Lanreotide

Lanreotide is a synthetic octapeptide analog of naturally occurring somatostatin (somatotropin release-inhibiting factor). Unlike the native 14-amino-acid peptide, which has a half-life of minutes, lanreotide's structural modifications confer a half-life of 23-30 days, enabling once-monthly dosing.

Lanreotide binds with high affinity to human somatostatin receptors 2 and 5 (SSTR2 and SSTR5), with substantially lower affinity for SSTR1, SSTR3, and SSTR4. These receptors are members of the G-protein coupled receptor superfamily and signal through inhibitory Gαi subunits. Receptor activation by lanreotide triggers adenylyl cyclase inhibition (reducing intracellular cyclic AMP), opening of potassium channels, closure of voltage-gated calcium channels, and modulation of MAP kinase and protein tyrosine phosphatase pathways. These signals collectively suppress cellular secretion and proliferation.

• In acromegaly: SSTR2 and SSTR5 are the predominant receptor subtypes expressed on GH-secreting pituitary somatotroph adenomas. Lanreotide binding reduces excess GH secretion and secondarily normalizes IGF-1 levels. Tumor volume reduction has also been observed.

• In GEP-NETs: SSTR2 is highly expressed on well-differentiated neuroendocrine tumor cells. Receptor activation suppresses secretion of serotonin, glucagon, gastrin, vasoactive intestinal peptide, and other tumor-associated hormones, while also activating anti-proliferative intracellular cascades.

• In carcinoid syndrome: Reduced serotonin and other vasoactive mediator secretion attenuates flushing and diarrhea.

Lanreotide additionally inhibits exocrine pancreatic secretion, gastric acid, gallbladder contractility, and bile secretion. Reduced gallbladder contractility underlies the class effect of cholelithiasis with long-term use.

Three key clinical programmes underpin lanreotide's approved indications.

Acromegaly: In Study 2 cited in the FDA label (n=63, 48-week phase III trial), 43% of patients achieved normalized age- and sex-adjusted IGF-1 levels and 38% met dual criteria of GH ≤2.5 ng/mL and normalized IGF-1. A separate phase III multicentre trial in 98 patients (Lucas and Astorga, Clin Endocrinol 2006; PMID 16918950) demonstrated that 54% achieved GH below 2.5 ng/mL with lanreotide Autogel at extended dosing intervals of 4-8 weeks.

GEP-NETs: The pivotal CLARINET trial (Caplin et al., N Engl J Med 2014; PMID 25014687; n=204) was a randomized, double-blind, placebo-controlled, multinational phase III study. Patients with advanced, grade 1-2, nonfunctioning, SSTR-positive GEP-NETs (Ki-67 <10%; 84% treatment-naive; tumors primarily pancreatic 45% or midgut 36%) were randomized 1:1 to lanreotide 120 mg or placebo every 28 days for up to 96 weeks. Lanreotide reduced the risk of disease progression or death by 53% (HR 0.47; 95% CI 0.30-0.73). Median PFS was not reached for lanreotide versus 16.6 months for placebo. At 24 months, 65% of lanreotide-treated patients remained progression-free versus 33% on placebo. Serious adverse events were similar between groups (25% lanreotide vs. 31% placebo). The CLARINET open-label extension (Caplin et al., Endocrine 2021; PMID 33052555; n=89) confirmed durable benefit, with a median PFS of 38.5 months (95% CI 30.9-59.4) in patients continuing lanreotide from the core study, with some patients receiving treatment for up to 102 months.

Carcinoid syndrome: The ELECT trial (Vinik et al., Endocrine Practice 2016; PMID 27214300; n=115) was a 16-week randomized, double-blind, placebo-controlled phase III study. Lanreotide 120 mg every 4 weeks reduced the percentage of days requiring short-acting octreotide rescue therapy from 48.5% (placebo) to 33.7% (lanreotide), an absolute reduction of 14.8 percentage points (P=0.017). Treatment success odds ratio was 2.4 in favor of lanreotide (P=0.036).

Typical dosage: 60-120 mg (every 4 weeks).

Lanreotide is administered as a deep subcutaneous injection into the superior outer quadrant of the buttock, alternating left and right sides with each dose. Available as prefilled syringes in 60 mg/0.2 mL, 90 mg/0.3 mL, and 120 mg/0.5 mL strengths.

