Two first-in-human, open-label, phase I dose-escalation safety trials of MEDI-528, a monoclonal antibody against interleukin-9, in healthy adult volunteers

The role of IL-2 cytokine family in asthma

BACKGROUND

The interleukin-2 (IL-2) family of cytokines, including IL-2, IL-4, IL-7, IL-9, IL-15, and IL-21, are pivotal regulators of the immune response, impacting both innate and adaptive immunity. Understanding their molecular characteristics, receptor interactions, and signalling pathways is essential for elucidating their roles in health and disease.

OBJECTIVES

This review provides a comprehensive overview of the IL-2 family of cytokines, highlighting their molecular biology, receptor interactions, and signalling mechanisms. Furthermore, it explores the involvement of IL-2 family cytokines in the pathogenesis of chronic respiratory diseases, with a specific focus on chronic obstructive pulmonary disease (COPD) and asthma.

METHODS

A thorough literature review was conducted to gather insights into the molecular biology, receptor interactions, and signalling pathways of IL-2 family cytokines. Additionally, studies investigating the roles of these cytokines in chronic respiratory diseases, particularly COPD and asthma, were analysed to discern their implications in wider pathophysiology of disease.

RESULTS

IL-2 family cytokines exert pleiotropic effects on immune cells, modulating cellular proliferation, differentiation, and survival. Dysregulation of IL-2 family cytokines has been implicated in the pathogenesis of chronic respiratory illnesses, including COPD and asthma. Elevated levels of IL-2 and IL-9 have been associated with disease severity in COPD, while IL-4 and IL-9 play crucial roles in asthma pathogenesis by promoting airway inflammation and remodelling.

CONCLUSION

Understanding the intricate roles of IL-2 family cytokines in chronic respiratory diseases provides valuable insights into potential therapeutic targets for these conditions. Targeting specific cytokines or their receptors may offer novel treatment modalities to attenuate disease progression and improve clinical outcomes in patients with COPD and asthma.

Inter-Antibody Variability in the Clinical Pharmacokinetics of Monoclonal Antibodies Characterized Using Population Physiologically Based Pharmacokinetic Modeling

The objective of this work was to develop a population physiologically based pharmacokinetic (popPBPK) model to characterize the variability in the clinical PK of monoclonal antibodies (mAbs) following intravenous (IV) and subcutaneous (SC) administration. An extensive literature search was conducted and clinical PK data for FDA-approved as well as non-approved mAbs were collected. Training and validation datasets of 44 and 9 mAbs exhibiting linear pharmacokinetics were used for model development. The variability in antibody PK was captured by accounting for different rate constants of pinocytosis (CLup) and intracellular degradation (kdeg) for different mAbs. Typical values for CLup and kdeg and their respective inter-antibody variabilities (ωClup, ωKdeg) were estimated to be 0.32 L/h/L and 26.1 h-1 (73% and 46%). Varied absorption profiles following SC dosing were characterized by incorporating inter-antibody variability in local degradation (kSC) and rate of lymphatic uptake (S_Lu) of mAbs. Estimates for typical kSC and S_Lu values, and ωKsc,ωS_Lu, were found to be 0.0015 h-1 and 0.54 (193%, and 49%). FDA-approved mAbs showed less local degradation (0.0014 h-1 vs. 0.0038 h-1) compared with other clinically tested mAbs, whereas no substantial differences in physiological processes involved in disposition were observed. To evaluate the generalizability of estimated PK parameters and model validation, the final popPBPK model was used to simulate the range of expected PK for mAbs following SC administration of nine different mAbs that were not used for model-building purposes. The predicted PK of all nine mAbs was within the expected range specified a priori. Thus, the popPBPK model presented here may serve as a tool to predict the clinical PK of mAbs with linear disposition before administering them to humans. The model may also support preclinical-to-clinical translation and 'first-in-human' dose determination for mAbs.

Interleukin-9 promotes mast cell progenitor proliferation and CCR2-dependent mast cell migration in allergic airway inflammation

Allergic asthma is a chronic lung disease characterized by airway hyperresponsiveness and cellular infiltration that is exacerbated by immunoglobulin E-dependent mast cell (MC) activation. Interleukin-9 (IL-9) promotes MC expansion during allergic inflammation but precisely how IL-9 expands tissue MCs and promotes MC function is unclear. In this report, using multiple models of allergic airway inflammation, we show that both mature MCs (mMCs) and MC progenitors (MCp) express IL-9R and respond to IL-9 during allergic inflammation. IL-9 acts on MCp in the bone marrow and lungs to enhance proliferative capacity. Furthermore, IL-9 in the lung stimulates the mobilization of CCR2+ mMC from the bone marrow and recruitment to the allergic lung. Mixed bone marrow chimeras demonstrate that these are intrinsic effects in the MCp and mMC populations. IL-9-producing T cells are both necessary and sufficient to increase MC numbers in the lung in the context of allergic inflammation. Importantly, T cell IL-9-mediated MC expansion is required for the development of antigen-induced and MC-dependent airway hyperreactivity. Collectively, these data demonstrate that T cell IL-9 induces lung MC expansion and migration by direct effects on the proliferation of MCp and the migration of mMC to mediate airway hyperreactivity.

The Dichotomy of Interleukin-9 Function in the Tumor Microenvironment

Interleukin 9 (IL-9) is a cytokine with potent proinflammatory properties that plays a central role in pathologies such as allergic asthma, immunity to parasitic infection, and autoimmunity. More recently, IL-9 has garnered considerable attention in tumor immunity. Historically, IL-9 has been associated with a protumor function in hematological malignancies and an antitumor function in solid malignancies. However, recent discoveries of the dynamic role of IL-9 in cancer progression suggest that IL-9 can act as both a pro- or antitumor factor in various hematological and solid malignancies. This review summarizes IL-9-dependent control of tumor growth, regulation, and therapeutic applicability of IL-9 blockade and IL-9-producing cells in cancer.

Monoclonal antibodies in the management of asthma: Dead ends, current status and future perspectives

Patients with moderate-to-severe asthma may now be treated using a variety of monoclonal antibodies that target key inflammatory cytokines involved in disease pathogenesis. Existing clinical data on anti-IgE, anti-IL-5 and other immunological pathways indicate these therapies to offer reduced exacerbation rates, improved lung function, greater asthma control and better quality of life. However, as several patients still do not achieve satisfactory clinical response with the antibodies available, many more biologics, aiming different immunological pathways, are under evaluation. This review summarizes recent data on existing and potential monoclonal antibodies in asthma. Recent advances have resulted in the registration of a new antibody targeting TSLP (tezepelumab), with others being under development. Some of the researched monoclonal antibodies (e.g. anti-IL-13 tralokinumab and lebrikizumab or anti-IL-17A secukinumab) have shown optimistic results in preliminary research; however, these have been discontinued in asthma clinical research. In addition, as available monoclonal antibody treatments have shown little benefit among patients with T₂-low asthma, research continues in this area, with several antibodies in development. This article summarizes the available pre-clinical and clinical data on new and emerging drugs for treating severe asthma, discusses discontinued treatments and outlines future directions in this area.

