Monotherapy with lanreotide depot for acromegaly: long-term clinical experience in a pituitary center

Long-acting somatostatin analogs are one of the main classes of medical therapy used for acromegaly and most patients require ongoing treatment. Few studies have evaluated the long-term efficacy and safety of lanreotide depot beyond 2 years. The goal of this study was to provide a long-term longitudinal assessment of efficacy and safety of lanreotide depot in lanreotide responders compared to a surgically cured control group. In this retrospective longitudinal case-control study, patients with acromegaly receiving lanreotide depot monotherapy continuously for at least 24 months (N = 24) and surgically cured patients (N = 39) were compared. Serum IGF-1, pituitary MRIs, lanreotide dose, co-morbidities and adverse effects were assessed longitudinally. In the lanreotide group, IGF-1 remained normal and unchanged over 6 years; comparable to the surgery only group. There was no difference in prevalence of normal IGF-1 between the lanreotide and surgery only groups at 6 months (100 vs. 97 %), 6 years (89 vs. 90 %) and at last follow-up (96 vs. 92 %). Tumor size remained stable (79 %) or decreased (21 %) in the lanreotide group. In the surgery only group, tumor size remained unchanged in all patients. Hemoglobin A(1C) did not differ between lanreotide and surgery only groups (baseline 5.8 vs. 6.1 %; last follow-up 6.0 vs. 5.7 %). Two (8 %) of the lanreotide and none of the surgery only group developed new diabetes mellitus. Lanreotide depot maintains normalization of IGF-1 in 89 % of responders after 6 years, comparable to surgically cured controls, and controlled tumor size in all without significant adverse effects.