Impact of anti-drug antibodies in preclinical pharmacokinetic assessment

Development and Validation of an ADA-Tolerant Assay for Quantification of an Exatecan-Based ADC in Monkey Plasma

BACKGROUND

The development of an anti-drug antibody (ADA)-tolerant pharmacokinetic (PK) assay is important when the drug exposure is irrelevant to toxicity in the presence of ADA. We aimed to develop and validate an ADA-tolerant assay for an exatecan-based antibody-drug conjugate (ADC) in monkey plasma.

RESULTS

The assay tolerated 5.00 µg/mL of ADA at 12 µg/mL of ADC. Its accuracy and precision results satisfied the acceptance criteria. Furthermore, the assay was free from hook and matrix effects and exhibited good dilutional linearity. Additionally, the ADC in plasma samples was stable under different storage conditions.

METHOD

An ADA-tolerant ADC assay was configured with an anti-payload antibody for capture, and a drug-target protein combined with a horseradish peroxidase (HRP)-labeled antibody against a drug-target-protein tag for detection. Samples were firstly acidified to dissociate drug and ADA complexes, and to convert the carboxylate form to the lactone form of exatecan molecules; then, the ADAs in the samples were removed with a naked antibody-coated microplate. The treated samples were further incubated with coated anti-payload antibody and captured ADC molecules were quantified by the detection reagent. The developed assay was optimized and validated against regulatory guidelines.

CONCLUSIONS

The assay met both methodological and sample-related ADA tolerance requirements, and was applicable to a nonclinical study in cynomolgus monkeys.

Evaluating Antibody Pharmacokinetics as Prerequisite for Determining True Efficacy as Shown by Dual Targeting of PD-1 and CD96

One important prerequisite for developing a therapeutic monoclonal antibody is to evaluate its in vivo efficacy. We tested the therapeutic potential of an anti-CD96 antibody alone or in combination with an anti-PD-1 antibody in a mouse colon cancer model. Early anti-PD-1 treatment significantly decreased tumor growth and the combination with anti-CD96 further increased the therapeutic benefit, while anti-CD96 treatment alone had no effect. In late therapeutic settings, the treatment combination resulted in enhanced CD8⁺ T cell infiltration of tumors and an increased CD8/Treg ratio. Measured anti-PD-1 concentrations were as expected in animals treated with anti-PD-1 alone, but lower at later time points in animals receiving combination treatment. Moreover, anti-CD96 concentrations dropped dramatically after 10 days and were undetectable thereafter in most animals due to the occurrence of anti-drug antibodies that were increasing antibody clearance. Comparison of the anti-PD-1 concentrations with tumor growth showed that higher antibody concentrations in plasma correlated with better therapeutic efficacy. The therapeutic effect of anti-CD96 treatment could not be evaluated, because plasma concentrations were too low. Our findings strongly support the notion of measuring both plasma concentration and anti-drug antibody formation throughout in vivo studies, in order to interpret pharmacodynamic data correctly.

Heat pre-treatment can abolish anti-drug antibody interference in ligand binding pharmacokinetic assays

Anti-drug antibodies (ADAs) can interfere with ligand binding assays (LBAs) by binding to epitopes recognized by the assay antibodies or by preventing assay antibody binding through steric hindrance. This can lead to underestimation of total drug concentration in pharmacokinetic (PK) samples which can confound decisions during drug development. We hypothesized that ADA interference in LBAs can be removed by sample heat pre-treatment. We heat pre-treated ADA-spiked samples by incubating them in a shallow water bath at 56–100 °C for 5–30 min prior to measuring the samples by a traditional electrochemiluminescence (ECL) assay. Heat pre-treatment at minimum 85 °C for 5 min completely removed the ADA interference. We then compared the analyte concentrations measured with and without heat pre-treatment of blood samples from toxicology studies performed for two different analytes in 60 cynomolgus monkeys and 29 minipigs, respectively. The overall difference in measured concentration of ADA-positive samples was significantly different from the overall difference in measured concentration of ADA-negative samples. For the cynomolgus monkey study samples, the ADA titer was determined, and the difference in measured concentration, when comparing heat pre-treatment to no heat pre-treatment, was significantly correlated to the ADA titer. Additionally, heat pre-treatment removed parallelism issues observed in a subset of study samples. Our data suggest that sample heat pre-treatment can abolish ADA interference in an LBA and could serve as a tool to assess the degree of ADA interference and the total drug concentration in a PK sample. Of note, before utilizing this strategy on a new analyte, it is necessary to assess whether heat pre-treatment negatively affects the detection of the analyte by the assay antibodies.

