Half-life prolongation of therapeutic proteins by conjugation to ATIII-binding pentasaccharides: a first-in-human study of CarboCarrier® insulin.

Aim: Conjugation to antithrombin III ATIII-binding pentasaccharides has been proposed as a novel method to extend the half-life of therapeutic proteins. We aim to validate this technological concept in man by performing a first-in-human study using CarboCarrier® insulin (SCH 900948) as an example. A rising single dose phase 1 study was performed assessing safety, tolerability, pharmacokinetics and relative bioactivity of CarboCarrier® insulin. Safety, tolerability and pharmacokinetics (PK) of single doses of CarboCarrier® insulin in healthy volunteers were explored, and the dose-response relationship and relative bioactivity of CarboCarrier® insulin in subjects with type 2 diabetes were investigated.

Methods: After an overnight fast, subjects were randomized to a treatment sequence. PK and pharmacodynamic (glucose, insulin and C-peptide) samples were obtained for up to 72 h post-dose. Effects of CarboCarrier® insulin were compared with those of NPH-insulin.

Results: CarboCarrier® insulin was safe and well-tolerated and no consistent pattern of adverse events occurred. CarboCarrier® insulin exposure (Cmax and AUC) increased proportionally with dose. The mean terminal elimination half-life ranged between 3.11 and 5.28 h. All CarboCarrier® insulin dose groups showed decreases in the mean change from baseline of plasma glucose concentrations compared with the placebo group.

Conclusions: CarboCarrier® insulin is pharmacologically active showing features of insulin action in man. The elimination half-life of the molecule was clearly extended compared with endogenous insulin, indicating that conjugation to ATIII-binding pentasaccharides is a viable approach to extend the half-life of therapeutic proteins in humans. This is an important step towards validation of the CarboCarrier® technology by making use of CarboCarrier® insulin as an example.