Preclinical pharmacokinetics, interspecies scaling, and tissue distribution of humanized monoclonal anti-IL-13 antibodies with different IL-13 neutralization mechanisms

Emerging Role of Interleukins for the Assessment and Treatment of Liver Diseases

BACKGROUND

The most common liver diseases are fibrosis, alcoholic liver disease, non-alcoholic fatty disease, viral hepatitis, and hepatocellular carcinoma. These liver diseases account for approximately 2 million deaths per year worldwide, with cirrhosis accounting for 2.1% of the worldwide burden. The most widely used liver function tests for diagnosis are alanine transaminase, aspartate transaminase, serum proteins, serum albumin, and serum globulins, whereas antivirals and corticosteroids have been proven to be useful for the treatment of liver diseases. A major disadvantage of these diagnostic measures is the lack of specificity to a particular tissue or cell type, as these enzymes are common to one or more tissues. The major adverse effect of current treatment methods is drug resistance. To overcome these issues, interleukins have been investigated. The balance of these interleukins determines the outcome of an immune response. Interleukins are considered interesting therapeutic targets for the treatment of liver diseases. In this review, we summarize the current state of knowledge regarding interleukins in the diagnosis, treatment, and pathogenesis of different acute and chronic liver diseases.

OBJECTIVE

To understand the role of interleukins in the assessment and treatment of different types of liver diseases.

METHODS

A literature search was conducted using PubMed, Science Direct, and NCBI with the following keywords: Interleukins, Acute Liver Failure, Alcoholic Liver Disease, Non-Alcoholic Fatty Liver Disease, Liver Fibrosis, Hepatocellular Carcinoma, Inflammation, Liver injury, Hepatoprotective effect. Clinical trial data on these interleukins have been searched on Clinicaltrials.gov.

RESULTS

Existing literature and preclinical and clinical trial data demonstrate that interleukins play a crucial role in the pathogenesis of liver diseases.

CONCLUSION

Our findings indicate that IL-1, IL-6, IL-10, IL-17, IL-22, IL-35, and IL-37 are involved in the progression and control of various liver conditions via the regulation of cell signaling pathways. However, further investigation on the involvement of these interleukins is necessary for their use as a targeted therapy in liver diseases.

A Mechanistic Site-Of-Action Model: A Tool for Informing Right Target, Right Compound, And Right Dose for Therapeutic Antagonistic Antibody Programs

Quantitative modeling is increasingly utilized in the drug discovery and development process, from the initial stages of target selection, through clinical studies. The modeling can provide guidance on three major questions–is this the right target, what are the right compound properties, and what is the right dose for moving the best possible candidate forward. In this manuscript, we present a site-of-action modeling framework which we apply to monoclonal antibodies against soluble targets. We give a comprehensive overview of how we construct the model and how we parametrize it and include several examples of how to apply this framework for answering the questions postulated above. The utilities and limitations of this approach are discussed.

Allometric scaling of therapeutic monoclonal antibodies in preclinical and clinical settings

Constant technological advancement enabled the production of therapeutic monoclonal antibodies (mAbs) and will continue to contribute to their rapid expansion. Compared to small-molecule drugs, mAbs have favorable characteristics, but also more complex pharmacokinetics (PK), e.g., target-mediated nonlinear elimination and recycling by neonatal Fc-receptor. This review briefly discusses mAb biology, similarities and differences in PK processes across species and within human, and provides a detailed overview of allometric scaling approaches for translating mAb PK from preclinical species to human and extrapolating from adults to children. The approaches described here will remain vital in mAb drug development, although more data are needed, for example, from very young patients and mAbs with nonlinear PK, to allow for more confident conclusions and contribute to further growth of this field. Improving mAb PK predictions will facilitate better planning of (pediatric) clinical studies and enable progression toward the ultimate goal of expediting drug development.

Whole-Body Pharmacokinetics of Antibody in Mice Determined using Enzyme-Linked Immunosorbent Assay and Derivation of Tissue Interstitial Concentrations

Here we have reported whole-body disposition of wild-type IgG and FcRn non-binding IgG in mice, determined using Enzyme-Linked Immunosorbent Assay (ELISA). The disposition data generated using ELISA are compared with previously published biodistribution data generated using radiolabelled IgG. In addition, we introduce a novel concept of ABC_IS values, which are defined as percentage ratios of tissue interstitial and plasma AUC values. These values can help in predicting tissue interstitial concentrations of monoclonal antibodies (mAbs) based on the plasma concentrations. Tissue interstitial concentrations derived from our study are also compared with previously reported values measured using microdialysis or centrifugation method. Lastly, the new set of biodistribution data generated using ELISA are used to refine the PBPK model for mAbs.

Optical and Optoacoustic Imaging Probes

Tissue has characteristic properties when it comes to light absorption and scattering. For optical (OI) and optoacoustic imaging (OAI) these properties can be utilised to visualise biological tissue characteristics, as, for example, the oxygenation state of haemoglobin alters the optical and optoacoustic properties of the molecule.

