Effect of antigen binding affinity and effector function on the pharmacokinetics and pharmacodynamics of anti-IgE monoclonal antibodies

Combined IgE neutralization and Bifidobacterium longum supplementation reduces the allergic response in models of food allergy

IgE is central to the development of allergic diseases, and its neutralization alleviates allergic symptoms. However, most of these antibodies are based on IgG1, which is associated with an increased risk of fragment crystallizable-mediated side effects. Moreover, omalizumab, an anti-IgE antibody approved for therapeutic use, has limited benefits for patients with high IgE levels. Here, we assess a fusion protein with extracellular domain of high affinity IgE receptor, FcεRIα, linked to a IgD/IgG4 hybrid Fc domain we term IgE_TRAP, to reduce the risk of IgG1 Fc-mediated side effects. IgE_TRAP shows enhanced IgE binding affinity compared to omalizumab. We also see an enhanced therapeutic effect of IgE_TRAP in food allergy models when combined with Bifidobacterium longum, which results in mast cell number and free IgE levels. The combination of IgE_TRAP and B. longum may therefore represent a potent treatment for allergic patients with high IgE levels.

IgE is a critical component of the allergic response and therapeutic targeting can alleviate symptomology. Here the authors propose the combined use of Bifidobacterium longum and a FcεRIα extracellular domain linked to a IgD/IgG4 hybrid Fc domain fusion protein called IgE_TRAP and show reduction of mast cell and IgE levels in models of food allergy.

Characterization and pre-clinical assessment of a proposed biosimilar to its originator Omalizumab

Omalizumab is an anti-IgE monoclonal antibody (mAb) approved for the treatment of moderate-to-severe asthma. Herein, we report physicochemical, biological, pharmacological, and toxicological characteristics of an Omalizumab biosimilar mAb named KA. We show that KA and its originator present only minimum differences. Their charge heterogeneity and primary, secondary structures are similar. The two molecules are comparable regarding in vitro activity, including molecular binding and cell-based inhibition. Pharmacological and toxicological properties were assessed using a mouse model of allergy and cynomolgus monkeys, and we determined that the efficacy, safety, and pharmacokinetic characteristics of KA are comparable to its originator. Our data, which demonstrated that KA has similar activity to the Omalizumab reference product in relevant preclinical models, calls for a clinical evaluation of its bio-similarity.

Mathematical Models to Characterize the Absorption, Distribution, Metabolism, and Excretion of Protein Therapeutics

Therapeutic proteins (TPs) have ranked among the most important and fastest-growing classes of drugs in the clinic, yet the development of successful TPs is often limited by unsatisfactory efficacy. Understanding pharmacokinetic (PK) characteristics of TPs is key to achieving sufficient and prolonged exposure at the site of action, which is a prerequisite for eliciting desired pharmacological effects. PK modeling represents a powerful tool to investigate factors governing in vivo disposition of TPs. In this mini-review, we discuss many state-of-the-art models that recapitulate critical processes in each of the absorption, distribution, metabolism/catabolism, and excretion pathways of TPs, which can be integrated into the physiologically-based pharmacokinetic framework. Additionally, we provide our perspectives on current opportunities and challenges for evolving the PK models to accelerate the discovery and development of safe and efficacious TPs. SIGNIFICANCE STATEMENT: This minireview provides an overview of mechanistic pharmacokinetic (PK) models developed to characterize absorption, distribution, metabolism, and elimination (ADME) properties of therapeutic proteins (TPs), which can support model-informed discovery and development of TPs. As the next-generation of TPs with diverse physicochemical properties and mechanism-of-action are being developed rapidly, there is an urgent need to better understand the determinants for the ADME of TPs and evolve existing platform PK models to facilitate successful bench-to-bedside translation of these promising drug molecules.