Allergic airway recall responses require IL-9 from resident memory CD4+ T cells

Asthma is a chronic inflammatory lung disease with intermittent flares predominately mediated through memory T cells. Yet, the identity of long-term memory cells that mediate allergic recall responses is not well defined. In this report, using a mouse model of chronic allergen exposure followed by an allergen-free rest period, we characterized a subpopulation of CD4+ T cells that secreted IL-9 as an obligate effector cytokine. IL-9-secreting cells had a resident memory T cell phenotype, and blocking IL-9 during a recall challenge or deleting IL-9 from T cells significantly diminished airway inflammation and airway hyperreactivity. T cells secreted IL-9 in an allergen recall-specific manner, and secretion was amplified by IL-33. Using scRNA-seq and scATAC-seq, we defined the cellular identity of a distinct population of T cells with a proallergic cytokine pattern. Thus, in a recall model of allergic airway inflammation, IL-9 secretion from a multicytokine-producing CD4+ T cell population was required for an allergen recall response.

Physiologically Based Modeling to Predict Monoclonal Antibody Pharmacokinetics in Humans from in vitro Physiochemical Properties

A model-based framework is presented to predict monoclonal antibody (mAb) pharmacokinetics (PK) in humans based on in vitro measures of antibody physiochemical properties. A physiologically based pharmacokinetic (PBPK) model is used to explore the predictive potential of 14 in vitro assays designed to measure various antibody physiochemical properties, including nonspecific cell-surface interactions, FcRn binding, thermal stability, hydrophobicity, and self-association. Based on the mean plasma PK time course data of 22 mAbs from humans reported in the literature, we found a significant positive correlation (R = 0.64, p = .0013) between the model parameter representing antibody-specific vascular to endothelial clearance and heparin relative retention time, an in vitro measure of nonspecific binding. We also found that antibody-specific differences in paracellular transport due to convection and diffusion could be partially explained by antibody heparin relative retention time (R = 0.52, p = .012). Other physiochemical properties, including antibody thermal stability, hydrophobicity, cross-interaction and self-association, in and of themselves were not predictive of model-based transport parameters. In contrast to other studies that have reported empirically derived expressions relating in vitro measures of antibody physiochemical properties directly to antibody clearance, the proposed PBPK model-based approach for predicting mAb PK incorporates fundamental mechanisms governing antibody transport and processing, informed by in vitro measures of antibody physiochemical properties, and can be expanded to include more descriptive representations of each of the antibody processing subsystems, as well as other antibody-specific information.

Estimation of Clearance and Bioavailability of Therapeutic Monoclonal Antibodies from Only Subcutaneous Injection Data in Humans Based on Comprehensive Analysis of Clinical Data

Introduction

Theoretically, the separate estimation of clearance (CL) and bioavailability (F) requires both intravenous and extravascular injection data. This study investigated whether CL and subcutaneous F of therapeutic monoclonal antibodies (mAbs) in humans can be separately estimated from subcutaneous injection data only.

Methods

First, the geometric mean of linear pharmacokinetic parameters (CL, intercompartmental CL [Q], volume of distribution in the central compartment [V_c], and volume of distribution in the peripheral compartment [V_p]) after intravenous injection for mAbs in humans that have been reported in public data sources was estimated from 103 mAbs with linear pharmacokinetics and 44 mAbs with nonlinear pharmacokinetics. Next, we estimated the CL and F of 25 mAbs with linear pharmacokinetics from plasma/serum mAb concentration–time profiles after subcutaneous injection in humans by fixing the geometric mean of Q, V_c, and V_p based on the public data. Moreover, the plasma/serum concentration–time profile of 25 mAbs after intravenous injection was simulated using the estimated CL and the geometric mean of Q, V_c, and V_p.

Results

There were no significant differences in parameters among subclasses (immunoglobulin [Ig] G1, 2, and 4) or in linearity (derivation from linear and nonlinear pharmacokinetics). Using only subcutaneous injection data, we successfully estimated the CL of 23/25 mAbs (92%) and F of all 25 mAbs (100%) within 1.5-fold of the observed value. Moreover, overall, the simulated concentration–time profiles were largely consistent with observed data (90.8% within 1.5-fold of the observed values).

Conclusions

This approach does not require intravenous injection data to separately estimate CL and F after subcutaneous injection in humans and can therefore accelerate the clinical development of mAbs.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40262-021-01023-z.

Machine Learning Attempts for Predicting Human Subcutaneous Bioavailability of Monoclonal Antibodies

PURPOSE

One knowledge gap related to subcutaneous (SC) delivery is unpredictable and variable bioavailability. This study was aimed to develop machine learning methods to predict whether mAb's bioavailability was ≥70% or below, without completely knowing the mechanism and causality between inputs and outputs.

METHODS

A database of mAb SC products was built. The model training and validation were accomplished based on this database and a set of the inputs (product properties) were mapped to the output (bioavailability) using different machine learning algorithms. Dimensionality reduction was undertaken using principal component analysis (PCA).

RESULTS

The bioavailability of the mAb products being investigated varied from 35% to 90%. The tree-based methods, including random forest (RF), Adaptive Boost (AdaBoost), and decision tree (DT) presented the best predictability and generalization power on bioavailability classification. The models based on Multi-layer perceptron (MLP), Gaussian Naïve Bayes (GaussianNB), and k nearest neighbor (kNN) algorithms also provided acceptable prediction accuracy.

CONCLUSION

Machine learning could be a potential tool to predict mAb's bioavailability. Since all input features were acquired using theoretical calculations and predictions rather than experiments, the models may be particularly applicable to some early-stage research activities such as mAb molecule triage, design/optimization, mutant screening, molecule selection, and formulation design.

IL-9-producing T cells: potential players in allergy and cancer

IL-9-producing CD4⁺ T cells have been considered to represent a distinct T helper cell (T_H cell) subset owing to their unique developmental programme in vitro, their expression of distinct transcription factors (including PU.1) and their copious production of IL-9. It remains debatable whether these cells represent a truly unique T_H cell subset in vivo, but they are closely related to the T helper 2 (T_H2) cells that are detected in allergic diseases. In recent years, increasing evidence has also indicated that IL-9-producing T cells may have potent abilities in eradicating advanced tumours, particularly melanomas. Here, we review the latest literature on the development of IL-9-producing T cells and their functions in disease settings, with a particular focus on allergy and cancer. We also discuss recent ideas concerning the therapeutic targeting of these cells in patients with chronic allergic diseases and their potential use in cancer immunotherapy.

Predicting monoclonal antibody pharmacokinetics following subcutaneous administration via whole-body physiologically-based modeling

Use of the subcutaneous (SC) route for administering monoclonal antibodies (mAbs) to treat chronic conditions has been hindered because of an incomplete understanding of fundamental mechanisms controlling mAb absorption from the SC site, and due to the limited translatability of preclinical studies. In this paper, we report on the development and evaluation of a whole-body physiologically-based model to predict mAb pharmacokinetics following SC administration. The circulatory model is based on the physiological processes governing mAb transport and includes two mAb-specific parameters representing differences in pinocytosis rate and the diffusive/convective transport rates among mAbs. At the SC administration site, two additional parameters are used to represent mAb differences in lymphatic capillary uptake and in pre-systemic clearance. Model development employed clinical intravenous (IV) plasma PK data from 20 mAbs and SC plasma PK data from 12 of these mAbs, as obtained from the literature. The resulting model reliably described both the IV and SC measured plasma concentration data. In addition, a metric based on the positive charge across the mAb's complementarity determining region vicinity was found to positively correlate with the model-based estimates of the mAb-specific parameter governing organ/tissue pinocytosis transport and with estimates of the mAb's SC lymphatic capillary clearance. These two relationships were incorporated into the model and accurately predicted the SC PK profiles of three out of four separate mAbs not included in model development. The whole-body physiologically-based model reported herein, provides a platform to characterize and predict the plasma disposition of monoclonal antibodies following SC administration in humans.