Silica microparticles for sustained zero-order release of an anti-CD40L antibody

Silica microparticle hydrogel depot (HG) formulation was prepared using spray drying of silica-based sol-gels for the sustained delivery of MR1 antibody which binds to CD40 ligand (CD40L). The formulation was tested in vitro for antibody release, surface morphology, particle size, rheology, and injectability. In vivo pharmacokinetic evaluation was performed for the microparticle formulation and free MR1 antibody in BALB/c female mice. Serum samples up to day 62 were assessed using an enzyme-linked immunosorbent assay. In vitro release indicated that the MR1 antibody was uniformly encapsulated in silica microparticles, and less than 5% burst release of the antibody was observed. In vivo pharmacokinetics showed a zero-order release up to 62 days from the MR1 silica microparticle HG-controlled release composition.

Dietary plant stanol ester consumption improves immune function in asthma patients: results of a randomized, double-blind clinical trial

BACKGROUND

In vitro and ex vivo studies have suggested that plant sterols and stanols can shift the T helper (Th) 1/Th2 balance toward a Th1-type immune response, which may be beneficial in Th2-dominant conditions such as asthma and allergies.

OBJECTIVE

We evaluated in vivo whether plant stanol esters affect the immune response in asthma patients.

DESIGN

Fifty-eight asthma patients participated in a randomized, double-blind, placebo-controlled intervention study. All subjects started with a 2-wk run-in period in which they consumed 150 mL control soy-based yogurt without added plant stanol esters/d. Next, an 8-wk experimental period was started in which one-half of the participants received plant stanol enriched soy-based yogurts (4.0 g plant stanols/d), whereas the other one-half of subjects continued the consumption of control yogurts. After 4 wk of daily plant stanol consumption, all participants were vaccinated against hepatitis A virus (HAV), and the increase of antibody titres was monitored weekly until 4 wk after vaccination.

RESULTS

Asthma patients in the plant stanol ester group showed higher antibody titres against HAV 3 and 4 wk after vaccination [19% (P = 0.037) and 22% (P = 0.030), respectively]. Also, substantial reductions in plasma total immunoglobulin E, interleukin (IL)-1β, and tumor necrosis factor-α were shown in the plant stanol ester group. The increase in serum plant stanol concentrations was correlated significantly with the decrease in IL-13 concentrations and the Th1 switch in the Th1/Th2 balance. However, no absolute differences in cytokine production between the plant stanol ester group and the control group were shown.

CONCLUSION

To the best of our knowledge, we are among the first authors to show that plant stanol ester consumption improves the immune function in vivo in asthma patients. This trial was registered at clinicaltrials.gov as NCT01715675.

Scale-up of a physiologically-based pharmacokinetic model to predict the disposition of monoclonal antibodies in monkeys

Preclinical assessment of monoclonal antibody (mAb) disposition during drug development often includes investigations in non-human primate models. In many cases, mAb exhibit non-linear disposition that relates to mAb-target binding [i.e., target-mediated disposition (TMD)]. The goal of this work was to develop a physiologically-based pharmacokinetic (PBPK) model to predict non-linear mAb disposition in plasma and in tissues in monkeys. Physiological parameters for monkeys were collected from several sources, and plasma data for several mAbs associated with linear pharmacokinetics were digitized from prior literature reports. The digitized data displayed great variability; therefore, parameters describing inter-antibody variability in the rates of pinocytosis and convection were estimated. For prediction of the disposition of individual antibodies, we incorporated tissue concentrations of target proteins, where concentrations were estimated based on categorical immunohistochemistry scores, and with assumed localization of target within the interstitial space of each organ. Kinetics of target-mAb binding and target turnover, in the presence or absence of mAb, were implemented. The model was then employed to predict concentration versus time data, via Monte Carlo simulation, for two mAb that have been shown to exhibit TMD (2F8 and tocilizumab). Model predictions, performed a priori with no parameter fitting, were found to provide good prediction of dose-dependencies in plasma clearance, the areas under plasma concentration versu time curves, and the time-course of plasma concentration data. This PBPK model may find utility in predicting plasma and tissue concentration versus time data and, potentially, the time-course of receptor occupancy (i.e., mAb-target binding) to support the design and interpretation of preclinical pharmacokinetic-pharmacodynamic investigations in non-human primates.

Across-Species Scaling of Monoclonal Antibody Pharmacokinetics Using a Minimal PBPK Model

PURPOSE

To examine the across-species scalability of monoclonal antibody (mAb) pharmacokinetics (PK) and assess similarities in tissue distribution across species using a recently developed minimal PBPK (mPBPK) model.

METHODS

Twelve sets of antibody PK data from various species were obtained from the literature, which were jointly and individually analyzed. In joint analysis, vascular reflection coefficients for tissues with either tight (σ 1 ) or leaky endothelium (σ 2 ) were assumed consistent across species with systemic clearance allometrically scaled (CL = a∙BW (b) ). Four parameters (σ 1 , σ 2 , a, and b) were estimated in the joint analysis. In addition, the PK from each species was individually analyzed to assess species similarities in tissue distribution.

