Introduction: Pasireotide is a multireceptor-targeted somatostatin analogue effective in the treatment of patients with Cushings disease (CD) but associated with an increased risk of hyperglycaemia. We prospectively investigate the role of an acute pasireotide suppression test (PST) in predicting long-term response in CD.
Methods: Eleven patients with CD (seven females, four males; mean age 45±17.3 years) received at 0900 h a single s.c. injection of 600 μg pasireotide. ACTH and cortisol levels were assessed before and every 2 h for 8 h after drug administration and then at midnight. Salivary cortisol was assessed before pasireotide administration, after 2 h and then at midnight. Blood glucose was measured before and then after 2 h after drug administration.
A partial response was defined as a reduction in hormonal parameters of 2549% from baseline from 2 to 8 h after drug administration while a reduction ≥50% was considered as a complete response.
After acute PST, all patients were continued on pasireotide 600 μg s.c. twice a day.
Follow-up data at month 3 are available for seven patients.
Results: A single-dose of 600 μg pasireotide decreased serum cortisol in 82% of patients (partial response in 4/11 and complete response in 5/11 patients). Regarding plasma ACTH, a partial response was achieved by 2/11 patients and a complete response by 5/11 patients. Midnight serum and salivary cortisol decreased with a restoration of cortisol rhythm in three patients. After 2 h from pasireotide administration glucose levels increased in all patients.
After 3 months, two patients with a complete response and three with a partial response to acute PST, normalized 24 h urinary free cortisol (UFC) levels. Two patients with a positive response to acute PST had decreased 24 h UFC by more than 25%.
Conclusions: A positive response to acute PST seems to be associated with a positive response in the medium-term.