Anti-PEG antibody bioanalysis: a clinical case study with PEG-IFN-λ-1a and PEG-IFN-α2a in naive patients

Development of a validated novel bead extraction method for the detection of anti-PEG antibodies in human serum

AIMS

Polyethylene glycol (PEG) is used in many applications including drug development. Due to exposure to environmental products, there is a high prevalence of preexisting anti-PEG antibodies in the global human population. The presence of anti-PEG antibodies is a concern for potentially reducing the efficacy of therapeutics after administration and represents a risk of safety events after exposure to PEGylated drug products. We developed and validated a creative and sensitive method for the detection of anti-PEG antibodies in human serum to support clinical programs for PEGylated drugs.

METHODS

In this method, biotin-PEG streptavidin beads were used to extract anti-PEG antibodies from human serum for analysis in an anti-PEG ELISA assay. The same serum sample was analyzed in an anti-drug antibody assay.

RESULTS

The anti-PEG antibody assay was validated with a screening cut point of 1.41 normalized signal, confirmatory cut point of 32.2% inhibition, sensitivity of 7.81 ng/mL and sufficient reproducibility, selectivity, and drug tolerance in accordance with the FDA 2019 Immunogenicity guidance.

CONCLUSION

This method of removal of anti-PEG antibodies enables the use of a single sample to detect anti-drug and anti-PEG antibodies to support drug development programs.

Adverse Impacts of PEGylated Protein Therapeutics: A Targeted Literature Review

The beneficial effects of polyethylene glycol (PEG)-conjugated therapeutics, such as increased half-life, solubility, stability, and decreased immunogenicity, have been well described. There have been concerns, however, about adverse outcomes with their use, but understanding of those adverse outcomes is still relatively limited. The present study aimed to characterize adverse outcomes associated with PEGylation of protein-based therapeutics on immunogenicity, pharmacologic properties, and safety. A targeted review of English language articles published from 1990 to September 29, 2023, was conducted. Of the 29 studies included in this review, 18 reported adverse safety outcomes such as hematologic complications, hepatic toxicity, injection site reactions, arthralgia, nausea, infections, grade 3 or 4 adverse events (AEs), and AE-related discontinuations and dose modifications. Fifteen studies reported immunogenicity-related outcomes, such as the prevalence of pre-existing antibodies to PEG, treatment-emergent antibody response, and hypersensitivity reactions to PEGylated drugs. Seven studies reported pharmacological outcomes such as increased clearance and reduced activity in response to PEGylated drugs. This review aims to contribute to a balanced view of PEGylated therapies by summarizing the adverse outcomes or lack of benefit associated with PEGylated therapeutics reported in the literature. We identified several studies characterizing adverse outcomes, pharmacological effects, and immunogenicity associated with the use of PEGylated therapeutics. Our findings suggest that using PEGylated therapeutics may require careful monitoring for adverse safety outcomes, including screening and monitoring for pre-existing antibodies and those induced in response to PEGylated therapy, as well as monitoring and adjusting the dosing of PEGylated therapeutics.

Effects of PEG antibodies on in vivo performance of LNP-mRNA vaccines

Polyethylene glycol (PEG) plays important roles in stabilizing and lengthening circulation time of lipid nanoparticle (LNP) vaccines. Nowadays various levels of PEG antibodies have been detected in human blood, but the impact and mechanism of PEG antibodies on the in vivo performance of LNP vaccines has not been clarified thoroughly. By illustrating the distribution characteristics of PEG antibodies in human, the present study focused on the influence of PEG antibodies on the safety and efficacy of LNP-mRNA vaccine against COVID-19 in animal models. It was found that PEG antibodies led to shortened blood circulation duration, elevated accumulation and mRNA expression in liver and spleen, enhanced expression in macrophage and dendritic cells, while without affecting the production of anti-Spike protein antibodies of COVID-19 LNP vaccine. Noteworthily, PEG antibodies binding on the LNP vaccine increased probability of complement activation in animal as well as in human serum and led to lethal side effect in large dosage via intravenous injection of mice. Our data suggested that PEG antibodies in human was a risky factor of LNP-based vaccines for biosafety concerns but not efficacy.

