Quantitative Analysis of Polyethylene Glycol (PEG)
and PEGylated Proteins in Animal Tissues by LC-MS/MS Coupled with
In-Source CID
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Abstract
The
covalent conjugation of polyethylene glycol (PEG, typical MW
> 10k) to therapeutic peptides and proteins is a well-established
approach to improve their pharmacokinetic properties and diminish
the potential for immunogenicity. Even though PEG is generally considered
biologically inert and safe in animals and humans, the slow clearance
of large PEGs raises concerns about potential adverse effects resulting
from PEG accumulation in tissues following chronic administration,
particularly in the central nervous system. The key information relevant
to the issue is the disposition and fate of the PEG moiety after repeated
dosing with PEGylated proteins. Here, we report a novel quantitative
method utilizing LC-MS/MS coupled with in-source CID that is highly
selective and sensitive to PEG-related materials. Both <sup>40K</sup>PEG and a tool PEGylated protein (ATI-1072) underwent dissociation
in the ionization source of mass spectrometer to generate a series
of PEG-specific ions, which were subjected to further dissociation
through conventional CID. To demonstrate the potential application
of the method to assess PEG biodistribution following PEGylated protein
administration, a single dose study of ATI-1072 was conducted in rats.
Plasma and various tissues were collected, and the concentrations
of both <sup>40K</sup>PEG and ATI-1072 were determined using the LC-MS/MS
method. The presence of <sup>40k</sup>PEG in plasma and tissue homogenates
suggests the degradation of PEGylated proteins after dose administration
to rats, given that free PEG was absent in the dosing solution. The
method enables further studies for a thorough characterization of
disposition and fate of PEGylated proteins