Regulatory considerations for development of bioanalytical assays for biotechnology products

Comparative assessment of bioanalytical method validation guidelines for pharmaceutical industry

The concepts, importance, and application of bioanalytical method validation have been discussed for a long time and validation of bioanalytical methods is widely accepted as pivotal before they are taken into routine use. United States Food and Drug Administration (USFDA) guidelines issued in 2001 have been referred for every guideline released ever since; may it be European Medical Agency (EMA) Europe, National Health Surveillance Agency (ANVISA) Brazil, Ministry of Health and Labour Welfare (MHLW) Japan or any other guideline in reference to bioanalytical method validation. After 12 years, USFDA released its new draft guideline for comments in 2013, which covers the latest parameters or topics encountered in bioanalytical method validation and approached towards the harmonization of bioanalytical method validation across the globe. Even though the regulatory agencies have general agreement, significant variations exist in acceptance criteria and methodology. The present review highlights the variations, similarities and comparison between bioanalytical method validation guidelines issued by major regulatory authorities worldwide. Additionally, other evaluation parameters such as matrix effect, incurred sample reanalysis including other stability aspects have been discussed to provide an ease of access for designing a bioanalytical method and its validation complying with the majority of drug authority guidelines.

Evaluating and Reporting the Immunogenicity Impacts for Biological Products--a Clinical Pharmacology Perspective

Immunogenicity assessment is important for biological products due to potential impacts of immunogenicity on safety and efficacy. We reviewed the prescribing information and the FDA's clinical pharmacology review of 121 approved biological products for evaluating and reporting of immunogenicity data. Of the 121 products, 89% (n = 108) reported the incidence of immunogenicity and 49% (n = 59) reported immunogenicity impact on efficacy. However, only 26% (n = 31) reported whether the immunogenicity affected pharmacokinetics. A subset of 16 products reported effects of anti-drug antibodies (ADA) on both systemic clearance and efficacy; 8 of 16 products had increased systemic clearance coinciding with reduced efficacy, and 6 of 16 products had no changes in either clearance or efficacy. Factors contributing to infrequent reporting of the ADA effect on exposure and methods for determining the effect of ADA on exposure are summarized. Measuring ADA and drug concentrations concurrently over time enables the evaluation of ADA impact on pharmacokinetics. Within-subject comparison of concentration data (before vs. after ADA formation) is a useful alternative to between-subject (ADA+ vs. ADA-) comparison when sample size is limited or when the majority of subjects developed ADA. The biological complexity of immune responses presents challenges to quantifying the ADA impact on pharmacokinetics using model-based methods. Our findings support that pharmacokinetic exposure is more sensitive than efficacy endpoints for evaluating ADA effects. A decrease in drug concentration due to formation of ADA during treatment can serve as an early indicator for potential reduced efficacy occurring at a later time.

When assay format matters: a case study on the evaluation of three assay formats to support a clinical pharmacokinetic study

Data generated using various immunoassay methods are an integral part of the development of protein therapeutics. These assays are used in clinical and preclinical studies to establish the pharmacokinetic (PK) and pharmacodynamic (PD) characteristics as well as to assess the immunogenicity properties of a therapeutic. PK assays measure therapeutic levels post-administration which is essential for understanding the effective dose and dose regimen for a therapeutic. Anti-OX40L is a fully humanized monoclonal antibody designed for the potential treatment of an autoimmune disease. The anti-OX40L human PK assay is required to be sensitive, robust, and precise. To address challenges due to assay sensitivity and reproducibility, as well as assay technology limitations, during development of the anti-OX40L human PK assay, three different assays, including an MSD-based electrochemiluminescence assay (ECLA), a fluorometric enzyme-linked immunosorbent assay (ELISA), and a colorimetric ELISA, were evaluated. The MSD-based assay was the most sensitive but posed risk of inter-well signal crosstalk. The fluorescence ELISA fell short on reproducibility. The colorimetric ELISA was ultimately chosen for supporting sample analysis. This paper presents characterization data obtained from each of these assay formats, challenges that were encountered in the development of the assay, and the rationale for selecting the ultimate assay format.

Carbon paste electrode modified with cuo-nanoparticles as a probe for square wave voltammetric determination of atrazine

BACKGROUND

Atrazine (ATZ) is a widely used herbicide in most countries because of its low cost and good selectivity. The concentration of ATZ that the EPA considers safe to consume in drinking water is 3 ppb. Therefore, recently, there have been concerns about its determination in trace levels. This compound is not electro-active, so in this research indirect electrochemical method for its detection in low levels was proposed.

OBJECTIVES

The main aim of this study is the indirect determination of ATZ in water samples by voltammetry using nano-particle modified electrode.