RESULTS

Twelve mAb PK profiles were well-captured by the mPBPK model in the joint analysis. The estimated σ 1 ranged 0.690 to 0.999 with an average of 0.908; and σ 2 ranged 0.258 to 0.841 with an average of 0.579. Clearance was reasonably scaled and b ranged 0.695 to 1.27 averaging 0.91. Predictions of plasma concentrations for erlizumab and canakinumab in humans using parameters obtained from fitting animal data were consistent with actual measurements.

CONCLUSIONS

Therapeutic mAbs given IV usually exhibit biexponential kinetics with their distribution properties best captured using physiological concepts. The mPBPK modeling approach may facilitate efforts in translating antibody distribution and overall PK across species.

Non-Clinical Pharmacokinetics, Prediction of Human Pharmacokinetics and First-in-Human Dose Selection for CNTO 5825, an Anti-Interleukin-13 Monoclonal Antibody

CNTO 5825 is a human anti-interleukin-13 (IL-13) monoclonal antibody (mAb) that inhibits binding of human IL-13 to IL-13Rα1 and IL-13Rα2. The purpose of this investigation was to predict human pharmacokinetics (PK) of CNTO 5825 using different allometric approaches and non-clinical PK data in order to select the right and safe doses for first-in-human (FIH) study. After intravenous (IV) administration of CNTO 5825, clearance (CL) ranged from 9.98 to 11.49 ml/day/kg in rats and from 5.78 to 7.19 ml/day/kg in cynomolgus monkeys. The volume of distribution at steady-state (Vss) in rats was large (151.52-155.64 ml/kg) compared to cynomolgus monkey (49.77-61.10 ml/kg). The terminal half-life (T1/2 ) ranged from 12.29 to 14.15 days in rats and from 6.61 to 7.73 days in cynomolgus monkeys. The PK of CNTO 5825 was linear in 1-10 mg/kg dose range in both species. The bioavailability after subcutaneous (SC) administration was 94% and 79% in rats and cynomolgus monkeys, respectively. The predicted CL and Vss based on allometric methods and PK data from rats and monkeys were within twofold of observed CL and Vss in human beings; the predicted CL and Vss in human beings (70 kg) based on time-invariant method with combined PK data from rats and monkeys were 4.84 ± 1.13 ml/day/kg and 68.93 ± 35.55 ml/kg, respectively. The selected doses for the FIH study based on time-invariant method and no observed adverse effect level in toxicity studies in rats and monkeys provided exposures that were subsequently shown to be well tolerated and safe in human beings.

Pharmacokinetics of anti-IL17A and anti-IL22 peptide-antibody bispecific genetic fusions in mice

The peptide-antibody (Ab) genetic fusion is a promising technology for targeting multiple antigens in a single Ab-like molecule. We have recently described generation and in vitro characterization of several such genetic fusions, using an interleukin (IL)-17A binding peptide and an anti-IL-22 Ab as a model system. In this study we assessed pharmacokinetic profiles of these model genetic fusions in mice. Specifically an IL-17A binding peptide was fused to either the heavy chain or both the heavy and the light chains of an anti-IL22 human IgG1 (referred to Compounds 1 or 2, respectively). Swiss Webster mice were given a single 10 mg/kg IV dose of Compound 1 or Compound 2 and serum concentrations were measured by a fused molecule immunoassay, in which IL-17A was used as a capture and anti-human IgG was used as a detector. In addition, serum samples were assayed using a total human IgG immunoassay. PK parameters were calculated by non-compartmental modeling. The two genetic fusions had similar PK profiles, with total body clearance of ~0.9-1.0 mL/h/kg, volume of distribution at steady-state of ~63-65 mL/kg, and elimination half-life of ~40 h. Our study provides the first characterization of the PK properties of peptide-Ab genetic fusions and suggests that although these genetic fusions appear to be eliminated faster than a typical Ab, the PK profile may be suitable for preclinical and clinical testing.

Pharmacokinetics, biocompatibility and bioavailability of a controlled release monoclonal antibody formulation

The sustained and localized delivery of monoclonal antibodies has become highly relevant, because of the increasing number of investigated local delivery applications in recent years. As the local delivery of antibodies is associated with high technological hurdles, very few successful approaches have been reported in the literature so far. Alginate-based delivery systems were previously described as promising sustained release formulations for monoclonal antibodies (mAbs). In order to further investigate their applicability, a single-dose animal study was conducted to compare the biocompatibility, the pharmacokinetics and the bioavailability of a human monoclonal antibody liquid formulation with two alginate-based sustained delivery systems after subcutaneous administration in rats. 28 days after injection, the depot systems were still found in the subcutis of the animals. A calcium cross-linked alginate formulation, which was injected as a hydrogel, was present as multiple compartments separated by subcutaneous tissue. An in situ forming alginate formulation was recovered as a single compact and cohesive structure. It can be assumed that the multiple compartments of the hydrogel formulation led to almost identical pharmacokinetic profiles for all tested animals, whereas the compact nature of the in situ forming system resulted in large interindividual variations in pharmacokinetics. As compared to the liquid formulation the hydrogel formulations led to lower mAb serum levels, and the in situ forming system to a shift in the time to reach the maximum mAb serum concentration (Tmax) from 2 to 4 days. Importantly, it was shown that after 28 days only marginal amounts of residual mAb were present in the alginate matrix and in the tissue at the injection site indicating nearly complete release. In line with this finding, systemic drug bioavailability was not affected by using the controlled release systems. This study successfully demonstrates the suitability and underlines the potential of polyanionic systems for local and controlled mAb delivery.

