A semi-universal assay platform to quantitate vaccines with potential applications for biotherapeutics

AIM

Biologics development often requires multiple immunoassays to evaluate both assay reagents and potential drug candidates resulting in extensive analytical development.

METHODOLOGY

We developed a semi-universal, 5-layer platform assay on Gyrolab using secondary antispecies or anti-isotype-specific capture and detection antibodies. We applied the assay to several multivalent vaccines.

RESULTS

Method performance exhibited a median accuracy of 110%, reproducibility of 9% CV and intermediate precision of 11% CV. System suitability criteria were met for 92.5% of the samples and only one out of 31 replicate samples exhibited a %CV greater than 20%.

CONCLUSION

The semi-universal Gyrolab assay allowed assay development without reagent labeling. The format could also be translated into a plate-based assay.

Techniques for quantitative LC–MS/MS analysis of protein therapeutics: advances in enzyme digestion and immunocapture

LC–MS/MS has been investigated to quantify protein therapeutics in biological matrices. The protein therapeutics is digested by an enzyme to generate surrogate peptide(s) before LC–MS/MS analysis. One challenge is isolating protein therapeutics in the presence of large number of endogenous proteins in biological matrices. Immunocapture, in which a capture agent is used to preferentially bind the protein therapeutics over other proteins, is gaining traction. The protein therapeutics is eluted for digestion and LC–MS/MS analysis. One area of tremendous potential for immunocapture-LC–MS/MS is to obtain quantitative data where ligand-binding assay alone is not sufficient, for example, quantitation of antidrug antibody complexes. Herein, we present an overview of recent advance in enzyme digestion and immunocapture applicable to protein quantitation.

Validation of an integrated series of ligand-binding assays for the quantitative determination of antibody–drug conjugates in biological matrices

Background: The bioanalytical strategy for antibody–drug conjugates (ADC) includes multiple integrated measurements of pharmacologically relevant ADC. Methods & results: Three ligand-binding assays were validated for the measurement of total antibody, active ADC and total ADC. Accuracy and precision demonstrate %bias from -8 to 14%, %CV from 3 to 11% and total error from 3 to 21%, with >98% samples meeting incurred sample reanalysis criteria. Each assay met stability, selectivity, dilutional integrity, carry over and specificity criteria with no interference from associated metabolite/impurity. Given the active ADC assay sensitivity to payload, active ADC was used to assess drug to antibody ratio. Discussion & conclusion: Implementation of a microfluidic automated platform enabled high throughput sample analysis of multiple analytes with minimal sample processing.

An integrated multiplatform bioanalytical strategy for antibody–drug conjugates: a novel case study

Background: The bioanalytical strategy for antibody–drug conjugates (ADC) includes numerous measurements integrally designed to provide comprehensive characterization of PK, PD and immunogenicity. This manuscript describes the utilization of reagents specifically tailored to an ADC with a microtubule polymerization inhibitor payload and cathepsin B cleavable linker. Methods: The PK strategy includes the evaluation of physiological levels of total antibody, active ADC, total ADC, antibody-conjugated payload and unconjugated payload. These data are evaluated in the context of target and antidrug antibody levels to elucidate bioactive ADC. Results & conclusion: Herein, we discuss how this strategy has been applied and present our preliminary observations. Continuously evolving to meet pipeline demands, the integrated bioanalytical data will provide critical insights into the exposure–response relationship.

Targeting an acid labile aspartyl–prolyl amide bond as a viable alternative to trypsin digestion to generate a surrogate peptide for LC–MS/MS analysis

Background: FGF21-AdPKE is a fusion protein and functionally inactivated in vivo by cleavage around the C-terminus. It is important to quantify the intact active protein in serum. Results & discussion: Taking advantage of a uniquely acid-labile aspartyl–prolyl amide bond, we developed an acid hydrolysis procedure based on heating FGF21-AdPKE in dilute formic acid to generate a surrogate peptide encompassing the last 17 amino acids at the C-terminus. The monkey serum samples were extracted with an immunocapture procedure with an antibody specific for AdPKE. The calibration range was 200–50000 ng/ml. The assay accuracy and precision were between 92.8–99.8% and 3.9–14.5%, respectively. The method was applied to analyze incurred serum samples from a cynomolgus monkey toxicokinetic study involving administration of FGF21-AdPKE. Conclusion: A method of combining immunocapture and acid hydrolysis to quantify a therapeutic protein in biological fluids was developed.

Parallelism: considerations for the development, validation and implementation of PK and biomarker ligand-binding assays

The goal of this article is to discuss the fundamental key questions around parallelism assessments: why to do it, when to do it and how to do it, with consideration for different molecule types and the scientific rationale that drives different approaches. Current practices for both PK and biomarker assays regarding which samples to pick, whether to pool or not pool samples, as well as generally accepted acceptance criteria are discussed, while also highlighting the many outstanding questions that remain. In order to reach the long-term goal of understanding and developing best practices for implementation of parallelism testing for both PK and biomarker assays, industry and regulators will need to keep the conversations going, and commit to generating and reviewing data for the purposes of our own education. Means to easily share data in open forums to facilitate and build common understandings should continue and will be necessary to expedite resolution of many of these questions.