A 7-Amino Acid Peptide Mimic from Hepatitis C Virus Hypervariable Region 1 Inhibits Mouse Lung Th9 Cell Differentiation by Blocking CD81 Signaling during Allergic Lung Inflammation

T helper (Th) cells orchestrate allergic lung inflammation in asthma pathogenesis. Th9 is a novel Th cell subset that mainly produces IL-9, a potent proinflammatory cytokine in asthma. A 7-amino acid peptide (7P) of the hypervariable region 1 (HVR1) of hepatitis C virus has been identified as an important regulator in the type 2 cytokine (IL-4, IL-5, and IL-13) immune response. However, it is unknown whether 7P regulates Th9 cell differentiation during ovalbumin- (OVA-) induced allergic lung inflammation. To address this, we studied wild-type mice treated with 7P and a control peptide in an in vivo mouse model of OVA-induced allergic inflammation and an in vitro cell model of Th9 differentiation, using flow cytometry, cytokine assays, and quantitative PCR. The binding of 7P to CD81 on naïve CD4⁺ T cells during lung Th9 differentiation was determined using CD81 overexpression and siRNA knockdown analyses. Administration of 7P significantly reduced Th9 cell differentiation after OVA sensitization and exposure. 7P also inhibited Th9 cell differentiation from naïve and memory CD4⁺ T cells in vitro. Furthermore, 7P inhibited the differentiation of human Th9 cells with high CD81 expression from naïve CD4⁺ T cells by blocking CD81 signaling. CD81 siRNA significantly reduced Th9 cell differentiation from naïve CD4⁺ T cells in vitro. Interestingly, CD81 overexpression in human naïve CD4⁺ T cells also enhanced Th9 development in vitro. These data indicate that 7P may be a good candidate for reducing IL-9 production in asthma.

Isolation and Purification of Th9 Cells for the Study of Inflammatory Diseases in Research and Clinical Settings

Th9 cells are associated with atopic and inflammatory diseases, and their increased levels and function correlate with the severity of symptoms in various inflammatory disorders including asthma, food allergy, atopic dermatitis, ulcerative colitis, and psoriatic arthritis. Thus, clinical trials are warranted to evaluate the role of Th9 cells in allergic diseases with the goal of controlling these ailments.Circulating T cells (naïve or memory CD4+ T cells) purified from human blood and expanded using anti-CD3 and anti-CD28 antibodies can be treated with appropriate cytokines in order to polarize them to the Th9 phenotype as evidenced by their production of IL-9. When treated in vitro with cholecalciferol or 1,25(OH)₂ vitamin D3, cells polarized under Th9 conditions significantly downregulate production of IL-9. The percentage of polarized Th9 memory cells from patients treated with steroids or other modalities can be monitored during clinical trials and compared to control populations.

From bench to bedside: Therapeutic potential of interleukin-9 in the treatment of asthma

Initially identified as a T cell and mast cell growth factor, interleukin (IL)-9 has long been recognized as an important mediator of asthma. Recently, accumulating results from transgenic mice demonstrated that systemic or lung-specific overexpression of IL-9 caused asthma-associated symptoms. Moreover, anti-mIL-9 antibody (Ab) blocking treatment alleviated disease in animal models of asthma. In light of the large quantity of data from the murine models, MEDI-528, a humanized anti-IL-9 monoclonal Ab has been produced to assess the activity of IL-9 on human asthma. In order to ascertain whether it is a successful translation from bench to bedside, the biological features of IL-9 were evaluated and up-to-date information regarding the role of IL-9 in different experimental murine models and human asthma were summarized.

Th9 cells and IL-9 in autoimmune disorders: Pathogenesis and therapeutic potentials

Naïve CD4⁺ T cells are pleiotropically divided into various T helper (Th) cell subsets, according to their pivotal roles in the regulation of immune responses. The differentiation of Th9 cells, an interleukin (IL)-9 producing subset, can be impacted by specific environmental cues, co-stimulation with transforming growth factor β (TGF-β) and IL-4, and other regulatory factors. Although IL-9 has been recognized as a classical Th2-related cytokine, recent studies have indicated that IL-9-producing cells contribute to a group of autoimmune disorders including systemic lupus erythematosus (SLE), multiple sclerosis (MS), inflammatory bowel diseases (IBD), rheumatoid arthritis (RA) and psoriasis. Studies of Th9 cells in autoimmune diseases, although in their infancy, are expected to be of growing interest in the study of potential mechanisms of cytokine regulatory pathways and autoimmune pathogenesis. Several in vitro and in vivo pre-clinical trials have been conducted to explore potential therapeutic strategies by targeting the IL-9 pathway. Specifically, anti-IL-9 monoclonal antibodies (mAbs) and IL-9 inhibitors may potentially be used for the clinical treatment of allergic diseases, autoimmune diseases or cancers. Here, we review recent research on Th9 cells and IL-9 pertaining to cell differentiation, biological characteristics and pivotal cellular inter-relationships implicated in the development of various diseases.

Determination of the starting dose in the first-in-human clinical trials with monoclonal antibodies: a systematic review of papers published between 1990 and 2013

A systematic review was performed to evaluate how the maximum recommended starting dose (MRSD) was determined in first-in-human (FIH) studies with monoclonal antibodies (mAbs). Factors associated with the choice of each MRSD determination method were also identified. PubMed was searched for FIH studies with mAbs published in English between January 1, 1990 and December 31, 2013, and the following information was extracted: MRSD determination method, publication year, therapeutic area, antibody type, safety factor, safety assessment results after the first dose, and number of dose escalation steps. Seventy-nine FIH studies with mAbs were identified, 49 of which clearly reported the MRSD determination method. The no observed adverse effects level (NOAEL)-based approach was the most frequently used method, whereas the model-based approach was the least commonly used method (34.7% vs 16.3%). The minimal anticipated biological effect level (MABEL)- or minimum effective dose (MED)-based approach was used more frequently in 2011–2013 than in 1990–2007 (31.6% vs 6.3%, P=0.036), reflecting a slow, but steady acceptance of the European Medicines Agency’s guidance on mitigating risks for FIH clinical trials (2007). The median safety factor was much lower for the MABEL- or MED-based approach than for the other MRSD determination methods (10 vs 32.2–53). The number of dose escalation steps was not significantly different among the different MRSD determination methods. The MABEL-based approach appears to be safer and as efficient as the other MRSD determination methods for achieving the objectives of FIH studies with mAbs faster.

Exploratory Population PK Analysis of Dupilumab, a Fully Human Monoclonal Antibody Against IL-4Rα, in Atopic Dermatitis Patients and Normal Volunteers

An exploratory population pharmacokinetic model for functional dupilumab was developed. Data from healthy volunteers and patients with atopic dermatitis (AD) receiving intravenous or subcutaneous doses were integrated. The data included 197 participants (2,518 measurements of dupilumab in serum) from six phase I and II studies. The data were analyzed using stochastic approximation expectation-maximization and importance sampling methods. The best structural model was a two-compartment model with parallel linear and Michaelis-Menten elimination from the central compartment. Estimated parameters were: central volume 2.74 L, elimination rate 0.0459 d^-1 , central-to-peripheral rate 0.0652 d^-1 , peripheral-to-central rate 0.129 d^-1 , bioavailability 60.7%, maximal target-mediated elimination rate 0.968 mg/L/d, and Michaelis-Menten constant 0.01 mg/L. Body weight was a significant covariate of the central volume. No gender effect was observed when controlling for weight. No differences between healthy volunteers and patients with AD were found. The model adequately described dupilumab pharmacokinetics for intravenous and subcutaneous routes of administration.

