Purpose: Little data is available regarding the safety and efficacy of switching to Pasireotide-LAR monotherapy in acromegaly patients with partial resistance to first generation somatostatin agonists (1gSRL) who require combination treatment with cabergoline or pegvisomant.
Method: In this monocentric prospective study within a tertiary university hospital, fifteen consecutive acromegalic adults partially resistant to 1gSRL treated with octreotide LAR or lanreotide SR, and cabergoline (N = 4, 3.5 mg/wk) or pegvisomant (N = 11, median dose 100 mg/wk), were switched to Pasireotide-LAR (8 with 40mg/Mo; 7 with 60 mg/Mo). Immunohistochemical expression level of SSTR5 and the granulation pattern of 9 somatotroph adenomas were retrospectively determined to test for a correlation with the therapeutic efficacy of Pasireotide-LAR.
Results: Median IGF-1 concentration at the first evaluation (median 3 Mo) was similar to baseline (1.0 vs 1.1 ULN). 11/15 patients had IGF-1 levels ≤ 1.3 ULN before and after the switch but individual changes were variable. Hyperglycemia was frequent and greater in diabetic patients. 7/15 patients stopped Pasireotide-LAR due to lack of control of IGF-1 or intolerance. 8/15 patients received Pasireotide-LAR for a median of 29 months with IGF-1 levels ≤ 1.3 ULN and acceptable glucose tolerance (median HbA1c 6.1%). 2 patients required initiation of oral antidiabetic treatment. The intensity of SSTR5 expression and the granulation pattern of adenomas were of limited value for the prediction of Pasireotide-LAR effectiveness.
Conclusion: Pasireotide-LAR may represent a suitable therapeutic alternative in a subset of acromegalic patients requiring combination therapy involving a 1gSRL.