Mecasermin is recombinant human IGF-1 approved as Increlex for narrowly defined severe primary IGF-1 deficiency in children. It is the approved, sequence-native reference point for the unapproved IGF-1 LR3 and IGF-1 DES analogues.

Established. Review the research and limitations before relying on this record.

Mecasermin is sequence-identical to human IGF-1. It binds the IGF-1 receptor and activates intracellular signalling that promotes cell survival, protein synthesis and linear skeletal growth. It acts downstream of growth hormone, so it can replace IGF-1 when the growth-hormone receptor pathway cannot produce it; it is not a substitute for somatropin in ordinary growth-hormone deficiency.

More than 80% of circulating IGF-1 is carried in a ternary complex with IGFBP-3 and acid-labile subunit, so clearance depends strongly on IGFBP-3 concentration. The label reports a 5.8-hour half-life after a single subcutaneous dose in only three severe-primary-IGF-1-deficiency subjects, making that estimate substantially less certain than it appears.

FDA approval covers growth failure in patients aged two years and older with severe primary IGF-1 deficiency or a growth-hormone gene deletion with neutralising antibodies to growth hormone. The label summarises five open-label clinical studies and long-term follow-up; growth velocity increased most strongly in the first year. This evidence does not establish mecasermin for general short stature, athletic performance, anti-ageing or the modified LR3 and DES molecules.

Severe hypoglycaemia, including seizures, is the defining risk because IGF-1 has insulin-like glucose-lowering effects. The label also warns about anaphylaxis, intracranial hypertension, lymphoid-tissue hypertrophy, slipped capital femoral epiphysis, progression of scoliosis and malignant neoplasia. It is contraindicated with closed epiphyses, active or suspected malignancy, or hypersensitivity.

This is a source-backed summary, not a recommendation. Read the mechanism, pharmacokinetic, human-evidence and reported-effect fields separately: a mechanism is not an outcome. Availability, legal status and product quality differ by jurisdiction; consult a qualified clinician.