SOM230, a new somatostatin analogue, is highly effective in the therapy of growth hormone/prolactin-secreting pituitary adenomas.
OBJECTIVE
We have previously shown that transgenic mice ubiquitously overexpressing the HMGA2 gene develop growth hormone/prolactin-secreting pituitary adenomas. This animal model has been used to evaluate the therapeutic efficacy of SOM230, a somatostatin analogue with high affinity for the somatostatin receptor subtypes 1, 2, 3, and 5, on the growth of the pituitary adenomas.


METHODS
Four groups of 3- and 9-month-old HMGA2 transgenic mice were treated for 3 months with a continuous s.c. injection of two different dosages of SOM230 (5 or 50 microg/kg/h), one dose of octreotide, corresponding to that used in human therapy, and a placebo, respectively. The development of the tumor before and after therapy was monitored by magnetic resonance imaging of the pituitary region and evaluation of the serum prolactin levels.


RESULTS
The highest dose of SOM230 induced a drastic regression of the tumor, whereas octreotide was not able to induce any significant tumor regression, although tumor progression was significantly slowed down. No significant differences were observed between the animals treated with the lowest dose of SOM230 and those receiving placebo.


CONCLUSIONS
These results clearly support the efficacy of the SOM230 treatment in human pituitary adenomas secreting prolactin based on the dramatic tumor shrinkage and fall in prolactin levels. This beneficial effect could be of crucial clinical usefulness in patients bearing tumors resistant to dopaminergic drugs.
Fedele
Monica
M
Istituto di Endocrinologia ed Oncologia Sperimentale del CNR e/o Dipartimento di Biologia e Patologia Cellulare e Molecolare, Università di Napoli Federico II, Naples, Italy.
De Martino
Ivana
I
Pivonello
Rosario
R
Ciarmiello
Andrea
A
Del Basso De Caro
M Laura
ML
Visone
Rosa
R
Palmieri
Dario
D
Pierantoni
Giovanna M
GM
Arra
Claudio
C
Schmid
Herbert A
HA
Hofland
Leo
L
Lombardi
Gaetano
G
Colao
Annamaria
A
Fusco
Alfredo
A
D000818:Animals; D049109:Cell Proliferation / Q000187:drug effects; D005260:Female; D049912:Growth Hormone-Secreting Pituitary Adenoma / Q000188:drug therapy* / Q000473:pathology; D025743:HMGA2 Protein / Q000235:genetics; D051379:Mice; D008822:Mice, Transgenic; D010911:Pituitary Neoplasms / Q000188:drug therapy* / Q000473:pathology; D013004:Somatostatin / Q000031:analogs & derivatives* / Q000494:pharmacology / Q000627:therapeutic use; D016896:Treatment Outcome
D025743:HMGA2 Protein; D013004:Somatostatin; C517782:pasireotide