Anti-drug antibodies in the current management of cancer

Monoclonal antibodies (mAbs) have become one of the main therapeutic weapons in modern oncology, mainly as targeted therapies, and immune checkpoint inhibitors. The generation of anti-drug antibodies (ADAs) after their administration can alter their pharmacokinetic, pharmacodynamic, efficacy and safety profile causing infusion-related reactions. Several risk factors have been associated with ADAs development, notably host genetics and immune status, comorbidity, concomitant medications, mAbs molecular structure, dose and route of administration. ADAs are not usually tested on daily clinical practice, being their analysis generally placed in early stages of drug development. ELISA-type assay the most common method. ADAs detection can involve important implications for treatment strategies of cancer patients, guiding therapeutic adjustment. In oncology, some studies about ADAs synthesis related to targeted therapies and immune checkpoint inhibitors have been recently published. Several strategies are proposed to reduce mAbs immunogenicity, such as different schedules, routes of administration or even the use of immunosuppressants. Another question that arises in relation to ADAs generation is the need to measure the concentration levels of active drug to guide the administration schedule. In this review, we will discuss all the aspects that are currently under discussion in relation with ADAs in oncology.

Non-human primates in the PKPD evaluation of biologics: Needs and options to reduce, refine, and replace. A BioSafe White Paper

Monoclonal antibodies (mAbs) deliver great benefits to patients with chronic and/or severe diseases thanks to their strong specificity to the therapeutic target. As a result of this specificity, non-human primates (NHP) are often the only preclinical species in which therapeutic antibodies cross-react with the target. Here, we highlight the value and limitations that NHP studies bring to the design of safe and efficient early clinical trials. Indeed, data generated in NHPs are integrated with in vitro information to predict the concentration/effect relationship in human, and therefore the doses to be tested in first-in-human trials. The similarities and differences in the systems defining the pharmacokinetics and pharmacodynamics (PKPD) of mAbs in NHP and human define the nature and the potential of the preclinical investigations performed in NHPs. Examples have been collated where the use of NHP was either pivotal to the design of the first-in-human trial or, inversely, led to the termination of a project prior to clinical development. The potential impact of immunogenicity on the results generated in NHPs is discussed. Strategies to optimize the use of NHPs for PKPD purposes include the addition of PD endpoints in safety assessment studies and the potential re-use of NHPs after non-terminal studies or cassette dosing several therapeutic agents of interest. Efforts are also made to reduce the use of NHPs in the industry through the use of in vitro systems, alternative in vivo models, and in silico approaches. In the case of prediction of ocular PK, the body of evidence gathered over the last two decades renders the use of NHPs obsolete. Expert perspectives, advantages, and pitfalls with these alternative approaches are shared in this review.

A survey of pharmacokinetic bioanalytical methods in biosimilar biological license applications for the assessment of target and antidrug antibody effects

The presence of circulating targets and antidrug antibodies can influence the ability of a bioanalytical method to measure therapeutic protein (TP) concentration relevant to exposure-response evaluations. This project surveyed biosimilar submissions for their bioanalytical methods. Survey results revealed that 97% of pharmacokinetic methods designed to measure theoretically free or partial-free TPs with respect to target indeed measured free or partial-free TPs when considering experimental testing results for target effects. Antidrug antibody effect is less often evaluated. The observed trend of measuring biologically active forms of TP is consistent with the scientific understanding that pharmacokinetics of biologically active forms is more likely to be relevant to the clinical responses and evaluation of clinically meaningful differences to contribute to biosimilarity assessments.

Liquid chromatography-mass spectrometry method for the quantification of an anti-sclerostin monoclonal antibody in cynomolgus monkey serum

Liquid chromatography tandem mass spectrometry (LC-MS/MS) has gradually become a promising alternative to ligand binding assay for the bioanalysis of biotherapeutic molecules, due to its rapid method development and high accuracy. In this study, we established a new LC-MS/MS method for the determination of the anti-sclerostin monoclonal antibody (SHR-1222) in cynomolgus monkey serum, and compared it to a previous electrochemiluminescence method. The antibody was quantified by detecting the surrogate peptide obtained by trypsin digestion. The surrogate peptide was carefully selected by investigating its uniqueness, stability and MS response. The quantitative range of the proposed method was 2.00-500 μg/mL, and this verified method was successfully applied to the toxicokinetic assessment of SHR-1222 in cynomolgus monkey serum. It was found that the concentrations of SHR-1222 in cynomolgus monkeys displayed an excellent agreement between the LC-MS/MS and electrochemiluminescence methods (ratios of drug exposure, 0.8-1.0). Notably, two monkeys in the 60 mg/kg dose group had abnormal profiles with a low detection value of SHR-1222 in their individual sample. Combining the high-level anti-drug antibodies (ADAs) in these samples and the consistent quantitative results of the two methods, we found that the decreased concentration of SHR-1222 was due to the accelerated clearance mediated by ADAs rather than the interference of ADAs to the detection platform. Taken together, we successfully developed an accurate, efficient and cost-effective LC-MS/MS method for the quantification of SHR-1222 in serum samples, which could serve as a powerful tool to improve the preclinical development of antibody drugs.

