rk Ma

Population Pharmacokinetic Meta-Analysis of Denosumab in Healthy Subjects and Postmenopausal Women with Osteopenia or Osteoporosis

AbstractBackground and Objective: Inhibition of the receptor activator of nuclear factor k-B ligand (RANKL) is a therapeutic target for treatment of bone disorders associated with increased bone resorption, such as osteoporosis. The objective of this analysis was to characterize the population pharmacokinetics of denosumab (AMG 162; Prolia®), a fully human IgG2 monoclonal antibody that binds to RANKL, in healthy subjects and postmenopausal women with osteopenia or osteoporosis. Methods: A total of 22944 serum free denosumab concentrations from 495 healthy subjects and 1069 post-menopausal women with osteopenia or osteoporosis were pooled. Denosumab was administered as either a single intravenous dose (n = 36), a single subcutaneous dose (n = 469) or multiple subcutaneous doses (n= 1059), ranging from 0.01 to 3 mg/kg (or 6–210 mg as fixed mass dosages), every 3 or 6 months for up to 48 months. An open, two-compartment pharmacokinetic model with a quasi-steady-state approximation of the target-mediated drug disposition model was used to describe denosumab pharmacokinetics, using NONMEM Version 7.1.0 software. Subcutaneous absorption was characterized by the first-order absorption rate constant (ka), with constant absolute bioavailability over the range of doses that were evaluated. Clearance and volume of distribution parameters were scaled by body weight, using a power model. Model evaluation was performed through visual predictive checks. Results: The subcutaneous bioavailability of denosumab was 64%, and the ka was 0.00883 h−1. The central volume of distribution and linear clearance were 2.49 L/66 kg and 3.06 mL/h/66 kg, respectively. The baseline RANKL level, quasi-steady-state constant and RANKL degradation rate were 614ng/mL, 138 ng/mL and 0.00148 h−1, respectively. Between-subject variability in model parameters was moderate. A fixed dose of 60 mg provided RANKL inhibition similar to that achieved by equivalent body weight-based dosing. The effects of age and race on the area under the serum concentration-time curve of denosumab were less than 15% over the range of covariate values that were evaluated. Conclusions: The non-linearity in denosumab pharmacokinetics is probably due to RANKL binding, and denosumab dose adjustment based on the patient demographics is not warranted.

Design and Synthesis of Conformationally Constrained Glucagon-Like Peptide-1 Derivatives with Increased Plasma Stability and Prolonged in Vivo Activity

A series of conformationally constrained derivatives of glucagon-like peptide-1 (GLP-1) were designed and evaluated. By use of [Gly (8)]GLP-1(7-37)-NH2 (2) peptide as a starting point, 17 cyclic derivatives possessing i to i + 4, i to i + 5, or i to i + 7 side chain to side chain lactam bridges from positions 18 to 30 were prepared. The effect of a helix-promoting alpha-amino-isobutyric acid (Aib) substitution at position 22 was also evaluated. The introduction of i to i + 4 glutamic acid-lysine lactam constraints in c[Glu (18)-Lys (22)][Gly (8)]GLP-1(7-37)-NH2 (6), c[Glu (22)-Lys (26)][Gly (8)]GLP-1(7-37)-NH2 (10), and c[Glu (23)-Lys (27)][Gly (8)]GLP-1(7-37)-NH2 (11) resulted in potent functional activity and receptor affinities comparable to native GLP-1. Selected GLP-1 peptides were chemoselectively PEGylated in order to prolong their in vivo activity. PEGylated peptides [Gly (8),Aib (22)]GLP-1(7-37)-Cys ((PEG))-Ala-NH2 (23) and c[Glu (22)-Lys (26)][Gly (8)]GLP-1(7-37)-Cys ((PEG))-Ser-Gly-NH2 (24) retained picomolar functional potency and avid receptor binding properties. Importantly, PEGylated GLP-1 peptide 23 exhibited sustained in vivo efficacy with respect to blood glucose reduction and decreased body weight for several days in nonhuman primates.

