Mecasermin
Also known as: Increlex, IPLEX, Mecasermin, Mecasermin rinfabate, recombinant human IGF-1, rhIGF-1
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Summary
Mecasermin is a recombinant human insulin‑like growth factor‑1 (rhIGF‑1) approved as a prescription drug for children with severe primary IGF‑1 deficiency or growth‑hormone (GH) gene deletion who have developed neutralising antibodies to GH. Administered by subcutaneous injection, it replaces the missing IGF‑1, thereby stimulating linear growth and improving height velocity in this specific population.
Mechanism of Action
Mecasermin mimics endogenous IGF‑1, binding to the IGF‑1 receptor on target cells and activating intracellular signalling cascades, principally the PI3K/Akt and MAPK pathways, which promote cell proliferation and protein synthesis in the growth plate. By supplying IGF‑1 directly, it bypasses the upstream GH‑JAK/STAT axis that normally drives hepatic IGF‑1 production, restoring the hormonal stimulus needed for longitudinal bone growth.
What the Research Shows
Clinical reports and reviews indicate that mecasermin, alone or as the IGF‑I/IGFBP‑3 complex (mecasermin rinfabate), raises growth velocity in children with severe primary IGF‑1 deficiency or GH1‑gene deletion. Studies note a short serum half‑life for unbound IGF‑I, especially in patients with low IGFBP‑3, and that complexing with IGFBP‑3 can prolong exposure and may lessen acute hypoglycaemia. Adverse events, chiefly hypoglycaemia, are common but usually not severe enough to halt therapy. Limited data exist on use in partial GH resistance, idiopathic short stature, diabetes, severe insulin resistance, osteopaenia, or burn injury, with outcomes similar to IGF‑I alone. Long‑term follow‑up suggests manageable safety, though pharmacokinetic data in humans remain sparse.
Reported Benefits
Evidence from approved indications shows mecasermin consistently increases linear growth rate and contributes to greater adult height in children with severe IGF‑1 deficiency or GH‑gene deletion. The IGF‑I/IGFBP‑3 formulation can extend drug half‑life, potentially reducing dosing frequency and mitigating acute hypoglycaemia, offering a practical advantage for patients requiring chronic therapy.
Limitations of the Evidence
The therapeutic benefit is documented only for severe primary IGF‑1 deficiency and GH‑gene deletion with anti‑GH antibodies; data for broader short‑stature conditions are insufficient. Pharmacokinetic information in humans is limited, and the IGF‑I/IGFBP‑3 complex (mecasermin rinfabate) is no longer marketed in the US or Europe. The short half‑life of unbound IGF‑I may necessitate daily injections, and the risk of hypoglycaemia requires careful monitoring.
Safety Considerations
Hypoglycaemia is the most frequently reported adverse event, occurring especially after subcutaneous dosing of unbound IGF‑I. Other adverse events are common but generally mild and rarely lead to treatment interruption. Long‑term observations indicate that serious safety concerns are uncommon, yet clinicians should monitor blood glucose and be vigilant in patients with diabetes or other hypoglycaemia risk factors.
How It Is Administered
Mecasermin is supplied for subcutaneous injection, typically administered once daily. The formulation may be provided as plain recombinant IGF‑1 or as a complex with IGFBP‑3 (mecasermin rinfabate), though the latter is no longer available in many regions. Injection technique follows standard subcutaneous practices.
Routes of Administration
Goals & Uses
- Muscle growth / anabolic effectsBody CompositionLow
- Increase linear growthEfficacyHigh
- Treatment of severe primary IGF-1 deficiency (SPIGFD)Growth DisorderHigh
- Improvement of insulin sensitivity / glucose metabolismMetabolicModerate
- Normalize IGF-1 serum levelsBiomarkerModerate
- Amyotrophic lateral sclerosis (ALS) treatmentNeurologicalLow
- Growth promotion in GH gene deletion with anti-GH antibodiesGrowth DisorderHigh
Contraindications
- Active malignancyOncologyHighUse caution or avoid depending on agent and context
- Hypersensitivity to mecasermin or excipientsAllergic/ImmunologicHigh
- Closed epiphysesSkeletalModerate
- Diabetic retinopathyOphthalmologyModerate
- Intravenous administrationRoute Of AdministrationHigh
- Active or suspected neoplasiaOncologicalHigh
Adverse Effects
- HypoglycemiaMetabolicCommonAbnormally low blood glucose
- Injection site reactionsLocalCommon
- Acromegaloid featuresEndocrine/MusculoskeletalUncommon
- Intracranial hypertensionNeurologicalRare
- LipohypertrophyDermatologicUncommon
- Slipped capital femoral epiphysisMusculoskeletalUncommon
- Tonsillar/adenoid hypertrophyENTCommon
Drug Interactions
- InsulinHighMay increase risk of low blood sugar
- Growth hormone therapyModerate
- Insulin or insulin secretagoguesHigh
- CorticosteroidsModerate
- Growth hormoneModerate
- Oral antidiabetic agents (sulfonylureas, etc.)Moderate
Population Constraints
- Patients with active cancerOncologicalAbsolute
- Neonates / infants < 2 yearsPediatricRelative
- Pregnant or breastfeeding womenReproductiveRelative
- Patients with scoliosisMusculoskeletalRelative
- Children with severe primary IGF-1 deficiencyPediatricAbsolute
- Diabetic PatientsMetabolicRelative
Regulatory Status
- European UnionApprovedApproved: Primary IGF-1 deficiencyEMA approval for pediatric patients.
