Endocrine Abstracts

Introduction: Around 20–30% of patients with acromegaly have hyperprolactinemia, which is associated with infertility and gonadal/sexual dysfunction. Current therapy involves somatostatin analogues for GH/IGF1 excess and a dopamine agonist to decrease prolactin levels. The objectives of this analysis were to assess treatment with pasireotide LAR or octreotide LAR alone in patients with acromegaly and hyperprolactinemia.

Methods: Patients with acromegaly (GH >5 μg/l or GH nadir ≥1 μg/l post-OGTT, and IGF1>ULN) who were de novo with a visible adenoma on MRI or medically naïve (no previous medical therapy but prior pituitary surgery) received pasireotide LAR 40 mg/28 days (n=176) or octreotide LAR 20 mg/28 days (n=182) for 12 months; dose titration (to pasireotide LAR 20/60 mg or octreotide LAR 10/30 mg) was permitted. This analysis focuses on the efficacy/safety of pasireotide LAR and octreotide LAR in patients with baseline hyperprolactinemia (prolactin above age/sex-matched ULN).

Results: 29 (16.5%) pasireotide LAR and 30 (16.5%) octreotide LAR patients had baseline hyperprolactinemia (mean prolactin 83.5 and 55.9 μg/l, respectively). After 12 months, 21/29 (72.4%; 95% CI 52.8, 87.3) pasireotide LAR and 17/30 (56.7%; 95% CI 37.4, 74.5) octreotide LAR patients had normalized prolactin levels; 10/29 (34.5%) and 13/30 (43.3%) had GH <2.5 μg/l, while 7/29 (24.1%) and 8/30 (26.7%) had normal IGF1, respectively. After 12 months, mean prolactin decreased by 60.4 and 39.6%, mean GH decreased by 71.1 and 67.6%, and mean IGF1 decreased by 41.1 and 39.6%, respectively, in pasireotide LAR and octreotide LAR patients. Tumor volume decreased by ~40% in both treatment groups. Pasireotide was well tolerated and most adverse events were mild/moderate; hyperglycemia-related adverse events were more common with pasireotide LAR than octreotide LAR.

Conclusions: In this subset of patients with baseline hyperprolactinemia, pasireotide LAR normalized prolactin in >70%, normalized IGF1 in ~25% and achieved GH <2.5 μg/l in ~35% of patients. Pasireotide may be an effective treatment for patients with a GH- and prolactin-secreting pituitary adenoma.