Population pharmacokinetic analysis of sifalimumab from a clinical phase IIb trial in systemic lupus erythematosus patients

AIMS

Sifalimumab, a human immunoglobulin (Ig) G1 monoclonal antibody against INF-alpha, is being studied as a treatment for systemic lupus erythematosus (SLE). This analysis characterized population pharmacokinetics (PK) of sifalimumab following repeat fixed dose and evaluated the utility of fixed dosing vs. body weight normalized dosing in SLE patients.

METHODS

PK data were collected in a phase IIb study where 298 patients received multiple intravenous doses (200-1200 mg) of sifalimumab every 4 weeks for 52 weeks. A population pharmacokinetic model was developed using 3961 quantifiable serum concentrations and the impact of patient demographics, clinical indices and biomarkers on pharmacokinetic parameters was evaluated. The appropriateness of the final model was evaluated using visual predictive check and bootstrap.

RESULTS

A two compartment model with first order elimination adequately described sifalimumab serum PK. The estimated typical clearance (CL) and central volume of distribution (V1 ) were 184 ml day(-1) and 2.82 l with 24% and 16% between-subject variability (BSV), respectively. Body weight, dose, 21 INF gene signature baseline and concomitant steroid use were identified as statistically significant covariates for CL and V1 and accounted for <10% of PK variability in the final model. Typical values and BSV of PK parameters from the current analysis with fixed dosing were similar to previous population PK results with body weight normalized dosing.

CONCLUSIONS

The transition from body weight normalized dosing to fixed dosing did not impact sifalimumab PK. These findings support the use of fixed dosing for sifalimumab in future clinical studies evaluating it as a potential treatment for SLE.

EAACI IG Biologicals task force paper on the use of biologic agents in allergic disorders

Biologic agents (also termed biologicals or biologics) are therapeutics that are synthesized by living organisms and directed against a specific determinant, for example, a cytokine or receptor. In inflammatory and autoimmune diseases, biologicals have revolutionized the treatment of several immune-mediated disorders. Biologicals have also been tested in allergic disorders. These include agents targeting IgE; T helper 2 (Th2)-type and Th2-promoting cytokines, including interleukin-4 (IL-4), IL-5, IL-9, IL-13, IL-31, and thymic stromal lymphopoietin (TSLP); pro-inflammatory cytokines, such as IL-1β, IL-12, IL-17A, IL-17F, IL-23, and tumor necrosis factor (TNF); chemokine receptor CCR4; and lymphocyte surface and adhesion molecules, including CD2, CD11a, CD20, CD25, CD52, and OX40 ligand. In this task force paper of the Interest Group on Biologicals of the European Academy of Allergy and Clinical Immunology, we review biologicals that are currently available or tested for the use in various allergic and urticarial pathologies, by providing an overview on their state of development, area of use, adverse events, and future research directions.

The development and in vivo function of T helper 9 cells

The specialized cytokine secretion profiles of T helper (TH) cells are the basis for a focused and efficient immune response. On the twentieth anniversary of the first descriptions of the cytokine signals that promote the differentiation of interleukin-9 (IL-9)-secreting T cells, this Review focuses on the extracellular signals and the transcription factors that promote the development of what we now term TH9 cells, which are characterized by the production of this cytokine. We summarize our current understanding of the contribution of TH9 cells to both effective immunity and immunopathological disease, and we propose that TH9 cells could be targeted for the treatment of allergic and autoimmune disease.

Peripheral blood Th9 cells and eosinophil apoptosis in asthma patients

BACKGROUND AND OBJECTIVE

Th9 cells producing interleukin (IL) 9 are novel subset of CD4+ T helper cells, which might contribute to airway inflammation in asthma. Moreover, the effect of IL-9 on eosinophils is still not fully understood. Study aim was to evaluate peripheral blood Th9 cells and eosinophil apoptosis in allergic asthma patients.

MATERIALS AND METHODS

Eighteen patients with allergic asthma and fourteen patients with allergic rhinitis were examined. Control group included sixteen healthy subjects. Allergic asthma and rhinitis patients did not use corticosteroids and antihistamines at least for 1 week. Peripheral blood eosinophils and CD4(+) cells were isolated by high density gradient centrifugation and magnetic separation. Th9 cells and apoptotic eosinophils were estimated by flow cytometer. Serum IL-9 and IL-5 concentration were determined by ELISA.

RESULTS

Peripheral blood Th9 cells percentage was increased in allergic asthma group compared with allergic rhinitis and control group (0.74%±0.32% vs. 0.19%±0.10% and 0.15%±0.08%, respectively, P<0.05). The same tendency was observed for IL-9 (P<0.01). Percentage of peripheral blood apoptotic eosinophils was decreased in allergic asthma and allergic rhinitis groups compared with control group (P<0.05). IL-9 concentration correlated with percentage of Th9 cells (r=0.64, P<0.05) and negatively with percentage of apoptotic eosinophils in allergic asthma group (r=-0.58, P<0.05). Negative correlation was found between apoptotic eosinophils count and IL-5 concentration in allergic asthma group (r=-0.76, P<0.05).

CONCLUSIONS

Patients with allergic asthma demonstrate increased peripheral blood Th9 cells count and serum IL-9, while eosinophil apoptosis is inversely related to IL-9 concentration.

Population pharmacokinetics of sifalimumab, an investigational anti-interferon-α monoclonal antibody, in systemic lupus erythematosus

Background and Objectives

Sifalimumab is a fully human immunoglobulin G1κ monoclonal antibody that binds to and neutralizes a majority of the subtypes of human interferon-α. Sifalimumab is being evaluated as a treatment for systemic lupus erythematosus (SLE). The primary objectives of this analysis were (a) to develop a population pharmacokinetic model for sifalimumab in SLE; (b) to identify and quantitate the impact of patient/disease characteristics on pharmacokinetic variability; and (c) to evaluate fixed versus body weight (WT)-based dosing regimens.

Methods

Sifalimumab serum concentration-time data were collected from a phase Ib study (MI-CP152) designed to evaluate the safety and tolerability of sifalimumab in adult patients with SLE. Sifalimumab was administered every 14 days as a 30- to 60-minute intravenous infusion with escalating doses of 0.3, 1.0, 3.0, and 10 mg/kg and serum concentrations were collected over 350 days. A total of 120 patients provided evaluable pharmacokinetic data with a total of 2,370 serum concentrations. Sifalimumab serum concentrations were determined using a validated colorimetric enzyme-linked immunosorbent assay (ELISA) with a lower limit of quantitation of 1.25 μg/mL. Population pharmacokinetic modeling of sifalimumab was performed using a non-linear mixed effects modeling approach with NONMEM VII software. Impact of patient demographics, clinical indices, and biomarkers on pharmacokinetic parameters were explored using a stepwise forward selection and backward elimination approach. The appropriateness of the final model was tested using visual predictive check (VPC). The impact of body WT-based and fixed dosing of sifalimumab was evaluated using a simulation approach. The final population model was utilized for phase IIb dosing projections.

