In Vitro Head-to-Head Comparison Between Octreotide and Pasireotide in GH-Secreting Pituitary Adenomas.
First-generation somatostatin analogs (SSAs), such as octreotide (OCT), are the first line medical therapy for acromegaly. Pasireotide (PAS), a newly developed SSA, has shown promising results in the treatment of acromegaly.



To compare the antisecretory effect of OCT and PAS in primary cultures of growth hormone (GH)-secreting pituitary adenomas (GH-omas). To correlate responses with the adenoma somatostatin receptor (SSTR) profile.



The effect of OCT and PAS on GH (and PRL) secretion was tested in 33 GH-oma cultures. SSTR expression was evaluated in adenoma samples.



Patients with acromegaly referred to the Erasmus Medical Center (Rotterdam, The Netherlands).



OCT and PAS treatment for 72 hours (10 nM).



GH (and PRL) concentrations in cell culture media. SSTR expression in adenoma samples.



The overall effect of OCT (-36.8%) and PAS (-37.1%) on GH secretion was superimposable. We identified three adenoma groups: PAS+ (PAS more effective than OCT), n = 6; PAS = OCT, n = 22; and OCT+ (OCT more effective than PAS), n = 5. PAS+ adenomas showed lower somatostatin receptor subtype (sst)2 messenger RNA (mRNA) and sst2/sst5 mRNA ratio, compared with the other groups (P < 0.05). PAS inhibited PRL hypersecretion more than OCT (P < 0.01).



Overall, OCT and PAS equally reduced GH secretion in vitro. Adenomas with lower sst2 mRNA expression and lower sst2/sst5 mRNA ratio were better responders to PAS compared with OCT. SSTR evaluation in GH-omas may become a tool for tailored SSA treatment in acromegaly.
Division of Endocrinology, Department of Internal Medicine, Erasmus University Medical Center, 3000 CA Rotterdam, The Netherlands.
Federico
F
Gatto
Division of Endocrinology, Department of Internal Medicine, Erasmus University Medical Center, 3000 CA Rotterdam, The Netherlands.|Pituitary Center Rotterdam, Erasmus University Medical Center, 3000 CA Rotterdam, The Netherlands.
Richard A
RA
Feelders
Division of Endocrinology, Department of Internal Medicine, Erasmus University Medical Center, 3000 CA Rotterdam, The Netherlands.
Sanne E
SE
Franck
Division of Endocrinology, Department of Internal Medicine, Erasmus University Medical Center, 3000 CA Rotterdam, The Netherlands.
Peter M
PM
van Koetsveld
Division of Endocrinology, Department of Internal Medicine, Erasmus University Medical Center, 3000 CA Rotterdam, The Netherlands.
Fadime
F
Dogan
Pituitary Center Rotterdam, Erasmus University Medical Center, 3000 CA Rotterdam, The Netherlands.|Department of Pathology, Erasmus University Medical Center, 3000 CA Rotterdam, The Netherlands.
Johan M
JM
Kros
Division of Endocrinology, Department of Internal Medicine, Erasmus University Medical Center, 3000 CA Rotterdam, The Netherlands.|Pituitary Center Rotterdam, Erasmus University Medical Center, 3000 CA Rotterdam, The Netherlands.
Sebastian J C M M
SJCMM
Neggers
Division of Endocrinology, Department of Internal Medicine, Erasmus University Medical Center, 3000 CA Rotterdam, The Netherlands.|Pituitary Center Rotterdam, Erasmus University Medical Center, 3000 CA Rotterdam, The Netherlands.
Aart-Jan
AJ
van der Lely
Division of Endocrinology, Department of Internal Medicine, Erasmus University Medical Center, 3000 CA Rotterdam, The Netherlands.
Steven W J
SWJ
Lamberts
Section of Endocrinology, Department of Internal Medicine and Medical Specialties, Center of Excellence for Biomedical Research, University of Genova, Genova 16126, Italy.
Diego
D
Ferone
Division of Endocrinology, Department of Internal Medicine, Erasmus University Medical Center, 3000 CA Rotterdam, The Netherlands.|Pituitary Center Rotterdam, Erasmus University Medical Center, 3000 CA Rotterdam, The Netherlands.
Leo J
LJ
Hofland
D000236:Adenoma / Q000235:genetics / Q000378:metabolism*; D000293:Adolescent; D000328:Adult; D000368:Aged; D018931:Antineoplastic Agents, Hormonal / Q000494:pharmacology*; D005260:Female; D049912:Growth Hormone-Secreting Pituitary Adenoma / Q000235:genetics / Q000378:metabolism*; D019382:Human Growth Hormone / Q000187:drug effects* / Q000378:metabolism; D006801:Humans; D007150:Immunohistochemistry; D066298:In Vitro Techniques; D008297:Male; D008875:Middle Aged; D015282:Octreotide / Q000494:pharmacology*; D016133:Polymerase Chain Reaction; D011388:Prolactin / Q000187:drug effects* / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D017481:Receptors, Somatostatin / Q000235:genetics / Q000378:metabolism; D013004:Somatostatin / Q000031:analogs & derivatives* / Q000494:pharmacology; D014407:Tumor Cells, Cultured; D055815:Young Adult
D018931:Antineoplastic Agents, Hormonal; D012333:RNA, Messenger; D017481:Receptors, Somatostatin; C103631:somatostatin receptor 3; D019382:Human Growth Hormone; D013004:Somatostatin; C094573:somatostatin receptor 5; D011388:Prolactin; C517782:pasireotide; C093733:somatostatin receptor 2; D015282:Octreotide