Effects of pegvisomant and somatostatin receptor ligands on incidence of vertebral fractures in patients with acromegaly

Purpose: Acromegalic osteopathy is an emerging complication of acromegaly characterized by increase in bone turnover, deterioration in bone microarchitecture and high risk of vertebral fractures (VFs). Somatostatin receptor ligands (SRLs) and pegvisomant (PegV) are used for treatment of acromegaly and there is evidence that both drugs may exert direct effects on peripheral targets regardless of biochemical control of disease. However, whether or not SRLs and PegV may directly influence skeletal health its is unknown. Methods: In this longitudinal study, we evaluated the incidence of radiological VFs in 83 patients (48 females, 35 males; median age 47 years, range 18–80 years) who were treated with SRLs alone (42 cases), PegV alone (6 cases) or in combination with SRLs (35 cases) for median period of 82 months (range 36–126). PegV was given when acromegaly was not controlled by SRLs alone. Results: During the follow-up, 29 patients (34.9%) developed incident VFs. In patients receiving PegV due to active disease during SRL therapy, incidence of VFs decreased significantly from 43.9 to 26.8% (p = 0.039). When acromegaly was controlled by PegV, the incidence of VFs was slightly but not significantly lower as compared to that observed in patients with biochemical control of disease by SRLs (10.0 vs. 26.7%; p = 0.09). In the multivariate logistic regression analysis, incident VFs were independently predicted by pre-existing VFs (odds ratio 61.0; p = 0.009), duration of active acromegaly (odds ratio 1.01; p = 0.05) and mean serum IGF-I during the follow-up (odds ratio 5.26; p = 0.03), regardless of the therapeutic regimen (odds ratio 1.05; p = 0.94). Conclusions: PegV and SRLs had comparable effects on VF risk in acromegaly. The activity of disease was the main determinant of VFs independently of the drug used to control acromegaly.