Results

Sifalimumab pharmacokinetics were best described using a two-compartment linear model with first order elimination. Following intravenous dosing, the typical clearance (CL) and central volume of distribution (V₁) were estimated to be 176 mL/day and 2.9 L, respectively. The estimates (coefficient of variation) of between-subject variability for CL and V₁ were 28 and 31 %, respectively. Patient baseline body WT, interferon gene signature from 21 genes, steroid use, and sifalimumab dose were identified as significant covariates for CL, whereas only baseline body WT was a significant covariate for V₁ and peripheral volume of distribution (V₂). Although the above-mentioned covariates were statistically significant, they did not explain variability in pharmacokinetic parameters to any relevant extent (<7 %). Thus, no dosing adjustments are necessary. VPC confirmed good predictability of the final population pharmacokinetic model. Simulation results demonstrate that both fixed and body WT-based dosing regimens yield similar median steady state concentrations and overall variability. Fixed sifalimumab doses of 200, 600, and 1,200 mg monthly (with a loading dose at Day 14) were selected for a phase IIb clinical trial.

Conclusion

A two-compartment population pharmacokinetic model adequately described sifalimumab pharmacokinetics. The estimated typical pharmacokinetic parameters were similar to other monoclonal antibodies without target mediated elimination. Although the population pharmacokinetic analysis identified some statistically significant covariates, they explained <7 % between-subject variability in pharmacokinetic parameters indicating that these covariates are not clinically relevant. The population pharmacokinetic analysis also demonstrated the feasibility of switching to fixed doses in phase IIb clinical trials of sifalimumab.

Update on biological therapeutics for asthma

Abstract:

Asthma poses a significant burden on patients, families, health care providers, and the medical system. While efforts to standardize care through guidelines have expanded, difficulty in managing severe asthma has encouraged research about its pathobiology and treatment options. Novel biologic therapeutics are being developed for the treatment of asthma and are of potential use for severe refractory asthma, especially where the increased cost of such agents is more likely justified. This review will summarize currently approved (omalizumab) and investigational biologic agents for asthma, such as antibodies, soluble receptors, and other protein-based antagonists, and highlight recent published data on efficacy and safety of these therapies in humans. As these newer agents with highly targeted pharmacology are tested in asthma, we are also poised to learn more about the role of cytokines and other molecules in the pathophysiology of asthma.

A randomized, controlled trial to evaluate the effect of an anti-interleukin-9 monoclonal antibody in adults with uncontrolled asthma

BACKGROUND

Preclinical studies suggest that interleukin-9 may be a central mediator in the development and maintenance of airway inflammation in asthma. The aim of this study was therefore to evaluate the effects of MEDI-528, an anti-interleukin-9 monoclonal antibody, in adults with confirmed uncontrolled moderate-to-severe asthma.

METHODS

In this prospective double-blind, multicenter, parallel-group study, 329 subjects were randomized (1:1:1:1) to subcutaneous placebo or MEDI-528 (30, 100, 300 mg) every 2 weeks for 24 weeks, in addition to their usual asthma medications. The primary endpoint was change in mean Asthma Control Questionnaire-6 (ACQ-6) score at week 13. Secondary endpoints included weighted asthma exacerbation rates and pre-bronchodilator forced expiratory volume in 1 second (FEV1) at weeks 13 and 25, as well as Asthma Quality of Life Questionnaire scores at weeks 12 and 25 and the safety of MEDI-528 throughout the study period. The primary endpoint was analyzed using analysis of covariance.

RESULTS

The study population (n = 327) was predominantly female (69%) with a mean age of 43 years (range 18-65). The mean (SD) baseline ACQ-6 score for placebo (n = 82) and combined MEDI-528 (n = 245) was 2.8 (0.7) and 2.8 (0.8); FEV1 % predicted was 70.7% (15.9) and 71.5% (16.7). Mean (SD) change from baseline to week 13 in ACQ-6 scores for placebo vs combined MEDI-528 groups was -1.2 (1.0) vs -1.2 (1.1) (p = 0.86). Asthma exacerbation rates (95% CI) at week 25 for placebo vs MEDI-528 were 0.58 (0.36-0.88) vs 0.49 (0.37-0.64) exacerbations/subject/year (p = 0.52). No significant improvements in FEV1 % predicted were observed between the placebo and MEDI-528 groups. Adverse events were comparable for placebo (82.9%) and MEDI-528 groups (30 mg, 76.5%; 100 mg, 81.9%; 300 mg, 85.2%). The most frequent were asthma (placebo vs MEDI-528, 30.5% vs 33.5%), upper respiratory tract infection (14.6% vs 17.1%), and headache (9.8% vs 9.8%).

CONCLUSIONS

The addition of MEDI-528 to existing asthma controller medications was not associated with any improvement in ACQ-6 scores, asthma exacerbation rates, or FEV1 values, nor was it associated with any major safety concerns.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT00968669.

Second-generation minimal physiologically-based pharmacokinetic model for monoclonal antibodies

Minimal physiologically-based pharmacokinetic (mPBPK) models provide a sensible modeling approach when fitting only plasma (or blood) data yielding physiologically-relevant PK parameters that may provide more practical value than parameters of mammillary models. We propose a second-generation mPBPK model specifically for monoclonal antibodies (mAb) by including (lumping) several essential components of mAb PK used in full PBPK models. These components include convection as the primary mechanism of antibody movement from plasma into tissues and return to plasma with interstitial fluid as the major extravascular distribution space. The model divides tissue spaces into two groups according to their vascular endothelial structure, leaky and tight, which consequently allows discernment of two types and general sites of distribution. This mPBPK model was applied to two mAbs in mice and ten mAbs with linear kinetics in humans. The model captured their plasma PK profiles well with predictions of concentrations in interstitial fluid for two types of tissues. Predictions of tissue concentrations for mAb 7E3 and 8C2 were consistent with actual measurements in mice, indicating the feasibility of this model in assessing extravascular distribution in the two categories of tissues. The vascular reflection coefficients (σ₁) of tight tissues (V(tight)) ranged 0.883-0.987 and coefficients (σ₂) for leaky tissues (V(leaky)) ranged 0.311 to 0.837. The plasma clearance (CL(p)) varied among the mAbs in humans from 0.0054 to 0.03 L/h. In addition, applying this model generates parameters for mAb transcapillary escape rates and assesses major sites of elimination. Four of ten mAbs exhibited better fitting statistics premised on elimination from interstitial fluid than from plasma. This approach allows comparisons of mAb PK when only plasma data are available, provides more realistic parameters and predictions than mammillary models, and may provide an intermediate step towards utilizing full PBPK models for mAbs.

Giving monoclonal antibodies to healthy volunteers in phase 1 trials: is it safe?

Many monoclonal antibodies (MAbs) have been studied in healthy volunteers in phase 1, but few data have been published on the safety of that practice. We aimed to review the available data, and thereby to estimate the risks of participation in phase 1trials of MAbs. We searched PubMed, the ClinicalTrials.gov database and Google, using the search terms 'monoclonal antibody', 'phase 1' and 'healthy volunteers'. We identified 70 completed trials of MAbs in healthy volunteers, but the published data were too sparse to allow confident assessment of the risks of MAbs in healthy volunteers. Our best estimate of risk of a life-threatening adverse event was between 1: 425 and 1: 1700 volunteer-trials, but all such events occurred in a single trial (of TGN1412). In a phase 1trial of a small molecule, the risk of death or a life-threatening adverse event appears to be 1: 100,000-1,000,000 volunteer-trials, which is similar to the risk of many ordinary daily activities. Most people would consider that level of risk to be 'minimal' or 'negligible' and, therefore, acceptable. On that basis, the safety record of MAbs in healthy volunteers has been ruined by the TGN1412 disaster. However, that experience is unlikely to be repeated, because of improvements in governance and practice of phase 1trials. If the experience of TGN1412 is disregarded, it seems reasonable to continue using healthy volunteers in phase 1trials of MAbs, provided that there are scientific and medical reasons to conclude that the risk is truly minimal.

