Immunogenicity assessment in non-clinical studies

Strategy and validation of a nonclinical generic plug-and-play antidrug antibody method for human monoclonal antibody biotherapeutics

The measurement of antidrug antibodies (ADA) in nonclinical studies provides limited value because the formation and incidence of nonclinical ADA does not translate to clinical experience. The formation and presence of ADA in nonclinical species can, however, correlate to reduced drug exposure and safety observations including vasculitis and immune complex disease. Generic ADA methods for humanized monoclonal antibody biotherapeutics mitigate the need to develop bespoke ADA methods during nonclinical drug development. A drug-tolerant, sensitive, generic ADA immunoassay has been developed and validated for measuring ADA in cynomolgus monkey serum samples, allowing for immediate qualification of future monoclonal antibody biotherapeutics. This approach allows us to differentiate complexed and free ADA in a rapidly deployable manner when needed.

Implementation of Systematic Bioanalysis of Antibody–Drug Conjugates for Preclinical Pharmacokinetic Study of Ado-Trastuzumab Emtansine (T-DM1) in Rats

Antibody–drug conjugates (ADCs) are composed of monoclonal antibodies covalently bound to cytotoxic drugs by a linker. They are designed to selectively bind target antigens and present a promising cancer treatment without the debilitating side effects of conventional chemotherapies. Ado-trastuzumab emtansine (T-DM1) is an ADC that received US FDA approval for the treatment of HER2-positive breast cancer. The purpose of this study was to optimize methods for the quantification of T-DM1 in rats. We optimized four analytical methods: (1) an enzyme-linked immunosorbent assay (ELISA) to quantify the total trastuzumab levels in all drug-to-antibody ratios (DARs), including DAR 0; (2) an ELISA to quantify the conjugated trastuzumab levels in all DARs except DAR 0; (3) an LC–MS/MS analysis to quantify the levels of released DM1; and (4) a bridging ELISA to quantify the level of anti-drug antibodies (ADAs) of T-DM1. We analyzed serum and plasma samples from rats injected intravenously with T-DM1 (20 mg/kg, single dose) using these optimized methods. Based on these applied analytical methods, we evaluated the quantification, pharmacokinetics, and immunogenicity of T-DM1. This study establishes the systematic bioanalysis of ADCs with validated assays, including drug stability in matrix and ADA assay, for future investigation on the efficacy and safety of ADC development.

Development of a bridging ELISA for detection of antibodies against ZV0203 in cynomolgus monkey serum

Immunogenicity has been a major concern in the safety evaluation of therapeutic proteins. The assessment of the unwanted immunogenicity of the therapeutic proteins performed in animals prior to clinical trials has been a regulatory requirement. In preclinical studies of therapeutic proteins, cynomolgus monkeys are usually the most relevant animal species. ZV0203, a recombinant humanized anti-human epidermal growth factor receptor 2 monoclonal antibody covalently bound to a cytotoxic drug (Duo-5), possesses a novel format of antibody drug conjugates. In this study, we reported the development, validation, and application of a bridging enzyme-linked immunosorbent assay for the detection of antibodies against ZV0203 in cynomolgus monkey serum. Drug interference at low positive control (18.0 ng/mL) and high positive control (130 ng/mL) of anti-ZV0203 antibodies was not observed when ZV0203 concentration is below 1.74 μg/mL and 1.49 μg/mL, respectively. In addition, no interference was found from mouse IgG1, but interference was observed with human IgG1. No effect of hemolysis was found on the analysis results of the testing samples present in 100% pooled rabbit serum containing 2% (V/V) erythrocyte hemolysates. Besides, spiked anti-ZV0203 antibody in rabbit serum was stable after 5 freeze/thaw cycles. The results showed that the method is suitable for the detection of anti-ZV0203 antibodies in cynomolgus monkey serum. The assay was also successfully applied in the repeated dose study of ZV0203.

