Analysis of Pre-existing IgG and IgM Antibodies against Polyethylene Glycol (PEG) in the General Population

Abstract

Circulating antibodies (Ab) that specifically bind polyethylene glycol (PEG), a biocompatible polymer routinely used in protein and nanoparticle therapeutics, have been associated with reduced efficacy of and/or adverse reactions to therapeutics modified with or containing PEG. Unlike most antidrug antibodies that are induced following initial drug dosing, anti-PEG Ab can be found in treatment-naïve individuals (i.e., individuals who have never undergone treatment with PEGylated drugs but most likely have been exposed to PEG through other means). Unfortunately, the true prevalence, quantitative levels, and Ab isotype of pre-existing anti-PEG Ab remain poorly understood. Here, using rigorously validated competitive ELISAs with engineered chimeric anti-PEG monoclonal Ab standards, we quantified the levels of anti-PEG IgM and different subclasses of anti-PEG IgG (IgG1-4) in both contemporary and historical human samples. We unexpectedly found, with 90% confidence, detectable levels of anti-PEG Ab in ∼72% of the contemporary specimens (18% IgG, 25% IgM, 30% both IgG and IgM). The vast majority of these samples contained low levels of anti-PEG Ab, with only ∼7% and ∼1% of all specimens possessing anti-PEG IgG and IgM in excess of 500 ng/mL, respectively. IgG2 was the predominant anti-PEG IgG subclass. Anti-PEG Ab's were also observed in ∼56% of serum samples collected during 1970-1999 (20% IgG, 19% IgM, and 16% both IgG and IgM), suggesting that the presence of PEG-specific antibodies may be a longstanding phenomenon. Anti-PEG IgG levels demonstrated correlation with patient age, but not with gender or race. The widespread prevalence of pre-existing anti-PEG Ab, coupled with high Ab levels in a subset of the population, underscores the potential importance of screening patients for anti-PEG Ab levels prior to administration of therapeutics containing PEG.

Figure 1.

Frequency distribution of (A) anti-PEG IgG and (B) anti-PEG IgM levels in contemporary human plasma samples (n = 377). GMC, geometric mean concentration; CI, 95% confidence intervals for the GMC. Cumulative frequency distribution of (C) anti-PEG IgG and (D) anti- PEG IgM levels in contemporary human plasma samples. Light gray lines represent the 90% CI, and detection cutoff limits are indicated by the vertical gray dashed lines.

Figure 2.

Frequency distribution of (A) anti-PEG IgG1, (B) IgG2, (C) IgG3, and (D) IgG4 levels in contemporary human plasma samples (n = 377). GMC, geometric mean concentration; CI, 95% confidence intervals for the GMC. Cumulative frequency distribution of (E) anti-PEG IgG1, (F) IgG2, (G) IgG3, and (H) IgG4 levels in contemporary human plasma samples. Light gray lines represent the 90% CI, and detection cutoff limits are indicated by the vertical gray dashed lines.

Figure 3.

Anti-PEG IgM, IgG, IgG1, and IgG2 levels by (A–D) age group, (E–H) gender, and (I–L) race in healthy individuals (n = 377). The data are depicted using Tukey’s method for box-and-whisker plots, with samples outside of the whiskers shown as open circles.

Figure 4.

Anti-PEG IgM, IgG, IgG1, and IgG2 prevalence by (A–D) age group, (E–H) gender, and (I–L) race in healthy individuals (n = 377).

Figure 5.

Frequency distribution of anti-PEG IgG and IgM levels in historical human serum samples collected in the (A,B) 1970s, (E,F) 1980s, and (I,J) 1990s (n = 30, 30, and 19, respectively). GMC, geometric mean concentration; CI, 95% confidence intervals for the GMC. Cumulative frequency distribution of anti-PEG IgG and IgM levels in historical human serum samples collected in the (C,D) 1970s, (G,H) 1980s, and (K,L) 1990s. Light gray lines represent the 90% CI, and detection cutoff limits are indicated by the vertical gray dashed lines.