Creative Diagnostics provides ELISA kits for measurement of free and conjugated PEG as well as ELISA kits for detection of anti-PEG IgM and IgG in mouse, rat, monkey, and human serum or plasma. These assay kits are useful in clinical safety studies to determine the immunogenicity of PEGylated biotherapeutics.
|Cat. No||Product Name||Linear Range|
|DEIA6158||High Sensitivity Polyethylene Glycol (PEG) ELISA Kit||0.064 - 1000 ng/mL|
|DEIA6159||Mouse anti-PEG IgG ELISA Kit||3.13 - 100 U/mL|
|DEIA6160||Mouse anti-PEG IgM ELISA Kit||6.25 – 100 U/mL|
|DEIASL085||Rat anti-PEG IgG ELISA Kit||6.25 – 100 U/mL|
|DEIASL086||Rat anti-PEG IgM ELISA Kit||3.125 – 100 U/mL|
|DEIASL087||Monkey anti-PEG IgG ELISA Kit||1.56 – 100 U/mL|
|DEIASL088||Monkey anti-PEG IgM ELISA Kit||6.25 – 100 U/mL|
PEGs are highly flexible linear or branched polymers in the 0.4-40 kDa MW range, synthetized with different end-groups. One of the end-groups is used for covalent attachment to free carboxy, amino, or sulphydryl groups on macromolecules, on drug delivery nanosystems (DDS) or on linkers that bind the PEG to DDS, such as phosphatidylethanolamine, via one of a variety of chemically reactive functional groups (acrylate, methacrylate, maleimide, dibenzocyclooctynol, vinyl sulfonate or vinyl or allyl ethers). The other end-group is most frequently a methyl group (methoxy-PEG), although hydroxy (–OH), amino (–NH3+), butoxy (–O-(CH2)3)-CH3) and tert-butoxy (–O-(CH3)3) terminal endings are also used.
PEGs are widely used in drug research and development to improve the efficacy of drugs, and a variety of PEG drugs have been put into clinical use. After PEGylation, the physicochemical properties of drug or protein molecules will change, such as molecular weight, apparent volume, hydrophilicity, conformation, steric hindrance, charge etc., and the renal clearance rate will also change. Due to the strong ability of PEG to bind water molecules, protein modified by PEG can form a hydration layer on the surface of protein, which can extend the half-life of protein or drug in vivo. Conjugation of polyethylene glycols (PEGs) to proteins or drug delivery nanosystems is a widely accepted method at present to increase the therapeutic index of complex nano-biopharmaceuticals. However, recent clinical studies have shown that PEG drugs can elicit the production of anti-PEG antibodies which is referred as “PEG immunogenicity”.
The immunogenicity of PEGylated drugs may be TD (T cell-dependent) or TI (T cell-independent), depending on the chemical nature of PEG-anchormolecule or DDS. PEGylated proteins induce immune responses mainly via the classical TD manner, while PEGylated NPs, like PEGylated liposomes, may induce Ab production via TI immunogenicity. However, neither of these mechanisms is identical to the pure (non-conjugated) protein or liposomal vaccine-induced primary and secondary immune responses.
For example, a typical protein-induced immunogenicity, characterized by a start of specific IgM production around day 5 and peak at about day 10. The rise and peak of IgG following isotype switching during the primary response is delayed by about 5 days, and the extent of IgG secretion slightly exceeds that of IgM. In contrast, during a secondary response, the IgM production is less and is followed by subtype switch with a rise and peak of IgG at around 11 and 15 days, respectively. During the secondary response the IgM production lessens while the IgG response starts and peaks earlier at a substantially increased quantity.
The clinical significance of PEG immunogenicity lies in the possibility that binding of anti-PEG Abs decreases the therapeutic efficacy and safety of PEGylated drugs. The therapeutic efficacy can be reduced either by blocking the drug's therapeutic effect in some way, an effect referred to as neutralization. The other way may be the enhancement of the drug's clearance, the ABC (Accelerated Blood Clearance) phenomenon, decreasing the drugs bioavailability. Finally, hypersensitivity reactions (HSRs) represent a health risk, with potentially severe, life threatening or deadly (pseudo)allergic reactions. Therefore, studying the production law of PEG antibody and its influence on protein drug metabolism is of great significance to improve the efficacy of PEG protein drugs.
ELISA is the most widely applied technique to detect anti-PEG Abs due to its high sensitivity and capability to quantify Ab levels at least in relative terms. In Creative Diagnostic's anti-PEG ELISA, a color reaction is generated by enzyme-conjugated host IgG or IgM specific Abs recognizing PEG-specific Abs in serum or plasma bound to a PEG coated surface. The concentration of anti-PEG IgG or IgM is proportional to the absorbance at 450 nm and can be derived from a standard curve. This assay primarily detects antibodies directed against the polyoxyethylene backbone of PEG.