Impact of anti-PEG antibody affinity on accelerated blood clearance of pegylated epoetin beta in mice

Antibodies that bind polyethylene glycol (PEG) can be induced by pegylated biomolecules and also exist in a significant fraction of healthy individuals who have never received pegylated medicines. The binding affinity of antibodies against PEG (anti-PEG antibodies) likely varies depending on if they are induced or naturally occurring. Anti-PEG antibodies can accelerate the clearance of pegylated medicines from the circulation, resulting in loss of drug efficacy, but it is unknown how accelerated blood clearance is affected by anti-PEG antibody affinity. We identified a panel of anti-PEG IgG and IgM antibodies with binding avidities ranging over several orders of magnitude to methoxy polyethylene glycol-epoetin beta (PEG-EPO), which is used to treat patients suffering from anemia. Formation of in vitro immune complexes between PEG-EPO and anti-PEG IgG or IgM antibodies was more obvious as antibody affinity increased. Likewise, high affinity anti-PEG antibodies produced greater accelerated blood clearance of PEG-EPO as compared to low affinity antibodies. The molar ratio of anti-PEG antibody to PEG-EPO that accelerates drug clearance in mice correlates with antibody binding avidity. Our study indicates that the bioactivity of PEG-EPO may be reduced due to rapid clearance in patients with either high concentrations of low affinity or low concentrations of high affinity anti-PEG IgG and IgM antibodies.

Directed evolution of and structural insights into antibody-mediated disruption of a stable receptor-ligand complex

Antibody drugs exert therapeutic effects via a range of mechanisms, including competitive inhibition, allosteric modulation, and immune effector mechanisms. Facilitated dissociation is an additional mechanism where antibody-mediated “disruption” of stable high-affinity macromolecular complexes can potentially enhance therapeutic efficacy. However, this mechanism is not well understood or utilized therapeutically. Here, we investigate and engineer the weak disruptive activity of an existing therapeutic antibody, omalizumab, which targets IgE antibodies to block the allergic response. We develop a yeast display approach to select for and engineer antibody disruptive efficiency and generate potent omalizumab variants that dissociate receptor-bound IgE. We determine a low resolution cryo-EM structure of a transient disruption intermediate containing the IgE-Fc, its partially dissociated receptor and an antibody inhibitor. Our results provide a conceptual framework for engineering disruptive inhibitors for other targets, insights into the failure in clinical trials of the previous high affinity omalizumab HAE variant and anti-IgE antibodies that safely and rapidly disarm allergic effector cells.

Facilitated dissociation is a mechanism where antibody-mediated disruption of high-affinity complexes can enhance the therapeutic effects of a drug. Here the authors present a yeast display approach to select and engineer omalizumab variants that dissociate receptor-bound IgE to accelerate its inhibition of the allergic response.

Preclinical characterization of bemarituzumab, an anti-FGFR2b antibody for the treatment of cancer

Bemarituzumab (FPA144) is a first-in-class, humanized, afucosylated immunoglobulin G1 monoclonal antibody (mAb) directed against fibroblast growth factor receptor 2b (FGFR2b) with two mechanisms of action against FGFR2b-overexpressing tumors: inhibition of FGFR2b signaling and enhanced antibody-dependent cell-mediated cytotoxicity (ADCC). Bemarituzumab is being developed as a cancer therapeutic, and we summarize here the key nonclinical data that supported moving it into clinical trials. Bemarituzumab displayed sub-nanomolar cross-species affinity for FGFR2b receptors, with >20-fold enhanced binding affinity to human Fc gamma receptor IIIa compared with the fucosylated version. In vitro, bemarituzumab induced potent ADCC against FGFR2b-expressing tumor cells, and inhibited FGFR2 phosphorylation and proliferation of SNU-16 gastric cancer cells in a concentration-dependent manner. In vivo, bemarituzumab inhibited tumor growth through inhibition of the FGFR2b pathway and/or ADCC in mouse models. Bemarituzumab demonstrated enhanced anti-tumor activity in combination with chemotherapy, and due to bemarituzumab-induced natural killer cell-dependent increase in programmed death-ligand 1, also resulted in enhanced anti-tumor activity when combined with an anti-programmed death-1 antibody. Repeat-dose toxicity studies established the highest non-severely-toxic dose at 1 and 100 mg/kg in rats and cynomolgus monkeys, respectively. In pharmacokinetic (PK) studies, bemarituzumab exposure increase was greater than dose-proportional, with the linear clearance in the expected dose range for a mAb. The PK data in cynomolgus monkeys were used to project bemarituzumab linear PK in humans, which were consistent with the observed human Phase 1 data. These key nonclinical studies facilitated the successful advancement of bemarituzumab into the clinic.

