Pegvisomant or pasirotide in PRL and GH co-secreting vs GH-secreting Pit-NETs.

Abstract

To evaluate the efficacy of second-line therapies in patients with acromegaly caused by a growth hormone (GH) and prolactin (PRL) co-secreting pituitary neuroendocrine tumor (GH/PRL-Pit-NET) and compare to those caused by a GH-Pit-NET. A multicenter retrospective study of patients with acromegaly on treatment with pasireotide or pegvisomant. Patients were classified in two groups: GH/PRL-Pit-NETs when evidence of hyperprolactinemia and immunohistochemistry (IHC) for GH and PRL was positive or if PRL were >200 ng/dL regardless of the PRL-IHC; and GH-Pit-NETs when the previously mentioned criteria were not met. A total of 28 cases with GH/PRL-Pit-NETs and 122 with GH-Pit-NETs met the inclusion criteria. GH/PRL-Pit-NETs presented at a younger age, caused hypopituitarism and were invasive more frequently than GH-Pit-NETs. There were 124 patients treated with pegvisomant and 49 with pasireotide at any time. The efficacy of pegvisomant for IGF-1 normalization was of 81.5% and of pasireotide of 71.4%. No differences in IGF-1 control with pasireotide neither with pegvisomant were observed between GH/PRL-Pit-NETs and GH-Pit-NETs. All GH/PRL-Pit-NET cases treated with pasireotide (n=6) and 82.6% (n=19/23) of the cases treated with pegvisomant normalized PRL levels. No differences in the rate of IGF-1 control between pegvisomant and pasireotide were detected in patients with GH/PRL-Pit-NETs (84.9% vs. 66.7%, P=0.178). Despite the more aggressive behavior of GH/PRL-Pit-NETs than GH-Pit-NETs, no differences in the rate of IGF-1 control with pegvisomant and pasireotide is observed between both groups, and both drugs are effective treatments to control IGF-1 and PRL hypersecretion in these tumors.