Acromegaly: The recommended starting dose is 90 mg every 4 weeks for 3 months. Thereafter, dose is adjusted based on GH levels and age/sex-normalized IGF-1: • 60 mg every 4 weeks if GH <1 ng/mL and IGF-1 is normal • 90 mg every 4 weeks if GH is 1-2.5 ng/mL and IGF-1 is normal • 120 mg every 4 weeks if GH >2.5 ng/mL or IGF-1 remains elevated In patients with moderate or severe renal or hepatic impairment, the recommended starting dose is 60 mg every 4 weeks.

GEP-NETs: 120 mg every 4 weeks. No dose adjustment is specified for renal or hepatic impairment in this indication per the current FDA label.

Carcinoid syndrome: 120 mg every 4 weeks.

All dosing information above reflects the current FDA-approved prescribing information (DailyMed, label updated July 2024). This information is provided for educational purposes only and does not constitute medical advice. Individualized dosing decisions, including management of drug interactions, organ impairment adjustments, and monitoring schedules, must be made by a qualified healthcare provider.

In NCCN and ENETS clinical guidelines, lanreotide is positioned as a first-line cytostatic agent for SSTR-positive, well-differentiated G1-G2 GEP-NETs, and as a backbone for symptom control in carcinoid syndrome. It is frequently used in combination or sequence with other modalities.

Lanreotide with everolimus: For patients progressing on SSA monotherapy, the mTOR inhibitor everolimus (AFINITOR) may be added or used sequentially. Current guidelines recommend that SSAs continue alongside everolimus where hormonal control is required.

Lanreotide with PRRT (177Lu-DOTATATE/Lutathera): Somatostatin analogs are commonly maintained as background therapy during peptide receptor radionuclide therapy (PRRT) and continued after completion. The last SSA dose before each PRRT infusion is typically timed 4 weeks prior to allow receptor availability; guidance varies by center.

Lanreotide with telotristat ethyl: For carcinoid syndrome symptoms inadequately controlled by SSA therapy alone, telotristat ethyl (Xermelo; a tryptophan hydroxylase inhibitor) is approved as add-on therapy and was studied alongside ongoing SSA treatment in the TELESTAR and TELECAST phase 3 trials.

Lanreotide in acromegaly with pegvisomant: Combination with the GH receptor antagonist pegvisomant has been described in patients with partial SSA response, though this is based on observational data and small case series rather than randomized trial evidence.

Lanreotide is approved by the U.S. Food and Drug Administration for one or more clinical indications. Refer to the prescribing information for full safety and dosing details.

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Reported side effects: diarrhea, cholelithiasis, abdominal pain, hyperglycemia, bradycardia, injection site reactions, nausea, hypertension, headache, thyroid function decreases

In acromegaly clinical trials, adverse reactions occurring in more than 5% of patients were diarrhea (37%), cholelithiasis (20%), abdominal pain (19%), nausea, and injection site reactions.

In GEP-NET trials, adverse reactions occurring in more than 10% of patients included abdominal pain (34%), hyperglycemia (14%), hypertension (14%), cholelithiasis (14%), musculoskeletal pain, vomiting, headache, and injection site reactions. In the CLARINET trial, serious adverse events occurred at similar rates in the lanreotide (25%) and placebo (31%) groups, and serious treatment-related events were rare (3% lanreotide vs. 1% placebo).

In carcinoid syndrome trials, adverse reactions at a rate 5% or more above placebo included headache, dizziness, and muscle spasm.

Cholelithiasis and biliary complications: Lanreotide inhibits gallbladder contractility and bile secretion, promoting gallstone formation with long-term use. Periodic monitoring is recommended; discontinuation should be considered if complications arise.

Glucose metabolism: Lanreotide may cause hypoglycemia (early, from glucagon suppression) or hyperglycemia (sustained use, from inhibited insulin secretion). Blood glucose monitoring is required; antidiabetic therapy should be adjusted accordingly.

Bradycardia: Sinus bradycardia was observed in 3-7% of patients in trials. Caution is warranted with concomitant beta-blockers or other rate-lowering drugs; dose adjustment of these agents may be needed.

Thyroid function: Decreases in thyroid hormone levels may occur; testing is recommended when clinically indicated.

Steatorrhea and pancreatic exocrine insufficiency: New or worsening fat malabsorption should prompt evaluation for exocrine insufficiency (label updated July 2024).

Drug interactions: May decrease cyclosporine bioavailability; may increase bromocriptine absorption; avoid co-administration with CYP3A4 substrates of narrow therapeutic index.

Contraindication: Hypersensitivity to lanreotide. No black box warning. Breastfeeding should be avoided during treatment and for 6 months after the last dose. Antibody formation occurred in fewer than 4% of patients and did not affect efficacy or safety outcomes.