2019 White Paper on Recent Issues in Bioanalysis: Chromatographic Assays (Part 1 - Innovation in Small Molecules and Oligonucleotides & Mass Spectrometric Method Development Strategies for Large Molecule Bioanalysis).

The 2019 13th Workshop on Recent Issues in Bioanalysis (WRIB) took place in New Orleans, LA, USA on April 1-5, 2019 with an attendance of over 1000 representatives from pharmaceutical/biopharmaceutical companies, biotechnology companies, contract research organizations and regulatory agencies worldwide. WRIB was once again a 5-day, week-long event - a full immersion week of bioanalysis, biomarkers, immunogenicity and gene therapy. As usual, it was specifically designed to facilitate sharing, reviewing, discussing and agreeing on approaches to address the most current issues of interest including both small- and large-molecule bioanalysis involving LCMS, hybrid LBA/LCMS, LBA cell-based/flow cytometry assays and qPCR approaches. This 2019 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 2019 edition of this comprehensive White Paper has been divided into three parts for editorial reasons. This publication (Part 1) covers the recommendations on Innovation in Small Molecules and Oligonucleotides & Mass Spec Method Development Strategies for Large Molecules Bioanalysis. Part 2 (2018 FDA BMV Guidance, 2019 ICH M10 BMV Draft Guideline and regulatory agencies' input on bioanalysis, biomarkers, immunogenicity and gene therapy) and Part 3 (New Insights in Biomarkers Assays Validation, Current & Effective Strategies for Critical Reagent Management, Flow Cytometry Validation in drug discovery & development & CLSI H62, Interpretation of the 2019 FDA Immunogenicity Guidance and The Gene Therapy Bioanalytical Challenges) are published in volume 11 of Bioanalysis, issues 23 and 24 (2019), respectively.

A convenient strategy to overcome interference in LC-MS/MS analysis: Application in a microdose absolute bioavailability study.

Stable isotope labeled (SIL) compounds have been commonly used as internal standards (IS) to ensure the accuracy and quality of liquid chromatography-mass spectrometry (LC-MS) bioanalytical assays. Recently, the application of SIL drugs and LC-MS assays to microdose absolute bioavailability (BA) studies has gained increasing attention. This approach can provide significant cost and time saving, and higher data quality compared to the accelerator mass spectrometry (AMS)-based method, since it avoids the use of radioactive drug, high-cost AMS instrumentation and complex measurement processes. It also eliminates potential metabolite interference with AMS-based assay. However, one major challenge in the application of this approach is the potential interference between the unlabeled drug, the microdose SIL drug, and the SIL-IS during LC-MS analysis. Here we report a convenient and cost-effective strategy to overcome the interference by monitoring the isotopic ion (instead of the commonly used monoisotopic ion) of the interfered compound in MS analysis. For the BMS-986205 absolute BA case study presented, significant interference was observed from the microdose IV drug [13C7,15N]-BMS-986205 to its SIL-IS, [13C7,15N, D3]-BMS-986205, since the difference of nominal molecular mass between the two compounds is only 3 mu, and there is a Cl atom in the molecules. By applying this strategy (monitoring the 37Cl ion for the analysis of the IS), a 90-fold reduction of interference was achieved, which allowed the use of a synthetically accessible SIL compound and enabled the fast progress of the absolute BA study. This strategy minimizes the number of stable isotope labels used for avoiding interference, which greatly reduces the difficulty in synthesizing the SIL compounds and generates significant time and cost savings. In addition, this strategy can also be used to reduce the MS response of the analyte, therefore, avoiding the detector saturation issue of LC-MS/MS assay for high concentration BMS-986205. A LC-MS/MS assay utilizing this strategy was successfully developed for the simultaneous analysis of BMS-986205 and [13C7, 15N]-BMS-986205 in dog plasma using [13C7,15N, D3]-BMS-986205 as the IS. The assay was successfully applied to a microdose absolute BA study of BMS-986205 in dogs. The assay was also validated in human plasma and used to support a human absolute BA study. The same strategy can also be applied to other compounds, including those not containing Cl or other elements with abundant isotopes, or other applications (e.g. selection of internal standard), and the applications were presented.

A systematic study of the effect of low pH acid treatment on anti-drug antibodies specific for a domain antibody therapeutic: Impact on drug tolerance, assay sensitivity and post-validation method assessment of ADA in clinical serum samples.

We developed a homogeneous bridging anti-drug antibody (ADA) assay on an electro chemiluminescent immunoassay (ECLIA) platform to support the immunogenicity evaluation of a dimeric domain antibody (dAb) therapeutic in clinical studies. During method development we evaluated the impact of different types of acid at various pH levels on polyclonal and monoclonal ADA controls of differing affinities and on/off rates. The data shows for the first time that acids of different pH can have a differential effect on ADA of various affinities and this in turn impacts assay sensitivity and drug tolerance as defined by these surrogate controls. Acid treatment led to a reduction in signal of intermediate and low affinity ADA, but not high affinity or polyclonal ADA. We also found that acid pretreatment is a requisite for dissociation of drug bound high affinity ADA, but not for low affinity ADA-drug complexes. Although we were unable to identify an acid that would allow a 100% retrieval of ADA signal post-treatment, use of glycine pH3.0 enabled the detection of low, intermediate and high affinity antibodies (Abs) to various extents. Following optimization, the ADA assay method was validated for clinical sample analysis. Consistencies within various parameters of the clinical data such as dose dependent increases in ADA rates and titers were observed, indicating a reliable ADA method. Pre- and post-treatment ADA negative or positive clinical samples without detectable drug were reanalyzed in the absence of acid treatment or presence of added exogenous drug respectively to further assess the effectiveness of the final acid treatment procedure. The overall ADA results indicate that assay conditions developed and validated based on surrogate controls sufficed to provide a reliable clinical data set. The effect of low pH acid treatment on possible pre-existing ADA or soluble multimeric target in normal human serum was also evaluated, and preliminary data indicate that acid type and pH also affect drug-specific signal differentially in individual samples. The results presented here represent the most extensive analyses to date on acid treatment of a wide range of ADA affinities to explore sensitivity and drug tolerance issues. They have led to a refinement of our current best practices for ADA method development and provide a depth of data to interrogate low pH mediated immune complex dissociation.

Strategies to Determine Assay Format for the Assessment of Neutralizing Antibody Responses to Biotherapeutics.

Most biotherapeutics can elicit immune responses in dosed recipients generating anti-drug antibodies (ADAs). Neutralizing antibodies (NAbs) are a subpopulation of ADAs that can potentially impact patient safety and directly mediate loss of drug efficacy by blocking the biological activity of a therapeutic product. Therefore, NAb detection is an important aspect of immunogenicity assessment, requiring sensitive and reliable methods reflective of the therapeutic mechanism of action (MoA). Both cell-based and non cell-based assays are viable options for NAb assessment. However, the scientific approach for the selection of a suitable assay format (cell-based or non cell-based) for NAb assessment is not currently well defined. In this manuscript, the authors summarize the design and utility of cell-based and non cell-based NAb assays and recommend a NAb assay format selection approach that relies on a combination of three factors. These include (i) the therapeutic MoA, (ii) the evidence of desirable assay performance characteristics, and (iii) risk of immunogenicity. The utility of correlating NAb response with pharmacodynamic data is also discussed. The aim of this paper is to provide a consistent strategy that will guide the selection of scientifically justified assay formats capable of detecting clinically relevant NAbs for biotherapeutics with varying MoAs and diverse complexity.