Best practices for optimization and validation of flow cytometry-based receptor occupancy assays

In the development of therapeutic compounds that bind cell surface molecules, it is critical to demonstrate the extent to which the drug engages its target. For cell-associated targets, flow cytometry is well-suited to monitor drug-to-target engagement through receptor occupancy assays (ROA). The technology allows for the identification of specific cell subsets within heterogeneous populations and the detection of nonabundant cellular antigens. There are numerous challenges in the design, development, and implementation of robust ROA. Among the most difficult challenges are situations where there is receptor modulation or when the target-antigen is expressed at low levels. When the therapeutic molecules are bi-specific and bind multiple targets, these challenges are increased. This manuscript discusses the challenges and proposes best practices for designing, optimizing, and validating ROA.

Williams G, Brocchini S, Awwad S. Injectables and Depots to Prolong Drug Action of Proteins and Peptides

Proteins and peptides have emerged in recent years to treat a wide range of multifaceted diseases such as cancer, diabetes and inflammation. The emergence of polypeptides has yielded advancements in the fields of biopharmaceutical production and formulation. Polypeptides often display poor pharmacokinetics, limited permeability across biological barriers, suboptimal biodistribution, and some proclivity for immunogenicity. Frequent administration of polypeptides is generally required to maintain adequate therapeutic levels, which can limit efficacy and compliance while increasing adverse reactions. Many strategies to increase the duration of action of therapeutic polypeptides have been described with many clinical products having been developed. This review describes approaches to optimise polypeptide delivery organised by the commonly used routes of administration. Future innovations in formulation may hold the key to the continued successful development of proteins and peptides with optimal clinical properties.

Designing an enzyme-linked immunosorbent assay for detection of anti-penicillin antibodies levels in various species of animals in Khuzestan province, Iran

The penicillin allergy is being increasingly recognized as a significant public health problem. Immunological responses to penicillin and other beta-lactam antibiotics are classified as immediate and non-immediate responses. This research aimed to develop an enzyme-linked immunosorbent assay (ELISA) for the detection of the reactive antibody value against penicillin in various species of animals. The serum samples were collected from nine species (forty mature animals in each species) including horse, dog, goat, sheep, buffalo, cattle, donkey, chicken, and fish. The concentrations of total antibody and immunoglobulin M (IgM) against penicillin were detected using an in-house ELISA test. The total anti-penicillin antibodies concentration from high to low in animals was as chicken, horse, fish, donkey, dog, goat, sheep, buffalo, and cattle, respectively. In cattle and sheep, the level of anti-penicillin IgM (APM) was significantly higher than non-IgM antibodies (APNM). Moreover, levels of APNM were very low in chicken and fish serums; no difference was seen regarding these values in buffalo and goat. The other species had significantly lower APM than the APNM. The ani-penicillin antibody levels in the noted animals were successfully detected using the developed ELISA. Most of the species have anti-penicillin antibodies; however, they have reactive antibodies with differences in levels and isotypes.

A method combining blue native polyacrylamide gel electrophoresis with liquid chromatography tandem-mass spectrometry to detect circulating immune complexes between therapeutic monoclonal antibodies and anti-drug antibodies in animals

Therapeutic monoclonal antibodies can potentially induce unwanted immune responses, resulting in the production of anti-drug antibodies (ADAs). The binding of ADAs to drugs and subsequent formation of immune complexes (ICs) can trigger various responses, dependent on the size, concentration, and subclass of ADAs. To better understand the impact of ADAs on pharmacokinetics, pharmacodynamics, and toxicological profiles, a bioanalytical method was developed for the detection of ICs between human monoclonal immunoglobulin G (IgG) and ADAs in biological samples. Regarding the experimental procedure, in brief, the human antibody-specific ICs and unbound human antibody in biological samples are separated through blue native polyacrylamide gel electrophoresis (BN-PAGE). The target fractions are then cut from the gel, followed by in-gel trypsin digestion and subsequent liquid chromatography tandem-mass spectrometry (LC-MS/MS) to monitor the human IgG-specific peptide. This method was able to detect various types of human antibodies with a lower limit of detection of 10 μg/mL in monkey serum. The assay performance for the detection of ICs was demonstrated using spiked samples, and pre-incubated ICs in monkey serum were clearly detected. Taken together, these findings indicate that our method enables a semi-quantitative analysis for estimating the ratio of human antibody included ICs in comparison to the total antibody. This method was successfully applied to an in vivo study using mice, and the data helped explain the unexpectedly rapid clearance of a humanized antibody due to the formation of large ICs. The combination of the separation of ICs by BN-PAGE and the detection of the human IgG-specific peptide by LC-MS/MS is a useful general bioanalytical approach for the detection of ICs in animals.