A strategic approach to nonclinical immunogenicity assessment: a recommendation from the European Bioanalysis Forum

Immunogenicity assays are required to evaluate anti-drug antibody (ADA) responses that can be generated against biotherapeutic modalities. Regulatory guidelines focus on clinical requirements, yet it has become apparent that industry has applied these clinical recommendations for immunogenicity assessment to nonclinical studies in varying degrees. ADAs are an anticipated outcome of dosing a humanized or fully human biotherapeutic into an animal. However, a nonclinical ADA response is rarely predictive of the immunogenic potential in humans. The addendum to ICH S6 recommends that immunogenicity should be explicitly examined where there is: evidence of altered pharmacodynamic activity; unexpected changes in exposure in the absence of a pharmacodynamic marker or evidence of immuno-mediated reactions. The European Bioanalytical Forum has extensively discussed and reached a consensus on a minimal strategic approach of when and what to include for nonclinical immunogenicity assessments. Additionally, this paper recommends a strategy for ADA assay validation and sample analysis for those cases when it is considered necessary to include an immunogenicity assessment in nonclinical toxicology studies.

Isotyping and Semi-Quantitation of Monkey Anti-Drug Antibodies by Immunocapture Liquid Chromatography-Mass Spectrometry

There is an urgent demand to develop new technologies to characterize immunogenicity to biotherapeutics. Here, we developed an immunocapture LC-MS assay to isotype and semi-quantify monkey anti-drug antibodies (ADAs) to fully human monoclonal antibody (mAb) drugs. ADAs were isolated from serum samples using an immunocapture step with the Fab of the full-length mAb cross-linked to magnetic beads to minimize matrix interference. A positive monoclonal antibody control against the human immunoglobulin kappa light chain was used as a calibration standard for ADA quantitation. The final LC-MS method contains 17 multiple reaction monitoring (MRM) transitions and an optimized 15-min LC method. The results suggested that IgG1 was the most abundant isotype in ADA-positive samples. IgG2 and IgG4 were identified at lower levels, whereas IgG3 and IgA levels were only observed at very minor levels. In addition, levels of total ADA measured by the LC-MS assay were comparable to results obtained using a traditional ligand binding assay (LBA). The LC-MS ADA assay enabled rapid immunogenicity assessment with additional isotype information that LBAs cannot provide.

Allometric scaling of therapeutic monoclonal antibodies in preclinical and clinical settings

Constant technological advancement enabled the production of therapeutic monoclonal antibodies (mAbs) and will continue to contribute to their rapid expansion. Compared to small-molecule drugs, mAbs have favorable characteristics, but also more complex pharmacokinetics (PK), e.g., target-mediated nonlinear elimination and recycling by neonatal Fc-receptor. This review briefly discusses mAb biology, similarities and differences in PK processes across species and within human, and provides a detailed overview of allometric scaling approaches for translating mAb PK from preclinical species to human and extrapolating from adults to children. The approaches described here will remain vital in mAb drug development, although more data are needed, for example, from very young patients and mAbs with nonlinear PK, to allow for more confident conclusions and contribute to further growth of this field. Improving mAb PK predictions will facilitate better planning of (pediatric) clinical studies and enable progression toward the ultimate goal of expediting drug development.

Toxicologic Pathology Forum: Opinion on Obligatory Microscopic Examination of Intermediate-Dose Groups in Toxicity Studies With Biotherapeutics in Cynomolgus Monkeys

In nonrodent toxicity studies that are usually conducted in cynomolgus monkeys or beagle dogs, the added value of examining all tissues from all dose groups (current practice) versus all tissues in only control and high-dose groups and target tissues in intermediate-dose groups by default, is a subject of debate. A previous retrospective review of 325 nonrodent toxicity studies that included a limited number of biotherapeutics suggested that the evaluation of all tissues from all groups was not justified as a routine practice and recommended the examination of all tissues in control and high-dose groups and only target tissues in intermediate-dose groups. In contrast, the present retrospective review which examined 213 nonrodent studies (212 in cynomolgus monkeys and 1 in dog) from 4 multinational pharmaceutical companies (Bristol-Myers Squibb, Novartis, Pfizer Inc, and Roche) conducted only with biotherapeutics showed that restricting the microscopic examination in intermediate-dose groups to target tissues has the potential to miss findings in 6.6% of studies, possibly impacting the overall study interpretation and conclusion. In conclusion and in the opinion of the authors, all tissues from all dose groups should be examined in toxicity studies with biotherapeutics conducted in nonrodent species.