Application of multi-factorial design of experiments to successfully optimize immunoassays for robust measurements of therapeutic proteins

Developing a process that generates robust immunoassays that can be used to support studies with tight timelines is a common challenge for bioanalytical laboratories. Design of experiments (DOEs) is a tool that has been used by many industries for the purpose of optimizing processes. The approach is capable of identifying critical factors and their interactions with a minimal number of experiments. The challenge for implementing this tool in the bioanalytical laboratory is to develop a user-friendly approach that scientists can understand and apply. We have successfully addressed these challenges by eliminating the screening design, introducing automation, and applying a simple mathematical approach for the output parameter. A modified central composite design (CCD) was applied to three ligand binding assays. The intra-plate factors selected were coating, detection antibody concentration, and streptavidin-HRP concentrations. The inter-plate factors included incubation times for each step. The objective was to maximize the logS/B (S/B) of the low standard to the blank. The maximum desirable conditions were determined using JMP 7.0. To verify the validity of the predictions, the logS/B prediction was compared against the observed logS/B during pre-study validation experiments. The three assays were optimized using the multi-factorial DOE. The total error for all three methods was less than 20% which indicated method robustness. DOE identified interactions in one of the methods. The model predictions for logS/B were within 25% of the observed pre-study validation values for all methods tested. The comparison between the CCD and hybrid screening design yielded comparable parameter estimates. The user-friendly design enables effective application of multi-factorial DOE to optimize ligand binding assays for therapeutic proteins. The approach allows for identification of interactions between factors, consistency in optimal parameter determination, and reduced method development time.

Ligand binding assay critical reagents and their stability: recommendations and best practices from the Global Bioanalysis Consortium Harmonization Team.

The L4 Global Harmonization Team on reagents and their stability focused on the management of critical reagents for pharmacokinetic, immunogenicity, and biomarker ligand binding assays. Regulatory guidance recognizes that reagents are important for ligand binding assays but do not address numerous aspects of critical reagent life cycle management. Reagents can be obtained from external vendors or developed internally, but regardless of their source, there are numerous considerations for their reliable long-term use. The authors have identified current best practices and provided recommendations for critical reagent lot changes, stability management, and documentation.

2015 White Paper on recent issues in bioanalysis: focus on new technologies and biomarkers (Part 3 – LBA, biomarkers and immunogenicity)

The 2015 9th Workshop on Recent Issues in Bioanalysis (9th WRIB) took place in Miami, Florida with participation of 600 professionals from pharmaceutical and biopharmaceutical companies, biotechnology companies, contract research organizations and regulatory agencies worldwide. WRIB was once again a 5 day, week-long event - A Full Immersion Bioanalytical Week - specifically designed to facilitate sharing, reviewing, discussing and agreeing on approaches to address the most current issues of interest in bioanalysis. The topics covered included both small and large molecules, and involved LCMS, hybrid LBA/LCMS and LBA approaches, including the focus on biomarkers and immunogenicity. This 2015 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 2015 edition of this comprehensive White Paper has been divided into three parts. Part 3 discusses the recommendations for large molecule bioanalysis using LBA, biomarkers and immunogenicity. Part 1 (small molecule bioanalysis using LCMS) and Part 2 (hybrid LBA/LCMS and regulatory inputs from major global health authorities) have been published in volume 7, issues 22 and 23 of Bioanalysis, respectively.

Automating bioanalytical sample analysis through enhanced system integration

BACKGROUND In the bioanalytical laboratory, challenges associated with manual, repetitive, labor-intensive processes can be addressed by powerful automated liquid handlers; however, their implementation has been difficult due to lack of efficient integration into laboratory workflows. Faster throughput is afforded to ligand binding assay (LBA) technologies via enhanced automation, but the upstream sample processing still remains a bottleneck. To be truly efficient, these technologies must be incorporated into a laboratory information management system (LIMS) to streamline data analysis and reporting. RESULTS Three off-the-shelf technologies that aid in improving bioanalytical laboratory efficiencies were utilized with minimal customization to streamline the sample analysis process. Information extracted via a sequence file from the LIMS run was utilized to perform the sample processing on the automated liquid handler. A file conversion tool converted the sequence files that allowed for sample processing and preparing the assay ready plate. The plate was then transferred to the LBA microfluidics platform to run the experiments. The integration was tested using a LBA PK assay that demonstrated good sample dilution and assay performance. CONCLUSION We successfully integrated LIMS with an automated liquid handler and a microfluidics platform to automate the sample analysis process in the bioanalytical laboratory. The utilization of off-the-shelf technologies with minimal customization requires minimal resources from laboratory scientists. It may be possible to implement this approach for other analytical platforms.

