Treatment of multiresistant prolactinomas with a combination of cabergoline and octreotide LAR.
BACKGROUND AND OBJECTIVES
Dopamine agonist (DA)-resistant prolactinomas are rare but they constitute a real challenge, since there are few therapeutic alternatives left for these patients.


DESIGN AND SETTING
Proof-of-concept study at a tertiary care, referral center.


PATIENTS AND METHODS
The studied population consisted of five patients (one female and four males, mean age at diagnosis 23.5 ± 19) with macroprolactinomas with persistent hyperprolactinemia and/or tumor mass despite high doses of cabergoline (CBG) and pituitary surgery, to whom 20 mg monthly of octreotide LAR was added for 6-13 months. Response was evaluated by measuring prolactin (PRL) levels and by magnetic resonance imaging. Immunohistochemistry (IHC) for pituitary hormones, Ki-67, and somatostatin receptor subtypes 2 and 5 was (SSTR2 and 5) was available in two of the subjects.


RESULTS
The addition of octreotide LAR to ongoing CBG treatment had no effect on either PRL levels or tumor size in three patients. In two of the five patients, combination treatment resulted in a significant reduction in PRL concentrations (from 7643 to 200 ng/mL and from 2587 to 470 ng/mL) as well as in adenoma size (93% reduction). IHC evaluation of tumor samples from two patients (a responder and a non-responder) revealed positive immunostaining for PRL and SSTR5 but not for other pituitary hormones or for SSTR2.


CONCLUSIONS
The addition of a somatostatin analog to ongoing CBG treatment may be effective in some patients with DA-resistant macroprolactinomas, independently of the adenoma's SSTR expression profile.
['Sosa-Eroza|Ernesto|E|', 'Espinosa|Etual|E|', 'Ramírez-Rentería|Claudia|C|', 'Mendoza|Victoria|V|', 'Arreola|Rocío|R|', 'Mercado|Moises|M|http://orcid.org/0000-0002-4748-9734']
D000293:Adolescent D000328:Adult D000971:Antineoplastic Combined Chemotherapy Protocols D000077465:Cabergoline D002648:Child D003692:Delayed-Action Preparations D019008:Drug Resistance, Neoplasm D005260:Female D006801:Humans D008297:Male D008875:Middle Aged D015282:Octreotide D010911:Pituitary Neoplasms D015175:Prolactinoma D000075082:Proof of Concept Study D016896:Treatment Outcome D055815:Young Adult
cabergoline octreotide dopamine agonist Macroprolactinoma somatostatin receptors