Brca2 deficiency drives gastrointestinal tumor formation and is selectively inhibited by mitomycin C

BRCA2 is crucial for repairing DNA double-strand breaks with high fidelity, and loss of BRCA2 increases the risks of developing breast and ovarian cancers. Herein, we show that BRCA2 is inactively mutated in 10% of gastric and 7% of colorectal adenocarcinomas, and that this inactivation is significantly correlated with microsatellite instability. Villin-driven Brca2 depletion promotes mouse gastrointestinal tumor formation when genome instability is increased. Whole-genome screening data showed that these BRCA2 monoallelic and biallelic mutant tumors were selectively inhibited by mitomycin C. Mechanistically, mitomycin C provoked double-strand breaks in cancer cells that often recruit wild-type BRCA2 for repair; the failure to repair double-strand breaks caused cell-cycle arrest at the S phase and p53-mediated cell apoptosis of BRCA2 monoallelic and biallelic mutant tumor cells. Our study unveils the role of BRCA2 loss in the development of gastrointestinal tumors and provides a potential therapeutic strategy to eliminate BRCA2 monoallelic and biallelic mutant tumors through mitomycin C.

Safety and Tolerability of Omalizumab: A Randomized Clinical Trial of Humanized Anti-IgE Monoclonal Antibody in Systemic Lupus Erythematosus

OBJECTIVE

Autoreactive IgE antibodies have been implicated in the pathogenesis of systemic lupus erythematosus (SLE). We hypothesize that omalizumab, a monoclonal antibody binding IgE, may improve SLE activity by reducing type I interferon (IFN) production by hampering plasmacytoid dendritic cells and basophil activation. This study was undertaken to assess the safety, tolerability, and clinical efficacy of omalizumab in mild to moderate SLE.

METHODS

Sixteen subjects with SLE and a Systemic Lupus Erythematosus Disease Activity Index 2000 (SLEDAI-2K) score of ≥4 and elevated autoreactive IgE antibody levels were randomized to receive omalizumab or placebo (2:1) for 16 weeks, followed by 16 weeks of open-label treatment and a 4-week washout period. The SLEDAI-2K score, British Isles Lupus Assessment Group index (BILAG 2004) score, and physician's global assessment of disease activity were recorded at each visit. The type I IFN-induced gene signature was determined using quantitative polymerase chain reaction.

RESULTS

Omalizumab was well tolerated with no allergic reactions, and mostly mild adverse events comparable to those experienced with placebo treatment. SLEDAI-2K scores improved in the omalizumab group compared to the placebo group at week 16 (P = 0.038), as well as during the open-label phase in subjects initially receiving placebo (P = 0.02). No worsening in BILAG scores or the physician's global assessment was detected. There was a trend toward a reduction in IFN gene signature in subjects treated with omalizumab (P = 0.11), especially in subjects with a high baseline IFN signature (P = 0.052).

CONCLUSION

Our findings indicate that omalizumab is well tolerated in SLE and is associated with improvement in disease activity. Larger randomized clinical trials will be needed to assess the efficacy of omalizumab in patients with SLE.

An in vitro FcRn- dependent transcytosis assay as a screening tool for predictive assessment of nonspecific clearance of antibody therapeutics in humans

A cell-based assay employing Madin–Darby canine kidney cells stably expressing human neonatal Fc receptor (FcRn) heavy chain and β2-microglobulin genes was developed to measure transcytosis of monoclonal antibodies (mAbs) under conditions relevant to the FcRn-mediated immunoglobulin G (IgG) salvage pathway. The FcRn-dependent transcytosis assay is modeled to reflect combined effects of nonspecific interactions between mAbs and cells, cellular uptake via pinocytosis, pH-dependent interactions with FcRn, and dynamics of intracellular trafficking and sorting mechanisms. Evaluation of 53 mAbs, including 30 marketed mAb drugs, revealed a notable correlation between the transcytosis readouts and clearance in humans. FcRn was required to promote efficient transcytosis of mAbs and contributed directly to the observed correlation. Furthermore, the transcytosis assay correctly predicted rank order of clearance of glycosylation and Fv charge variants of Fc-containing proteins. These results strongly support the utility of this assay as a cost-effective and animal-sparing screening tool for evaluation of mAb-based drug candidates during lead selection, optimization, and process development for desired pharmacokinetic properties.

