Anti-drug Antibody Validation Testing and Reporting Harmonization

Immunogenicity assays are required to measure antidrug antibodies that are generated against biotherapeutic modalities. As for any ligand-binding assays, critical reagents (CR) play a crucial role in immunogenicity assays, as the robustness and reliability of an assay are defined by the quality and long-term availability of these reagents. The current regulatory guidelines do not provide clear directions on how to implement and verify lot-to-lot changes of CR during an assay life cycle, or the acceptance criteria that should be used when implementing new lots of CR. These aspects were extensively discussed within the European Bioanalysis Forum community. In this paper, CR for immunogenicity assays are identified and the minimum requirements for introducing new lots of CR in immunogenicity assays are described.

Detection of drug specific circulating immune complexes from in vivo cynomolgus monkey serum samples

Novel data analysis methods to overcome cut point challenges and enable comprehensive assessment of antidrug binding activity in confirmatory assays

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. ADAsare 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 markerorevidence 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.

Philippe Grandjean is the 2015 BCPT Nordic Prize Awardee.

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

Coronavirus disease 2019 (COVID-19) was first detected in Mexico in February 2020. Even though health authorities did not perceive then the value of viral detection tests, we anticipated the demand for them. We set up to develop an expeditious severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) molecular diagnostic service through the implementation of standardized protocols for biospecimen sampling, transportation, biobanking, preanalytical validation, and nucleic acids (NA) testing (NAT). Nasopharyngeal and oropharyngeal swabs collected in a special transportation medium were the biospecimens from which NAs were purified either manually or automatically. Viral RNA genome presence was determined using commercial SARS-CoV-2 detection kits (based on reverse transcription coupled with real-time PCR [RT-PCR]). Improvements in laboratory processing speed and reliability resulted from semi-automatizing laboratory processes and adopting a quality control/quality assurance system (QC/QA), respectively. NAs that were purified, either manually or automatically, were validated by preanalytical spectrophotometric characterization. Automated purification was less prone to contamination and reduced the processing time. The following six RT-PCR kits were evaluated for their convenience, specificity, sensitivity, time consumption, and required materials (in order, starting with the kit with the best results): RIDA gene and Viasure (tied), Vircell, LightMix, 1copy, and Logix Smart. Redesigning the laboratories' working areas, equipment, fluxes of personnel and material, and personnel skills, and overemphasizing biosafety safeguards were major challenges encountered in the middle of the sanitary crisis. Adopting a QC/QA system, utilizing automatization processes, and working closely with health authorities were key factors in our success. IMPORTANCE Rearranging our diagnostic laboratories to improve the fight against a new unexpected, unpredictable, and sudden public health threat demanded that we move quickly to redesign not only the laboratory processes but also the distribution of space, personnel activities, and fluxes of material coming in and out. We also had to work closely with governmental health authorities to gain their trust in our technical competence. Gaining the confidence of the clients, i.e., mainly individuals, the human resource departments of factories and corporations sending employees for testing, and medical institutions, and implementing as much automatization as possible of processes, in which only officially approved reagents (for extraction and analysis of NA) were used to generate opportune trustable testing results, were key factors. Our laboratories have gathered a considerable amount of experience and significant number of solutions, considering our geographic contexts alongside this continuously morphing pandemic, validating many techniques that might help other laboratories find a better and more precise workflow.

Drug development is a lengthy, expensive, and complex process, and clinical development is the longest and the most expensive stage of drug development. To obtain market authorization of a new drug, applicants must prove the effectiveness and the safety of a drug through clinical trials. Korea has the same requirements for new drug approval as in developed countries and bridging data are required for approval of a new drug that was developed in another country. Clinical evaluation in humans consists of 3 phases, from phase 1 to phase 3, and the failure rates remain high while the clinical trial cost increases rapidly. Not only pharmaceutical sponsors but also patients and physicians want new, innovative medicines faster, simultaneously with improved productivity of drug development. With strong competition and market forces, the pressure to accelerate drug development and to predict the efficacy and safety profile of a drug candidate at an earlier stage is increasing. To improve the productivity of new drug development, modern principles of pharmaceutical sciences, clinical pharmacology, and information technology are being researched and employed by both health authorities and sponsors. Many global pharmaceutical companies are also pursuing geographical expansion strategies to enroll subjects faster among more diverse ethnic groups. To deliver innovative medicines to patients in a faster and more cost-effective ways, close and continuous collaboration among sponsors, academia, and health authorities is essential.

