Endocrine Abstracts

Pegvisomant (PEG) is effective in acromegaly control and exerts a positive impact on glucose metabolism. The current study aimed at investigating the effects of 10-years PEG treatment on disease control, pituitary adenoma size, and metabolic profile in patients with acromegaly resistant to somatostatin analogues (SRLs). Twenty-two patients (9 men,13 women, age 45.54 ± 12.83 years) treated with PEG for 10 years, in monotherapy or in combination with SRLs, were included in the current study. In the whole patient cohort, anthropometric (BMI, systolic and diastolic blood pressure), hormonal (GH, IGF-I), biochemical (fasting glucose and insulin, lipid profile) parameters, and maximal tumour diameter were evaluated before and after 10-years of PEG treatment. After10-years PEG therapy, IGF-I levels persisted significantly decreased in all the patients (P<0.0001) compared to baseline, with full normalization in 91%. No significant change in dose of either PEG or SRLs was required. Tumour maximal diameter slightly decreased in the whole cohort. Fasting glucose (FG) was significantly increased (P=0.035), whereas HbA1c and diabetes prevalence remained stable. Fasting insulin (FI) and HOMA-IR decreased, HOMA-β was significantly reduced (P=0.013), whereas ISI_0, was increased. A significant decrease in total- (P=0.03) and LDL- (P=0.05) cholesterol, and a slight increase in triglycerides were found. At baseline, GH and IGF-I levels significantly correlated with systolic blood pressure (SBP), FI, HOMA-IR, HOMA-β, and ISI₀. Baseline IGF-I correlated with percent change after 10 years (Δ) of FI (r=-0.354, P=0.015), and HDL (r=0.045, P=0.045). PEG dose was directly correlated to BMI (r=0.509, P=0.016), and triglycerides (r=0.554, P=0.007), and inversely to age (r=-0.455, P=0.030). Disease duration before PEG was directly related to BMI (r=0.446, P=0.037), and inversely to 10-years HOMA-IR (r=-0.563, P=0.029), HDL (r=-0.424, P=0.049), ΔFG (r=-0.462, P=0.03), ΔFI (r=-0.546, P=0.05), and ΔTG (r=-0.445, P=0.034). Long-term PEG therapy is effective and safe, without requiring an increase in dose to maintain disease control even after a decade of therapy. PEG beneficial impact on both insulin and lipid metabolism persists after prolonged therapy. PEG treatment should be started as soon as possible in patients resistant to SRLs as the extent of the metabolic improvement is inversely correlated to disease duration before PEG introduction.