Identification and elimination of target-related matrix interference in a neutralizing anti-drug antibody assay

Cannabidiol-Loaded Solid Lipid Nanoparticles Ameliorate the Inhibition of Proinflammatory Cytokines and Free Radicals in an In Vitro Inflammation-Induced Cell Model

Cannabidiol (CBD) is a non-psychoactive compound derived from Cannabis sativa. It has demonstrated promising effects in combating inflammation and holds potential as a treatment for the progression of chronic inflammation. However, the clinical application of CBD is limited due to its poor solubility and bioavailability. This study introduces an effective method for preparing CBD-loaded solid lipid nanoparticles (CBD-SLNs) using a combination of low-energy hot homogenization and ultrasonication. We enhanced this process by employing statistical optimization with response surface methodology (RSM). The optimized CBD-SLN formulation utilizes glyceryl monostearate as the primary lipid component of the nanocarrier. The CBD-SLN formulation is screened as a potential tool for managing chronic inflammation. Stable, uniformly dispersed spherical nanoparticles with a size of 123 nm, a surface charge of -32.1 mV, an encapsulation efficiency of 95.16%, and a drug loading of 2.36% were obtained. The CBD-SLNs exhibited sustained release properties, ensuring prolonged and controlled CBD delivery, which could potentially amplify its therapeutic effects. Additionally, we observed that CBD-SLNs significantly reduced both reactive oxygen and nitrogen species and proinflammatory cytokines in chondrocyte and macrophage cell lines, with these inhibitory effects being more pronounced than those of free CBD. In conclusion, CBD-SLNs demonstrated superiority over free CBD, highlighting its potential as an effective delivery system for CBD.

M2b macrophages protect against myocardial remodeling after ischemia/reperfusion injury by regulating kinase activation of platelet-derived growth factor receptor of cardiac fibroblast

Background

Myocardial injury is a major cause of myocardial remodeling. Macrophages are important in cardiac repair as a result of their interactions with fibroblasts. As regulatory macrophages, M2b macrophages modulate inflammatory immune responses without participating in wound healing and could have enhanced protective effects on myocardial remodeling. Therefore, we tested the hypothesis that M2b macrophages could improve cardiac function and ameliorate myocardial fibrosis after the myocardial ischemia/reperfusion injury (MI/RI).

Methods

In vivo, MI/RI models were established with Sprague-Dawley (SD) rats and either M2b macrophages (MT group) or the same volume of vehicle (CK group) was injected into the ischemic zone. Two weeks after the operation, cardiac function and diameters were determined by echocardiography examination. Level of myocardial fibrosis was measured by Sirius red staining and the expression of fibrosis-related factors. In vitro, cardiac fibroblasts (CFs) were co-cultured with M2b macrophages or cultured with M2b macrophage supernatant. Expression of α-smooth muscle actin (α-SMA) and connective tissue growth factor (CCN2/CTGF) in the CFs were measured by western blotting and immunofluorescence staining. In addition, the expression of platelet-derived growth factors (PDGFs), the expression of platelet-derived growth factor receptors (PDGFRs) and the phosphorylation of PDGFRs was detected by western blotting.

Results

A significantly higher rat survival rate, improved left ventricular (LV) systolic function, decreased diameter of the LV and alleviated myocardial fibrosis were observed in the MT group than in the CK group. In vitro, the activation of CFs was significantly reduced by the M2b macrophages treatments, relative to the blank control. In addition, the kinase activation of PDGFRs was decreased by M2b macrophage treatments both in vivo and in vitro.

Conclusions

Our study demonstrated that the administration of M2b macrophages could attenuate myocardial remodeling after MI/RI. The regulation of the activation of PDGFRs in CFs is an important part of the protective mechanism.

Neutralizing Antibody Assay Development with High Drug and Target Tolerance to Support Clinical Development of an Anti-TFPI Therapeutic Monoclonal Antibody

Immunogenicity is a major challenge for protein therapeutics which can potentially reduce drug efficacy and safety and is often being monitored by anti-drug antibody (ADA) and neutralizing antibody (NAb) assays. Circulating targets and residual drugs in matrices can have significant impacts on accuracy of results from ADA and NAb assays, and sufficient drug and target tolerance for these assays are necessary. Here, we report the development of a competitive ligand binding (CLB) NAb assay for an anti-TFPI (tissue factor pathway inhibitor) monoclonal antibody (PF-06741086) with high drug and target tolerance to support ongoing clinical studies. A double acid affinity capture elution approach was used to mitigate drug interference, and a robust target removal strategy was employed to enhance target tolerance. The validated NAb assay has sensitivity of 313 ng/mL, drug tolerance of 50 μg/mL, and target tolerance of 1200 ng/mL. A step-by-step tutorial of assay development is described in this manuscript along with the rationale for using a high drug/target tolerant NAb assay. The NAb assay cut point factor obtained was 0.78. Other assay performance characteristics, e.g., precision and selectivity, are also discussed. This validated method demonstrated a superior drug and target tolerance to warrant specific and precise characterization of the NAb responses in support of ongoing clinical studies.

