Assessment of mirvetuximab soravtansine immunogenicity in patients with folate receptor alpha-positive ovarian cancer

Aim: The aim of this research was to evaluate the immunogenicity of mirvetuximab soravtansine (MIRV), an antibody-drug conjugate in patients with folate receptor alpha-positive ovarian cancer across four clinical studies.Materials & methods: An assay was developed and validated for the detection of antidrug antibodies (ADAs) against MIRV. A cell-based method was also developed and validated for the detection of neutralizing anti-MIRV antibodies (NAbs). Both ADAs and NAbs were assessed across four clinical studies in 734 patients.Results: Across studies, MIRV demonstrated low immunogenicity with 7.8% of patients with treatment-emergent ADAs, 7.2% with treatment-unaffected ADAs, and 0.5% with treatment-enhanced ADAs. MIRV trough concentrations were comparable in ADA-negative and ADA-positive individuals. Limited data suggest that MIRV ADAs may be associated with decreased efficacy. Due to the very limited number of NAb-positive individuals, no conclusions could be drawn on the effect of NAb on efficacy.Conclusion: Both the validation tests and the data from the MIRV clinical studies demonstrated that these assays were suitable and reliable for the detection of MIRV ADAs and NAbs. These validated assays will continue to be used to monitor MIRV immunogenicity in future clinical trials.

A competitive ligand binding assay for detection of neutralizing antibodies against an insulin analog

Biotherapeutics have the potential to trigger undesired immune responses in the patients. For therapeutic proteins, immunogenicity is manifested as anti-drug antibodies (ADA). Because ADA could compromise pharmacokinetics, efficacy, and safety, regulatory agencies require immunogenicity assessment during clinical development. A tiered bioanalytical approach is recommended to monitor clinical immunogenicity, and neutralizing antibodies (NAb) are studied in Tier 4 if the molecule is immunogenic. Although cell-based assays, which reflect the pharmacological mechanism of action, are in some cases the preferred assay format for detecting NAbs, they are associated with operational complexity and sometimes suboptimal assay performance. Alternatively, non-cell-based assays have also been developed and implemented. In our current study, a competitive ligand binding assay (CLBA) was developed to detect NAbs for insulin efsitora alfa (efsitora, basal insulin Fc, LY3209590), a novel fusion protein being studied for the treatment of Type 1 diabetes and Type 2 diabetes. The CLBA demonstrated acceptable sensitivity, drug tolerance, precision, and robustness, and thus provides a suitable approach for detecting NAbs against efsitora.

Phage-derived anti-idiotype and anti-YTE antibodies in development of MK-1654 pharmacokinetic and immune response assays

Background: MK-1654 is a fully human monoclonal antibody with YTE mutations currently in phase III clinical trials for prophylactic use in protecting infants from human respiratory syncytial virus infection. Materials & methods: We generated anti-idiotype (anti-ID) and anti-YTE antibodies against MK-1654 by panning with MorphoSys HuCal phage libraries, and used the antibodies in the development of MK-1654 pharmacokinetic (PK) and immune response (IR) assays. Results: Detection of MK-1654 in nonhuman primate and human nasal wash samples showed combined use of anti-ID and anti-YTE antibodies can deliver desired sensitivity and accuracy in PK studies. IR studies showed anti-ID can serve as suitable positive control in neutralizing antibody assays. Conclusion: Phage-derived anti-IDs and anti-YTEs are suitable for PK and IR assays.

Anti-Drug Antibodies in the Biological Therapy of Autoimmune Rheumatic Diseases

Autoimmune rheumatic diseases are a cluster of heterogeneous disorders that share some clinical symptoms such as pain, tissue damage, immune deregulation, and the presence of inflammatory mediators. Biologic disease-modifying antirheumatic drugs are some of the most effective treatments for rheumatic diseases. However, their molecular and pharmacological complexity makes them potentially immunogenic and capable of inducing the development of anti-drug antibodies. TNF inhibitors appear to be the main contributors to immunogenicity because they are widely used, especially in rheumatoid arthritis. Immunogenicity response on these treatments is crucial since the appearance of ADAs has consequences in terms of safety and efficacy. Therefore, this review proposes an overview of the immunogenicity of biological agents used in autoimmune rheumatic diseases highlighting the prevalence of anti-drug antibodies.