Meeting report on protein particles and immunogenicity of therapeutic proteins: Filling in the gaps in risk evaluation and mitigation

Consistent performance of anti-drug antibody (ADA) assays through all stages of clinical development is critical for the assessment of immunogenicity and interpretation of PK, PD, safety, and efficacy. The electrochemiluminescent assays commonly employed for ADA measurement use drug conjugated with ruthenium and biotin to bind ADA in samples. Here we report an association between high nonspecific ADA responses in certain drug-naïve individuals and the storage buffer of the conjugated reagents used in a monoclonal antibody ADA assay. Ruthenylated reagents stored in phosphate-buffered saline (PBS) buffer had increased levels of aggregate and produced variable and high baseline responses in some subjects. Reagents stored in a histidine-sucrose buffer (HSB) had lower aggregate levels and produced low sample responses. In contrast to PBS, conjugated reagents formulated in HSB remained low in aggregate content and in sample response variability after 5 freeze/thaw cycles. A reagent monitoring control (RMC) serum was prepared for the real-time evaluation of conjugated reagent quality. Using appropriate buffers for storage of conjugated reagents together with RMCs capable of monitoring of reagent aggregation status can help ensure consistent, long-term performance of ADA methods.

Immunogenicity assessments are critical for evaluating biological therapeutics. Preexisting immune reactivity can affect clinical safety and efficacy and confound anti-drug antibody (ADA) assay cut point determination, complicating identification of treatment-emergent ADA. In the ALXN-X program, approximately 50% of naïve human serum samples showed preexisting reactivity, with some signals exceeding background by more than 100-fold, challenging ADA method development (cut points, sensitivity, drug tolerance). Competitive inhibition experiments were conducted to map the binding site of the preexisting reactivity and depletion with protein A/G agarose was performed to further characterize the preexisting reactivity. A modified ADA assay with an engineered drug molecule was developed to mitigate its impact on assay performance. This preexisting reactivity binds to the C-terminal conserved framework sequence of the drug molecule. Characterization indicated that the preexisting reactivity is likely attributable to immunoglobulins. The modified ADA assay can effectively mitigate the impact of the preexisting reactivity on the assay performance, while maintaining the ability to detect ADA response specific to the unique epitopes of ALXN-X. Preexisting, immunoglobulin-mediated reactivity targeting ALXN-X's Cterminal framework sequence complicates ADA assay performance. A modified ADA assay mitigates this interference while preserving detection of ALXN-X-specific ADA, supporting more reliable immunogenicity assessment.

Immunogenicity testing for antidrug antibodies (ADA) faces challenges when high levels of the drug are present in clinical patient samples. In addition, most functional cell-based assays designed to characterize the neutralizing ability of ADA are vulnerable to interference from endogenous serum components. Bead extraction and acid dissociation (BEAD) has been successfully applied to extract ADA from serum samples prior to conduction of cell-based assays. However, in the BEAD, certain amounts of the drug and endogenous serum components (so-called residual drug and serum components) from serum samples are carried over to final BEAD eluates due to formation of protein complexes with ADA or nonspecific binding with the beads. Using current enzyme-linked immunosorbent assay (ELISA)-based ligand-binding assays, it is difficult to evaluate the residual drug, which is complexed with excessive amounts of ADA and endogenous serum components in the BEAD eluates. Here, we describe an innovative application of LC-MS/MS for simultaneous detection of the residual human monoclonal antibody drug and endogenous human IgG and the neutralizing antibody positive-control (NAb-PC) in the BEAD eluates. In this study, the low levels of the residual drug and human IgG in the BEAD eluates indicate that the BEAD efficiently removed the high-concentration drug and serum components from the serum samples. Meanwhile, the NAb-PC recovery (∼42%) in the BEAD provided an acceptable detection limit for the cell-based assay. This novel application of LC-MS/MS to immunogenicity assay development demonstrates the advantages of LC-MS/MS in selectivity and multiplexing, which provides direct and fast measurements of multiple components for immunogenicity assay development.

Comparison of different immunoassay methods to detect human anti-drug antibody using the WHO erythropoietin antibody reference panel for analytes

In the current issue of the Journal, Aljawad et al (1) (pages 373–376) focus on the availability of transient elastography in Canada. This is an important clinical care delivery issue for all gastroenterologists, hepatologists and every practitioner who provides care for individuals with suspected or confirmed liver disease. Transient elastography (Fibroscan, Echosens, France) quantifies hepatic fibrosis using mechanical wave generated by a special transducer. The principle is simple: the speed of a propagating wave through the liver is influenced by the stiffness of the tissue – the stiffer the liver, the faster the wave passes through.

Aim: To demonstrate the importance of critical reagent characterization for immunogenicity assay development for multi-specific drugs using two case studies.Methods: Bridging anti-drugantibody (ADA) assay with acid-dissociated samples were used for both cases.Results: In the first case study, the unexpected interference in an ADA assay from clinical samples was identified; a model was created to replicate the issue, and an anti-target antibody was identified to mitigate the target interference. In the second case study, an issue due to non-specific binding of a domain-specific confirmatory reagent was identified, and various mitigation techniques were evaluated.Conclusion: A thorough characterization of the critical reagents helped identify the issues with these ADA case studies and provided strategies for resolving them.