A capillary electrophoresis based approach for the identification of anti-drug antibodies against camelid VHH biologics (Nanobodies®)

Undesired immune responses against protein therapeutics may adversely affect the pharmacokinetics, efficacy, and safety of the product. The presence of anti-drug-antibodies (ADA) has been the key determinant of immunogenic responses. Here we describe the use of a capillary electrophoresis platform for the identification of ADAs against several experimental camelid VHH biologics (Nanobodies®). Hereafter, we refer to this assay as WESADA. We modified the Wes platform by ProteinSimple to screen serum samples for ADA against covalently linked multi-modular Nanobodies and compared it to standard ADA methodologies. We were able to identify ADA positive samples and determine which individual VHH module in a multivalent Nanobody construct stimulated the predominant ADA response. WESADA requires denaturation of the experimental immobilized drug, which could affect recognition of the immunogenic epitope and alter ADA signal. To address this issue, we demonstrated that signal can be immunodepleted by pre-incubation of serum samples with native Nanobody. This capillary electrophoresis based approach allows for rapid analysis without the need for individually tailored assay optimization or reagent labeling, while consuming small amounts of sample and drug. It also allows for the simultaneous ADA analysis of multiple targets of different molecular size in the same experimental sample. WESADA is not intended to replace traditional ADA assay formats, but it facilitates the expedient immunogenic assessment of a large number of experimental drug candidates in the early developmental space.

Removal of interstitial hyaluronan with recombinant human hyaluronidase improves the systemic and lymphatic uptake of cetuximab in rats

Interstitial, e.g. subcutaneous (SC) or intradermal (ID), administration of monoclonal antibodies (mAb) is less invasive than intravenous administration and leads to mAb uptake into both lymphatic and blood capillaries draining the injection site. Interstitial administration, however, is hindered by the presence of hyaluronan (HA), a glycosaminoglycan that is a major fluid barrier in the interstitial space. The transient removal of HA with recombinant human hyaluronidase (rHuPH20) helps facilitate the interstitial administration of often high therapeutic doses of mAb in the clinic. rHuPH20's impact on the systemic pharmacokinetics of several mAbs has been previously described, however effects on route of absorption (lymph vs blood) are unknown. The current study has therefore explored the lymphatic transport and bioavailability of cetuximab and trastuzumab after SC and ID coadministration in the presence and absence of rHuPH20 in rats. After SC administration cetuximab absolute bioavailability increased from 67 % to 80 % in the presence of rHuPH20. Cetuximab recovery in the lymphatics also increased after SC (35.8 % to 49.4 %) and ID (26.7 % to 58.8 %) administration in the presence of rHuPH20. When the injection volume (and therefore dose) was increased 10-fold in the presence of rHuPH20 cetuximab plasma exposure increased approximately linearly (12- and 8.9-fold respectively after SC and ID administration), although the proportional contribution of cetuximab lymphatic transport reduced slightly (6.2-fold increase for both administration routes). In contrast, co-administration with rHuPH20 did not lead to increases in plasma exposure for trastuzumab after SC or ID administration, most likely reflecting the fact that the reported absolute bioavailability of trastuzumab (in the absence of rHuPH20) is high (∼77-99 %). However, lymphatic transport of trastuzumab did increase when coadministered ID with rHuPH20 in spite of the lack of change to overall bioavailability. The data suggest that co-administration with rHuPH20 is able to increase the volume of mAb that can be administered interstitially, and in some instances can increase the amount absorbed into both the blood and the lymph. In the current studies the ability of rHuPH20 to enhance interstitial bioavailability was higher for cetuximab where intrinsic interstitial bioavailability was low, when compared to trastuzumab where interstitial bioavailability was high.