A novel monoclonal antibody to secreted frizzled-related protein 2 inhibits tumor growth

Secreted frizzled-related protein 2 (SFRP2) is overexpressed in human angiosarcoma and breast cancer and stimulates angiogenesis via activation of the calcineurin/NFATc3 pathway. There are conflicting reports in the literature as to whether SFRP2 is an antagonist or agonist of β-catenin. The aims of these studies were to assess the effects of SFRP2 antagonism on tumor growth and Wnt-signaling and to evaluate whether SFRP2 is a viable therapeutic target. The antiangiogenic and antitumor properties of SFRP2 monoclonal antibody (mAb) were assessed using in vitro proliferation, migration, tube formation assays, and in vivo angiosarcoma and triple-negative breast cancer models. Wnt-signaling was assessed in endothelial and tumor cells treated with SFRP2 mAb using Western blotting. Pharmacokinetic and biodistribution data were generated in tumor-bearing and nontumor-bearing mice. SFRP2 mAb was shown to induce antitumor and antiangiogenic effects in vitro and inhibit activation of β-catenin and nuclear factor of activated T-cells c3 (NFATc3) in endothelial and tumor cells. Treatment of SVR angiosarcoma allografts in nude mice with the SFRP2 mAb decreased tumor volume by 58% compared with control (P = 0.004). Treatment of MDA-MB-231 breast carcinoma xenografts with SFRP2 mAb decreased tumor volume by 52% (P = 0.03) compared with control, whereas bevacizumab did not significantly reduce tumor volume. Pharmacokinetic studies show the antibody is long circulating in the blood and preferentially accumulates in SFRP2-positive tumors. In conclusion, antagonizing SFRP2 inhibits activation of β-catenin and NFATc3 in endothelial and tumor cells and is a novel therapeutic approach for inhibiting angiosarcoma and triple-negative breast cancer.

Agonistic TAM-163 antibody targeting tyrosine kinase receptor-B: applying mechanistic modeling to enable preclinical to clinical translation and guide clinical trial design

TAM-163, an agonist monoclonal antibody targeting tyrosine receptor kinase-B (TrkB), is currently being investigated as a potential body weight modulatory agent in humans. To support the selection of the dose range for the first-in-human (FIH) trial of TAM-163, we conducted a mechanistic analysis of the pharmacokinetic (PK) and pharmacodynamic (PD) data (e.g., body weight gain) obtained in lean cynomolgus and obese rhesus monkeys following single doses ranging from 0.3 to 60 mg/kg. A target-mediated drug disposition (TMDD) model was used to describe the observed nonlinear PK and Emax approach was used to describe the observed dose-dependent PD effect. The TMDD model development was supported by the experimental determination of the binding affinity constant (9.4 nM) and internalization rate of the drug-target complex (2.08 h(-1)). These mechanistic analyses enabled linking of exposure, target (TrkB) coverage, and pharmacological activity (e.g., PD) in monkeys, and indicated that ≥ 38% target coverage (time-average) was required to achieve significant body weight gain in monkeys. Based on the scaling of the TMDD model from monkeys to humans and assuming similar relationship between the target coverage and pharmacological activity between monkey and humans, subcutaneous (SC) doses of 1 and 15 mg/kg in humans were projected to be the minimally and the fully pharmacologically active doses, respectively. Based on the minimal anticipated biological effect level (MABEL) approach for starting dose selection, the dose of 0.05 mg/kg (3 mg for a 60 kg human) SC was recommended as the starting dose for FIH trials, because at this dose level<10% target coverage was projected at Cmax (and all other time points). This study illustrates a rational mechanistic approach for the selection of FIH dose range for a therapeutic protein with a complex model of action.

Antibody biodistribution coefficients: inferring tissue concentrations of monoclonal antibodies based on the plasma concentrations in several preclinical species and human

Tissue vs. plasma concentration profiles have been generated from a physiologically-based pharmacokinetic model of monoclonal antibody (mAb). Based on the profiles, we hypothesized that a linear relationship between the plasma and tissue concentrations of non-binding mAbs could exist; and that the relationship may be generally constant irrespective of the absolute mAb concentration, time, and animal species being analyzed. The hypothesis was verified for various tissues in mice, rat, monkey, and human using mAb or antibody-drug conjugate tissue distribution data collected from diverse literature. The relationship between the plasma and various tissue concentrations was mathematically characterized using the antibody biodistribution coefficient (ABC). Estimated ABC values suggest that typically the concentration of mAb in lung is 14.9%, heart 10.2%, kidney 13.7%, muscle 3.97%, skin 15.7%, small intestine 5.22%, large intestine 5.03%, spleen 12.8%, liver 12.1%, bone 7.27%, stomach 4.98%, lymph node 8.46%, adipose 4.78%, brain 0.351%, pancreas 6.4%, testes 5.88%, thyroid 67.5% and thymus is 6.62% of the plasma concentration. The validity of using the ABC to predict mAb concentrations in different tissues of mouse, rat, monkey, and human species was evaluated by generating validation data sets, which demonstrated that predicted concentrations were within 2-fold of the observed concentrations. The use of ABC to infer tissue concentrations of mAbs and related molecules provides a valuable tool for investigating preclinical or clinical disposition of these molecules. It can also help eliminate or optimize biodistribution studies, and interpret efficacy or toxicity of the drug in a particular tissue.

