Coopmans et al., reported a patient with an highly aggressive, dopamine agonist-resistant prolactinoma, who only achieved biochemical and tumor control during pasireotide long-acting release (PAS-LAR) therapy , a second-generation somatostatin receptor ligand (SRL). Interestingly, cystic degeneration, tumor cell necrosis, or both was observed after PAS-LAR administration suggesting an antitumor effect. This case shows that PAS-LAR therapy holds clinical potential in selective aggressive, dopamine-resistant prolactinomas that express somatostatin (SST) receptor subtype 5 and appears to be a potential new treatment option before starting temozolomide. In addition, PAS-LAR therapy may induce cystic degeneration, tumor cell necrosis, or both in prolactinomas 1).
Long-acting pasireotide and bromocriptine provided biochemical control of growth hormone and prolactin in a patient with plurihormonal pituitary macroadenoma, allowing near-complete tumor excision while restoring pituitary function and avoiding adjunctive radiotherapy. Pasireotide initiation resulted in hyperglycemia, which stabilized after a few months and resolved upon pasireotide discontinuation 2).
Pasireotide has greater affinity for the Somatostatin receptor 5 (SSTR5).
SSTR5 receptors have been found in high density in functional Cushing's disease ACTH-PAs, and treatment with this agent reduces abnormal ACTH secretion and reduces tumor volume. Adverse effects include an increased risk of developing or worsening diabetes mellitus and the adverse gastrointestinal effects commonly seen with this class of drug.
Switching to pasireotide long-acting release (PAS-LAR), either as monotherapy, or combination with pegvisomant, can control IGF-1 levels in the majority of patients. PAS-LAR demonstrated a pegvisomant sparing effect of 66% compared to the combination with somatostatin analogues (LA-SSAs). Hyperglycemia was the most important safety issue 3).
A case of Nelson's syndrome with clinically significant and dramatic biochemical and clinical responses to pasireotide administration is reported. Hyperglycemia was noted after pasireotide administration. Pasireotide may represent a useful tool in the medical management of Nelson's syndrome. Further study of the potential benefits and risks of pasireotide in this population is necessary 4).