Pasireotide is a synthetic peptide and one of three somatostatin analogs approved by the FDA, alongside octreotide and lanreotide, covered elsewhere on this site. It occupies a specific niche: patients whose disease doesn't respond well enough to the other two.
What It Is
Pasireotide is a cyclohexapeptide, a synthetic analog of the natural hormone somatostatin, developed by Novartis and sold under the brand names Signifor (a short-acting subcutaneous injection) and Signifor LAR (a long-acting intramuscular injection given once monthly). Like other somatostatin analogs, it works by binding to somatostatin receptors and suppressing hormone secretion from the pituitary gland and certain tumors.
Regulatory Status and Approved Uses
Signifor was FDA-approved in December 2012 for Cushing's disease in adult patients for whom pituitary surgery was not an option or did not cure the condition. Signifor LAR followed with FDA approval in 2014 for acromegaly in patients who have had an inadequate response to, or cannot tolerate, surgery or treatment with octreotide or lanreotide. Both uses target rare endocrine conditions, and pasireotide is generally positioned as a second-line option rather than a first choice.
How It Differs From Octreotide and Lanreotide
The key distinction is receptor targeting. Octreotide and lanreotide bind primarily to somatostatin receptor subtype 2 (SST2). Pasireotide binds with high affinity to subtype 5 (SST5) in addition to subtypes 1, 2, and 3, giving it a broader receptor-binding profile. This matters clinically in Cushing's disease, where the pituitary tumors involved tend to express more SST5 than SST2, which is part of why pasireotide can work in patients whose tumors don't respond well to the SST2-focused drugs. A dedicated comparison of all three somatostatin analogs, including dosing schedules and side-effect differences, is covered in this site's companion comparison article.
What the Research Shows
Pasireotide's approval for both indications was supported by randomized, placebo-controlled or active-comparator Phase 3 trials in adult patients, which is a materially stronger evidence base than most peptides discussed on this site, many of which have only animal or preclinical data. That said, the patient populations in these rare-disease trials are necessarily small compared to trials for common conditions like diabetes, which is typical for orphan-disease drug development and is reflected in a narrower post-marketing safety dataset than, for example, a GLP-1 drug used by millions of patients.
Safety Considerations
Pasireotide's most clinically significant risk is hyperglycemia: it can raise blood sugar more frequently and more severely than octreotide or lanreotide, to the point that new-onset diabetes and worsening of existing diabetes are common findings in its trials, and glucose monitoring is a standard part of treatment. Other documented risks include gallstones, elevated liver enzymes, slowed heart rate, and QT interval prolongation on an EKG, which is why baseline and follow-up cardiac and metabolic monitoring are part of its prescribing information. Anyone prescribed pasireotide should talk to their doctor about a monitoring plan for blood sugar and heart rhythm before starting treatment.
The Bottom Line
Pasireotide is a legitimate, FDA-approved second-line option for two specific rare endocrine diseases, built on real human trial data rather than animal research alone. Its broader receptor-binding profile is what gives it a role when octreotide or lanreotide fall short, but that same mechanism comes with a more pronounced blood sugar risk that sets it apart from the other two drugs in its class.