Targeting interleukin-4 in asthma: lost in translation?

The first discovery that interleukin-4 (IL-4) is crucial in the development of allergic airway inflammation originates from the early 1990s. Whereas initial studies in experimental animal models provided the community with the optimistic view that targeting IL-4 would be the ultimate solution for treating asthma, the translation of these findings to the clinic has not been evident and has not yet fulfilled the expectations. Many technical challenges have been encountered in the attempts to modulate IL-4 expression or activity and in transferring knowledge of preclinical studies to clinical trials. Moreover, biological redundancies between IL-4 and IL-13 have compelled a simultaneous blockade of both cytokines. A number of phase I/II studies are now providing us with clinical evidence that targeting IL-4/IL-13 may provide some clinical benefit. However, the initial view that asthma is a purely Th2-mediated disease had to be revised. Currently, different asthma phenotypes have been described, implying that blocking specifically Th2 cytokines, such as IL-4, IL-5, and IL-13, should be targeted to only a specific subset of patients. Taking this into consideration, IL-4 (together with IL-13) deserves attention as subject of further investigations to treat asthma. In this review, we will address the role of IL-4 in asthma, describe IL-4 signaling, and give an overview of preclinical and clinical studies targeting the IL-4 Receptor pathway.

IL-13 antibodies influence IL-13 clearance in humans by modulating scavenger activity of IL-13Rα2

Human studies using Abs to two different, nonoverlapping epitopes of IL-13 suggested that epitope specificity can have a clinically significant impact on clearance of IL-13. We propose that Ab modulation of IL-13 interaction with IL-13Rα2 underlies this effect. Two Abs were administered to healthy subjects and mild asthmatics in separate dose-ranging studies and allergen-challenge studies. IMA-638 allows IL-13 interaction with IL-13Rα1 or IL-13Rα2 but blocks recruitment of IL-4Rα to the IL-13/IL-13Rα1 complex, whereas IMA-026 competes with IL-13 interaction with IL-13Rα1 and IL-13Rα2. We found ∼10-fold higher circulating titer of captured IL-13 in subjects treated with IMA-026 compared with those administered IMA-638. To understand how this difference could be related to epitope, we asked whether either Ab affects IL-13 internalization through cell surface IL-13Rα2. Humans inducibly express cell surface IL-13Rα2 but lack the soluble form that regulates IL-13 responses in mice. Cells with high IL-13Rα2 expression rapidly and efficiently depleted extracellular IL-13, and this activity persisted in the presence of IMA-638 but not IMA-026. The potency and efficiency of this clearance pathway suggest that cell surface IL-13Rα2 acts as a scavenger for IL-13. These findings could have important implications for the design and characterization of IL-13 antagonists.

Monoclonal antibodies: interspecies scaling with minimal preclinical information

Interspecies scaling for predicting human pharmacokinetics with information from multiple animal species is an established approach for small-molecule drugs. However, in general, the strategy is not a viable approach for therapeutic monoclonal antibodies, since relevant preclinical information is often limited due to highly specific biological activity and unique disposition mechanisms of these biologic agents. Existing data from a limited database indicates that applying minimal but relevant preclinical information and an appropriate approach; for example, fixed-exponent, provides a pragmatic and reasonably accurate prediction of human pharmacokinetics. This article briefly reviews the factors that affect the disposition of monoclonal antibodies and reiterates the importance of biological similarities between animal species and humans when selecting preclinical information for interspecies scaling. The article outlines the rationalization for utilizing the one-species with fixed-exponent approach, with discussions focused on the assumptions in allometry and monoclonal antibodies disposition mechanisms, and provides specific considerations related to practically applying such an approach.

Airway disease: the use of large animal models for drug discovery

Large animal models have contributed to our current understanding of respiratory pathophysiology and the effects of pulmonary disease modifying drugs. For drug development, the benefit of using large animals over smaller animal species is primarily due to the greater similarity between humans and equivalent sized animals in terms of gross anatomy, morphometry, structure and physiology of their respiratory systems. Thus, when appropriate lung structure and function are required for correctly assessing the efficacy of novel drugs, large animals can play an important role in the development of these drugs to combat respiratory disease. The most widely used and best characterised large animal for drug development has been the sheep model of asthma. Recently, large animal models for chronic obstructive pulmonary disease (COPD) and cystic fibrosis (CF) have been reported but thus far have not been used extensively for drug development. Some important limitations of using large animals are the large costs associated with this type of research, as well as the poorer understanding of disease mechanisms in these species relative to rodents. In this review we discuss the extent of correlations between preclinical testing performed in large animal models and the initial indication of clinical efficacy in ongoing clinical trials.

