Insulin is among the most important protein therapeutics. However, degradation and aggregation from exposure to environmental stressors during storage and transportation decreases its efficacy and poses a risk to patients from inadequate dosing. Previously, we prepared a conjugate of insulin with trehalose glycopolymer by reductive amination and demonstrated its improved environmental stability in vitro and in vivo. However, this conjugate required 5-fold insulin dosage compared to native insulin to achieve the same activity in mice due to the non-specific, heterogeneous conjugation strategy. We present a site-specific grafting from strategy to prepare insulin-trehalose glycopolymer conjugate with improved bioactivity and thermal stability. An insulin macroinitiator targeting modification at lysine of the B chain to minimize impact on bioactivity was prepared, isolated, and characterized by mass spectral analysis. Trehalose monomer was polymerized directly from this macroinitiator under mild aqueous conditions by activators generated by electron transfer atom transfer radical polymerization (AGET ATRP). We confirmed stabilization to heat with the new conjugation strategy using high performance liquid chromatography (HPLC) assay. Finally, the site-specific conjugate required an improved 3-fold insulin dosage compared to native insulin to lower blood glucose to the same extent by insulin tolerance test (ITT) in mice, equivalent to the analogous site-specific poly(ethylene glycol) (PEG) conjugate. These results demonstrate a conjugation strategy that can be used to prepare conjugates with improved stability and greater retention of bioactivity.

Site-specific grafting from strategy improves both activity and stability of insulin-trehalose glycopolymer conjugate

2019 Fall National Meeting

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.