Site‐specific PEGylation of exenatide analogues markedly improved their glucoregulatory activity

Abstract

BACKGROUND AND PURPOSEExenatide is a 39-amino-acid peptide widely used to manage type 2 diabetes mellitus. However, it has a short plasma half-life and requires a twice daily injection regime. To overcome these drawbacks we used maleimide-polyethylene glycol to induce site-specific PEGylation. EXPERIMENTAL APPROACHThe analogue PB-105 (ExC39) was produced by replacing cysteine at position 39 of exenatide to provide a free thiol group. PB-105 showed the same glucoregulatory activity as exenatide in mice. Site-specific PEGylation of PB-105 was performed to produce PB-110 (ExC39PEG5kDa), PB-106 (ExC39PEG20kDa), PB-107 (ExC39PEG30kDa) and PB-108 (ExC39PEG40kDa). Their effects on intracellular cAMP, acute glucoregulatory activity and pharmacokinetic profile were compared in mice and rats. KEY RESULTSPEGylation shifted the concentration-response curve of PB-105 to the right in a parallel, polyethylene glycol mass-dependent manner but with an inflexion point of at least 20 kDa. The activities of PB-107 and PB-108 but not PB-106 were reduced by 90% and 99%. PEGylation affected in vivo glucoregulatory activity in the same 'Inflexion-Shift' fashion at least at 20 kDa, but linearly increased plasma duration and systemic exposure without inflexion. PB-106 had a plasma t1/2 approximately 10-fold that of PB-105, and exhibited superior glucoregulatory activity compared with PB-105 in normal and diabetic mice. CONCLUSIONS AND IMPLICATIONSSite-specific PEGylation of exenatide with a permanent amide linkage affects its activity in a new type of 'Inflexion-Shift' fashion. PB-106 is a putative new analogue for treating diabetes; it possesses no loss of in vitro activity, prolonged plasma duration and superior, improved in vivo glucoregulatory activity compared with exenatide.

The structure and function of the glucagon‐like peptide‐1 receptor and its ligands

“…However, the half‐life of GLP‐1 in vivo is short, and it is rapidly degraded to GLP‐1(9‐36)amide by DPPIV (Deacon et al ., 1995; Knudsen and Pridal, 1996; Hansen et al ., 1999), and hence, there are continuing attempts to find long‐lasting peptide agonists with glucoregulatory properties (e.g. Gong et al ., 2011). Indeed, current therapeutic approaches have utilized DPPIV‐resistant mimetics of GLP‐1, most notably exenatide (Iltz et al ., 2006) and liraglutide (Neumiller and Campbell, 2009), both of which are in current therapeutic use.…”

High molecular weight PEGylation of human pancreatic polypeptide at position 22 improves stability and reduces food intake in mice

“…Several previous investigations have reported a deterioration of target potency with increasing PEG mass (Gong et al , ; Bianchi et al , ; Qiu et al , ), which is thought to originate from PEG‐chain length‐dependent altered steric shielding (Mu et al , ). We found that PEGylation of hPP on lysine side‐chains at positions 22 and 30 using different precursor peptides (hPP 2–36 and [Q 34 ]hPP) also induced significant reductions in activity that correlated mostly with PEG size.…”

Sex differences in central inflammatory pain sensitization are associated with differential expression of glycine receptors and GLP-1 at the spinal cord

“…In agreement with these results, we showed that female rats reduced GLP-1 hormone expression after the Zymosan injection. It was reported that GLP-1 hormone had an antinociceptive effect in formalin injected male rats [11,24]. This effect was related with the modulation of opioidergic system [25].…”