Projecting human pharmacokinetics of therapeutic antibodies from nonclinical data: what have we learned?

The pharmacokinetics (PK) of therapeutic antibodies is determined by target and non-target mediated mechanisms. These antibody-specific factors need to be considered during prediction of human PK based upon preclinical information. Principles of allometric scaling established for small molecules using data from multiple animal species cannot be directly applied to antibodies. Here, different methods for projecting human clearance (CL) from animal PK data for 13 therapeutic monoclonal antibodies (mAbs) exhibiting linear PK over the tested dose ranges were examined: simple allometric scaling (CL versus body weight), allometric scaling with correction factors, allometric scaling based on rule of exponent and scaling from only cynomolgus monkey PK data. A better correlation was obtained between the observed human CL and the estimated human CL based on cynomolgus monkey PK data and an allometric scaling exponent of 0.85 for CL than other scaling approaches. Human concentration-time profiles were also reasonably predicted from the cynomolgus monkey data using species-invariant time method with a fixed exponent of 0.85 for CL and 1.0 for volume of distribution. In conclusion, we expanded our previous work and others and further confirmed that PK from cynomolgus monkey alone can be successfully scaled to project human PK profiles within linear range using simplify allometry and Dedrick plots with fixed exponent.

An open-label, single-dose bioavailability study of the pharmacokinetics of CAT-354 after subcutaneous and intravenous administration in healthy males

AIM

To assess the bioavailability and pharmacokinetics of CAT-354, an anti-IL-13 human monoclonal IgG4 antibody, following subcutaneous (s.c.) and intravenous (i.v.) administration.

METHODS

This was a single-dose, randomized, open-label, parallel-group bioavailability study. Healthy male subjects aged 20-54 years were randomly assigned to one of three dose groups (n= 10/group) to receive CAT-354: 150 mg i.v.; 150 mg s.c. or 300 mg s.c. (two 150 mg injections). Serum pharmacokinetics, adverse events (AEs), vital signs, electrocardiograms and laboratory parameters were assessed.

RESULTS

CAT-354 showed bioavailability of 62% and 60% after 150 mg and 300 mg s.c. doses, respectively, and linear pharmacokinetics over the dose range tested. Peak serum concentrations in the s.c. groups occurred after 3-9 (median 5) days, with a mean elimination half-life of 19.2 +/- 3.1 days (150 mg) and 19.4 +/- 3.59 days (300 mg) after s.c. and 21.4 +/- 2.46 days after i.v. administration. Volume of distribution at steady state (V(ss)) was 4960 +/- 1440 ml kg(-1) after i.v. (slightly greater than plasma volume). Average apparent clearances (CL/F) were 292 +/- 82.3 and 307 +/- 109 ml day(-1) after 150 and 300 mg s.c., respectively; systemic CL of 188 +/- 84.0 ml day(-1) after i.v. dosing was consistent with endogenous IgG and reticuloendothelial elimination. No severe or serious AEs occurred. Among 40 reported AEs, 25 were headache, sinus disorders/respiratory symptoms and changes in body temperature perception.

CONCLUSIONS

CAT-354 exhibited bioavailability of approximately 60% when given s.c. to healthy male subjects.

Biodistribution of [125I]-labeled therapeutic proteins: application in protein drug development beyond oncology

The majority of biodistribution studies of therapeutic proteins published to date focus on tumor-targeting agents. In this report we present a number of case studies that demonstrate the utility of biodistribution studies during preclinical development of biotherapeutics for non oncology indications, as well as provide a practical perspective on the methodology applied to these studies. For the commonly used classes of biologics (such as human monoclonal antibodies), biodistribution profiles may be compared to those of other therapeutics of the same class and compounds with unexpected off-target mediated uptake may be identified. Temporal biodistribution profiles may be used to address kinetics and reversibility of target- and/or off-target-mediated accumulation. In cases when circulating biotherapeutic is rapidly eliminated from circulation due to the formation of anti-product antibodies, tissue data may provide useful insight on test article exposure at the site of therapeutic action (or at the site of toxicity). Comparison of temporal biodistribution profiles between the genetically engineered and wild-type mouse strains or between the disease models and healthy animals may provide useful insight on sites and kinetics of target-mediated elimination. Finally, biodistribution studies will be a useful tool to study in vivo disposition for a variety of existing and upcoming novel classes of protein compounds.

Pharmacokinetic allometric scaling of antibodies: application to the first-in-human dose estimation

The objectives of this study are: (i) to evaluate the predictive performance of interspecies scaling for antibodies to predict clearance, volume of distribution at steady state, and half-life in humans from animal data and (ii) to estimate first-in-human dose based on the predicted human clearance. Four methods were used to predict clearance in humans: (1) clearance versus body weight (simple allometry), (2) the product of clearance and maximum life-span potential (MLP) versus body weight, (3) the product of clearance and brain weight versus body weight, and (4) the application of a fixed exponent of 0.75. Based on the predicted human clearance, six methods were used to estimate the first-in-human dose. The predicted pharmacokinetic parameters and the estimated first-in-human dose of antibodies were compared with the observed human values. The results of the study indicated that the clearance of antibodies can be predicted with reasonable accuracy in humans and a good estimate of first human dose can be obtained from the predicted human clearance.