Immunogenicity and toxicokinetics assessment of the mono-PEGylated recombinant human interleukin-11 in cynomolgus monkeys

AIM

Protein therapeutics have potential to elicit immune responses resulting in undesirable anti-drug antibodies (ADA) that might affect product efficacy and patient safety, and should be assessed in animals before applying the treatment to humans. In this paper, we aim to assess the immunogenicity and toxicokinetics of the mono-PEGylated recombinant human interleukin-11 (rhIL-11), a novel protein therapeutic for the treatment of chemotherapy-induced thrombocytopenia, in repeated administration to cynomolgus monkeys.

MAIN METHODS

Enzyme-linked immunosorbent assay (ELISA) methods were developed to measure ADA responses and plasma PEGylated IL-11 (PEG-IL11) concentration in monkeys. Assay parameters of immunogenicity and toxicokinetics methods were evaluated during validation in accordance with regulatory guidelines. We also employed cell-based assays to test the neutralizing activity of ADA provoked in monkeys.

KEY FINDINGS

The results showed that weak immunogenicity occurred in some monkeys after receiving repeated dose of 0.1-0.3 mg/kg by subcutaneous administration and disappeared after the recovery period. More pronounced immunogenicity occurred at high dose of 0.9 mg/kg, with a higher positive rate and titer, and some ADAs had neutralizing activity, but it can be greatly reduced after recovery. Such ADAs generated in monkeys may be accounted for the plasma toxicokinetics changes of PEG-IL11 and a minor reduction in systemic exposure.

SIGNIFICANCE

These methods have been successfully applied to immunogenicity and toxicokinetic studies of PEG-IL11 in repeated dose toxicity following subcutaneous administration to monkeys, and could be successfully used in clinical trials after some modifications.

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.

Regulatory and strategic considerations for addressing immunogenicity and related responses in biopharmaceutical development programs

The last three decades have seen the biotherapeutic drug market evolve from promising concept to market dominance in a range of clinical indications. This growth has been spurred by the success of established drug classes like monoclonal antibodies, but also by the introduction of biosimilars, and more recently, multiple novel cell and gene therapies. Biotherapeutic drug development presents many unique challenges, but unintended immune responses are among the most common reasons for program attrition. Anti-drug antibodies can impact the safety and efficacy of drug products, and related immune responses, like the cytokine release syndrome that occurred in the infamous TGN-1412 clinical trial, can be challenging to predict with nonclinical models. For this reason, it is important that development programs proceed with a scientifically grounded and measured approach to these responses. This process begins at the discovery stage with the application of “quality by design,” continues into the clinic with the development of quality assays and management strategies, and culminates in the effective presentation of this information in regulatory documents. This review provides an overview of some of the key strategic and regulatory considerations for biotherapeutics as they pertain to immunogenicity and related responses.

Sagacity in antibody humanization for therapeutics, diagnostics and research purposes: considerations of antibody elements and their roles

The humanization of antibodies for therapeutics is a critical process that can determine the success of antibody drug development. However, the science underpinning this process remains elusive with different laboratories having very different methods. Well-funded laboratories can afford automated high-throughput screening methods to derive their best binder utilizing a very expensive initial set of equipment affordable only to a few. Often within these high-throughput processes, only standard key parameters, such as production, binding and aggregation are analyzed. Given the lack of suitable animal models, it is only at clinical trials that immunogenicity and allergy adverse effects are detected through anti-human antibodies as per FDA guidelines. While some occurrences that slip through can be mitigated by additional desensitization protocols, such adverse reactions to grafted humanized antibodies can be prevented at the humanization step. Considerations such as better antibody localization, avoidance of unspecific interactions to superantigens and the tailoring of antibody dependent triggering of immune responses, the antibody persistence on cells, can all be preemptively considered through a holistic sagacious approach, allowing for better outcomes in therapy and for research and diagnostic purposes.

