Efficacy of cabergoline in non-irradiated patients with acromegaly: a multi-centre cohort study

Objective This study aimed to elucidate the efficacy (as per current biochemical criteria) of cabergoline monotherapy or as addition to long-acting somatostatin receptor ligand (SRL) in patients with acromegaly and no previous pituitary radiotherapy. Design Multi-centre, retrospective, cohort study (four UK pituitary centres: Birmingham, Bristol, Leicester, and Oxford). Methods Clinical, laboratory, and imaging data were analysed. Results Sixty-nine patients on cabergoline monotherapy were included (median insulin-like growth factor 1 [IGF-1] x upper limit of normal [ULN] pre-cabergoline 2.13 [1.02-8.54], median treatment duration 23 months, and median latest weekly dose 3 mg); 31.9% achieved normal IGF-1 (25% growth hormone [GH]-secreting and 60% GH+prolactin co-secreting tumours); median weekly cabergoline dose was similar between responders and non-responders. Insulin-like growth factor 1 normalization was related with GH+prolactin co-secreting adenoma (B 1.50, P = .02) and lower pre-cabergoline IGF-1 x ULN levels (B -0.70, P = .02). Both normal IGF-1 and GH < 1 mcg/L were detected in 12.9% of cases and tumour shrinkage in 29.4% of GH-secreting adenomas. Twenty-six patients on SRL + cabergoline were included (median IGF-1 x ULN pre-cabergoline 1.7 [1.03-2.92], median treatment duration 36 months, and median latest weekly dose 2.5 mg); 23.1% achieved normal IGF-1 (15.8% GH-secreting and 33.3% GHprolactin co-secreting tumours). Normal IGF-1 and GH < 1 mcg/L were detected in 17.4%. Results Sixty-nine patients on cabergoline monotherapy were included (median insulin-like growth factor 1 [IGF-1] x upper limit of normal [ULN] pre-cabergoline 2.13 [1.02-8.54], median treatment duration 23 months, and median latest weekly dose 3 mg); 31.9% achieved normal IGF-1 (25% growth hormone [GH]-secreting and 60% GH+prolactin co-secreting tumours); median weekly cabergoline dose was similar between responders and non-responders. Insulin-like growth factor 1 normalization was related with GH+prolactin co-secreting adenoma (B 1.50, P = .02) and lower pre-cabergoline IGF-1 x ULN levels (B -0.70, P = .02). Both normal IGF-1 and GH < 1 mcg/L were detected in 12.9% of cases and tumour shrinkage in 29.4% of GH-secreting adenomas. Twenty-six patients on SRL + cabergoline were included (median IGF-1 x ULN pre-cabergoline 1.7 [1.03-2.92], median treatment duration 36 months, and median latest weekly dose 2.5 mg); 23.1% achieved normal IGF-1 (15.8% GH-secreting and 33.3% GHprolactin co-secreting tumours). Normal IGF-1 and GH < 1 mcg/L were detected in 17.4%. Conclusions In non-irradiated patients, cabergoline normalizes IGF-1 in around one-third and achieves both IGF-1 and GH targets in approximately one out of ten cases. SRL + cabergoline is less efficient than previously reported possibly due to differences in study methodology and impact of confounding factors.