Physiologically-based PK/PD modelling of therapeutic macromolecules

Therapeutic proteins are a diverse class of drugs consisting of naturally occurring or modified proteins, and due to their size and physico-chemical properties, they can pose challenges for the pharmacokinetic and pharmacodynamic studies. Physiologically-based pharmacokinetics (PBPK) modelling has been effective for early in silico prediction of pharmacokinetic properties of new drugs. The aim of the present workshop was to discuss the feasibility of PBPK modelling of macromolecules. The classical PBPK approach was discussed with a presentation of the successful example of PBPK modelling of cyclosporine A. PBPK model was performed with transport of the cyclosporine across cell membranes, affinity to plasma proteins and active membrane transporters included to describe drug transport between physiological compartments. For macromolecules, complex PBPK modelling or permeability-limited and/or target-mediated distribution was discussed. It was generally agreed that PBPK modelling was feasible and desirable. The role of the lymphatic system should be considered when absorption after extravascular administration is modelled. Target-mediated drug disposition was regarded as an important feature for generation of PK models. Complex PK-models may not be necessary when a limited number of organs are affected. More mechanistic PK/PD models will be relevant when adverse events/toxicity are included in the PK/PD modelling.

Interspecies scaling of therapeutic monoclonal antibodies: initial look

The authors evaluated interspecies scaling for the prediction of human clearance of 18 therapeutic monoclonal antibodies (mAbs). Human and monkey/chimpanzee data of 14 mAbs were classified based on the targeted antigens (soluble or membrane bound). Simple allometry and/or a time-invariant method (elementary Dedrick plot) were performed. Results indicate that human clearance might be accurately predicted from monkey data for mAbs targeting soluble receptors or membrane-bound receptors with limited tissue distribution using simplified allometry. The optimal exponents were estimated to be 0.85 or 0.90. If nonlinearity is anticipated at the human efficacious dose, pharmacokinetic parameters obtained at high doses in animals might not be sufficient for full pharmacokinetic characterization and prediction. Using prespecified criteria, including predicted human clearance (< or = or > 10 mL/d/kg), simplified allometric scaling might be helpful in predicting the effect of receptor-mediated clearance for mAbs targeting membrane-bound antigens. Furthermore, simplified allometry and an elementary Dedrick plot provide similar results in predicted clearance. Given the significant advantages offered by simplified allometry, it should be used when data are available from only 1 species. When reasonable data from > or =3 species are available, traditional allometry should be explored. Overall, clearance prediction is useful for human dose prediction in drug discovery and development.

Current status and challenges of cytokine pharmacology

The major concern of pharmacology about cytokines has originated from plentiful data showing association between gross changes in their production and pathophysiological processes. Despite the enigmatic role of cytokines in diseases, a number of them have become a subject of cytokine and anti-cytokine immunotherapies. Production of cytokines can be influenced by many endogenous and exogenous stimuli including drugs. Cells of the immune system, such as macrophages and lymphocytes, are richly endowed with receptors for the mediators of physiological functions, such as biogenic amines, adenosine, prostanoids, steroids, etc. Drugs, agonists or antagonists of these receptors can directly or indirectly up- and down-regulate secretion of cytokines and expression of cytokine receptors. Vice versa, cytokines interfere with drug pharmacokinetics and pharmacodynamics through the interactions with cytochrome P450 and multiple drug resistance proteins. The aim of the review is to encourage more intensive studies in these fields of cytokine pharmacology. It also outlines major areas of searching promising candidates for immunotherapeutic interventions.

Evaluation of an immunoassay for human-specific quantitation of therapeutic antibodies in serum samples from non-human primates

Pharmacokinetic characterization of therapeutic antibodies plays an important role during preclinical and clinical development. However, accurate pharmacokinetic evaluation of therapeutic antibodies in serum samples from non-human primates is often complicated by insufficient specificity of the assays to measure drug levels. The present paper describes the use of a murine monoclonal antibody in an immunoassay format to specifically and quantitatively measure human therapeutic antibodies in serum from non-human primates. This murine antibody is directed against a unique epitope on the constant region CH2 domain of all isotypes of human immunoglobulin G (IgG). The antibody, designated anti-human Fcgamma-pan: R10Z8E9, does not cross-react with serum from mouse, rat, and the non-human primates marmoset, rhesus macaque, cynomolgus monkey and baboon when using an enzyme-linked immunosorbent assay (ELISA) or surface plasmon resonance technology (Biacore) format for measurement of the therapeutic antibody. Use of the antibody anti-human Fcgamma-pan: R10Z8E9 as capturing and detection reagent allowed human-specific quantitation of total therapeutic antibody anti-IGF-1R in spiked cynomolgus monkey serum via a Sandwich ELISA format. In contrast, a commercially available polyclonal antibody (PAB) directed to the Fcgamma fragment of human IgG only specifically measured the therapeutic antibody in buffer samples, but not in serum from cynomolgus monkeys. This generic human IgG assay was already applied in several pharmacokinetic studies in cynomolgus monkeys to determine serum levels of different therapeutic antibodies, including the anti-IGF-1R. Validation of the assay for a humanized IgG1 therapeutic antibody against a membrane protein revealed a lower limit of quantitation of 8 ng/mL in undiluted serum. Intra-assay and inter-assay precision was characterized by a coefficient of variation of less than 10% and accuracy was within 15%. Dilutional linearity was evidenced by a recovery of 98.7-114% of expected concentrations. In conclusion, the monoclonal antibody anti-human Fcgamma-pan: R10Z8E9 provides a standard means for human-specific quantitation of therapeutic antibodies with high sensitivity in serum samples from non-human primates in a generic human IgG assay.