Preclinical safety profile of disitamab vedotin：a novel anti-HER2 antibody conjugated with MMAE

The HER2 pathway plays a pivotal role in cell proliferation and differentiation, while the receptor overexpression caused by amplification of HER2 gene is associated with the growth of several tumors. Previously published clinical trials have demonstrated that antibody-conjugated drugs (ADCs) remarkably improved clinical effects compared with antibodies alone for the same target. In order to provide more effective drugs, we developed Disitamab vedotin based on ADC. The antibody part was a humanized monoclonal antibody targeting HER2, the small molecule toxin was monomethyl auristatin E (MMAE), a synthetic antineoplastic agent. A protease cleavable linker covalently attached MMAE to the antibody. In this study, we characterized the toxicity profile of Disitamab vedotin through single- and repeat-dose toxicity studies in monkeys. The toxicities of small molecules and naked antibody (Disitamab) were also assessed in these studies. Monkeys were well tolerated with Disitamab vedotin at doses of 6 mg/kg, while equivalent MMAEs resulted in severe myelosuppression. This finding proves that ADCs improve the therapeutic effect. In addition, the safety profiles of Disitamab vedotin and MMAE were similar and consistent with the activation mechanism of MMAE. Toxicology finding included bone marrow/hematology toxicity and lymphoid organ toxicity, while no significant toxicity was observed in animals treated with naked antibody. These side effects were found to be consistent with data acquired from clinical phase I/II patients treated with Disitamab vedotin.

Repeated Oral Administration of a KDEL-tagged Recombinant Cholera Toxin B Subunit Effectively Mitigates DSS Colitis Despite a Robust Immunogenic Response

Cholera toxin B subunit (CTB), a non-toxic homopentameric component of Vibrio cholerae holotoxin, is an oral cholera vaccine antigen that induces an anti-toxin antibody response. Recently, we demonstrated that a recombinant CTB variant with a Lys-Asp-Glu-Leu (KDEL) endoplasmic reticulum retention motif (CTB-KDEL) exhibits colon mucosal healing effects that have therapeutic implications for inflammatory bowel disease (IBD). Herein, we investigated the feasibility of CTB-KDEL for the treatment of chronic colitis. We found that weekly oral administration of CTB-KDEL, dosed before or after the onset of chronic colitis, induced by repeated dextran sodium sulfate (DSS) exposure, could significantly reduce disease activity index scores, intestinal permeability, inflammation, and histological signs of chronicity. To address the consequences of immunogenicity, mice (C57BL/6 or C3H/HeJ strains) were pre-exposed to CTB-KDEL then subjected to DSS colitis and CTB-KDEL treatment. While the pre-dosing of CTB-KDEL elicited high-titer anti-drug antibodies (ADAs) of the immunoglobin A (IgA) isotype in the intestine of C57BL/6 mice, the therapeutic effects of CTB-KDEL were similar to those observed in C3H/HeJ mice, which showed minimal ADAs under the same experimental conditions. Thus, the immunogenicity of CTB-KDEL does not seem to impede the protein's mucosal healing efficacy. These results support the development of CTB-KDEL for IBD therapy.

Mitigating target interference in bridging immunogenicity assay with target-blocking reagents and mild basic pH

Background: Soluble drug target in clinical study samples generated false positive results in anti-drug antibody (ADA) bridging assays due to target-mediated bridging. Results: The combination of two target-blocking reagents and mild basic assay pH resulted in high tolerance to recombinant target protein and reduced levels of positivity in clinical study samples with pharmacokinetic profiles that did not indicate significant ADA response. Testing with low-affinity ADA positive serum from immunized rabbits and known ADA positive samples from nonclinical studies in rats confirmed the assay's ability to detect ADA positive samples and the minimal impact of basic pH and target-blocking reagents on ADA detection. Conclusion: These strategies provide alternatives for mitigating target interference when standard target-blocking antibodies alone are ineffective.

