Efficacy and Safety of Pegvisomant in Patients with Acromegaly: A Real Life Perspective from a Tertiary Center

Introduction: Pegvisomant is a growth hormone receptor antagonist used as second-line medical therapy in patients with acromegaly. Evidence suggests that pegvisomant is an effective and safe option that can be used in monotherapy or in association with somatostatin analogs (SSAs). Methods: Clinical files of patients with acromegaly treated with pegvisomant between 2005 and 2023 in a single center were reviewed. Clinical, biochemical, and imaging data were collected. Biochemical response was defined as insulin-like growth factor I (IGF-1)<1.3× upper limit of normal (ULN). Descriptive statistics were performed. Results: Eleven patients were included, 72.7% female, mean age 44.3 ± 10.0 years. All had previously undergone surgery and had been treated with first-generation SSAs, nine (81.8%) with the association of dopamine agonist and SSA, and three (27.3%) with pasireotide. Patients started pegvisomant due to inadequate disease control with previous regimens or drug intolerance/adverse effect. Ten patients started pegvisomant as monotherapy and one in addition to an SSA. Mean IGF-1 reduction was 47.1 ± 28.6 ng/mL, and biochemical response was achieved in 9 (81.8%) patients. During follow-up, 3 patients previously controlled with pegvisomant showed elevation of IGF-1 to levels >1.3× ULN. SSAs were added in all three, resulting in subsequent biochemical response in one patient. Tumor growth was not observed in any patient during pegvisomant use (mean time 6.3 ± 5.2 years). Conclusion: Pegvisomant is an effective and safe drug in the treatment of acromegaly patients resistant to SSAs. In patients with more aggressive tumors resistant to pegvisomant, combination of pegvisomant and SSA may further reduce IGF-1 levels and lead to adequate disease control.