Affinity maturation of an TpoR targeting antibody in full-length IgG form for enhanced agonist activity

It has been observed that converting scFv formatted antibodies to full-length IgG often associates with loss of affinity. We aim to address this issue in this paper by establishing an integrated affinity maturation method applying yeast display technology platform. To demonstrate that, we employed a human thrombopoietin receptor targeting antibody named 3D9 which was identified previously from a combinational antibody library in scFv-Fc fusion protein form. We have observed that significant potency loss happened when 3D9 was transformed to full-length IgG form. In this study, we tested whether the potency of the full-length IgG can be improved by affinity maturation of 3D9 using a modified Fab yeast display platform. An efficient CDR3 targeted mutagenesis strategy was designed for Fab library with pre-designed CDR diversity. Next generation sequencing was also used for evaluation of the enrichment process and investigation of sequence-function relationship of the antibody. A variant with improved affinity and higher potency was identified. The study demonstrates that the strategy we used here are efficient for optimizing affinity and activity of full-length IgGs.

Pharmacokinetic and Pharmacodynamic Considerations in the Design of Therapeutic Antibodies

The design and development of therapeutic monoclonal antibodies (mAbs) through optimizing their pharmacokinetic (PK) and pharmacodynamic (PD) properties is crucial to improve efficacy while minimizing adverse events. Many of these properties are interdependent, which highlights the inherent challenges in therapeutic antibody design, where improving one antibody property can sometimes lead to changes in others. Here, we discuss optimization approaches for PK/PD properties of therapeutic mAbs.

Improvement of pharmacokinetic properties of therapeutic antibodies by antibody engineering

Monoclonal antibodies (mAbs) have become an important therapeutic option for several diseases. Since several mAbs have shown promising efficacy in clinic, the competition to develop mAbs has become severe. In efforts to gain a competitive advantage over other mAbs and provide significant benefits to patients, innovations in antibody engineering have aimed at improving the pharmacokinetic properties of mAbs. Because engineering can provide therapeutics that are more convenient, safer, and more efficacious for patients in several disease areas, it is an attractive approach to provide significant benefits to patients. Further advances in engineering mAbs to modulate their pharmacokinetics were driven by the increase of total soluble target antigen concentration that is often observed after injecting a mAb, which then requires a high dosage to antagonize. To decrease the required dosage, several antibody engineering techniques have been invented that reduce the total concentration of soluble target antigen. Here, we review the various ways that antibody engineering can improve the pharmacokinetic properties of mAbs.

Translational pharmacokinetics and pharmacodynamics of monoclonal antibodies

Monoclonal antibodies (mAbs) are an important therapeutic class with complex pharmacology and interdependent pharmacokinetic (PK) and pharmacodynamics (PD) properties. Understanding the PK and PD of mAbs and their biological and mechanistic underpinnings are crucial in enabling their design and selection, designing appropriate efficacy and toxicity studies, translating PK/PD parameters to humans, and optimizing dose and regimen to maximize success in the clinic. Significant progress has been made in this field however many critical questions still remain. This article gives a brief overview of the PK and PD of mAbs, factors that influence them, and areas of ongoing inquiry. Current tools and translational approaches to predict the PK/PD of mAbs in humans are also discussed.

Treating IgE-mediated diseases via targeting IgE-expressing B cells using an anti-CεmX antibody

Targeting the IgE pathway is a clinically validated strategy for treating IgE-mediated diseases. Omalizumab, an anti-IgE antibody, which binds to free IgE and prevents the binding of IgE to FcεRI on mast cells and basophils has been approved for severe persistent allergic asthma and chronic spontaneous (idiopathic) urticaria. The therapeutic efficacy of anti-IgE has also been reported in allergic rhinitis, allergic bronchopulmonary aspergillosis, latex allergy, atopic dermatitis, allergic urticaria, anaphylaxis, and others. Anti-CεmX, which binds to membrane-bound IgE (mIgE) on IgE-switched B cells, lyses mIgE-expressing B lymphoblasts and prevents the allergen-induced generation of IgE-producing plasma cells, offers an alternative mechanism of intervening with the IgE inflammatory pathway. Because anti-CεmX does not bind to free IgE, it can modulate the IgE pathway regardless of the serum IgE levels in treated patients. These unique pharmacologic mechanisms potentially enable anti-CεmX to provide different clinical utilities from anti-IgE and serve as a therapeutic and a prophylactic in some IgE-mediated diseases, which are not adequately treated with current medicine.

