Efficacy of 12-month treatment with the GH receptor antagonist pegvisomant in patients with acromegaly resistant to long-term, high-dose somatostatin analog treatment: effect on IGF-I levels, tumor mass, hypertension and glucose tolerance.
OBJECTIVE
We aimed to investigate the efficacy of pegvisomant in patients with acromegaly resistant to long-term (> or = 24-month), high-dose treatment with octreotide-LAR (40 mg/month) or lanreotide (120 mg/month).


METHODS
This was an open, prospective study.


METHODS
We studied 16 patients with acromegaly (nine women; aged 28-61 years). The main outcome measures were IGF-I levels, blood pressure, glucose tolerance and safety (liver function and tumor size). Pegvisomant was given at doses of 10-40 mg s.c. daily. Dose titration was performed every month by IGF-I assay.


RESULTS
Three patients spontaneously stopped pegvisomant treatment after 6-9 months because of poor compliance; from the measurement of serum pegvisomant, another patient was found not to inject herself properly. After 6 months, IGF-I levels decreased by 63 +/- 19% (767.8 +/- 152.9 vs 299.8 +/- 162.9 microg/l, P < 0.0001, t-test); serum IGF-I levels normalized in 57%. After 12 months, IGF-I levels normalized in nine (75%) patients and were reduced by over 50% in another three (25%). The mean tumor volume remained stable during the study (1198 +/- 1234 vs 1196 +/- 1351 mm(3), P = 0.37): it did not change ( +/- 25% vs basal) in nine patients, increased by 39.4% and 40.8% in two and decreased by 30.8-46.5% in four. The total/high-density lipoprotein (HDL):cholesterol ratio (from 4.4 +/- 1.0 to 3.7 +/- 0.6, P = 0.0012), glucose levels (from 5.6 +/- 1.2 to 4.4 +/- 1.4 mmol/l, P = 0.026), insulin levels (from 12.4 +/- 6.7 to 8.1 +/- 3.0 mUl/l, P = 0.0023) and homeostasis model assessment (HOMA) index (from 3.4 +/- 2.1 to 1.9 +/- 1.0, P = 0.0017) decreased.


CONCLUSIONS
Treatment for 12 months with pegvisomant normalized IGF-I levels, and improved cardiovascular risk parameters and insulin sensitivity in patients with acromegaly resistant to long-term, high-dose treatment with somatostatin analogs. The tolerance of treatment was good.
Colao
Annamaria
A
Department of Molecular and Clinical Endocrinology and Oncology, Section of Endocrinology, Federico II University of Naples, Italy. colao@unina.it
Pivonello
Rosario
R
Auriemma
Renata S
RS
De Martino
Maria Cristina
MC
Bidlingmaier
Martin
M
Briganti
Francesco
F
Tortora
Fabio
F
Burman
Pia
P
Kourides
Ione A
IA
Strasburger
Christian J
CJ
Lombardi
Gaetano
G
D000172:Acromegaly / Q000188:drug therapy*; D000328:Adult; D001794:Blood Pressure / Q000187:drug effects; D003924:Diabetes Mellitus, Type 2 / Q000209:etiology; D004351:Drug Resistance; D005260:Female; D005951:Glucose Tolerance Test; D006439:Hemodynamics / Q000502:physiology; D006727:Hormone Antagonists / Q000627:therapeutic use; D019382:Human Growth Hormone / Q000008:administration & dosage / Q000009:adverse effects / Q000031:analogs & derivatives* / Q000097:blood / Q000627:therapeutic use; D006801:Humans; D006973:Hypertension / Q000150:complications*; D007334:Insulin-Like Growth Factor I / Q000378:metabolism*; D008111:Liver Function Tests; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D015282:Octreotide / Q000627:therapeutic use; D010911:Pituitary Neoplasms / Q000473:pathology*; D011446:Prospective Studies; D011986:Receptors, Somatotropin / Q000037:antagonists & inhibitors*; D012307:Risk Factors
D006727:Hormone Antagonists; D011986:Receptors, Somatotropin; D019382:Human Growth Hormone; D007334:Insulin-Like Growth Factor I; C406545:pegvisomant; D015282:Octreotide