Mechanism of interferon alpha therapy for chronic hepatitis B and potential approaches to improve its therapeutic efficacy

Hepatitis B virus (HBV) chronically infects 296 million people worldwide and causes more than 820,000 deaths annually due to cirrhosis and hepatocellular carcinoma. Current standard-of-care medications for chronic hepatitis B (CHB) include nucleos(t)ide analogue (NA) viral DNA polymerase inhibitors and pegylated interferon alpha (PEG-IFN-α). NAs can efficiently suppress viral replication and improve liver pathology, but not eliminate or inactivate HBV covalently closed circular DNA (cccDNA). CCC DNA is the most stable HBV replication intermediate that exists as a minichromosome in the nucleus of infected hepatocyte to transcribe viral RNA and support viral protein translation and genome replication. Consequentially, a finite duration of NA therapy rarely achieves a sustained off-treatment suppression of viral replication and life-long NA treatment is most likely required. On the contrary, PEG-IFN-α has the benefit of finite treatment duration and achieves HBsAg seroclearance, the indication of durable immune control of HBV replication and functional cure of CHB, in approximately 5% of treated patients. However, the low antiviral efficacy and poor tolerability limit its use. Understanding how IFN-α suppresses HBV replication and regulates antiviral immune responses will help rational optimization of IFN therapy and development of novel immune modulators to improve the rate of functional cure. This review article highlights mechanistic insight on IFN control of HBV infection and recent progress in development of novel IFN regimens, small molecule IFN mimetics and combination therapy of PEG-IFN-α with new direct-acting antivirals and therapeutic vaccines to facilitate the functional cure of CHB.

To PEGylate or not to PEGylate: Immunological properties of nanomedicine's most popular component, polyethylene glycol and its alternatives

Polyethylene glycol or PEG has a long history of use in medicine. Many conventional formulations utilize PEG as either an active ingredient or an excipient. PEG found its use in biotechnology therapeutics as a tool to slow down drug clearance and shield protein therapeutics from undesirable immunogenicity. Nanotechnology field applies PEG to create stealth drug carriers with prolonged circulation time and decreased recognition and clearance by the mononuclear phagocyte system (MPS). Most nanomedicines approved for clinical use and experimental nanotherapeutics contain PEG. Among the most recent successful examples are two mRNA-based COVID-19 vaccines that are delivered by PEGylated lipid nanoparticles. The breadth of PEG use in a wide variety of over the counter (OTC) medications as well as in drug products and vaccines stimulated research which uncovered that PEG is not as immunologically inert as it was initially expected. Herein, we review the current understanding of PEG's immunological properties and discuss them in the context of synthesis, biodistribution, safety, efficacy, and characterization of PEGylated nanomedicines. We also review the current knowledge about immunological compatibility of other polymers that are being actively investigated as PEG alternatives.

Polyethylene Glycol Immunogenicity: Theoretical, Clinical, and Practical Aspects of Anti-Polyethylene Glycol Antibodies

Polyethylene glycol (PEG) is a flexible, hydrophilic simple polymer that is physically attached to peptides, proteins, nucleic acids, liposomes, and nanoparticles to reduce renal clearance, block antibody and protein binding sites, and enhance the half-life and efficacy of therapeutic molecules. Some naïve individuals have pre-existing antibodies that can bind to PEG, and some PEG-modified compounds induce additional antibodies against PEG, which can adversely impact drug efficacy and safety. Here we provide a framework to better understand PEG immunogenicity and how antibodies against PEG affect pegylated drug and nanoparticles. Analysis of published studies reveals rules for predicting accelerated blood clearance of pegylated medicine and therapeutic liposomes. Experimental studies of anti-PEG antibody binding to different forms, sizes, and immobilization states of PEG are also provided. The widespread use of SARS-CoV-2 RNA vaccines that incorporate PEG in lipid nanoparticles make understanding possible effects of anti-PEG antibodies on pegylated medicines even more critical.

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

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 N-terminally 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.

Flow cytometry analysis of anti-polyethylene glycol antibodies in human plasma

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A rapid, sensitive, and specific flow cytometry assay was developed to detect anti-PEG IgG and IgM in human blood plasma.

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Using the method, anti-PEG IgG or IgM were detected in 65% of plasma samples from 300 healthy blood donors.

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The presence of anti-PEG IgG and IgM was confirmed using three validation assays.

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The highest prevalence of both anti-IgG and anti-IgM was in individuals 18–24 years of age.

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No correlation was found between anti-PEG IgG and IgM concentrations.