Immunogenicity of a peptide-based anti-IgE conjugate vaccine in non-human primates

The anti-human immunoglobulin E (IgE) monoclonal antibody, omalizumab (Xolair®, Genentech, South San Fransisco, CA), is effective in the treatment of poorly controlled moderate to severe allergic asthma and chronic idiopathic urticaria. It acts by specifically binding to the constant domain (Cϵ3) of free human IgE in the blood and interstitial fluid. Although efficacious, use of omalizumab is limited due to restrictions on patient weight and pre-existing IgE levels, and frequent dosing (q2-4 weeks). A vaccine inducing anti-IgE antibodies has the potential for similar clinical benefits with less frequent dosing and relatively lower cost of goods. We developed a vaccine containing two IgE peptide-conjugates targeting the Cϵ3 domain of human IgE. As part of preclinical evaluation of the vaccine to optimize formulation and dose prior to initiating clinical studies, we evaluated the vaccine in non-human primates, and demonstrate the induction of anti-peptide antibodies that can bind to conformationally intact human IgE and are capable, at least in some animals, of substantial lowering circulating IgE levels.

Predicting pharmacokinetic profile of therapeutic antibodies after iv injection from only the data after sc injection in cynomolgus monkey

1. The number of developed therapeutic monoclonal antibodies (mAbs) has increased in this decade. This study aims to predict their pharmacokinetic profiles after intravenous (iv) injection using only the data taken after subcutaneous (sc) injection in cynomolgus monkey. 2. Two-compartment model parameters, Q, V_c and V_p, were collected from the published data after iv injection in cynomolgus monkey for 21 mAbs (Group A). Bioavailability after sc injection (F), CL and serum/plasma concentration after iv injection of other published 19 mAbs (Group B) were predicted using the estimated geometric means of Q, V_c and V_p in Group A and the serum/plasma concentration after sc injection in Group B. 3. F and CL of 18 out of 19 mAbs in Group B were successfully predicted within 30% difference of observed value. Moreover, most of the observed serum/plasma concentrations after iv injection of mAbs in Group B were successfully predicted within 2-fold difference. Our approach suggests that iv injection might not be required to evaluate absorption of mAbs after sc injection in cynomolgus monkey. Therefore, our approach might reduce the time and cost of drug development, reduce the burden on resources, and also contribute to animal welfare.

Clinical Decision Support Tools: The Evolution of a Revolution

Dashboard systems for clinical decision support integrate data from multiple sources. These systems, the newest in a long line of dose calculators and other decision support tools, utilize Bayesian approaches to fully individualize dosing using information gathered through therapeutic drug monitoring. In the treatment of inflammatory bowel disease patients with infliximab, dashboards may reduce therapeutic failures and treatment costs. The history and future development of modern Bayesian dashboard systems is described.

Pharmacokinetics, Pharmacodynamics, and Safety of MEDI4212, an Anti-IgE Monoclonal Antibody, in Subjects with Atopy: A Phase I Study

INTRODUCTION

The anti-IgE therapy omalizumab is currently licensed for the treatment of moderate to severe allergic asthma and chronic idiopathic urticaria. Owing to limitations in the use of omalizumab, a need exists for optimized anti-IgE therapies to broaden clinical indications and patient populations, and to improve dosing schedules. The objective of this phase I, randomized, placebo/omalizumab-controlled, first-in-human, dose-escalation study was to evaluate the pharmacokinetics, pharmacodynamics, and safety of the high-affinity, anti-IgE therapy MEDI4212 in non-Japanese and Japanese subjects with atopy and/or diagnostic IgE ≥ 30 IU/mL.