Neutralization Activity of Anti-drug Antibodies Against a Biotherapeutic Can Be Predicted from a Comprehensive Pharmacokinetics, Pharmacodynamics, and Anti-drug Antibody Data Analysis

Historically, a neutralization antibody (NAb) assay is considered critical in immunogenicity assessment of biologic therapeutics, even with low anti-drug antibody (ADA) positive rates. In 2019, FDA new guidelines issued on immunogenicity testing acknowledged the possibility of using "a highly sensitive PD marker or an appropriately designed PK assay or both that generate data that inform clinical activity" to replace a NAb assay. In the current manuscript, we present data for PK, PD, and ADA assays which collectively succeed to replace the standalone NAb assay. The data include a total LC/MS-based PK assay, a serum neutralization antibody (SNA) assay that essentially measures pharmacodynamically functional PK and can detect NAb activity in the presence of 1:1 ratio of drug, and a highly drug-tolerant ADA assay. In addition, a model-based meta-analysis (MBMA) demonstrated that the ability of SNA assay to detect NAb at 1:1 ratio of drug is sensitive enough to monitor clinically meaningful efficacy change, which is 50% reduction of SNA titer. Our strategy of preparing a holistic data package discussed here may provide a roadmap to the community for alternatives in assaying neutralizing activity of ADA.

Confirmatory detection of neutralizing antibodies to AAV gene therapy using a cell-based transduction inhibition assay

Successful treatment with adeno-associated virus (AAV)-based gene therapies can be limited by pre-existing anti-AAV antibodies. Cell-based transduction inhibition (TI) assays are useful to characterize the neutralizing potential of anti-AAV antibodies in patient samples. While these assays are commonly used, they are not specific for neutralizing antibodies (NAbs) against AAV, also detecting non-antibody-based factors that inhibit AAV transduction in vitro but may not substantially decrease efficacy in vivo. This paper describes the development and bioanalytical validation of a confirmatory assay to improve the specificity of detecting anti-AAV5 NAbs in cell-based TI assays. Samples that screen positive for transduction inhibitors are subsequently depleted of all classes of immunoglobulins using agarose resins conjugated with protein A, G, and L (AGL), which restores AAV5 transduction for NAb-containing samples. Unconjugated agarose resin serves as a mock control for non-specific depletion effects and facilitates normalization of the transduction efficiencies between an AGL- and mock-treated sample; the normalized value is termed the AGL/mock ratio. During validation, a confirmatory cut point for the AGL/mock ratio was derived; sensitivity, precision, selectivity, and matrix interference were also assessed. This confirmatory TI assay facilitates a characterization of humoral immunity to AAV gene therapy by reliably distinguishing NAbs from non-antibody-based neutralizing factors.

A competitive ligand-binding assay for the detection of neutralizing antibodies against dostarlimab (TSR-042)

Dostarlimab is a humanized anti–PD-1 monoclonal antibody. Dostarlimab (JEMPERLI; TSR-042) was recently approved in the USA and in the EU. The presence of neutralizing antibodies (NAbs) is a cause for concern because they block the therapeutic function of the antibody and reduce drug efficacy. Therefore, programs developing therapeutic biologics need to develop and validate assays that adequately assess the presence of NAbs in the serum of patients treated with biologic therapies. Presented here is the development and validation of a competitive ligand-binding assay that specifically detects anti-dostarlimab NAbs in human serum. Precision, sensitivity, hook effect, selectivity, assay robustness, stabilities, and system suitability were evaluated. In addition, drug tolerance of the assay with the implementation of a drug removal process was investigated. The cut point factor for the detection of NAbs in human serum at a 1% false-positive rate was determined. The assay’s precision, sensitivity, hook effect, selectivity, robustness, and drug interference were tested and found to be acceptable. With system suitability and stability established, this assay has been used to evaluate NAbs to guide the development of dostarlimab.

Trial registration: Clinicaltrials.gov, NCT02715284. Registered 9 March 2016

Strategies to develop highly drug-tolerant cell-based neutralizing antibody assay: neutralizing antidrug antibodies extraction and drug depletion

Aim: Drug interference poses great analytical challenges for cell-based neutralizing antidrug antibodies (NAb) assay. The work aimed to improve assay drug tolerance through biotin-drug extraction with acid dissociation method optimization and developing new approach. Results: The NAb extraction with biotin-drug extraction with acid dissociation approach has been optimized by reducing biotinylated drug leaching and improving NAb elution efficiency, resulting in drug tolerance of up to 160 μg/ml. To circumvent the low acid elution efficiency of NAb from drug, a novel drug depletion approach was developed, which combined acid dissociation and drug targeted crosslinked capture, achieved drug tolerance up to 400 μg/ml. At last, a strategy workflow for sample pretreatment approach selection and optimization was established for improving drug tolerance of NAb assay. Conclusion: We demonstrated that reduced biotinylated drug leaching and the high NAb elution efficiency was critical for improving assay drug tolerance. Drug depletion offers an alternative approach to overcome low NAb elution efficiency.