Polyethylene glycol (PEG) is a biocompatible polymer used in biotherapeutics to increase bioavailability, reduce the frequency of administration, and optimize pharmacokinetics. Anti-PEG antibodies have been detected in healthy individuals and may decrease efficacy and alter the pharmacokinetics of PEGylated therapeutics; however, the prevalence of anti-PEG antibodies is unclear. In this study, a flow cytometry assay was optimized to detect anti-PEG IgG and IgM in human blood plasma. Three hundred (300) plasma samples from healthy blood donors were screened; anti-PEG IgG or IgM was detected in 65.3% of the total population, with 21.3% having anti-PEG IgG, 19.0% having anti-PEG IgM, and 25.0% having both anti-PEG IgG and IgM. The presence of anti-PEG IgG and IgM was confirmed using a 0.5% Tween-20 interference assay, a 20 kDa PEGylated polystyrene bead binding assay, and Western blotting of purified plasma from human IgG and IgM purification columns. The concentrations of anti-PEG IgG and IgM in positive samples ranged from 39 ng/mL to 18.7 μg/mL and 26 ng/mL to 11.6 μg/mL, respectively. The highest prevalence of both anti-IgG and anti-IgM was in individuals 18–24 years of age. The prevalence of anti-PEG IgG and IgM tended to be higher in women but did not differ among races. Age, sex, and race were not associated with the concentrations of anti-PEG IgG or IgM. No correlation was found between anti-PEG IgG and IgM concentrations. Our study indicates that flow cytometry can be used to detect anti-PEG IgG and IgM antibodies in human plasma.

Pre-existing antibodies against polyethylene glycol reduce asparaginase activities on first administration of pegylated E. coli asparaginase in children with acute lymphocytic leukemia

Antibodies against polyethylene glycol (PEG) in healthy subjects raise concerns about the efficacy of pegylated drugs. We evaluated the prevalence of antibodies against PEG among patients with acute lymphoblastic leukemia (ALL) prior to and/or immediately after their first dose of pegylated E.coli asparaginase (PEG-ASNase). Serum samples of 701 children, 673 with primary ALL, 28 with relapsed ALL, and 188 adults with primary ALL were analyzed for anti-PEG IgG and IgM. Measurements in 58 healthy infants served as reference to define cut-points for antibody-positive and -negative samples. Anti-PEG antibodies were detected in ALL patients prior the first PEG-ASNase with a prevalence of 13.9% (anti-PEG IgG) and 29.1% (anti-PEG IgM). After administration of PEG-ASNase the prevalence of anti-PEG antibodies decreased to 4.2% for anti-PEG IgG and to 4.5% for anti-PEG IgM. Pre-existing anti-PEG antibodies did not inhibit PEG-ASNase activity but significantly reduced PEGASNase activity levels in a concentration dependent manner. Although pre-existing anti-PEG antibodies did not boost, pre-existing anti-PEG IgG were significantly associated with firstexposure hypersensitivity reactions (CTCAE grade 2) (p

Development and validation of a novel immunogenicity assay to detect anti-drug and anti-PEG antibodies simultaneously with high sensitivity

Polyethylene glycol (PEG) represents an effective strategy to improve the pharmacokinetic profile of a molecule as it extends the biotherapeutic's half-life, masks immunogenic epitopes or modifies its distribution. The addition of one or multiple PEG moieties, in either linear or branched form, is known to carry the risk of potentially inducing an immunogenic response against PEG. The importance of accurately quantifying anti-PEG antibodies during a clinical study is well recognized and stems from the fact that anti-PEG antibodies have been shown to negatively impact the efficacy of the biotherapeutic that the PEG is coupled to. As a consequence, sponsors are encouraged to develop immunogenicity assays to assess appropriately the presence of anti-drug antibodies (ADA) against the protein component as well as the PEG. However, detection of anti-PEG antibodies is complicated by a number of technical challenges, including the availability of appropriate positive control material. In addition, the fact that some anti-PEG antibodies are known to circulate as low-affinity IgM, drives the need for an assay able to detect low affinity anti-PEG ADA even in the presence of high concentrations of the biotherapeutic. To address this need, we developed and validated an Affinity Capture Elution (ACE)-AGL assay to detect anti-drug and anti-PEG antibodies. In this assay, which we call ACE-AGL, ADA are captured by biotin-PEG-drug, acid eluted and re-captured on a second plate coated with protein AGL. ADA are then detected using Ruthenium-PEG-drug. The new assay format described is highly sensitive to both anti-drug and anti-PEG antibodies and very drug-tolerant. The ACE-AGL assay is easy to perform and has been successfully validated at two separate CROs. We propose the ACE-AGL format as a valid and effective alternative to the currently available assay methods.