Novel therapies in asthma: leukotriene antagonists, biologic agents, and beyond

Asthma is one of the most common conditions seen in clinical practice and carries both a significant disease burden in terms of patient morbidity and a high economic burden in both direct and indirect costs. Despite this, it remains a comparatively poorly understood disease, with only modest advances in treatment over the past decade. Corticosteroids remain the cornerstone of therapy. Both patient compliance with medications and physician adherence to evidence-based guidelines are often poor, and a high percentage of patients continue to have inadequately controlled disease even with optimal therapy. Following a contextual overview of the current treatment guidelines, this review focuses on novel asthma therapies, beginning with the introduction of the leukotriene receptor antagonist zafirlukast in the 1990s, continuing through advanced endoscopic therapy and into cytokine-directed biologic agents currently in development. Along with clinically relevant biochemistry and pharmacology, the evidence supporting the place of these therapies in current guidelines will be highlighted along with data comparing these agents with more conventional treatment. A brief discussion of other drugs, such as those developed for unrelated conditions and subsequently examined as potential asthma therapies, is included.

Targeting interleukins to treat severe asthma

Severe asthma is thought to be a heterogeneous disease with different phenotypes predicated primarily on the nature of the inflammatory cell infiltrate and response to corticosteroid therapy. This group of patients often has refractory disease with an associated increase in morbidity and mortality, and there remains a need for better therapies for severe asthmatics. Inflammatory changes in asthma are driven by immune mechanisms, within which interleukins play an integral role. Interleukins are cell-signaling cytokines that are produced by a variety of cells, predominantly T cells. Knowledge about their actions has improved the understanding of the pathogenesis of asthma and provided potential targets for novel therapies. To date, this has not translated into clinical use. However, there are ongoing clinical trials that use monoclonal antibodies for various interleukins, some of which have shown to be promising in Phase II studies.

Applications of minimal physiologically-based pharmacokinetic models

Conventional mammillary models are frequently used for pharmacokinetic (PK) analysis when only blood or plasma data are available. Such models depend on the quality of the drug disposition data and have vague biological features. An alternative minimal-physiologically-based PK (minimal-PBPK) modeling approach is proposed which inherits and lumps major physiologic attributes from whole-body PBPK models. The body and model are represented as actual blood and tissue (usually total body weight) volumes, fractions (f ( d )) of cardiac output with Fick's Law of Perfusion, tissue/blood partitioning (K ( p )), and systemic or intrinsic clearance. Analyzing only blood or plasma concentrations versus time, the minimal-PBPK models parsimoniously generate physiologically-relevant PK parameters which are more easily interpreted than those from mammillary models. The minimal-PBPK models were applied to four types of therapeutic agents and conditions. The models well captured the human PK profiles of 22 selected beta-lactam antibiotics allowing comparison of fitted and calculated K ( p ) values. Adding a classical hepatic compartment with hepatic blood flow allowed joint fitting of oral and intravenous (IV) data for four hepatic elimination drugs (dihydrocodeine, verapamil, repaglinide, midazolam) providing separate estimates of hepatic intrinsic clearance, non-hepatic clearance, and pre-hepatic bioavailability. The basic model was integrated with allometric scaling principles to simultaneously describe moxifloxacin PK in five species with common K ( p ) and f ( d ) values. A basic model assigning clearance to the tissue compartment well characterized plasma concentrations of six monoclonal antibodies in human subjects, providing good concordance of predictions with expected tissue kinetics. The proposed minimal-PBPK modeling approach offers an alternative and more rational basis for assessing PK than compartmental models.

Role of innate lymphocytes in infection and inflammation

Cooperation between the innate and adaptive immune responses is critical for enabling protective immunity against various invading microbes. Distinct types of effector T cells have different functions in adaptive immune responses. Th1 cells play important roles in the control of intracellular bacteria by producing IFN-γ to activate macrophages and in anti-viral immunity by producing IFN-γ and activating cytotoxic T lymphocytes. Th2 cell-derived cytokines are important in activating mast cells, eosinophils, and goblet cells in anti-helminth immunity. Th17 cells are pivotal for the inflammatory response mediated by neutrophils, which resists extracellular bacterial infection. In all cases, it is critical that the innate immune responses limit the growth and expansion of invading microbes until antigen-specific adaptive immune responses are established. Recent studies have identified multiple subsets in innate lymphocytes corresponding to previously defined Th subsets. Classical natural killer cells, RORγ⁺ lymphoid tissue inducer-related cells, and Th2-type innate lymphocytes play distinct roles in innate immune responses by producing Th1, Th17, and Th2 cytokines, respectively. Cooperation between innate lymphocytes and antigen-specific T and B cells are likely important in protective immunity against distinct types of microbes. The most recently identified subset is the RORγ-independent Lin⁻Thy-1⁺IL-7R⁺GATA3⁺ innate lymphocyte subset such as natural helper (NH) cell, which is Id2- and IL-7-dependent. This population produces Th2 cytokines, most notably IL-5 and IL-13, and plays a major role in innate immune responses during anti-helminth immunity. In addition, these cells are likely involved in the pathophysiology of some types of allergic diseases. We summarize here current knowledge regarding various innate lymphocyte subsets. In particular, we focus on the Th2-type innate lymphocyte subset.

The tick salivary protein sialostatin L inhibits the Th9-derived production of the asthma-promoting cytokine IL-9 and is effective in the prevention of experimental asthma

Ticks developed a multitude of different immune evasion strategies to obtain a blood meal. Sialostatin L is an immunosuppressive cysteine protease inhibitor present in the saliva of the hard tick Ixodes scapularis. In this study, we demonstrate that sialostatin L strongly inhibits the production of IL-9 by Th9 cells. Because we could show recently that Th9-derived IL-9 is essentially involved in the induction of asthma symptoms, sialostatin L was used for the treatment of experimental asthma. Application of sialostatin L in a model of experimental asthma almost completely abrogated airway hyperresponsiveness and eosinophilia. Our data suggest that sialostatin L can prevent experimental asthma, most likely by inhibiting the IL-9 production of Th9 cells. Thus, alternative to IL-9 neutralization sialostatin L provides the basis for the development of innovative therapeutic strategies to treat asthma.

An IL-9 fate reporter demonstrates the induction of an innate IL-9 response in lung inflammation

Interleukin 9 (IL-9) is a cytokine implicated in lung inflammation, but its cellular origin and function remain unclear. Here we describe a reporter mouse strain designed to fate map cells that have activated IL-9. We show that during papain-induced lung inflammation IL-9 production was largely restricted to innate lymphoid cells (ILC). IL-9 production by ILC was dependent on IL-2 from adaptive immune cells and was rapidly lost in favor of other cytokines, such as IL-13 and IL-5. Blockade of IL-9 production via neutralizing antibodies substantially reduced IL-13 and IL-5, suggesting that ILC provide the missing link between the well-established functions of IL-9 on the regulation of T_H2 cytokines and responses.