Development and validation of a functional cell-based neutralizing antibody assay for ipilimumab

Ipilimumab is the first US FDA-approved immune checkpoint-blocking antibody drug to harness the patient's own immune cells. One of the postmarketing requirements is to develop a cell-based neutralizing antibody assay. Here, we share some of the most challenging aspects encountered during the assay development: new cell line construction; an unexpected inhibition of T-cell activation by low concentrations of ipilimumab; and two issues caused by sample pretreatment with acid dissociation to overcome drug interference: instability of neutralizing antibody positive control at low pH, and incompatibility of commonly used acid dissociation buffers in the cell assay. After troubleshooting and optimization, we successfully validated the assay and used the assay to test clinical samples to date.

An innovative and highly drug-tolerant approach for detecting neutralizing antibodies directed to therapeutic antibodies

Aim: Immunogenicity testing of biotherapeutic drugs is a regulatory requirement. Herein, we describe a drug-tolerant assay for detecting neutralizing antibodies against a therapeutic antibody. Results: Excess target of the therapeutic antibody was incorporated into the detection step of an affinity capture elution assay. Signal generated from binding of antidrug antibody (ADA) to the therapeutic antibody was compared with signal from binding of ADA to the therapeutic antibody preincubated with its target. The results demonstrated that the target blocked binding of the therapeutic antibody to neutralizing monkey ADA and to two anti-idiotypic antibodies. Conclusion: This highly drug-tolerant novel approach enables the detection of neutralizing antibodies and allows for one basic assay format to achieve complete characterization of ADA responses.

Immunogenicity of Biotherapeutics: Causes and Association with Posttranslational Modifications

Today, potential immunogenicity can be better evaluated during the drug development process, and we have rational approaches to manage the clinical consequences of immunogenicity. The focus of the scientific community should be on developing sensitive diagnostics that can predict immunogenicity-mediated adverse events in the small fraction of subjects that develop clinically relevant anti-drug antibodies. Here, we discuss the causes of immunogenicity which could be product-related (inherent property of the product or might be picked up during the manufacturing process), patient-related (genetic profile or eating habits), or linked to the route of administration. We describe various posttranslational modifications (PTMs) and how they may influence immunogenicity. Over the last three decades, we have significantly improved our understanding about the types of PTMs of biotherapeutic proteins and their association with immunogenicity. It is also now clear that all PTMs do not lead to clinical immunogenicity. We also discuss the mechanisms of immunogenicity (which include T cell-dependent and T cell-independent responses) and immunological tolerance. We further elaborate on the management of immunogenicity in preclinical and clinical setting and the unique challenges raised by biosimilars, which may have different immunogenic potential from their parent biotherapeutics.

Managing unwanted immunogenicity of biologicals

All protein drugs (biologicals) have an immunogenic potential and we are armed with multiple guidelines, regulatory documents and white papers to assist us in assessing the level of risk for unwanted immunogenicity of new biologicals. However, for certain biologicals, significant immunogenicity becomes only apparent after their use in patients. Causes of immunogenicity are multifactorial but not yet fully understood. Within the pharmaceutical industry there are only a few opportunities to openly discuss the causes and consequences of immunogenicity with regard to the development of new biologicals. The annual Open Scientific Symposium of the European Immunogenicity Platform (EIP) is one such meeting that brings together scientists and clinicians from academia and industry to build know-how and expertise in the field of immunogenicity. The critical topics discussed at the last EIP meeting (February 2014) will be reviewed here. The current opinion of this expert group is that the assessment of unwanted immunogenicity can be improved by using prediction tools, optimizing the performance of immunogenicity assays and learning from the clinical impact of other biologicals that have already been administered to patients. A multidisciplinary approach is warranted to better understand and minimize drug immunogenicity and its clinical consequences.

Life cycle management of critical ligand-binding reagents

Bioanalytical laboratories develop and validate ligand-binding assays (LBA) used to quantify the concentration of analytes of interest in various buffers and relevant biological matrices. The building blocks of LBA are reagents that recognize molecular and structural motifs on ligands, which are combined in various LBA formats to minimize biological matrix interferences and specifically detect and quantify the analyte of interest. The use of these LBA-requiring critical reagents, can span decades as programs mature to commercialization. Since critical reagents are generated mostly from biological systems, attention to their life cycle management, quality, characterization and sustainability are vital to the success of bioanalytical laboratories. Integrating de novo reagent generation, reagent biophysical characterization, LBA development, validation, and use, with reagent resupply processes leverages interdisciplinary activities and ensures smooth operations of a bioanalytical laboratory.