Pharmacokinetic and pharmacodynamic modeling of a humanized anti-IL-13 antibody in naive and Ascaris-challenged cynomolgus monkeys

PURPOSE

Neutralization of IL-13 is an attractive approach for treatment of asthma. In this report, we developed a novel PK-PD model that described the relationship between the circulating concentrations of total IL-13 and a neutralizing anti-IL-13 antibody (Ab-02) in the model of acute airway inflammation induced by Ascaris challenge to cynomolgus monkeys, as well as in naive monkeys.

METHODS

Cynomolgus monkeys were administered a single intravenous or subcutaneous dose of Ab-02. Total IL-13 and Ab-02 concentrations were measured by immunoassays.

RESULTS

Modeling and simulations indicated that: (1) Ascaris challenge induced approximately three-fold increase in circulating IL-13 concentrations, when compared to naive animals, consistent with the notion that Ascaris-induced airway inflammation was IL-13-mediated; (2) the transient increase in total IL-13 concentrations observed in both naive and Ascaris-challenged monkeys following Ab-02 administration was due to the increase in Ab-02-bound IL-13, while free IL-13 was decreased; and (3) the extent and duration of neutralization of circulating IL-13 were different in naive and Ascaris-challenged monkeys for the same Ab-02 dose regimen.

CONCLUSIONS

The PK-PD model presented in this report may be applied to study drug-ligand interactions when a free ligand cannot be directly assayed but total ligand concentrations are modulated by the drug administration.

Monoclonal antibody pharmacokinetics and pharmacodynamics

More than 20 monoclonal antibodies have been approved as therapeutic drugs by the US Food and Drug Administration, and it is quite likely that the number of approved antibodies will double in the next 7-10 years. Antibody drugs show several desirable characteristics, including good solubility and stability, long persistence in the body, high selectivity and specificity, and low risk for bioconversion to toxic metabolites. However, many antibody drugs demonstrate attributes that complicate drug development, including very poor oral bioavailability, incomplete absorption following intramuscular or subcutaneous administration, nonlinear distribution, and nonlinear elimination. In addition, antibody administration often leads to an endogenous antibody response, which may alter the pharmacokinetics and efficacy of the therapeutic antibody. Antibodies have been developed for a wide range of disease conditions, with effects produced through a complex array of mechanisms. This article attempts to provide a brief overview of the main determinants of antibody pharmacokinetics and pharmacodynamics. Clinical Pharmacology & Therapeutics (2008); 84, 5, 548-558 doi:10.1038/clpt.2008.170.

Interleukin-13 neutralization by two distinct receptor blocking mechanisms reduces immunoglobulin E responses and lung inflammation in cynomolgus monkeys

Interleukin (IL)-13 is a key cytokine driving allergic and asthmatic responses and contributes to airway inflammation in cynomolgus monkeys after segmental challenge with Ascaris suum antigen. IL-13 bioactivity is mediated by a heterodimeric receptor (IL-13Ralpha1/IL-4Ralpha) and can be inhibited in vitro by targeting IL-13 interaction with either chain. However, in cytokine systems, in vitro neutralization activity may not always predict inhibitory function in vivo. To address the efficacy of two different IL-13 neutralization mechanisms in a primate model of atopic disease, two humanized monoclonal antibodies to IL-13 were generated, with highly homologous properties, differing in epitope recognition. Ab01 blocks IL-13 interaction with IL-4Ralpha, and Ab02 blocks IL-13 interaction with IL-13Ralpha1. In a cynomolgus monkey model of IgE responses to A. suum antigen, both Ab01 and Ab02 effectively reduced serum titers of Ascaris-specific IgE and diminished ex vivo Ascaris-triggered basophil histamine release, assayed 8 weeks after a single administration of antibody. The two antibodies also produced comparable reductions in pulmonary inflammation after lung segmental challenge with Ascaris antigen. Increased serum levels of IL-13, lacking demonstrable biological activity, were seen postchallenge in animals given either anti-IL-13 antibody but not in control animals given human IgG of irrelevant specificity. These findings demonstrate a potent effect of IL-13 neutralization on IgE-mediated atopic responses in a primate system and show that IL-13 can be efficiently neutralized by targeting either the IL-4Ralpha-binding epitope or the IL-13Ralpha1-binding epitope.