Monoclonal antibodies for the treatment of asthma

Asthma is a chronic inflammatory disease of the airways which can have a detrimental effect on quality of life and in extreme cases cause death. Although the majority of patients can control their asthma symptoms with a combination of steroids and beta agonists there is still a group of patients whose asthma remains symptomatic despite the best available treatment. These severe asthmatic patients represent the unmet medical need in asthma and are the focus of those developing novel monoclonal antibody based drugs. The complex networks of cytokines and cells involved in the pathology of asthma provide plenty of scope for intervention with monoclonal antibody based drugs which are able to block cytokine or chemokine receptor interactions, deplete cells expressing a specific receptor or block cell/cell interactions. At present anti-IgE (Xolair©) is the only monoclonal antibody based drug approved for the treatment of asthma. However, a number of other antibody based drugs have been clinically tested in asthma including anti-IL-5, anti-IL-4, anti-IL-13, anti-TNFα, anti-CCR3, anti-CCR4 and anti-OX40L. This review will examine the development of these monoclonal antibody based therapies. Since many of these therapies have targeted key pathways in asthma pathology these studies provide information on patient stratification and asthma pathology.

Treatment of allergic asthma: modulation of Th2 cells and their responses

Atopic asthma is a chronic inflammatory pulmonary disease characterised by recurrent episodes of wheezy, laboured breathing with an underlying Th2 cell-mediated inflammatory response in the airways. It is currently treated and, more or less, controlled depending on severity, with bronchodilators e.g. long-acting beta agonists and long-acting muscarinic antagonists or anti-inflammatory drugs such as corticosteroids (inhaled or oral), leukotriene modifiers, theophyline and anti-IgE therapy. Unfortunately, none of these treatments are curative and some asthmatic patients do not respond to intense anti-inflammatory therapies. Additionally, the use of long-term oral steroids has many undesired side effects. For this reason, novel and more effective drugs are needed. In this review, we focus on the CD4+ Th2 cells and their products as targets for the development of new drugs to add to the current armamentarium as adjuncts or as potential stand-alone treatments for allergic asthma. We argue that in early disease, the reduction or elimination of allergen-specific Th2 cells will reduce the consequences of repeated allergic inflammatory responses such as lung remodelling without causing generalised immunosuppression.

Signals through 4-1BB inhibit T regulatory cells by blocking IL-9 production enhancing antitumor responses

Previous studies from our laboratory indicate that intratumoral (i.t.) injections of CpG-ODN are the most effective adjuvant strategy to induce an antitumor immune response in tolerant BALB-neuT mice but insufficient for tumor eradication. We evaluated whether this treatment strategy could be enhanced by the presence of anti-OX40 and anti-4-1BB antibodies. Treatment with anti-4-1BB resulted in a greater antitumor response than anti-OX40. The results indicate that anti-4-1BB but not anti-OX40 inhibited the suppressive function of T regulatory cells (Tregs). Through microarray analysis we evaluated the mechanism by which anti-4-1BB inhibits iTregs using the Foxp3-GFP mice. We observed specific transcriptional differences in over 100 genes in iTregs treated with anti-4-1BB, and selected those genes that remained unaffected by exposure to anti-OX40. Interleukin 9 was transcriptionally down-regulated 28-fold by anti-4-1BB treatment, and this was matched by a significant reduction of IL-9 secretion by iTregs. Furthermore, blockade of the common γ-chain receptor resulted in the inhibition of iTreg-suppressive function. More importantly, neutralization of IL-9 plus i.t. injections of CpG-ODN induces tumor rejection in BALB-neuT and MUC-1 tolerant transgenic mice. These results indicate that IL-9 plays a role in iTreg biology during the tumor inflammatory process enhancing/promoting the suppressive function of these cells and that the blockade of IL-9 could serve as a novel strategy to modulate the function of Tregs to enhance the antitumor effect of tumor vaccines.

A brief history of IL-9

IL-9 was first described in the late 1980s as a member of a growing number of cytokines that had pleiotropic functions in the immune system. Although many biological functions have been attributed to IL-9, it remains an understudied cytokine. A resurgence of interest in IL-9 has been spurred by recent work demonstrating a role for IL-9 in regulating inflammatory immunity and defining the transcription factors that activate the Il9 gene in cells that most efficiently produce IL-9. In this review, we summarize the characterization of IL-9 biological activities, highlight roles for the cytokine that are clearly defined, and outline questions regarding IL-9 functions that still require further exploration.

Immunotherapy in asthma

Asthma is a chronic inflammatory disorder of the airways in which many cells and cellular elements play a role. Chronic inflammation is associated with airway hyper-responsiveness that leads to recurrent episodes of wheezing, breathlessness, chest tightness and coughing, as well as variable airflow obstruction within the lung. With time, such airflow obstruction may become permanent due to remodeling. It has been treated for more than 100 years by subcutaneous immunotherapy with allergen extracts but in recent years, other forms and types of immunotherapy have been introduced. Perhaps the most successful of these to date, is sublingual immunotherapy, which has attained significant usage in European countries but has yet to make inroads into clinical practice in North America. Other mechanisms to modify the inflammatory responses of asthma have included immunotherapy with recombinant allergens, the use of allergen peptides targeting antigen-specific T cells and the administration of Toll-like receptor agonists coupled to allergen proteins. As the inflammatory responses in asthma frequently involve IgE, a modified monoclonal antibody to IgE and interfering with its binding to the IgE receptor have gained acceptance for treating severe allergic asthma. Other monoclonal antibodies or recombinant receptor antagonists are being assessed for their ability to block other contributors to the inflammatory response. Finally, attempts have been made to generate autoantibody responses to cytokines implicated in asthma. Most of these therapies aim to modify or inhibit the so-called Th 2 immune response, which is implicated in many forms of asthma, or to inhibit cytokines involved in these responses. However, an added benefit of classical immunotherapy seems to be the ability to prevent the allergic progression to new sensitivities and new forms of allergic disease.

Small animals models for drug discovery

There has been an explosion of studies of animal models of asthma in the past 20 years. The elucidation of fundamental immunological mechanisms underlying the development of allergy and the complex cytokine and chemokines networks underlying the responses have been substantially unraveled. Translation of findings to human asthma have been slow and hindered by the varied phenotypes that human asthma represents. New areas for expansion of modeling include virally mediated airway inflammation, oxidant stress, and the interactions of stimuli triggering innate immune and adaptive immune responses.

Safety profile and clinical activity of multiple subcutaneous doses of MEDI-528, a humanized anti-interleukin-9 monoclonal antibody, in two randomized phase 2a studies in subjects with asthma

Background

Interleukin-9 (IL-9)-targeted therapies may offer a novel approach for treating asthmatics. Two randomized placebo-controlled studies were conducted to assess the safety profile and potential efficacy of multiple subcutaneous doses of MEDI-528, a humanized anti-IL-9 monoclonal antibody, in asthmatics.

Methods

Study 1: adults (18-65 years) with mild asthma received MEDI-528 (0.3, 1, 3 mg/kg) or placebo subcutaneously twice weekly for 4 weeks. Study 2: adults (18-50 years) with stable, mild to moderate asthma and exercise-induced bronchoconstriction received 50 mg MEDI-528 or placebo subcutaneously twice weekly for 4 weeks. Adverse events (AEs), pharmacokinetics (PK), immunogenicity, asthma control (including asthma exacerbations), and exercise challenge test were evaluated in study 1, study 2, or both.