- United StatesApprovedApproved: Growth failure due to primary IGF-1 deficiency, Growth failure due to GH gene deletionFDA label includes pediatric use up to 18 years.
- United KingdomApprovedApproved: Long-term treatment of growth failure in children and adolescents with severe primary IGF-1 deficiencyApproved via EMA pre-Brexit; recognized in UK. Subject to MHRA oversight post-Brexit.
FDA‑approved (US) as Increlex for pediatric growth disorders; also approved in the EU and other jurisdictions.
Evidence & Sources
- Journal ArticleModerateNorman P2006-01-01T00:00:00.000000Z
- Journal ArticleModerateKemp SF2007-01-01T00:00:00.000000Z
- Journal ArticleModerateKemp SF2009-01-01T00:00:00.000000Z
- Journal ArticleModerateWilliams RM, et al.2008-01-01T00:00:00.000000Z
- Journal ArticleModerateJaffe CA, Barkan AL1994-01-01T00:00:00.000000Z
Frequently Asked Questions
What condition is mecasermin approved to treat?
It is approved for children with severe primary IGF‑1 deficiency or growth‑hormone gene deletion who have developed neutralising antibodies to GH, conditions that result in markedly reduced endogenous IGF‑1.
How does mecasermin differ from growth‑hormone therapy?
Mecasermin supplies IGF‑1 directly, bypassing the need for GH to stimulate IGF‑1 production. It is used when GH is ineffective because of antibodies or gene deletion, whereas GH therapy relies on an intact GH‑IGF‑1 axis.
What are the main safety concerns with mecasermin?
The principal safety issue is hypoglycaemia, especially after injection of unbound IGF‑I. Other adverse events are common but usually mild; regular monitoring of blood glucose is recommended.
Is the IGF‑I/IGFBP‑3 complex still available?
Mecasermin rinfabate, the IGF‑I/IGFBP‑3 complex, was withdrawn from the US and European markets for regulatory reasons, so it is generally not accessible for clinical use in those regions.
Can mecasermin be used for idiopathic short stature?
Current evidence is insufficient to support its use for idiopathic short stature or partial GH resistance, and regulatory approval is limited to the specific IGF‑1 deficiency indications.
What is Mecasermin?
Mecasermin is a recombinant human insulin‑like growth factor‑1 (rhIGF‑1) approved as a prescription drug for children with severe primary IGF‑1 deficiency or growth‑hormone (GH) gene deletion who have developed neutralising antibodies to GH. Administered by subcutaneous injection, it replaces the missing IGF‑1, thereby stimulating linear growth and improving height velocity in this specific population.
What is Mecasermin used for?
Mecasermin is educationally associated with: Muscle growth / anabolic effects, Increase linear growth, Treatment of severe primary IGF-1 deficiency (SPIGFD), Improvement of insulin sensitivity / glucose metabolism, Normalize IGF-1 serum levels, Amyotrophic lateral sclerosis (ALS) treatment, Growth promotion in GH gene deletion with anti-GH antibodies. Educational only — not medical advice.
How is Mecasermin administered?
Recorded routes of administration: Subcutaneous.
What are the potential side effects of Mecasermin?
Reported adverse effects include: Hypoglycemia, Injection site reactions, Acromegaloid features, Intracranial hypertension, Lipohypertrophy, Slipped capital femoral epiphysis, Tonsillar/adenoid hypertrophy. This list is not exhaustive — consult a qualified clinician.
Who should avoid Mecasermin?
Recorded contraindications: Active malignancy, Hypersensitivity to mecasermin or excipients, Closed epiphyses, Diabetic retinopathy, Intravenous administration, Active or suspected neoplasia. Consult a qualified clinician before use.