Evaluating a Multiscale Mechanistic Model of the Immune System to Predict Human Immunogenicity for a Biotherapeutic in Phase 1

A mechanistic model of the immune response was evaluated for its ability to predict anti-drug antibody (ADA) and their impact on pharmacokinetics (PK) and pharmacodynamics (PD) for a biotherapeutic in a phase 1 clinical trial. Observed ADA incidence ranged from 33 to 67% after single doses and 27-50% after multiple doses. The model captured the single dose incidence well; however, there was overprediction after multiple dosing. The model was updated to include a T-regulatory (Treg) cell mediated tolerance, which reduced the overprediction (relative decrease in predicted incidence rate of 21.5-59.3% across multidose panels) without compromising the single dose predictions (relative decrease in predicted incidence rate of 0.6-13%). The Treg-adjusted model predicted no ADA impact on PK or PD, consistent with the observed data. A prospective phase 2 trial was simulated, including co-medication effects in the form of corticosteroid-induced immunosuppression. Predicted ADA incidences were 0-10%, depending on co-medication dosage. This work demonstrates the utility in applying an integrated, iterative modeling approach to predict ADA during different stages of clinical development.

Pharmacokinetic comparison of a diverse panel of non-targeting human antibodies as matched IgG1 and IgG2 isotypes in rodents and non-human primates

In this study we compared the pharmacokinetic profile of four unrelated antibodies, which do not bind to mammalian antigens, in IgG1 and IgG2 frameworks in both rats and non-human primates (NHP). This allowed for extensive cross comparison of the impact of antibody isotype, complementarity determining regions (CDR) and model species on pharmacokinetics without the confounding influence of antigen binding in the hosts. While antibody isotype had no significant impact on the pharmacokinetics, the CDRs do alter the profile, and there is an inverse correlation between the neonatal Fc receptor (FcRn) affinity and pharmacokinetic performance. Faster clearance rates were also associated with higher isoelectric points; however, although this panel of antibodies all possess basic isoelectric points, ranging from 8.44 to 9.18, they also have exceptional in vivo half-lives, averaging 369 hours, and low clearance rates, averaging 0.18 ml/h/kg in NHPs. This pattern of pharmacokinetic characteristics was conserved between rats and NHPs.

Importance of Feedback and Feedforward Loops to Adaptive Immune Response Modeling

The human adaptive immune system is a very complex network of different types of cells, cytokines, and signaling molecules. This complex network makes it difficult to understand the system level regulations. To properly explain the immune system, it is necessary to explicitly investigate the presence of different feedback and feedforward loops (FFLs) and their crosstalks. Considering that these loops increase the complexity of the system, the mathematical modeling has been proved to be an important tool to explain such complex biological systems. This review focuses on these regulatory loops and discusses their importance on systems modeling of the immune system.

Investigation of the Mechanism of Therapeutic Protein-Drug Interaction Between Methotrexate and Golimumab, an Anti-TNFα Monoclonal Antibody

A prominent example of human therapeutic protein-drug interaction (TP-DI) is between methotrexate (MTX) and anti-TNFα mAbs. One plausible mechanism for this TP-DI is through the pharmacodynamic effect of MTX on immunogenicity. However, there is no definitive evidence to substantiate this mechanism, and other competing hypotheses, such as MTX suppressing FcγRI expression thereby affecting mAb PK, have also been proposed. In order to understand this mechanism, a cynomolgus monkey study was conducted using golimumab as a model compound. Golimumab elicited high incidences of immunogenicity in healthy cynomolgus monkeys. Concomitant dosing of MTX delayed the onset and reduced the magnitude of anti-drug antibody (ADA) formation. The impact of MTX on golimumab PK correlated with the ADA status. Prior to ADA formation, MTX has no discernable effect on golimumab PK. Additionally, no alteration in FcγRI expression was observed following MTX treatment. The impact of MTX on golimumab immunogenicity and PK has been observed in patients with rheumatoid arthritis, psoriatic arthritis (PsA), and ankylosing spondylitis. In a representative phase 3 study of golimumab in patients with PsA, patients not receiving concomitant MTX was reported to have ~ 30% lower steady-state trough golimumab levels compared to those who received MTX. However, further analysis showed that PsA patients who were negative for ADA in both treatment groups had comparable trough levels of golimumab. Taken together, our results suggest that the mechanism of TP-DI between MTX and golimumab can mostly be attributed to the pharmacodynamic effect of MTX, i.e., the lowering of immunogenicity and immunogenicity-mediated clearance of mAbs.

