Validation of a Triplex Pharmacokinetic Assay for Simultaneous Quantitation of HIV-1 Broadly Neutralizing Antibodies PGT121, PGDM1400, and VRC07-523-LS

The outcome of the recent Antibody Mediated Prevention (AMP) trials that tested infusion of the broadly neutralizing antibody (bnAb) VRC01 provides proof of concept for blocking infection from sensitive HIV-1 strains. These results also open up the possibility that triple combinations of bnAbs such as PGT121, PGDM1400, as well as long-lasting LS variants such as VRC07-523 LS, have immunoprophylactic potential. PGT121 and PGDM1400 target the HIV-1 V3 and V2 glycan regions of the gp120 envelope protein, respectively, while VRC07-523LS targets the HIV-1 CD4 binding site. These bnAbs demonstrate neutralization potency and complementary breadth of HIV-1 strain coverage. An important clinical trial outcome is the accurate measurement of in vivo concentrations of passively infused bnAbs to determine effective doses for therapy and/or prevention. Standardization and validation of this testing method is a key element for clinical studies as is the ability to simultaneously detect multiple bnAbs in a specific manner. Here we report the development of a sensitive, specific, accurate, and precise multiplexed microsphere-based assay that simultaneously quantifies the respective physiological concentrations of passively infused bnAbs in human serum to ultimately define the threshold needed for protection from HIV-1 infection.

Pharmacokinetic Study of Anti-osteoarthritic Compounds of a Standardized Fraction from Sphaeralcea Angustifolia

Sphaeralcea angustifolia has been widely used in inflammatory conditions such as blows, bruises, fractures, and wounds. The compounds identified as active in plants and suspension cell culture of S. angustifolia were tomentin, scopoletin, and sphaeralcic acid. To consolidate the integral use of knowledge about the S. angunstifolia and strengthen its pharmacological use in patients with knee osteoarthritis, the pharmacokinetic behavior of the active compounds was characterized. The SaTSS (S. angustifoloia standardized in Tomentin, Scopoletin, and Sphaeralcic acid) anti-ostearthritic fraction was obtained from cell suspension. The analytical method of High-Performance Liquid Chromatography (HPLC) for tomentin, scopoletin, and sphaeralcic acid were validated determining the accuracy, precision linearity, sensibility, specificity, detection limits, and quantification time-range parameters, as well as extraction efficiency and stability of compounds. The pharmacokinetic assay was performed with ICR mice strain, in which the mice were administrated with a single oral or intravenous dose (400 mg/kg with 7.1 mg/kg of scopoletin and tomentin in mixture and 34.6 mg/kg of sphaeralcic acid) of the SaTSS standardized active fraction. The results of the validated analytical methods allowed establishing, in a validated manner, that a coumarin mixture and sphaeralcic acid present in the SaTES fraction were detected in plasma. According to the values of Akaike Information Criteria (AIC), Sum of Squares (SS), Schwarz Criteria (SC), and by the determination coefficient (R2), the compounds follow a two-compartment model.

Using multiple platforms for critical reagents selection process to support pharmacokinetic ligand-binding assay development

We have evaluated the utility of epitope binning on biolayer interferometry (BLI) as a strategy to funnel the selection of candidate pairs suitable for pharmacokinetic assay development. Totally, 8 anti-Ids in 64 possible combinations were tested by BLI, ELISA and Gyrolab®. Two epitope binning approaches were utilized, in-tandem and classic sandwich. Both formats identified four mutually exclusive bins providing 31 and 25 possible antibody pair combinations, respectively. In contrast, the ELISA and Gyrolab yielded 18 and 9 positive pairs, respectively, with only a partial correlation to the BLI results. Several positive pairs by ELISA and Gyrolab, screened negative by BLI. Just over half of the pairs predicted by BLI were positive on ELISA and less than a quarter were positive on Gyrolab. This evaluation showed, in our case, that BLI was limited in its ability to predict candidate pairs that would be successful in pharmacokinetic method development.

The importance of quality critical reagents for the entire developmental lifecycle of a biopharmaceutical: a pharmacokinetic case study

Background: High-quality critical reagents are essential to the successful support of biotherapeutic drug development regardless of the analytical platform used for support. The lack of such a reagent, early in the development lifecycle of a biotherapeutic can have detrimental impact on resource and translation of data across development phases. Results: Here, a pharmacokinetic assay case study is shared that illustrates what can occur when there is a lack of a reproducible and sustainable critical reagent early in the development lifecycle of a biotherapeutic. Various assay formats and critical reagents, as well as reagents generation programs, were initiated to find a reagent and assay format which was fit for purpose. Conclusions: Identification of appropriate critical reagents early in the development lifecycle of a biotherapeutic as advantageous.

European Bioanalysis Forum recommendation on singlicate analysis for ligand binding assays: time for a new mindset

It is well accepted that chromatographic assay methods employ singlicate analysis for toxicokinetic and pharmacokinetic analysis. While conversely, it has been the norm for ligand-binding assays to be run in at least duplicate analyses, stemming mainly from concerns over inherent assay variability and reagent quality. Regulatory guidelines and guidance on bioanalytical method validation has, in the most part, recommended multiple replicates for immunoassays and this has led to the industry being comfortable and familiar with duplicate analysis. Over the last few years, the discussion on whether singlicate analysis is acceptable for ligand-binding assays has grown and the status quo is being challenged for regulated bioanalysis performed using immunoassays. Through interrogation of preclinical and clinical pharmacokinetic assay data from the European Bioanalysis Forum community, the application of a singlicate analysis strategy has shown to have no impact on toxicokinetic and pharmacokinetic parameters when compared with duplicate analysis from the same studies. Therefore, now is the time to adopt a new mindset when it comes to sample analysis for toxicokinetic and pharmacokinetic ligand-binding assays and embrace singlicate analysis in the regulated environment.

Well-developed ligand-binding assays demonstrate robust performance using singlet analysis

Aim: Replicate sample testing has long been regarded as a necessity for bioanalytical laboratory testing, especially in the realm of ligand-binding assays (LBAs). In an era in which results were derived from crude test tube-based assays, the replication of results was warranted. Those assays were often imprecise and required multiple replicates to arrive at results that approached accuracy. However, given technological advancements and excellent accuracy and precision of many modern LBAs, the practice of replicate testing should be re-evaluated. Although most regulatory guidelines allow for singlet testing when sufficient robustness and precision are demonstrated during validation, duplicate testing is still common practice. Recently however, several articles have been published that support singlet analysis for LBAs performed on a platform with automated liquid handling. Results: Data from five pharmacokinetic assay validations and five clinical and preclinical studies originally run in duplicate were re-evaluated in singlet and found to be nearly identical to the original duplicate results. Conclusion: We confirm that well-developed LBAs produce comparable data whether evaluated in singlet or duplicate. Additionally, automation is not requisite for singlet testing.