The importance of handling high-value biologicals: Physico-chemical instability and immunogenicity of monoclonal antibodies

The present review specifies the various chemical and physical factors that can influence drug stability and immunogenicity, and the treatment outcomes of antibody biologicals. Although monoclonal antibodies (mAbs) are known to be more resistant to environmental changes compared with other proteins, the molecules themselves can be subjected to chemical and physical processes that promote their degradation and transformation into their specific amino-acid moieties. With increasing use of medicinal products that contain mAbs, and their self-administration by the patients, the issue of the correct manipulation of these drugs is of increasing importance. This review summarises the correct handling of mAb biologicals from the point of view of the pharmacist, clinical biochemist and patient, as is supported by relevant cases from the literature and our own data and experience. In particular, if there is a break in the cold chain, both healthcare professionals and patients need to be aware of the potential pharmacokinetics and pharmacodynamics alterations to these biologicals. Furthermore, any alterations in the protein structure can induce harmful immune reactions, including anaphylaxis and cytokine storms, or result in the production of neutralising or blocking Abs. Overall, considering also that treatment costs usually remain high, drug stability can have a tremendous effect on the clinical, humanistic and economic outcomes of such treatments.

Therapeutic Potential of Cholera Toxin B Subunit for the Treatment of Inflammatory Diseases of the Mucosa

Cholera toxin B subunit (CTB) is a mucosal immunomodulatory protein that induces robust mucosal and systemic antibody responses. This well-known biological activity has been exploited in cholera prevention (as a component of Dukoral^® vaccine) and vaccine development for decades. On the other hand, several studies have investigated CTB's immunotherapeutic potential in the treatment of inflammatory diseases such as Crohn's disease and asthma. Furthermore, we recently found that a variant of CTB could induce colon epithelial wound healing in mouse colitis models. This review summarizes the possible mechanisms behind CTB's anti-inflammatory activity and discuss how the protein could impact mucosal inflammatory disease treatment.

Development, validation, and application of ELISA for detection of anti-HD105 antibodies in pre-clinical safety evaluation using monkeys

Unwanted immunogenicity of protein therapeutics can result in severe side effects and should be assessed in animals before applying the treatment to humans. Monkeys are the most relevant choice for pre-clinical toxicity testing of antibody-based therapeutics. To assess the immunogenicity of HD105, a novel antibody therapeutic that targets both vascular endothelial growth factor and Delta-like-ligand 4, a bridging enzyme-linked immunosorbent assay was developed as an anti-drug antibody (ADA) assay and validated for use in pre-clinical studies using non-human primates. This method was found to have suitable assay sensitivity, intra- and inter-assay precision, confirmation, drug tolerance, recovery, and sample stability for measuring ADA in monkey serum samples. The results showed that ADA elevation occurred following repeated doses of HD105, and that ADA production was negatively associated with serum HD105 concentration. These results suggest that intravenous administration of HD105 induces production of ADA in monkeys and that the detection of ADA may be negatively influenced by free HD105 in serum.

Application of a Plug-and-Play Immunogenicity Assay in Cynomolgus Monkey Serum for ADCs at Early Stages of Drug Development

Immunogenicity assessment during early stages of nonclinical biotherapeutic development is not always warranted. It is rarely predictive for clinical studies and evidence for the presence of anti-drug antibodies (ADAs) may be inferred from the pharmacokinetic (PK) profile. However, collecting and banking samples during the course of the study are prudent for confirmation and a deeper understanding of the impact on PK and safety. Biotherapeutic-specific ADA assays commonly developed can require considerable time and resources. In addition, the ADA assay may not be ready when needed if the study of PK and safety data triggers assay development. During early stages of drug development for antibody-drug conjugates (ADCs), there is the added complication of the potential inclusion of several molecular variants in a study, differing in the linker and/or drug components. To simplify analysis of ADAs at this stage, we developed plug-and-play generic approaches for both the assay format and the data analysis steps. Firstly, the assay format uses generic reagents to detect ADAs. Secondly, we propose a cut point methodology based on animal specific baseline variability instead of a population data approach. This assay showed good sensitivity, drug tolerance, and reproducibility across a variety of antibody-derived biotherapeutics without the need for optimization across molecules.

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.