Pharmacological inhibition of myostatin protects against skeletal muscle atrophy and weakness after anterior cruciate ligament tear

Anterior cruciate ligament (ACL) tears are among the most frequent knee injuries in sports medicine, with tear rates in the US up to 250,000 per year. Many patients who suffer from ACL tears have persistent atrophy and weakness even after considerable rehabilitation. Myostatin is a cytokine that directly induces muscle atrophy, and previous studies rodent models and patients have demonstrated an upregulation of myostatin after ACL tear. Using a preclinical rat model, our objective was to determine if the use of a bioneutralizing antibody against myostatin could prevent muscle atrophy and weakness after ACL tear. Rats underwent a surgically induced ACL tear and were treated with either a bioneutralizing antibody against myostatin (10B3, GlaxoSmithKline) or a sham antibody (E1-82.15, GlaxoSmithKline). Muscles were harvested at either 7 or 21 days after induction of a tear to measure changes in contractile function, fiber size, and genes involved in muscle atrophy and hypertrophy. These time points were selected to evaluate early and later changes in muscle structure and function. Compared to the sham antibody group, 7 days after ACL tear, myostatin inhibition reduced the expression of proteolytic genes and induced the expression of hypertrophy genes. These early changes in gene expression lead to a 22% increase in muscle fiber cross-sectional area and a 10% improvement in maximum isometric force production that were observed 21 days after ACL tear. Overall, myostatin inhibition lead to several favorable, although modest, changes in molecular biomarkers of muscle regeneration and reduced muscle atrophy and weakness following ACL tear. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:2499-2505, 2017.

Immune Suppression During Preclinical Drug Development Mitigates Immunogenicity-Mediated Impact on Therapeutic Exposure

In the clinical setting, anti-drug antibodies (ADA) against biotherapeutics can influence patient safety and interfere with product efficacy. High immunogenicity has been addressed in clinic by concomitant immune suppression, such as co-administration of methotrexate with enzyme replacement therapy (ERT) and combination tacrolimus/sirolimus treatment for prophylaxis against organ transplant rejection. This study investigates the use of such immune suppressants in mitigating ADA responses to a fully human monoclonal antibody (mAb1) in preclinical animal studies. Three groups of Sprague Dawley rats (n = 18) were treated with low (0.01 mg/kg), moderate (50 mg/kg), or high (300 mg/kg) doses of mAb1. Experimental groups also received either methotrexate or tacrolimus/sirolimus immune suppressive regimens. ELISA-based methods were utilized to measure and characterize ADA and mAb1 pharmacokinetics (PK). Results demonstrated a stepwise increase in immunogenicity with mAb1 dosage. Methotrexate significantly lowered incidence of anti-variable region antibodies at moderate mAb1 dose (P < 0.05), while tacrolimus/sirolimus did likewise at moderate and high doses (P < 0.01) of mAb1. Except for low-dose mAb1 + methotrexate, all immunosuppressed groups displayed more than a 70-fold decrease in ADA magnitude (P < 0.05). This abrogation in ADA response correlated with more mAb1 in circulation by week 4 for moderate- and high-dosed mAb1 groups. These data provide an approach to mitigate preclinical immunogenicity by the use of immunosuppressant regimens. Such preconditioning can support preclinical drug development of human therapeutics that are antigenic to animals. Similar approaches could be investigated for wider application to novel therapeutics.

Non-clinical Safety Evaluation of Biotherapeutics - Challenges, Opportunities and new Insights

New challenges and opportunities in nonclinical safety testing of biotherapeutics were presented and discussed at the 5th European BioSafe Annual General Membership meeting in November 2015 in Ludwigshafen. This article summarizes the presentations and discussions from both the main and the breakout sessions. The following topics were covered in six main sessions: The following questions were discussed across 4 breakout sessions (i-iv) and a case-study based general discussion (v).

Mouse Models for Assessing Protein Immunogenicity: Lessons and Challenges

The success of clinical and commercial therapeutic proteins is rapidly increasing, but their potential immunogenicity is an ongoing concern. Most of the studies that have been conducted over the past few years to examine the importance of various product-related attributes (in particular several types of aggregates and particles) and treatment regimen (such as dose, dosing schedule, and route of administration) in the development of unwanted immune responses have utilized one of a variety of mouse models. In this review, we discuss the utility and drawbacks of different mouse models that have been used for this purpose. Moreover, we summarize the lessons these models have taught us and some of the challenges they present. Finally, we provide recommendations for future research utilizing mouse models to improve our understanding of critical factors that may contribute to protein immunogenicity.

