Pasireotide Research & Studies

Pasireotide long-acting release (LAR), a long-acting somatostatin receptor ligand, has shown potential antitumour activity in somatotroph pituitary tumours, as indicated by increased T2-signal intensity on magnetic resonance imaging (MRI). However, long-term follow-up data on its effects are limited. This study aimed to evaluate the long-term antitumour effects of pasireotide and its impact on clinical outcomes in patients with acromegaly.

"First-generation" somatostatin receptor agonists (SSTRAs) octreotide and lanreotide are the most commonly used first-line pharmacological therapy for patients with acromegaly. A subset of patients respond only partially or not at all to the first-generation SSTRA, necessitating the use of additional pharmacological agents or other modes of therapy. Pasireotide is a "second-generation" SSTRA that has multi-receptor activity. Prospective studies have shown promise in the use of pasireotide in patients with poor response to first-generation SSTRA. Here we elucidate the molecular pathways of resistance to first-generation SSTRA, the mechanism of action, pre-clinical and clinical evidence of the use of pasireotide in patients having incomplete / lack of response to first-generation SSTRA. We also discuss the clinical, pathological, and radiological markers predicting response to pasireotide, and the difference in side-effect profiles of pasireotide, compared to first-generation SSTRA.

Pasireotide, a novel multireceptor-targeted somatostatin receptor ligand (SRL) is characterized by a higher affinity to somatostatin receptor type 5 than type 2, unlike first-generation SRLs. Because of the broader binding profile, pasireotide has been suggested to have a greater clinical efficacy in acromegaly than first-generation SRLs and to be efficacious in Cushing's disease. The consequence of this binding profile is the increased blood glucose level in some patients. This results from the inhibition of both insulin secretion and the incretin effect and only a modest suppression of glucagon. A monthly intramuscular formulation of long-acting release pasireotide has been approved for both acromegaly and Cushing's disease treatment. This review presents data on the efficacy and safety of pasireotide treatment mostly in patients with acromegaly and Cushing's disease. Moreover, other possible therapeutic applications of pasireotide are mentioned.

First-line treatment for Cushing´s disease is transsphenoidal surgery. But in cases of persistent or recurrent disease after surgery, contraindications to surgery, severe hypercortisolism control before surgery, or for patients waiting for radiotherapy effects, medical therapy may be indicated. Pituitary-directed agents include cabergoline and pasireotide. Both drugs present similar potential for biochemical control and pasireotide has additionally been proved to reduce tumor volume. Moreover, pasireotide was evaluated in high quality studies. In respect to safety, both drugs are well tolerated and safe, but special attention should be given for cardiac valve disease and psychiatric disorder for cabergoline, and hyperglycemia for pasireotide.

Cushing's disease is a rare but devastating and difficult to manage condition. The somatostatin analogue pasireotide is the only pituitary-targeting pharmaceutical approved for the treatment of Cushing's disease but is accompanied by varying efficacy and potentially severe side effects. Finding means to predict which patients are more likely to benefit from this treatment may improve their management. More than half of corticotroph tumours harbour mutations in the USP8 gene, and there is evidence of higher somatostatin receptor 5 (SSTR5) expression in the USP8-mutant tumours. Pasireotide has a high affinity for SSTR5, indicating that these tumours may be more sensitive to treatment. To test this hypothesis, we examined the inhibitory action of pasireotide on adrenocorticotrophic hormone synthesis in primary cultures of human corticotroph tumour with assessed USP8 mutational status and in immortalized murine corticotroph tumour cells overexpressing human USP8 mutants frequent in Cushing's disease. Our in vitro results demonstrate that pasireotide exerts a higher antisecretory response in USP8-mutant corticotroph tumours. Overexpressing USP8 mutants in a murine corticotroph tumour cell model increased endogenous somatostatin receptor 5 (Sstr5) transcription. The murine Sstr5 promoter has two binding sites for the activating protein 1 (AP-1) and USP8 mutants possibly to mediate their action by stimulating AP-1 transcriptional activity. Our data corroborate the USP8 mutational status as a potential marker of pasireotide response and describe a potential mechanism through which USP8 mutants may regulate SSTR5 gene expression.

Pasireotide (SOM230) is a multi-receptor ligand somatostatin analogue (SSA) developed as the successor of the first-generation SSAs. Currently, pasireotide is recommended for the treatment of patients with Cushing's disease in whom surgery was unsuccessful, and patients with acromegaly who either remain uncontrolled after surgical therapy or in whom tumor resection is not possible.

Acromegaly is a chronic disease with high morbidity and enhanced mortality if left untreated. Treatment options include surgery, medical therapy (somatostatin analogues (SA), dopamine agonists (DA) and growth hormone receptor antagonists) and radiotherapy. Despite these treatment options, "real-life" studies have shown that approximately 50% of patients are not controlled. In this scenario, a next-generation SA, pasireotide, has recently been approved for the treatment of acromegaly.

Malignant insulinoma usually has a poor prognosis, as no efficient medical treatment is available. The somatostatin analogs octreotide and lanreotide have limited ability to control the hypoglycemic events. Pasireotide is a multi-receptor targeted somatostatin-analog with improved affinity for SSTR5. There is to date no reported treatment experience with this drug in such tumors.

Pasireotide (Signifor(®), Signifor(®) LAR) is a somatostatin analogue recently approved for the treatment of acromegaly. Unlike the first-generation agents, octreotide and lanreotide, which bind preferentially to somatostatin receptor (SSTR)-2, pasireotide binds to multiple SSTRs. This article reviews the clinical use and summarizes the pharmacological properties of intramuscular pasireotide in the treatment of acromegaly. The efficacy of pasireotide 40 mg every 28 days was superior to that of intramuscular octreotide 20 mg every 28 days with regard to biochemical control in a 12-month, phase III trial in medically naive patients. Similarly, in a 6-month, phase III trial in patients with acromegaly inadequately controlled with somatostatin analogues for at least 6 months, the efficacy of pasireotide 40 or 60 mg was superior to that of continued octreotide 30 mg or lanreotide autogel 120 mg (each drug was administered once every 28 days) with regard to biochemical control. The tolerability profile of intramuscular pasireotide is generally similar to that of first-generation agents, except for a higher incidence of hyperglycaemia-related adverse events with pasireotide. In clinical trials, the risk of developing pasireotide-associated hyperglycaemia was numerically greater in patients categorized as diabetic or prediabetic at baseline than in those with normal glucose tolerance. Careful monitoring of glycaemic status is required prior to and during pasireotide treatment and antidiabetic therapy should be commenced as indicated. Thus, in the treatment of acromegaly, pasireotide may be a more effective somatostatin analogue than other approved agents of the same class; however, the increased risk of hyperglycaemia needs to be considered and proactively managed.

Postoperative pancreatic fistula is a major contributor to complications and death associated with pancreatic resection. Pasireotide, a somatostatin analogue that has a longer half-life than octreotide and a broader binding profile, decreases pancreatic exocrine secretions and may prevent postoperative pancreatic fistula.