Determination of label efficiency and label degree of critical reagents by LC-MS and native MS

Long term investigation of formulation buffers to mitigate stability issues of conjugated critical reagents

Stability of conjugated critical reagents supporting ligand binding assays to enable biotherapeutic drug development is a universal concern. Formulation buffer employed for long-term cold storage may be key to mitigate protein aggregation issues. We investigated biophysical and functional attributes of murine mAb and human multispecific drug labeled with biotin, ruthenium, and Alexa fluor 647 frozen at -80 °C in PBS or a protein storage buffer for 3-15 months. Aggregation was observed at 4 months in mAb A-Ru (11.2%) and -Alexa (10%) in PBS followed by precipitation and reduced biological binding at 15 months. Increased aggregation in drug Ru (11.7%, 6 months) and Alexa (6.9%, 15 months) were noted but without impact on performance. There were no observations with biotin labeled reagents.

A comprehensive LC-MS based study of factors influencing biotinylation of critical reagents

Aim: Critical reagents (CR) are applied in ligand binding assays (LBA) and biotinylation is a widely conjugation method used for critical reagents. However, insufficient characterization and inconsistent biotinylation can lead to LBA failures and necessitate extensive troubleshooting. This publication developed the detection of biotinylated CR and evaluates efficiency of biotinylation conditions to ensure the reliability of reagents and accuracy when implemented in LBA.Materials & methods: Intact mass analysis was applied to characterize a CR with complex glycosylation and biotinylation patterns. Peptide mapping was developed to identify the biotinylation sites.Results: Biotinylation degrees and sites were clearly illustrated.Conclusion: A CR and its biotinylation were successfully characterized. The relationship between biotinylation efficiency and labeling conditions was clearly illustrated.

Unique challenges required reassessment and alterations to critical reagents to rescue a neutralizing antibody assay

Aim: To redevelop a neutralizing antibody (NAb) assay to be much more drug tolerant, have a large dynamic range and have high inhibition when using high levels of positive control (PC).Materials & methods: Early assay data suggested that typical biotin labeling of the capture reagent (Drug 1, produced in a human cell line) was blocking it from binding with the PC or the detection target, and that the detection target was out competing the PC. Methodical biotin labeling experiments were performed at several challenge ratios and an Fc linker was added to the detection target.Results & conclusion: A larger dynamic range, high inhibition and higher drug tolerance were achieved by adding an acid dissociation step to the assay, performing atypical biotin labeling of Drug 1 and switching to a detection target that contained an Fc linker to increase steric hinderance and decrease its binding affinity to Drug 1.

2023 White Paper on Recent Issues in Bioanalysis: EU IVDR 2017/746 Implementation/Impact, IVD/CDx/CLIA Approved Assays, High Dimensional Cytometry, Multiplexing Technologies, LBA Tissue Analysis, Vaccine Study Endpoints, Cell-Based Assays for Biomarkers, Cell Therapy and Vaccines (PART 2 - Recommendations on Development & Validation of Biomarkers, IVD, CDx, Cell-Based, Flow Cytometry, Ligand-Binding and Enzyme Assays; Advanced Critical Reagents Strategies)

The 17th Workshop on Recent Issues in Bioanalysis (17th WRIB) took place in Orlando, FL, USA on 19-23 June 2023. Over 1000 professionals representing pharma/biotech companies, CROs, and multiple regulatory agencies convened to actively discuss the most current topics of interest in bioanalysis. The 17th WRIB included 3 Main Workshops and 7 Specialized Workshops that together spanned 1 week to allow an exhaustive and thorough coverage of all major issues in bioanalysis of biomarkers, immunogenicity, gene therapy, cell therapy and vaccines.Moreover, in-depth workshops on "EU IVDR 2017/746 Implementation and impact for the Global Biomarker Community: How to Comply with these NEW Regulations" and on "US FDA/OSIS Remote Regulatory Assessments (RRAs)" were the special features of the 17th edition.As in previous years, WRIB continued to gather a wide diversity of international, industry opinion leaders and regulatory authority experts working on both small and large molecules as well as gene, cell therapies and vaccines to facilitate sharing and discussions focused on improving quality, increasing regulatory compliance, and achieving scientific excellence on bioanalytical issues.This 2023 White Paper encompasses recommendations emerging from the extensive discussions held during the workshop and is aimed to provide the bioanalytical community with key information and practical solutions on topics and issues addressed, in an effort to enable advances in scientific excellence, improved quality and better regulatory compliance. Due to its length, the 2023 edition of this comprehensive White Paper has been divided into three parts for editorial reasons.This publication (Part 2) covers the recommendations on Biomarkers, IVD/CDx, LBA and Cell-Based Assays. Part 1A (Mass Spectrometry Assays and Regulated Bioanalysis/BMV), P1B (Regulatory Inputs) and Part 3 (Gene Therapy, Cell therapy, Vaccines and Biotherapeutics Immunogenicity) are published in volume 16 of Bioanalysis, issues 9 and 7 (2024), respectively.

Screening Non-neutralizing Anti-idiotype Antibodies Against a Drug Candidate for Total Pharmacokinetic and Target Engagement Assay

Non-neutralizing anti-idiotype antibodies against a therapeutic monoclonal antibody (mAb) play a crucial role in the creation of total pharmacokinetic (PK) assays and total target engagement (TE) assays during both pre-clinical and clinical development. The development of these anti-idiotype antibodies is challenging. In this study, we utilized a hybridoma platform to produce a variety of anti-idiotype antibodies against GSK2857914, a humanized IgG1 anti-BCMA monoclonal antibody. The candidate clones were evaluated using surface plasmon resonance (SPR) and bio-layer interferometry (BLI) for binding affinity, binding profiling, matrix interference, and antibody pairing determination. We discovered that three anti-idiotype antibodies did not prevent BCMA from binding to GSK2857914. All three candidates demonstrated high binding affinities. One of the three exhibited minimal matrix inference and could pair with the other two candidates. Additionally, one of the three clones was biotinylated as a capture reagent for the total PK assay, and another was labeled with ruthenium as a detection reagent for both the total PK assay and total TE assay. The assay results clearly show that these reagents are genuine non-neutralizing anti-idiotypic antibodies and are suitable for total PK and TE assay development. Based on this and similar studies, we conclude that the hybridoma platform has a high success rate for generating non-neutralizing anti-idiotype antibodies. Our methodology for developing and characterizing non-neutralizing anti-idiotype antibodies to therapeutic antibodies can be generally applied to any antibody-based drug candidate's total PK and total TE assay development.