1. Dosage

Mecasermin (Increlex) is the recombinant DNA form of human insulin-like growth factor-1 (rhIGF-1). In normal circulation, over 98% of rhIGF-1 is available in bound form to IGFBP-3, which allows IGF-1 to remain inactive until released to target tissues. This reduces the potential for adverse events associated with free levels of IGF-1. In patients with growth hormone insensitivity syndrome, the serum half-life of unbound IGF-1 is decreased, as these patients have lower rhIGFBP-3 concentrations. Patients with IGF-1 gene deletion have normal levels of rhIGFBP-3. Mecasermin is FDA-approved for use in treating growth failure in children with severe primary IGF-1 deficiency (primary IGFD) or with growth hormone (GH) gene deletion who have developed neutralizing antibodies to GH. Mecasermin has also been evaluated for use in short children with low IGF-1 levels; results showed improvement in height velocities following mecasermin use compared to untreated patients after one year of treatment^1-3.