Development of a Highly Specific Anti-drug Antibody Assay in Support of a Nanoparticle-based Therapeutic

PEGylated biotherapeutics can elicit anti-PEG (polyethylene glycol) immune responses in patients treated with this category of drugs. While anti-PEG antibody assays for this class of biotherapeutics have become a common element of the clinical immunogenicity testing strategy, the overall antibody incidence induced by the nanoparticle (NP) delivery system (such as ACCURINS®) has not been fully studied to date. To support the immunogenicity assessment of one of Pfizer's NP-based therapeutics, consisting of gedatolisib (GEDA) encapsulated in ACCURINS® (GEDA-NP), we developed an anti-GEDA-NP antibody (ADA) assay on the MSD platform for the detection of GEDA-NP induced ADA in human serum. The focus of our strategy was on developing a clinically relevant ADA assay and systematically addressing assay interference through rigorous assay optimization. Our efforts led to a fit-for-purpose assay for the detection of anti-GEDA-NP ADA in serum samples obtained from breast cancer patients. Results from method qualification indicated robust assay performance, as highlighted by inter and intra-assay precision within 25% CV for all controls, and reproducible response profiles across multiple runs during the assessment of assay cut points with breast cancer samples. The assay sensitivity was between 4.3 ng/mL and 123 ng/mL for surrogate positive controls of IgG and IgM isotypes, respectively. Additionally, assay interference from nonspecific matrix proteins and circulating drug was addressed, which ensured accurate assessment of ADA incidence that can be attributed to GEDA-NP.

Antibodies against polyethylene glycol in human blood: A literature review

Polyethylene glycol (PEG) conjugation, i.e. PEGylation, is a successful strategy to improve the pharmacokinetics and pharmacodynamics of biopharmaceuticals. In the past few decades, PEGylation technology has developed tremendously, and >15 PEGylated therapeutics have been brought to market, with more in development. However, the widely accepted assumption that PEG would have no antigenicity or immunogenicity is increasingly challenged with popularization of PEGylation technique. Although PEGylation indeed reduces the immunogenicities of the modified molecules, and even appears to completely eliminate their immunogenicities, yet emerging clinical evidence of anti-PEG antibodies (including both pre-existing and PEGylated therapeutics-treatment induced anti-PEG antibodies) have been attracted more and more attention. Anti-PEG antibodies were detected in not only patients treated with PEGylated therapeutics but also PEGylated drugs treatment-naïve individuals with a prevalence from <1% to 72%. In patients, the existing anti-PEG antibodies may attenuate therapeutic efficacy of PEGylated drugs and increase adverse effects. Although there is no golden standard avenue, several types of methods, including passive hemagglutination, Western Blot, enzyme linked immunosorbent assay, flow cytometry, Meso Scale Discovery technology, Acoustic Membrane Microparticle assay, and surface plasmon resonace technique, were established and used to screen, confirm and quantitatively detect anti-PEG antibodies. Herein, we focused on reviewing the prevalence of anti-PEG antibodies in healthy and PEGylated therapeutics-treated patients, and highlighting the detection methods for pre-screening and quantitative detection of anti-PEG antibodies.

Both IgM and IgG Antibodies Against Polyethylene Glycol Can Alter the Biological Activity of Methoxy Polyethylene Glycol-Epoetin Beta in Mice

Pre-existing antibodies that bind polyethylene glycol are present in about 40% of healthy individuals. It is currently unknown if pre-existing anti-polyethylene glycol (PEG) antibodies can alter the bioactivity of pegylated drugs with a single long PEG chain, which represents the majority of newly developed pegylated medicines. Methoxy polyethylene glycol-epoetin beta (PEG-EPO) contains a single 30 kDa PEG chain and is used to treat patients suffering from anemia. We find that the pre-existing human anti-PEG IgM and IgG antibodies from normal donors can bind to PEG-EPO. The prevalence and concentrations of anti-PEG IgM and IgG antibodies were also higher in patients that responded poorly to PEG-EPO. Monoclonal anti-PEG IgM and IgG antibodies at concentrations found in normal donors blocked the biological activity of PEG-EPO to stimulate the production of new erythrocytes in mice and accelerated the clearance of 125I-PEG-EPO, resulting in PEG-EPO accumulation primarily in the liver and spleen. Accelerated clearance by the anti-PEG IgG antibody was mediated by the Fc portion of the antibody. Importantly, infusing higher doses of PEG-EPO could compensate for the inhibitory effects of anti-PEG antibodies, suggesting that pre-existing anti-PEG antibodies can be "dosed through." Our study indicates that the bioactivity and therapeutic activity of PEG-EPO may be reduced in patients with elevated levels of pre-existing anti-PEG antibodies. New pegylated medicines with a single long PEG chain may also be affected in patients with high levels of anti-PEG antibodies.