Advantages and Limitations of Commonly Used Nonhuman Primate Species in Research and Development of Biopharmaceuticals

Nonhuman primates (NHPs) have been used extensively during the past four decades for research and nonclinical development because they are close to humans in terms of genetics, anatomy, physiology, and immunology. They have been widely used in the development of infection models, leading to the generation of vaccines and drugs, as well as in the nonclinical pharmacologic and toxicologic assessment of biopharmaceuticals, especially in the fields of immunotherapy and oncology, despite the constant pressure to move to lower species. In many cases, NHPs are the only species that allows a correct risk assessment for humans. Nevertheless, limitations inherent to each species have to be considered before an investigation. This chapter shines some light on the respective interests and limitations of using cynomolgus monkeys, rhesus monkeys, and marmosets in medical research and nonclinical development, with a specific focus on reproduction and immunology.

Antibody dissociation rates are predictive of neutralizing antibody (NAb) course: a comparison of interferon beta-1b-treated Multiple Sclerosis (MS) patients with transient versus sustained NAbs

A proportion of multiple sclerosis (MS) patients treated with interferon-β (IFNβ) develop neutralizing antibodies (NAbs), which can reduce therapeutic efficacy. In the Betaseron/Betaferon in Newly Emerging MS for Initial Treatment (BENEFIT) study, 88/277 patients developed NAbs, 48 having transient positivity and 29 having sustained positivity. This study aimed to investigate the antibody binding characteristics of serial sera in a subset of these two patient groups. Using Biacore™, a surface plasmon resonance-based technology that monitors biomolecular interactions in real time, we immobilized pure IFNβ-1b and analyzed antibody binding responses and dissociation rates of these sera. NAb titers correlated directly with binding responses and inversely with dissociation rates, and sera from sustained NAb patients demonstrated significantly higher binding responses and slower dissociation rates than sera from transient NAb patients. Thus, transient and sustained NAbs are quantitatively and qualitatively different, and interestingly, binding responses and dissociation rates at month 12 could predict the NAb course.

Universal immunogenicity validation and assessment during early biotherapeutic development to support a green laboratory

BACKGROUND

Immunogenicity support during nonclinical biotherapeutic development can be resource intensive if supported by conventional methodologies. A universal indirect species-specific immunoassay can eliminate the need for biotherapeutic-specific anti-drug antibody immunoassays without compromising quality. By implementing the R's of sustainability (reduce, reuse, rethink), conservation of resources and greener laboratory practices were achieved in this study.

RESULTS

Statistical analysis across four biotherapeutics supported identification of consistent product performance standards (cut points, sensitivity and reference limits) and a streamlined universal anti-drug antibody immunoassay method implementation strategy.

CONCLUSION

We propose an efficient, fit-for-purpose, scientifically and statistically supported nonclinical immunogenicity assessment strategy. Utilization of a universal method and streamlined validation, while retaining comparability to conventional immunoassays and meeting the industry recommended standards, provides environmental credits in the scientific laboratory. Collectively, individual reductions in critical material consumption, energy usage, waste and non-environment friendly consumables, such as plastic and paper, support a greener laboratory environment.

Immunogenicity/hypersensitivity of biologics

This continuing education course was designed to provide an overview of the immunologic mechanisms involved in immunogenicity and hypersensitivity reactions following administration of biologics in nonclinical toxicity studies, the methods used to determine whether such reactions are occurring, and the associated clinical and anatomic pathology findings. Hypersensitivity reactions have classically been divided into type I, II, III, and IV reactions; type I and III reactions are those most often observed following administration of biologics. A variety of methods can be used to detect these reactions. Antemortem methods include hematology; detection of antidrug antibodies, circulating immune complexes and complement fragments, and immunoglobulin E in serum; tests for serum complement activity; and evaluation of complement receptor 1 on erythrocytes. Postmortem methods include routine light microscopy and electron microscopy, which can demonstrate typical findings associated with hypersensitivity reactions, and immunohistochemistry, which can detect the presence of immune complexes in tissues, including the detection of the test article. A final determination of whether findings are related to a hypersensitivity reaction in individual animals or across the entire study should rely on the overall weight of evidence, as findings indicative of these reactions are not necessarily consistent across all affected animals.