METHODS

Subjects with atopy and/or baseline IgE ≥ 30 IU/mL were randomized to a single dose of subcutaneous (5, 15, 60, 150, or 300 mg) or intravenous (300 mg) MEDI4212, subcutaneous omalizumab, or placebo. Following administration, pharmacokinetic, pharmacodynamic [IgE (free and total), and cellular FcεRI expression], and safety assessments were made.

RESULTS

MEDI4212 rapidly suppressed free serum IgE to a greater extent than omalizumab; however, recovery of free IgE to baseline in MEDI4212-dosed subjects was rapid when compared with the slow and gradual recovery seen in omalizumab-dosed individuals. The loss of IgE suppression corresponded with a rapid decrease of serum MEDI4212. FcεRI expression on dendritic cells and basophils was reduced following MEDI4212 dosing. MEDI4212 was well tolerated by subjects; adverse events were generally of low severity and no subjects discontinued due to adverse events.

CONCLUSIONS

The increased potency of MEDI4212 may be of clinical interest for individuals with high-diagnostic IgE levels where more extensive IgE suppression is required for clinical response. However, the modest duration of free IgE suppression below the target concentration noted with MEDI4212 in this study suggests limited potential for dosing schedule advantages over omalizumab.

FUNDING

MedImmune.

TRIAL REGISTRATION

ClinicalTrials.gov identifier, NCT01544348.

PK/PD analysis of a novel pH-dependent antigen-binding antibody using a dynamic antibody-antigen binding model

Previously, we have reported novel engineered antibody with pH-dependent antigen-binding (recycling antibody), and with both pH-dependent antigen-binding and increased FcRn-binding at neutral pH (sweeping antibody). The purpose of this study is to perform PK/PD predictions to better understand the potential applications of the antibodies as therapeutics. To demonstrate the applicability of recycling and sweeping antibodies over conventional antibodies, PK/PD analyses were performed. PK/PD parameters for antibody and antigen dynamics were estimated from the results of a pharmacokinetic study in human FcRn transgenic mice. A simulation study was performed using the estimated PK/PD parameters with various target antigen profiles. In comparison to conventional antibody, recycling antibody enhanced antibody-antigen complex clearance by 3 folds, while sweeping antibody accelerated antigen clearance by 10 folds in a pharmacokinetic study. Simulation results showed that recycling and sweeping antibodies can improve dosage frequency and reduce the required dose for target antigens with various clearances, plasma concentrations or binding kinetics. Moreover, importance of the association rate constant to enhance the beneficial effect of antibodies was shown. These results support the conclusion that recycling and sweeping antibodies can be applied to various target antigens with different profiles, and expand the number of antigens that antibodies can target.

Dashboard systems: Pharmacokinetic/pharmacodynamic mediated dose optimization for monoclonal antibodies

Many marketed drugs exhibit high variability in exposure and response. While these drugs are efficacious in their approved indications, finding appropriate dose regimens for individual patients is not straightforward. Similar dose adjustment problems are also seen with drugs that have a complex relationship between exposure and response and/or a narrow therapeutic window. This is particularly true for monoclonal antibodies, where prolonged dosing at a sub-therapeutic dose can also elicit anti-drug antibodies which will further compromise safety and efficacy. Thus, finding appropriate doses quickly would represent a substantial improvement in healthcare. Dashboard systems, which are decision-support tools, offer an improved, convenient means of tailoring treatment for individual patients. This article reviews the clinical need for this approach, particularly with monoclonal antibodies, the design, development, and testing of such systems, and the likely benefits of dashboard systems in clinical practice. We focus on infliximab for reference.

Immunotherapy in allergy and cellular tests: state of art

The basophil activation test (BAT) is an in vitro assay where the activation of basophils upon exposure to various IgE-challenging molecules is measured by flow cytometry. It is a cellular test able to investigate basophil behavior during allergy and allergy immunotherapy. A panoply of critical issues and suggestive advances have rendered this assay a promising yet puzzling tool to endeavor a full comprehension of innate immunity of allergy desensitization and manage allergen or monoclonal anti-IgE therapy. In this review a brief state of art of BAT in immunotherapy is described focusing onto the analytical issue pertaining BAT performance in allergy specific therapy.