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

OBJECTIVE: 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, Oxford). METHODS: Clinical, laboratory, imaging data were analysed. RESULTS: Sixty-nine patients on cabergoline monotherapy were included [median IGF-1 xUpper Limit of Normal (ULN) pre-cabergoline 2.13 (1.02-8.54), median treatment duration 23 months, median latest weekly dose 3 mg]. 31.9% achieved normal IGF-1 (25% GH-secreting, 60% GH+prolactin co-secreting tumours); median weekly cabergoline dose was similar between responders and non-responders. IGF-1 normalisation was related with GH+prolactin co-secreting adenoma (B 1.50, p=0.02) and lower pre-cabergoline IGF-1 xULN levels (B -0.70, p=0.02). 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 xULN pre-cabergoline 1.7 (1.03-2.92), median treatment duration 36 months, median latest weekly dose 2.5 mg]. 23.1% achieved normal IGF-1 (15.8% GH-secreting, 33.3% GH+prolactin co-secreting tumours). Normal IGF-1 and GH<1 mcg/L were detected in 17.4%. CONCLUSIONS: In non-irradiated patients, cabergoline normalises 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 studies methodology and impact of confounding factors.