Mecasermin rinfabate for severe insulin-like growth factor-I deficiency

Recombinant human insulin-like growth factor (rhIGF)-I has been shown to increase growth velocity in children with IGF-I deficiency, either as a result of growth hormone-insensitivity syndrome or IGF-I gene deletion (one case study). There have been adverse events, particularly hypoglycemia, reported with administration of unbound rhIGF-I. In addition, the serum half-life of unbound rhIGF-I is shorter when administered to patients with growth hormone-insensitivity syndrome, who have low serum concentrations of its binding proteins IGFBP-3 and acid-labile subunit, than when administered to normal volunteers or to patients with an IGF-I gene deletion (who had normal levels of IGFBP-3). Mecasermin rinfabate, an equimolar mixture of rhIGF-I and the recombinant form of its principal binding protein rhIGFBP-3 (rhIGF-I/ rhIGFBP-3), was developed to prolong the half-life and to reduce the risk of acute adverse events (particularly hypoglycemia) associated with administration of rhIGF-I. Published data demonstrate the efficacy of mecasermin rinfabate in treating severe primary IGF-I deficiency, and mecasermin rinfabate appears to have a longer half-life in patients with growth hormone-insensitivity syndrome than unbound rhIGF-I.