in patients with mixed pituitary adenomas in whom simultaneously elevated prolactin (PRL) and GH are observed 12), while, in patients who are partially responsive to the maximum SA dose, additive therapy with cabergoline could normalize IGF-1 in about half of the patients, including those without prolactinemia 13).

Pituitary surgery might be indicated on pegvisomant treatment, due to side effects, adenoma growth or intention to cure after primary treatment.

1)

Pegvisomant (Somavert) for Acromegaly.The Medical Letter on Drugs and Therapeutics.1160c.45.55-56
2)

Neggers SJ, van Aken MO, de Herder WW, et al. Quality of life in acromegalic patients during long-term somatostatin analog treatment with and without pegvisomant. J Clin Endocrinol Metab. 2008;93(10):3853–3859.
3)

van der Lely AJ, Hutson RK, Trainer PJ, Besser GM, Barkan AL, Katznelson L, Klibanski A, Herman-Bonert V, Melmed S, Vance ML, Freda PU, Stewart PM, Friend KE, Clemmons DR, Johannsson G, Stavrou S, Cook DM, Phillips LS, Strasburger CJ, Hackett S, Zib KA, Davis RJ, Scarlett JA, Thorner MO. Long-term treatment of acromegaly with pegvisomant, a growth hormone receptor antagonist. Lancet. 2001 Nov 24;358(9295):1754-9. PubMed PMID: 11734231.
4)

Dichtel LE, Kimball A, Yuen KCJ, et al. Effects of Growth Hormone Receptor Antagonism and Somatostatin Analog Administration on Quality of Life in Acromegaly [published online ahead of print, 2020 Aug 10]. Clin Endocrinol (Oxf). 2020;10.1111/cen.14309. doi:10.1111/cen.14309
5)

Fendri S, Karaca P, Tiev E, Buchfelder M, Lalau J. Control of disease activity and tumor size after introduction of pegvisomant in a lanreotide-resistant acromegalic patient. Ann Endocrinol (Paris) 2013;74(1):49–52. [PubMed]
6)

Neggers SJ, de Herder WW, Feelders RA, van der Lely AJ. Conversion of daily pegvisomant to weekly pegvisomant combined with long-acting somatostatin analogs, in controlled acromegaly patients. Pituitary. 2011;14(3):253–258. [PMC free article] [PubMed]
7)

Madsen M, Poulsen PL, Orskov H, Møller N, Jørgensen JO. Cotreatment with pegvisomant and a somatostatin analog (SA) in SA-responsive acromegalic patients. J Clin Endocrinol Metab. 2011;96(8):2405–2413. [PubMed]
8)

van der Lely A, Bernabeu I, Cap J, et al. Coadministration of lanreotide Autogel and pegvisomant normalizes IGF1 levels and is well tolerated in patients with acromegaly partially controlled by somatostatin analogs alone. Eur J Endocrinol. 2011;164(3):325–333.
9) , 10)

Madsen M, Poulsen PL, Orskov H, Møller N, Jørgensen JO. Cotreatment with pegvisomant and a somatostatin analog (SA) in SA-responsive acromegalic patients. J Clin Endocrinol Metab. 2011;96(8):2405–2413.
11)

Melmed S, Colao A, Barkan A, et al. Acromegaly Consensus Group Guidelines for acromegaly management: an update. J Clin Endocrinol Metab. 2009;94(5):1509–1517.
12)

Sowiń ski J, Sawicka N, Piatek K, Zybek A, Ruchala M. Pharmacoeconomic aspects of the treatment of pituitary gland tumours. Contemp Oncol (Pozn) 2013;17(2):137–143.
13)

Sandret L, Maison P, Chanson P. Place of cabergoline in acromegaly: a meta-analysis. J Clin Endocrinol Metab. 2011;96(5):1327–1335.

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