Experience with pegvisomant treatment in acromegaly in a single Brazilian tertiary reference center: efficacy, safety and predictors of response

OBJECTIVE: To describe the safety and efficacy of pegvisomant therapy and the predictors of treatment response in acromegaly patients at a single tertiary reference center in Brazil. MATERIALS AND METHODS: We retrospectively reviewed the clinical, hormonal and radiological data of acromegaly patients treated with pegvisomant in our center. We also evaluated the presence of the d3 isoform of the growth hormone receptor (d3GHR). RESULTS: Twenty-seven patients were included (17 women). Pegvisomant was used in combination with octreotide LAR in 20 patients (74%), in combination with cabergoline in one (4%) and as monotherapy in six (22%). IGF-I normalization was achieved in 23 patients (85%). Mild and transitory elevation of liver enzymes was observed in two patients (7.4%), tumor growth in one (3.4%) and lipodystrophy in two (7.4%). One patient stopped the drug due to headaches. The GHR isoforms were evaluated in 14 patients, and the presence of at least one d3GHR allele was observed in 43% of them, but it was not a predictor of treatment response. Only pre-treatment IGF-I level was a predictor of treatment response. CONCLUSION: Pegvisomant treatment was highly effective and safe in our series of Brazilian patients. A better chance of disease control can be expected in those with lower pre-pegvisomant IGF-I levels.