Development and validation of a cell based assay for the detection of neutralizing antibodies against recombinant insulins

Recombinant biopharmaceuticals can induce generation of anti-drug antibodies, which could potentially neutralize therapeutic drug activity. In this report, we describe development and validation of a cell-based assay for detection of neutralizing antibodies (Nab) against insulin and insulin analogues. In order to achieve clinically meaningful sensitivity the method used an early signalling event, insulin induced insulin receptor phosphorylation as the endpoint. Percentage insulin receptor phosphorylation in cell lysates was measured using ECL based ELISA. Presence of neutralizing antibodies (Nab) in samples will inhibit insulin induced receptor phosphorylation and consequently lead to a reduction in the percentage of phosphorylated insulin receptor. Additionally, usage of human insulin receptor overexpressing recombinant CHO cell line further improved the assay sensitivity by reducing the fixed drug (EC50) concentration used for induction of receptor phosphorylation. To ensure adequate free drug tolerance a pre-treatment step was introduced, where serum samples underwent acid dissociation and charcoal extraction before drug incubation. In order to distinguish ADA positive samples containing true Nab from samples containing non-antibody phosphorylation inhibitory serum factors, a confirmatory tier was integrated based on immunodepletion using protein AGL mix. Assay parameters including determination of screening and confirmatory cut-points, intra and inter assay precision, selectivity, specificity and stability were assessed during validation in accordance with recent regulatory guidelines and white papers. The advantage of selecting insulin receptor phosphorylation as assay endpoint made the assay capable of detecting Nab against insulin and insulin analogues.

Platelet-derived growth factor receptor/platelet-derived growth factor (PDGFR/PDGF) system is a prognostic and treatment response biomarker with multifarious therapeutic targets in cancers

Progress in cancer biology has led to an increasing discovery of oncogenic alterations of the platelet-derived growth factor receptors (PDGFRs) in cancers. In addition, their overexpression in numerous cancers invariably makes PDGFRs and platelet-derived growth factors (PDGFs) prognostic and treatment markers in some cancers. The oncologic alterations of the PDGFR/PDGF system affect the extracellular, transmembrane and tyrosine kinase domains as well as the juxtamembrane segment of the receptor. The receptor is also involved in fusions with intracellular proteins and receptor tyrosine kinase. These discoveries undoubtedly make the system an attractive oncologic therapeutic target. This review covers elementary biology of PDGFR/PDGF system and its role as a prognostic and treatment marker in cancers. In addition, the multifarious therapeutic targets of PDGFR/PDGF system are discussed. Great potential exists in the role of PDGFR/PDGF system as a prognostic and treatment marker and for further exploration of its multifarious therapeutic targets in safe and efficacious management of cancer treatments.

Indirect assessment of neutralizing anti-drug antibodies utilizing pharmacokinetic assay data

Neutralizing anti-drug antibodies (NAbs) can adversely impact efficacy and safety of biologic therapeutics. However, current assay formats to detect NAbs are limited in their use during the dosing phase due to interference by circulating drug, resulting in low drug tolerance. To improve the drug tolerance for NAb detection, an alternative approach for indirect NAb (iNAb) assessment was developed and qualified that uses a combination of pharmacokinetic (PK) assays to measure the serum concentrations of free and total drug. It is demonstrated that the ratio of free to total drug concentrations, referred to as F/T ratio, is a novel PK parameter that can indicate neutralizing activity in test samples. The iNAb assessment correctly identified NAb-positive samples with high drug concentrations that led to false negative results in a conventional NAb assay. Moreover, iNAb reliably distinguished between NAbs and non-neutralizing anti-drug antibodies over a wide range of concentrations. A proposal on how to deploy iNAb assessment within a broader immunogenicity testing strategy is presented.

A Neutralizing Antibody Assay Based on a Reporter of Antibody-Dependent Cell-Mediated Cytotoxicity

Benralizumab is a humanized anti-IL5 receptor α (IL5Rα) monoclonal antibody (mAb) with enhanced (afucosylation) antibody-dependent cell-mediated cytotoxicity (ADCC) function. An ADCC reporter cell-based neutralizing antibody (NAb) assay was developed and characterized to detect NAb against benralizumab in human serum to support the clinical development of benralizumab. The optimal ratio of target cells to effector cells was 3:1. Neither parental benralizumab (fucosylated) nor benralizumab Fab resulted in ADCC activity, confirming the requirement for ADCC activity in the NAb assay. The serum tolerance of the cells was determined to be 2.5%. The cut point derived from normal and asthma serum samples was comparable. The effective range of benralizumab was determined, and 35 ng/mL [80% maximal effective concentration (EC80)] was chosen as the standard concentration to run in the assessment of NAb. An affinity purified goat anti-benralizumab polyclonal idiotype antibody preparation was shown to have NAb since it inhibited ADCC activity in a dose-dependent fashion. The low endogenous concentrations of IL5 and soluble IL5 receptor (sIL5R) did not demonstrate to interfere with the assay. The estimated assay sensitivities at the cut point were 1.02 and 1.10 μg/mL as determined by the surrogate neutralizing goat polyclonal and mouse monoclonal anti-drug antibody (ADA) controls, respectively. The assay can detect NAb (at 2.5 μg/mL) in the presence of 0.78 μg/mL benralizumab. The assay was not susceptible to non-specific matrix effects. This study provides an approach and feasibility of developing an ADCC cell-based NAb assay to support biopharmaceuticals with an ADCC function.

Review on modeling anti-antibody responses to monoclonal antibodies

Monoclonal antibodies (mAbs) represent a therapeutic strategy that has been increasingly used in different diseases. mAbs are highly specific for their targets leading to induce specific effector functions. Despite their therapeutic benefits, the presence of immunogenic reactions is of growing concern. The immunogenicity identified as anti-drug antibodies (ADA) production due to the continuous administration of mAbs may affect the pharmacokinetics (PK) and/or the pharmacodynamics (PD) of mAbs administered to patients. Therefore, the immunogenicity and its clinical impact have been studied by several authors using PK modeling approaches. In this review, the authors try to present all those models under a unique theoretical mechanism-based framework incorporating the main considerations related to ADA formation, and how ADA may affect the efficacy or toxicity profile of some therapeutic biomolecules.