Utility of a Bayesian Mathematical Model to Predict the Impact of Immunogenicity on Pharmacokinetics of Therapeutic Proteins

The impact of an anti-drug antibody (ADA) response on pharmacokinetic (PK) of a therapeutic protein (TP) requires an in-depth understanding of both PK parameters and ADA characteristics. The ADA and PK bioanalytical assays have technical limitations due to high circulating levels of TP and ADA, respectively, hence, significantly hindering the interpretation of this assessment. The goal of this study was to develop a population-based modeling and simulation approach that can identify a more relevant PK parameter associated with ADA-mediated clearance. The concentration-time data from a single dose PK study using five monoclonal antibodies were modeled using a non-compartmental analysis (NCA), one-compartmental, and two-compartmental Michaelis-Menten kinetic model (MMK). A novel PK parameter termed change in clearance time of the TP (α) derived from the MMK model could predict variations in α much earlier than the time points when ADA could be bioanalytically detectable. The model could also identify subjects that might have been potentially identified as false negative due to interference of TP with ADA detection. While NCA and one-compartment models can estimate loss of exposures, and changes in clearance, the two-compartment model provides this additional ability to predict that loss of exposure by means of α. Modeling data from this study showed that the two-compartment model along with the conventional modeling approaches can help predict the impact of ADA response in the absence of relevant ADA data.

Quantification of a bifunctional drug in the presence of an immune response: a ligand-binding assay specific for ‘active’ drug

Aim: During development of biologics, safety and efficacy assessments are often hampered by immune responses to the treatment. The raised antidrug antibodies (ADA) might interfere with the bioanalytical method and complicate result interpretation if non-fully characterized bioanalytical methods were applied. Methods: Here, we report an approach to characterize a ligand-binding assay (LBA) for the quantification of active drug exposure of a bifunctional therapeutic protein in the presence of antidrug antibodies, by correlating LBA results with those of a cell-based PK assay. Results: A clear correlation between both assays could be observed when monoclonal and polyclonal antibodies against the toxin moiety of the drug were used as ADA surrogates, and results were confirmed with human ADA-positive sera. Conclusion: The observed correlation between the LBA-based and cell-based PK assay indicated the suitability of the developed LBA for the determination of active drug exposure in the presence of an immune response.

Measurement of Free Versus Total Therapeutic Monoclonal Antibody in Pharmacokinetic Assessment is Modulated by Affinity, Incubation Time, and Bioanalytical Platform

Decisions about efficacy and safety of therapeutic proteins (TP) designed to target soluble ligands are made in part by their ex vivo quantification. Ligand binding assays (LBAs) are critical tools in measuring serum TP levels in pharmacokinetic, toxicokinetic, and pharmacodynamic studies. This study evaluated the impact of reagent antibody affinities, assay incubation times, and analytical platform on free or total TP quantitation. An ELISA-based LBA that measures monoclonal anti-sclerostin antibody (TPx) was used as the model system. To determine whether the method measures free or total TPx, the effects of K on, K off, and K D were determined. An 8:1 molar ratio of sclerostin (Scl) to TPx compared to a 1:1 molar ratio produced by rabbit polyclonal antibodies to TPx was required to achieve IC50, a measure of TPx interference effectiveness, making it unclear whether the ELISA truly measured free TPx. Kinetic analysis revealed that Scl had a rapid dissociation rate (K off) from TPx and that capture and detection antibodies had significantly higher binding affinities (K D) to TPx. These kinetic limitations along with long ELISA incubation times lead to the higher molar ratios (8:1) required for achieving 50% inhibition of TPx. However, a microfluidic platform with the same reagent pairs required shorter incubations to achieve a lower Scl IC50 molar ratio (1:1). The findings from this study provide the bioanalytical community with a deeper understanding of how reagent and platform selection for LBAs can affect what a particular method measures, either free or total TP concentrations.

Immunogenicity of biologic treatments for psoriasis: therapeutic consequences and the potential value of concomitant methotrexate

The five biologic agents approved for the treatment of psoriasis-etanercept, infliximab, adalimumab, ustekinumab, and secukinumab-have been transformative in the clinical management of severe forms of the disease. However, a significant number of patients fail to respond to these agents or experience a loss of efficacy over time, which may be attributable to the development of antidrug antibodies (ADAs). Increasing evidence, primarily in the context of rheumatoid arthritis or other chronic inflammatory diseases, suggests that concomitant administration of methotrexate may prevent or diminish the development of ADAs, thereby improving response rates. However, methotrexate is infrequently coadministered with biologic agents in patients with psoriasis, and the potential benefits of this strategy in the context of psoriasis are largely unexplored. In this review, we discuss clinical studies regarding the development and consequences of antibodies targeting biologic agents used in the treatment of psoriasis and present key findings describing the potential role of methotrexate as an inhibitor of immunogenicity. We also discuss clinical considerations pertaining to the use of methotrexate as a tool to reduce immunogenicity, and encourage further investigation into potential techniques to optimize this treatment approach in patients with psoriasis.