Outcome of pediatric patients with acute lymphoblastic leukemia/lymphoblastic lymphoma with hypersensitivity to pegaspargase treated with PEGylated Erwinia asparaginase, pegcrisantaspase: A report from the Children's Oncology Group

BACKGROUND

Erwinia asparaginase is a Food and Drug Administration approved agent for the treatment of acute lymphoblastic leukemia (ALL) for patients who develop hypersensitivity to Escherichia coli derived asparaginases. Erwinia asparaginase is efficacious, but has a short half-life, requiring six doses to replace one dose of the most commonly used first-line asparaginase, pegaspargase, a polyethylene glycol (PEG) conjugated E. coli asparaginase. Pegcristantaspase, a recombinant PEGylated Erwinia asparaginase with improved pharmacokinetics, was developed for patients with hypersensitivity to pegaspargase. Here, we report a series of patients treated on a pediatric phase 2 trial of pegcrisantaspase.

PROCEDURE

Pediatric patients with ALL or lymphoblastic lymphoma and hypersensitivity to pegaspargase enrolled on Children's Oncology Group trial AALL1421 (Jazz 13-011) and received intravenous pegcrisantaspase. Serum asparaginase activity (SAA) was monitored before and after dosing; immunogenicity assays were performed for antiasparaginase and anti-PEG antibodies and complement activation was evaluated.

RESULTS

Three of the four treated patients experienced hypersensitivity to pegcrisantaspase manifested as clinical hypersensitivity reactions or rapid clearance of SAA. Immunogenicity assays demonstrated the presence of anti-PEG immunoglobulin G antibodies in all three hypersensitive patients, indicating a PEG-mediated immune response.

CONCLUSIONS

This small series of patients, nonetheless, provides data, suggesting preexisting immunogenicity against the PEG moiety of pegaspargase and poses the question as to whether PEGylation may be an effective strategy to optimize Erwinia asparaginase administration. Further study of larger cohorts is needed to determine the incidence of preexisting antibodies against PEG-mediated hypersensitivity to pegaspargase.

Immediate-type hypersensitivity to polyethylene glycols: a review

Polyethylene glycols (PEGs) or macrogols are polyether compounds widely used in medical and household products. Although generally considered biologically inert, cases of mild to life-threatening immediate-type PEG hypersensitivity are reported with increasing frequency. Nevertheless, awareness of PEG's allergenic potential remains low, due to a general lack of suspicion towards excipients and insufficient product labelling. Information on immediate-type reactions to PEG is limited to anecdotal reports, and the potential for PEG sensitization and cross-sensitization to PEGylated drugs and structurally related derivatives is likely underestimated. Most healthcare professionals have no knowledge of PEG and thus do not suspect PEG's as culprit agents in hypersensitivity reactions. In consequence, patients are at risk of misdiagnosis and commonly present with a history of repeated, severe reactions to a range of unrelated products in hospital and at home. Increased awareness of PEG prevalence, PEG hypersensitivity, and improved access to PEG allergy testing, should facilitate earlier diagnosis and reduce the risk of inadvertent re-exposure. This first comprehensive review provides practical information for allergists and other healthcare professionals by describing the clinical picture of 37 reported cases of PEG hypersensitivity since 1977, summarizing instances where PEG hypersensitivity should be considered and proposing an algorithm for diagnostic management.

Assay signal as an alternative to titer for assessment of magnitude of an antidrug antibody response

Background: Titer methods are commonly used to characterize the magnitude of an antidrug antibody response. Assay S/N is an appealing alternative, but the circumstances under which use of signal-to-noise (S/N) is appropriate have not been well defined. Results: We validated both titer and S/N-based methods for several therapeutics. S/N correlated strongly with titer both in aggregate and when examined on a per subject basis. Analysis of impact of antibody magnitude on pharmacokinetics yielded the same result using either method. Each assay demonstrated excellent precision, good linearity, and adequate drug tolerance. Conclusion: Under these circumstances, assay S/N is a valid alternative to titer for assessment of the magnitude of an antidrug antibody response.