Implementation of a universal analytical method in early-stage development of human antibody therapeutics: application to pharmacokinetic assessment for candidate selection

BACKGROUND Effective bioanalytical support for pharmacokinetic assessment of therapeutics in early development remains challenging. Concurrent evaluation of multiple candidates per program is typical, requiring efficient characterization in various preclinical species; an ambitious effort often complicated by assay reagent unavailability and limited sample volume. Accordingly, a universal anti-human Fc assay for human monoclonal antibody and derived therapeutics was developed using a microfluidics platform to address these bioanalytical challenges. RESULTS The universal assay with standardized format was qualified for quantitation of human IgG Fc-containing biotherapeutics in matrices from commonly used preclinical species. Results from this assay compared well with those from traditional colorimetric immunoassays. Furthermore, result comparison between the universal and target-specific assays provided additional information on the effect of antidrug antibodies and in vivo drug catabolism. CONCLUSION This assay has wide applicability as a default bioanalytical approach in therapeutic candidate selection and preliminary pharmacokinetics evaluation during early-stage therapeutic development.

Validation of a Ligand Binding Assay Using Dried Blood Spot Sampling

Dried blood spots (DBS) technology has been introduced as a microsampling alternative to traditional plasma or serum sampling for pharmacokinetics or toxicokinetics evaluation. The application of DBS has been established for many small molecule drugs at discovery, nonclinical, and clinical stages. However, the application of DBS for large molecule therapeutics development is not yet well-established. This article describes the method validation of a ligand binding assay (LBA) for DBS sampling of a therapeutic monoclonal antibody—AMG 162 (Denosumab). The original serum LBA was modified for the DBS method. A fit-for-purpose method validation was performed to evaluate accuracy and precision, selectivity, dilutional linearity, and stability. In addition, the parameters relevant to DBS, such as spot volume, extraction recovery, whole blood stability, and hematocrit effects, were evaluated. The validation results demonstrated assay robustness with inter-assay precision of ≤19%, inter-assay accuracy of ≤9%, and total error of ≤24%. Selectivity, extraction recovery, dilutional linearity, and stability were demonstrated. The validation results revealed some limitations of the possible effect of blood hematocrit on therapeutic concentration measurements and the caution required using whole blood for standards and quality controls preparation. This is the first article to describe a thorough method validation of an LBA using DBS for a therapeutic monoclonal antibody. The lessons learned can serve as a model process for future method validation of other LBAs for large molecule therapeutics or biomarkers using the DBS sampling method.

A strategy for improving comparability across sites for ligand binding assays measuring therapeutic proteins

Outsourcing and multi-site testing has increased for ligand binding assays supporting protein therapeutic measurement. It is common to combine and compare data across studies with data from multiple bioanalytical sites. We designed a prospective study to determine the benefits of increasing control over the transfer process to improve ruggedness. The experiment involved the testing of 30 incurred samples at 3 stages with incremental laboratory harmonization in standard/quality controls and assay components: Stage I represented a transfer of a detailed protocol and critical reagents. Stage II, a single source of standards and quality controls were provided to each site. Stage III, standards and quality controls plus a ready-to-use kit were provided. The results indicated that all testing facilities failed agreement testing using the stage I procedure. The introduction of standards from a single source improved the agreement. The modification reduced variation by 33% compared to the stage I approach. There was no additional benefit when a packaged kit was provided. In conclusion, introduction of a single source of standards and quality controls reduced the inter-site component of variation and should allow for combinability of data.

Applications of a planar electrochemiluminescence platform to support regulated studies of macromolecules: benefits and limitations in assay range.

Development and validation of ligand binding methods that can measure therapeutic antibodies (TA) accurately and precisely are essential for bioanalysis that supports regulated pharmacokinetic (PK) and toxicokinetic (TK) studies. Non-bead (planar) electrochemiluminescence (ECL) methods are known to have high sensitivity and a wide assay range and are therefore potentially useful in supporting research studies in the early phases of development as well as for diagnostic fields and multiplex biomarker applications. Here, we demonstrate the applications for using ECL for regulated studies associated with protein drug development. Three planar ECL methods were developed, validated, and implemented to quantify three different TAs to support PK/TK studies. An automated liquid handler was used for the preparation of standards, quality controls, and validation samples to minimize assay variability. Robustness and ruggedness were tested during pre-study validations. During method optimization, the potential assay ranges were 3 log orders. To improve assay accuracy and precision, assay ranges in all 3 methods were truncated by at least 50% at the upper end before proceeding to pre-study validations. All 3 methods had assay ranges of about 2 logs during pre-study validations. The inter-assay accuracy and precision during pre-study validations were <6% and 8%, respectively. The total error of the assays was <15% for both in-study and pre-study validations in all 3 methods. With the incorporation of a robotic workstation we concluded that performance in all 3 planar ECL methods was extremely precise and accurate during pre-study and in-study validations, enabling >90% assay success during sample analyses. Although there were limitations in the assay ranges, the strength of this technology in assay accuracy, precision, and reproducibility can be beneficial for macromolecule analyses in support of PK and TK studies in a regulated environment.