Clinical pharmacokinetics of the anti-interleukin-20 monoclonal antibody NNC0109-0012 in healthy volunteers and patients with psoriasis or rheumatoid arthritis

INTRODUCTION

NNC0109-0012, a novel human monoclonal antibody that binds to and neutralizes the activity of interleukin-20, was investigated as a potential treatment for inflammatory diseases. Pharmacokinetic (PK) modeling was performed using data from four completed clinical phase 1/2 trials to better understand the clinical PK of NNC0109-0012.

METHODS

The populations included were patients with rheumatoid arthritis (RA), chronic plaque psoriasis, and healthy volunteers. NNC0109-0012 was administered subcutaneously at various dose levels (0.01-3 mg/kg) as single dose, once weekly, or multiple doses every second week for up to 12 doses. Noncompartmental methods were used to describe the PK parameters. Population PK was analyzed using nonlinear mixed-effects modeling, with body weight as the main covariate and gender, age, and population as additional covariates.

RESULTS

Across studies (N = 116), mean age and body weight ranged from 38 to 58 years and 72 to 96 kg, respectively. NNC0109-0012 displays linear PK. Time to maximum plasma concentration occurred at approximately 1 week, and the terminal half-life was approximately 3 weeks. Clearance and volume of distribution increased proportionally to body weight. No difference in clearance or volume of distribution was observed between gender or different age groups; however, clearance was slightly lower in healthy volunteers than in patients with RA.

CONCLUSION

The PK profile of NNC0109-0012 is similar to other monoclonal antibodies directed against soluble targets.

Strategic characterization of anti-drug antibody responses for the assessment of clinical relevance and impact

All therapeutic proteins have the potential to induce anti-drug antibodies (ADA). Clinically relevant ADA can impact efficacy and/or safety of a biological therapeutic. Immunogenicity assessment strategy evaluates binding and neutralizing ADA, and the need for additional characterization (e.g., epitope, titer and so on) is determined using a risk-based approach. The choice of characterization assays depends on the type, application and immunogenicity of the therapeutic. ADA characterization can impact the interpretation of the risk profile of a given therapeutic, and offers insight into opportunities for risk mitigation and management. This article describes common ADA characterization methods. Strategic assessment and characterization of clinically relevant ADA are discussed, in order to support clinical options for safe and effective patient care and disease management.

A white paper--consensus and recommendations of a global harmonization team on assessing the impact of immunogenicity on pharmacokinetic measurements

The Global Bioanalysis Consortium (GBC) set up an international team to explore the impact of immunogenicity on pharmacokinetic (PK) assessments. The intent of this paper is to define the field and propose best practices when developing PK assays for biotherapeutics. We focus on the impact of anti-drug antibodies (ADA) on the performance of PK assay leading to the impact on the reported drug concentration and exposure. The manuscript describes strategies to assess whether the observed change in the drug concentration is due to the ADA impact on drug clearance rates or is a consequence of ADA interference in the bioanalytical method applied to measure drug concentration. This paper provides the bioanalytical scientist guidance for developing ADA-tolerant PK methods. It is essential that the data generated in the PK, ADA, pharmacodynamic and efficacy/toxicity evaluations are viewed together. Therefore, the extent for the investigation of the PK sensitivity to the presence of ADA should be driven by the project needs and risk based.

Immunogenicity and PK/PD evaluation in biotherapeutic drug development: scientific considerations for bioanalytical methods and data analysis

With the advent of novel technologies, considerable advances have been made in the evaluation of the relationship between PK and PD. Ligand-binding assays have been the primary assay format supporting PK and immunogenicity assessments. Critical and in-depth characterizations of the ligand-binding assay of interest can provide valuable understanding of the limitations, for interpreting PK/PD and immunogenicity results. This review illustrates key challenges with regard to understanding the relationship between anti-drug antibody and PK/PD, including confounding factors associated with the development and validation of ligand-binding assays, mechanisms by which anti-drug antibody impacts PK/PD, factors to consider during data analyses and interpretation, and a perspective on integrating immunogenicity data into the well-established quantitative modeling approach. Through recognizing these challenges, we propose some opportunities for improvements in the development and validation of fit-for-purpose bioanalytical methods.

Murine Models of Inflammatory Bowel Disease (IBD)

Animal models of human disease are a critical tool in both basic research and drug development. The results of preclinical efficacy studies often inform progression of therapeutic candidates through the drug development pipeline; however, the extent to which results in inflammatory bowel disease (IBD) models predict human drug response is an ongoing concern. This review discusses how murine models are currently being used in IBD research. We focus on the considerations and caveats for commonly used models in preclinical efficacy studies and discuss the value of models that utilize specific pathogenic pathways of interest rather than model all aspects of human disease.