Polyglycerol for Half-Life Extension of Proteins—Alternative to PEGylation?

Abstract

Since several decades, PEGylation is known to be the clinical standard to enhance pharmacokinetics of biotherapeutics. In this study, we introduce polyglycerol (PG) of different lengths and architectures (linear and hyperbranched) as an alternative polymer platform to poly(ethylene glycol) (PEG) for half-life extension (HLE). We designed site-selective Nterminally modified PG-protein conjugates of the therapeutic protein anakinra (IL-1ra, Kineret) and compared them systematically with PEG analogues of similar molecular weights. Linear PG and PEG conjugates showed comparable hydrodynamic sizes and retained their secondary structure, whereas binding affinity to IL-1 receptor 1 decreased with increasing polymer length, yet remained in the low nanomolar range for all conjugates. The terminal half-life of a 40 kDa linear PG-modified anakinra was extended 4-fold compared to the unmodified protein, close to its PEG analogue. Our results demonstrate similar performances of PEG-and PG-anakinra conjugates and therefore highlight the outstanding potential of polyglycerol as a PEG alternative for half-life extension of biotherapeutics.

Reincarnation of the Analytical Ultracentrifuge: Emerging Opportunities for Nanomedicine

“…9,46−49 Much efforts have also been devoted into the characterization of natural and synthetic (man-made) polymer systems. 24,31,45,50−54 Translation to nanomedicines concerns EMA and FDA approved drug formulations utilizing stealth polymers such as the "gold standard" poly(ethylene glycol) (PEG) 51 and recently discussed alternatives such as, e.g., poly(2-alkyl-2-oxazoline)s (POx)s 50,55 and linear polyglycerols (LPG)s. 56 The determination of the buoyancy factor, ( υϱ 0 ), in eqs 3 and 4 is common for studies with polymer systems by density increment measurements utilizing a densimeter, allowing the assessment of υ. 24,31,45,50−54 The study of the above-mentioned polymer systems is oftentimes performed in concert with the concept of intrinsic viscosities finding its origin with Staudinger (vide supra).…”

“…A contemporary area of research is the conjugation of poorly water-soluble drug components and therapeutic proteins to stealth polymers, dominated by PEGs. 63 Other emerging examples make use of linear POx 55 and LPGs, 56 showing promise for replacement of PEGs. Only a few studies have examined the investigation of such materials by the AUC.…”

“…The AUC enables characterization of solution components covering the entire colloidal size range by widely adjustable rotor speeds and, therefore, centrifugal forces. From its beginnings, it has been primarily used for the characterization of particles, proteins, and macromolecules of natural origin. ,− Much efforts have also been devoted into the characterization of natural and synthetic (man-made) polymer systems. ,,,− Translation to nanomedicines concerns EMA and FDA approved drug formulations utilizing stealth polymers such as the “gold standard” poly­(ethylene glycol) (PEG) and recently discussed alternatives such as, e.g., poly­(2-alkyl-2-oxazoline)­s (POx)­s , and linear polyglycerols (LPG)­s . The determination of the buoyancy factor, (1 – υϱ 0 ), in eqs and is common for studies with polymer systems by density increment measurements utilizing a densimeter, allowing the assessment of υ. ,,,− …”

Acetal‐Based Functional Epoxide Monomers: Polymerizations and Applications

“…Due to the well‐known biocompatibility of the resulting PGs, this system has provided a potential opportunity in biomedical applications. [ 54–56 ] Depending on the type of acetal moiety, it is also possible to control the degradation kinetics in physiological pH windows. In this section, we cover recent progress in acetal‐bearing epoxide monomers and their pH‐responsive degradation for potential biomedical applications.…”

Neutral polyphosphocholine-modified liposomes as boundary superlubricants

“…[25,26] The types of polymers include: polyethylene glycol (PEG), [27] polyzwitterions, [28,29] poly[N-(2hydroxypropyl) methacrylamide] (PHPMA), [30] poly(2-oxazoline), [31] poly(N-vinyl-2pyrrolidone) (PVP), [32] hyaluronic acid (HA), [33] among which PEGylation is the most widely used. [34,35] However, water molecules form relatively weak hydrogen bonding with PEG moieties, [36] which may impair the efficient lubricating properties provided by PC vesicles.…”