2017 White Paper on recent issues in bioanalysis: a global perspective on immunogenicity guidelines & biomarker assay performance (Part 3 – LBA: immunogenicity, biomarkers and PK assays)

The 2017 11th Workshop on Recent Issues in Bioanalysis took place in Los Angeles/Universal City, California, on 3–7 April 2017 with participation of close to 750 professionals from pharmaceutical/biopharmaceutical companies, biotechnology companies, contract research organizations and regulatory agencies worldwide. WRIB was once again a 5-day, week-long event – a full immersion week of bioanalysis, biomarkers and immunogenicity. As usual, it was specifically designed to facilitate sharing, reviewing, discussing and agreeing on approaches to address the most current issues of interest including both small- and large-molecule analysis involving LC–MS, hybrid ligand-binding assay (LBA)/LC–MS and LBA approaches. This 2017 White Paper encompasses recommendations emerging from the extensive discussions held during the workshop, and is aimed to provide the bioanalytical community with key information and practical solutions on topics and issues addressed, in an effort to enable advances in scientific excellence, improved quality and better regulatory compliance. Due to its length, the 2017 edition of this comprehensive White Paper has been divided into three parts for editorial reasons. This publication (Part 3) covers the recommendations for large-molecule bioanalysis, biomarkers and immunogenicity using LBA. Part 1 (LC–MS for small molecules, peptides and small molecule biomarkers) and Part 2 (hybrid LBA/LC–MS for biotherapeutics and regulatory agencies’ inputs) are published in volume 9 of Bioanalysis, issues 22 and 23 (2017), respectively.

Measurement of Pre-Existing IgG and IgM Antibodies against Polyethylene Glycol in Healthy Individuals

Polyethylene glycol (PEG) is a biocompatible polymer that is often attached to therapeutic molecules to improve bioavailability and therapeutic efficacy. Although antibodies with specificity for PEG may compromise the safety and effectiveness of PEGylated medicines, the prevalence of pre-existing anti-PEG antibodies in healthy individuals is unclear. Chimeric human anti-PEG antibody standards were created to accurately measure anti-PEG IgM and IgG antibodies by direct ELISA with confirmation by a competition assay in the plasma of 1504 healthy Han Chinese donors residing in Taiwan. Anti-PEG antibodies were detected in 44.3% of healthy donors with a high prevalence of both anti-PEG IgM (27.1%) and anti-PEG IgG (25.7%). Anti-PEG IgM and IgG antibodies were significantly more common in females as compared to males (32.0% vs 22.2% for IgM, p < 0.0001 and 28.3% vs 23.0% for IgG, p = 0.018). The prevalence of anti-PEG IgG antibodies was higher in younger (up to 60% for 20 year olds) as opposed to older (20% for >50 years) male and female donors. Anti-PEG IgG concentrations were negatively associated with donor age in both females (p = 0.0073) and males (p = 0.026). Both anti-PEG IgM and IgG strongly bound PEGylated medicines. The described assay can assist in the elucidation of the impact of anti-PEG antibodies on the safety and therapeutic efficacy of PEGylated medicines.

Emerging Technologies and Generic Assays for the Detection of Anti-Drug Antibodies

Anti-drug antibodies induced by biologic therapeutics often impact drug pharmacokinetics, pharmacodynamics response, clinical efficacy, and patient safety. It is critical to assess the immunogenicity risk of potential biotherapeutics in producing neutralizing and nonneutralizing anti-drug antibodies, especially in clinical phases of drug development. Different assay methodologies have been used to detect all anti-drug antibodies, including ELISA, radioimmunoassay, surface plasmon resonance, and electrochemiluminescence-based technologies. The most commonly used method is a bridging assay, performed in an ELISA or on the Meso Scale Discovery platform. In this report, we aim to review the emerging new assay technologies that can complement or address challenges associated with the bridging assay format in screening and confirmation of ADAs. We also summarize generic anti-drug antibody assays that do not require drug-specific reagents for nonclinical studies. These generic assays significantly reduce assay development efforts and, therefore, shorten the assay readiness timeline.