Measuring biotherapeutics with endogenous counterparts and pre-existing antibodies: an interferon case study

BACKGROUND

This article presents case study data demonstrating the importance of having a thorough understanding of matrix-interference in support of global clinical trials.

METHODS/RESULTS

A ligand-binding assay used in the measurement of interferon lambda in human serum was transferred from the reference laboratory to a US-based comparator laboratory and then to a China-based comparator laboratory. The method was successfully validated at each laboratory, however, during cross-validation, there were notable differences, including 30-60% difference in incurred study sample results. The differences were attributed to matrix factors included in the serum pool used to prepare standards and quality controls. Newly procured serum (n = 75 individuals) was tested for assay interference. 12% contained either pre-existing antibodies (auto-antibodies) or were identified as pharmacokinetic assay outliers.

CONCLUSION

Prescreening of serum to exclude reactive individuals resulted in successful cross-validation and the establishment of a high integrity pharmacokinetic assay in support of global clinical trials.

Assay formats: Recommendation for best practices and harmonization from the global bioanalysis consortium harmonization team

As part of the GBC (Global Bioanalysis Consortium), the L3 assay format team has focused on reviewing common platforms used to support ligand binding assays in the detection of biotherapeutics. The following review is an overview of discussions and presentations from around the globe with a group of experts from different companies to allow an international harmonization of common practices and suggestions for different platforms. Some of the major platforms include Gyrolab, Erenna, RIA, AlphaLISA, Delfia, Immuno-PCR, Luminex, BIAcore, and ELISAs. The review is meant to support bioanalysts in taking decisions between different platforms depending on the needs of the analyte with a number of recommendations to help integration of platforms into a GLP environment.

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.

Rapid development of multiple 'fit-for-purpose' assays on an automatic microfluidic system using a streamlined process in support of early biotherapeutics discovery programs

BACKGROUND

With a rapid increase in the number of novel biotherapeutic programs in the pipelines, efficient development of ligand-binding assays for PK and PD studies in the early discovery stage has become more important than ever.

METHODOLOGY

A four-step process was evaluated to quickly develop multiple 'fit-for-purpose' Gyrolab(®) ligand-binding assays in parallel. It covered the following four steps: reagent labeling, reagent screening, assay optimization; and, assay qualification.

RESULTS

Eight assays for two programs were developed and qualified in less than 2 weeks. These assays met the specifications of sufficient sensitivity with LLOQ between 2 and 50 ng/ml, %CV <25% and recoveries between 75 and 125% for QC samples.

CONCLUSION

The streamlined four-step process enabled timely development of multiple high-throughput assays in parallel with minimal hands-on time. Consequently, it dramatically increased assay development productivity to support the discovery programs.

Novel detection of DNA-alkylated adducts of antibody–drug conjugates with potentially unique preclinical and biomarker applications

Background: MDX-1203 is an antibody–drug conjugate (ADC) currently in clinical trials for the treatment of renal carcinoma. The active ingredient of MDX-1203 is a DNA minor groove-binding cytotoxic drug that forms a covalently linked adduct with an adenine base. Formation of this adenine adduct prevents DNA replication, thus triggering cell death. Results: A method has been developed to successfully isolate, identify and quantitate the adenine adduct using LC–MS/MS. The method is highly useful to validate the mode of action of this class of ADCs. Additionally, we have demonstrated that this method could potentially be utilized to assess the efficacy of the ADC in in vitro studies by measuring the amount of adenine adduct in various cells expressing the antigen. Conclusion: Upon validation, this method could serve as an invaluable tool to evaluate compounds in preclinical in vivo models and in utilizing the DNA adduct as a potential biomarker.

Validation and life-cycle management of a quantitative ligand-binding assay for the measurement of Nulojix®, a CTLA-4–Fc fusion protein, in renal and liver transplant patients

Background: Nulojix® is a fusion protein composed of the Fc portion of a human IgG1 linked to the extracellular modified domain of CTLA-4. Nulojix differs from another Bristol Myers Squibb product, Orencia® by two amino acids and was approved by the FDA on 15 June 2011 for the prophylaxis of organ rejection in adult patients receiving kidney transplant. Results: A sandwich ELISA utilizing two monoclonal antibodies against CTLA-4 was employed for Nulojix quantification and pharmacokinetic analysis. At least 17 analysts have qualified on the assay and contributed to reportable results over the last 7 years. In-study accuracy and precision demonstrate suitable performance: %bias within -4 to 4%, %CV ≤13% and total error within 6–15%. Incurred sample reanalysis was completed in applicable disease-state populations. The assay was automated and validated in additional clinical matrices (ascites and urine) and Nulojix quantification was validated in the presence of clinically relevant co-administered compounds. In 2011, the biotinylation procedure was modified meriting a regression change (quadratic to 4-parameter logistic) and associated partial validation. Conclusion: This long-term pharmacokinetic program provides a good example of the dynamic clinical environment and adaptation requirements of ligand-binding assays.