Preclinical safety profile of trastuzumab emtansine (T-DM1): mechanism of action of its cytotoxic component retained with improved tolerability

Trastuzumab emtansine (T-DM1) is the first antibody-drug conjugate (ADC) approved for patients with human epidermal growth factor receptor 2 (HER2)-positive metastatic breast cancer. The therapeutic premise of ADCs is based on the hypothesis that targeted delivery of potent cytotoxic drugs to tumors will provide better tolerability and efficacy compared with non-targeted delivery, where poor tolerability can limit efficacious doses. Here, we present results from preclinical studies characterizing the toxicity profile of T-DM1, including limited assessment of unconjugated DM1. T-DM1 binds primate ErbB2 and human HER2 but not the rodent homolog c-neu. Therefore, antigen-dependent and non-antigen-dependent toxicity was evaluated in monkeys and rats, respectively, in both single- and repeat-dose studies; toxicity of DM1 was assessed in rats only. T-DM1 was well tolerated at doses up to 40 mg/kg (~4400 μg DM1/m(2)) and 30 mg/kg (~ 6000 μg DM1/m(2)) in rats and monkeys, respectively. In contrast, DM1 was only tolerated up to 0.2mg/kg (1600 μg DM1/m(2)). This suggests that at least two-fold higher doses of the cytotoxic agent are tolerated in T-DM1, supporting the premise of ADCs to improve the therapeutic index. In addition, T-DM1 and DM1 safety profiles were similar and consistent with the mechanism of action of DM1 (i.e., microtubule disruption). Findings included hepatic, bone marrow/hematologic (primarily platelet), lymphoid organ, and neuronal toxicities, and increased numbers of cells of epithelial and phagocytic origin in metaphase arrest. These adverse effects did not worsen with chronic dosing in monkeys and are consistent with those reported in T-DM1-treated patients to date.

Immunogenicity of mAbs in non-human primates during nonclinical safety assessment

The immunogenicity of biopharmaceuticals used in clinical practice remains an unsolved challenge in drug development. Non-human primates (NHPs) are often the only relevant animal model for the development of monoclonal antibodies (mAbs), but the immune response of NHPs to therapeutic mAbs is not considered to be predictive of the response in humans because of species differences. In this study, we accessed the drug registration files of all mAbs registered in the European Union to establish the relative immunogenicity of mAbs in NHPs and humans. The incidence of formation of antidrug-antibodies in NHPs and patients was comparable in only 59% of the cases. In addition, the type of antidrug-antibody response was different in NHP and humans in 59% of the cases. Humanization did not necessarily reduce immunogenicity in humans. Immunogenicity interfered with the safety assessment during non-clinical drug development when clearing or neutralizing antibodies were formed. While important to interpret the study results, immunogenicity reduced the quality of NHP data in safety assessment. These findings confirm that the ability to compare relative immunogenicity of mAbs in NHPs and humans is low. Furthermore, immunogenicity limits the value of informative NHP studies.

Impact of anti-drug antibodies in preclinical pharmacokinetic assessment

The administration of human biotherapeutics is often associated with a higher incidence of immunogenicity in preclinical species. The presence of anti-drug antibodies (ADAs) in the test samples can affect the accurate measurement of therapeutic protein (TP) in bioanalytical methods designed to support pharmacokinetic (PK) and toxicokinetic (TK) assessments. The impact can vary depending on the bioanalytical method platform and study dosing design. The goal of this study is to evaluate the impact of ADA response on the bioanalytical methods in support of PK/TK and the associated study data interpretation. Sprague Dawley rats were administered with four weekly doses of 50 mg/kg TP, a humanized monoclonal antibody. The TP in serum samples was measured using three bioanalytical methods that quantified bound and/or unbound TP to ADA. The ADA response in the animals was classified into negative, low, medium, and high based on the magnitude of the response. The presence of ADA in samples led to discrepant TP measurements between the methods, especially at time points where the TP concentrations were low. This could be due to ADA interference to the accurate measurement of ADA-bound TP concentrations. The TP concentration at last time point (C last) was reduced by 82.8%, 98.6%, and 99.8%, respectively, for samples containing low, medium, and high levels of ADA. The interfering effects of the ADA on bioanalytical methods and exposure were evident as early as 2 weeks post-dosing. This modeling approach can provide the better understanding of ADA impact on PK exposure in multiple doses.