The Mystery of Antibodies Against Polyethylene Glycol (PEG) - What do we Know?

PURPOSE

Recent findings demonstrated anti-PEG antibody formation in some healthy individuals and patients who have not received PEGylated biotherapeutics. Some of these findings evoked criticism because of shortcomings in the antibody assays used. To better understand this topic, we established robust antibody analytics and screened two cohorts of healthy individuals and one cohort of hemophilia patients for the expression of anti-PEG antibodies.

METHODS

A flow cytometry approach and a fully validated ELISA platform were established to detect specific anti-PEG antibodies. Immunohistochemistry was used to test for potential binding of anti-PEG antibodies to human tissues.

RESULTS

IgM and/or IgG anti-PEG antibodies are expressed by some healthy individuals and by some patients with hemophilia who have not received PEGylated biotherapeutics. These antibodies can be either transient or persistent and recognize PEGs of different sizes with or without terminal methoxy groups. Age and location of healthy individuals influence the prevalence of IgG but not of IgM antibodies. Anti-PEG antibodies do not cross-react with human tissues supporting the safety of the antibodies.

CONCLUSION

We confirm that some healthy individuals and some patients with hemophilia express specific antibodies against PEG which are not associated with any pathology and do not bind to human tissues.

Pre-existing Antibody: Biotherapeutic Modality-Based Review

Pre-existing antibodies to biotherapeutic drugs have been detected in drug-naïve subjects for a variety of biotherapeutic modalities. Pre-existing antibodies are immunoglobulins that are either specific or cross-reacting with a protein or glycan epitopes on a biotherapeutic compound. Although the exact cause for pre-existing antibodies is often unknown, environmental exposures to non-human proteins, glycans, and structurally similar products are frequently proposed as factors. Clinical consequences of the pre-existing antibodies vary from an adverse effect on patient safety to no impact at all and remain highly dependent on the biotherapeutic drug modality and therapeutic indication. As such, pre-existing antibodies are viewed as an immunogenicity risk factor requiring a careful evaluation. Herein, the relationships between biotherapeutic modalities to the nature, prevalence, and clinical consequences of pre-existing antibodies are reviewed. Initial evidence for pre-existing antibody is often identified during anti-drug antibody (ADA) assay development. Other interfering factors known to cause false ADA positive signal, including circulating multimeric drug target, rheumatoid factors, and heterophilic antibodies, are discussed.

Development of a Generic Anti-PEG Antibody Assay Using BioScale's Acoustic Membrane MicroParticle Technology

Immunogenicity testing for PEGylated biotherapeutics should include methods to detect both anti-protein and anti-PEG antibodies (anti-PEG). Although some methods have been published for the detection of anti-PEG antibodies, the information is incomplete and, in some cases, reagents used (such as Tween-20) are known to interfere with detection. This rapid communication describes the use of BioScale's Acoustic Membrane MicroParticle (AMMP®) technology using the ViBE® Workstation to measure anti-PEG antibodies in human serum samples. Briefly, a sample spiked with monoclonal human IgG anti-PEG antibody is diluted in buffer and incubated with paramagnetic beads coated with linear chain mPEG to capture anti-PEG antibodies. The complex is then captured on an acoustic membrane coated with Protein A. The change in mass on the membrane caused by the binding of the complex to the membrane results in a signal proportional to the mass of anti-PEG antibodies. The data indicate that an assay with a sensitivity of less than 1000 ng/mL for IgG is achievable. This level of sensitivity is better than current published reports on IgG anti-PEG antibody detection.

An integrated multiplatform bioanalytical strategy for antibody–drug conjugates: a novel case study

Background: The bioanalytical strategy for antibody–drug conjugates (ADC) includes numerous measurements integrally designed to provide comprehensive characterization of PK, PD and immunogenicity. This manuscript describes the utilization of reagents specifically tailored to an ADC with a microtubule polymerization inhibitor payload and cathepsin B cleavable linker. Methods: The PK strategy includes the evaluation of physiological levels of total antibody, active ADC, total ADC, antibody-conjugated payload and unconjugated payload. These data are evaluated in the context of target and antidrug antibody levels to elucidate bioactive ADC. Results & conclusion: Herein, we discuss how this strategy has been applied and present our preliminary observations. Continuously evolving to meet pipeline demands, the integrated bioanalytical data will provide critical insights into the exposure–response relationship.