Results

In study 1 (N = 36), MEDI-528 showed linear serum PK; no anti-MEDI-528 antibodies were detected. Asthma control: 1/27 MEDI-528-treated subjects had 1 asthma exacerbation, and 2/9 placebo-treated subjects had a total of 4 asthma exacerbations (one considered a serious AE). In study 2, MEDI-528 (n = 7) elicited a trend in the reduction in mean maximum decrease in FEV₁ post-exercise compared to placebo (n = 2) (-6.49% MEDI-528 vs -12.60% placebo; -1.40% vs -20.10%; -5.04% vs -15.20% at study days 28, 56, and 150, respectively). Study 2 was halted prematurely due to a serious AE in an asymptomatic MEDI-528-treated subject who had an abnormal brain magnetic resonance imaging that was found to be an artifact on further evaluation.

Conclusions

In these studies, MEDI-528 showed an acceptable safety profile and findings suggestive of clinical activity that support continued study in subjects with mild to moderate asthma.

Trial registration

ClinicalTrials (NCT): NCT00507130 and ClinicalTrials (NCT): NCT00590720

Taking immunogenicity assessment of therapeutic proteins to the next level

Therapeutic proteins provide innovative and effective therapies for numerous diseases. However, some of these products are associated with unwanted immunogenicity that may lead to clinical consequences such as reduced or loss of efficacy, altered pharmacokinetics (PK), general immune and hypersensitivity reactions, and neutralisation of the natural counterpart (e.g. the physiological hormone). Regulatory guidance on immunogenicity assessment needs to take into consideration a great diversity of products, indications and patient populations as well as constantly advancing manufacturing technologies. Such guidance needs to be sufficiently specific while, at the same time, allowing interactive discussion and adjusted benefit-risk weighing of each product on a case-by-case basis, e.g. for a unique treatment of a life threatening disease acceptable treatment risks may differ considerably from the ones in case of less serious disease. This theme was the focus of the international conference "Taking immunogenicity assessment of therapeutic proteins to the next level", held at the Paul-Ehrlich-Institut in Langen, Germany, on the 10-11. June 2010. The objectives of the conference were to highlight how the field could move from that of a mere description of risk factors to a system of risk assessment and mitigation, as well as an understanding of the impact of unwanted immunogenicity on the overall benefit/risk consideration for a medicinal product. More than 150 experts from industry, academia and regulatory authorities worldwide discussed the phenomenon of undesired immunogenicity from different perspectives. The conference focussed on issues relevant to three areas: (1) new European guidelines that are currently the subject of discussion; (2) testing strategies for immunogenicity assessment; and (3) scientific progress on the product-related factors that may contribute to the development of pathogenesis of immunogenicity, in particular in the field of protein aggregation and post-translational modifications. This report provides an overview of issues, insights, and conclusions that were discussed and achieved during the meeting.

Airway remodeling in asthma: new mechanisms and potential for pharmacological intervention

The chronic inflammatory response within the airways of asthmatics is associated with structural changes termed airway remodeling. This remodeling process is a key feature of severe asthma. The 5-10% of patients with a severe form of the disease account for the higher morbidity and health costs related to asthma. Among the histopathological characteristics of airway remodeling, recent reports indicate that the increased mass of airway smooth muscle (ASM) plays a critical role. ASM cell proliferation in severe asthma implicates a gallopamil-sensitive calcium influx and the activation of calcium-calmodulin kinase IV leading to enhanced mitochondrial biogenesis through the activation of various transcription factors (PGC-1α, NRF-1 and mt-TFA). The altered expression and function of sarco/endoplasmic reticulum Ca(2+) pump could play a role in ASM remodeling in moderate to severe asthma. Additionally, aberrant communication between an injured airway epithelium and ASM could also contribute to disease severity. Airway remodeling is insensitive to corticosteroids and anti-leukotrienes whereas the effect of monoclonal antibodies (the anti-IgE omalizumab, the anti-interleukin-5 mepolizumab or anti-tumor necrosis factor-alpha) remains to be investigated. This review focuses on potential new therapeutic strategies targeting ASM cells, especially Ca(2+) and mitochondria-dependent pathways.

Th9: a new player in asthma pathogenesis?

CD4(+) T helper (Th) cells act as important regulators of the mammalian adaptive immune response. CD4(+) Th cells were originally characterized as either Th1 or Th2 types, based on the cytokines they produce. Over the past two decades, however, we have attained a much more detailed understanding of CD4(+) T-cell differentiation, functions, and gene expression profiles, which led to the identification of additional types, such as the Th17 and induced regulatory T cells. Recently, researchers have characterized yet another novel and distinct population that exists among these immune-modulatory cells. The 'Th9' cells were first identified as a Th2 subpopulation that produced exceptionally large quantities of the Th2-specific cytokine interleukin 9. However, experimental analysis revealed that Th9 cells had divergent regulatory capabilities and were critically involved in different immune processes. In particular, we now know that Th9 acts as a major contributor to the onset and progression of allergies, especially asthma. Here, we will review the heterogeneity and biology of CD4(+) Th cells and summarize the characteristics known to date of interleukin 9 and Th9 cells to build a framework for better understanding of their roles in disease processes, especially in allergy-induced asthma.

Neutralization of IL-9 ameliorates experimental autoimmune encephalomyelitis by decreasing the effector T cell population

Multiple sclerosis is a CD4(+) T cell-mediated autoimmune disease affecting the CNS. Multiple sclerosis and its animal model, experimental autoimmune encephalomyelitis (EAE), have been thought to be Th1-mediated diseases. However, recent studies provide strong evidence that the major pathogenic T cell subsets in EAE are Th17 cells. IL-9, a hematopoietic growth factor, is considered to be a mediator of Th17 cells, but the precise mechanisms of its action are largely unknown. The present study was designed to investigate the role of IL-9 in autoimmune demyelination. IL-9 blockade with anti-IL-9 mAb inhibited the development of EAE, reduced the serum levels of IL-17, the CNS mRNA expression of IL-17, IL-6, IFN-γ, and TNF-α, and the myelin oligodendrocyte glycoprotein (MOG)-induced IL-17, IFN-γ secretion of lymphocytes. Furthermore, anti-IL-9 mAb in culture suppressed IL-17 production of MOG-reactive T cells and their potency in adoptive transfer EAE. These findings indicate that the protective effect of IL-9 blockade in EAE was likely mediated via inhibition of the development of MOG peptide-specific T cells, which in turn led to reduced infiltration of T cells into the CNS. Thus, anti-IL-9 mAb treatment may provide an effective therapeutic strategy against autoimmune diseases.

The transcription factor PU.1 is required for the development of IL-9-producing T cells and allergic inflammation

CD4⁺ T helper cells acquire effector phenotypes that promote specialized inflammatory responses. We show that the ETS family transcription factor, PU.1 was required for the development of an interleukin 9 (IL-9)-secreting subset of T_H cells. Decreasing PU.1 expression either by conditional deletion in murine T cells or siRNA in human T cells impaired IL-9 production, while ectopic PU.1 expression promoted IL-9 production. Mice with PU.1-deficient T cells developed normal T_H2 responses in vivo, but exhibited attenuated allergic pulmonary inflammation corresponding to decreased Il9 and chemokine expression in peripheral T cells and in lungs as compared to wild-type mice. Together, these data suggest a critical role for PU.1 in generating the T_H9 phenotype and in the development of allergic inflammation.