MATERIALS AND METHODS

A nano-CuO modified carbon paste electrode (NMCPE) is constructed and its application for indirect square wave voltammetric (SWV) detection of ATZ is reported. The sensing performance mechanism of the nano-CuO modified carbon paste electrode toward atrazine is due to complexation of the analyte with Cu (II) ion. The peak current for copper (II) reduction decreases with increase in the ATZ concentration and is monitored for its determination. Instrumental and chemical parameters influencing the detection of ATZ were optimized.

RESULTS

The results revealed that decrease in peak current was proportional to ATZ concentration over the range of 5-75 ng/mL. The limit of detection (LOD) and limit of quantification (LOQ) were 2 ng/mL and 5.6 ng/mL (n = 20), respectively. The relative standard deviation (n = 10) for the determination of 10 and 50 ng/mL of ATZ solution was estimated as 4.9% and 4.2 %, respectively.

CONCLUSIONS

This easily fabricated electrode together with the fast and sensitive SW voltammetry was successfully applied for the determination of concentration of ATZ at trace levels, in different water samples.

Immunogenicity and PK/PD evaluation in biotherapeutic drug development: scientific considerations for bioanalytical methods and data analysis

With the advent of novel technologies, considerable advances have been made in the evaluation of the relationship between PK and PD. Ligand-binding assays have been the primary assay format supporting PK and immunogenicity assessments. Critical and in-depth characterizations of the ligand-binding assay of interest can provide valuable understanding of the limitations, for interpreting PK/PD and immunogenicity results. This review illustrates key challenges with regard to understanding the relationship between anti-drug antibody and PK/PD, including confounding factors associated with the development and validation of ligand-binding assays, mechanisms by which anti-drug antibody impacts PK/PD, factors to consider during data analyses and interpretation, and a perspective on integrating immunogenicity data into the well-established quantitative modeling approach. Through recognizing these challenges, we propose some opportunities for improvements in the development and validation of fit-for-purpose bioanalytical methods.

A generic template for automated bioanalytical ligand-binding assays using modular robotic scripts in support of discovery biotherapeutic programs

Background: Sample dilution and reagent pipetting are time-consuming steps in ligand-binding assays (LBAs). Traditional automation-assisted LBAs use assay-specific scripts that require labor-intensive script writing and user training. Results: Five major script modules were developed on Tecan Freedom EVO liquid handling software to facilitate the automated sample preparation and LBA procedure: sample dilution, sample minimum required dilution, standard/QC minimum required dilution, standard/QC/sample addition, and reagent addition. The modular design of automation scripts allowed the users to assemble an automated assay with minimal script modification. The application of the template was demonstrated in three LBAs to support discovery biotherapeutic programs. Conclusion: The results demonstrated that the modular scripts provided the flexibility in adapting to various LBA formats and the significant time saving in script writing and scientist training. Data generated by the automated process were comparable to those by manual process while the bioanalytical productivity was significantly improved using the modular robotic scripts.

Strategic selection and development of immunogenicity binding methods

The principal components of a meaningful immunogenicity program consist of an initial binding screen followed by confirmation and quantitation of the positive samples. This comprehensive article first describes evolving technologies and assay formats that encourage scientists to start development with appropriate analytical goals that are specific to their clinical program. The selection of the technology and format is based primarily on the product’s structure, treatment indication, intended treatment schedule and pharmacokinetic profile. Feasibility studies are described to satisfy specific criteria before proceeding to optimization. Preparation procedures and storage conditions of critical reagents and controls are provided that will render them suitable throughout the length of the project. A multifactor approach to robustness is recommended that assures consistently sensitive, accurate, precise and specific methods that are verified during prevalidation experiments. Finally, a checklist itemizes all the requirements to develop a compliant validation protocol.

Pharmacokinetics and toxicology of therapeutic proteins: Advances and challenges

Significant progress has been made in understanding pharmacokinetics (PK), pharmacodynamics (PD), as well as toxicity profiles of therapeutic proteins in animals and humans, which have been in commercial development for more than three decades. However, in the PK arena, many fundamental questions remain to be resolved. Investigative and bioanalytical tools need to be established to improve the translation of PK data from animals to humans, and from in vitro assays to in vivo readouts, which would ultimately lead to a higher success rate in drug development. In toxicology, it is known, in general, what studies are needed to safely develop therapeutic proteins, and what studies do not provide relevant information. One of the major complicating factors in nonclinical and clinical programs for therapeutic proteins is the impact of immunogenicity. In this review, we will highlight the emerging science and technology, as well as the challenges around the pharmacokinetic- and safety-related issues in drug development of mAbs and other therapeutic proteins.