Anti-IL-4/IL-13 for the treatment of asthma: the story so far.

Introduction: Severe asthma is a global health concern with high morbidity and mortality. Understanding of its complex pathophysiology continues to increase, providing specific immune targets for therapeutic intervention.Areas covered: In this review, we focus on the role of IL-4 and IL-13 in severe asthma and on the biologic therapies developed to target them, particularly dupilumab, a monoclonal antibody against the IL-4 receptor α subunit and IL-4/IL-13 receptor complex. A literature search was undertaken for all studies of monoclonal antibodies against IL-4 and IL-13.Expert Opinion: Dupilumab decreases the rate of severe asthma exacerbations and improves symptoms, lung function, and quality of life. Importantly, these effects are also observed during reduction of maintenance oral corticosteroid doses. Those with the highest T2 biomarkers derive the greatest benefit and the presence of atopic dermatitis or chronic rhinosinusitis with or without nasal polyposis may recommend dupilumab as the preferred biologic treatment for a patient.

IL-4 and IL-13 Receptor Signaling From 4PS to Insulin Receptor Substrate 2: There and Back Again, a Historical View.

In this historical perspective, written in honor of Dr. William E. Paul, we describe the initial discovery of one of the dominant substrates for tyrosine phosphorylation stimulated by IL-4. We further describe how this "IL-4-induced phosphorylated substrate" (4PS) was characterized as a member of the insulin receptor substrate (IRS) family of large adaptor proteins that link IL-4 and insulin receptors to activation of the phosphatidyl-inositol 3' kinase pathway as well as other downstream signaling pathways. The relative contribution of the 4PS/IRS pathway to the early models of IL-4-induced proliferation and suppression of apoptosis are compared to our more recent understanding of the complex interplay between positive and negative regulatory pathways emanating from members of the IRS family that impact allergic responses.

Tuning the Cytokine Responses: An Update on Interleukin (IL)-4 and IL-13 Receptor Complexes.

Interleukin (IL)-4 and IL-13 are related cytokines that regulate many aspects of allergic inflammation. They play important roles in regulating the responses of lymphocytes, myeloid cells, and non-hematopoietic cells. In T-cells, IL-4 induces the differentiation of naïve CD4 T cells into Th2 cells, in B cells, IL-4 drives the immunoglobulin (Ig) class switch to IgG1 and IgE, and in macrophages, IL-4 and IL-13 induce alternative macrophage activation. This review gives a short insight into the functional formation of these cytokine receptors. I will discuss both the binding kinetics of ligand/receptor interactions and the expression of the receptor chains for these cytokines in various cell types; both of which are crucial factors in explaining the efficiency by which these cytokines induce intracellular signaling and gene expression. Work initiated in part by William (Bill) E. Paul on IL-4 some 30 years ago has now grown into a major building block of our current understanding of basic immunology and the immune response. This knowledge on IL-4 has growing clinical importance, as therapeutic approaches targeting the cytokine and its signal transduction are becoming a part of the clinical practice in treating allergic diseases. Just by reading the reference list of this short review, one can appreciate the enormous input Bill has had on shaping our understanding of the pathophysiology of allergic inflammation and in particular the role of IL-4 in this process.

Therapeutic Targeting of the Interleukin-4/Interleukin-13 Signaling Pathway: In Allergy and Beyond.

Inflammation triggered by interleukin-4 (IL-4)/IL-13 is mediated by IL-4 and IL-13 receptors that are present on multiple cell types, including epithelial cells, smooth muscle, fibroblasts endothelial cells and immune cells. IL-4 exerts its activities by interacting with two specific cell surface receptors: one designated the type 1 IL-4 receptor (IL-4R); the other designated the type 2 IL-4R, a receptor complex that is also the functional receptor for IL-13. "Traditionally," IL-4 and IL-13 have been studied in the context of T helper 2-associated immune responses (i.e., type 2 immunity). In these settings, IL-4, IL-13 and their cognate receptor chains display pivotal roles where IL-4 is considered an instigator of type 2 immune responses and IL-13 an effector molecule. Thus, therapeutic targeting of the IL-4/IL-13 pathway is under extensive research, mainly for the treatment of allergic diseases. Nonetheless, in addition to IL-4's and IL-13's roles in type 2 immune responses, recent data highlight key activities for IL-4 and IL-13 in additional settings including metabolism, bone resorption, and even cognitive learning. This review summarizes the established knowledge that has accumulated regarding the roles of IL-4, IL-13, and their receptors in allergic diseases, with an emphasis on asthma, atopic dermatitis and eosinophilic esophagitis. Further, we provide an overview of the pharmacological entities targeting these cytokines and/or their receptors, which have been developed and clinically examined over the years. Finally, we will briefly highlight emerging evidence of potential new roles for IL-4 and IL-13 in other pathologies.

Targeted anti-IL-13 therapies in asthma: current data and future perspectives.

INTRODUCTION: The identification of patients with severe asthma who will benefit from a personalized management approach remains an unmet need. Interleukin-13 (IL-13) is a cytokine possessing a significant role in asthma pathogenesis and progression of disease. Humanised monoclonal antibodies against IL-13 and IL-13 and IL-4 receptors are mainly proposed as add-on therapy in patients with TH2-high inflammation with uncontrolled asthma despite maximum therapy. AREAS COVERED: The role of IL-13 in airway inflammation in severe asthma, the targeted anti-IL-13 therapies and biomarkers that predict response to anti-IL-13 treatment are discussed. EXPERT OPINION: New effective individualized therapies in severe asthma are urgently needed to block specific inflammatory pathways using monoclonal antibodies. Studies on anti-IL-13 therapies showed that asthmatic patients could benefit from this novel targeted therapy as far as lung function and exacerbation rate are concerned. TH2-high and especially periostin-high groups of asthmatics with moderate-to-severe uncontrolled asthma seem to compose the group that could benefit from anti-IL-13 therapy. Targeting IL-13 alone may not be sufficient to achieve asthma control. Inhibition of IL-13 and IL-4 with mabs may be more encouraging and patients will probably have additional benefits from these therapeutic interventions because of IL-13/IL-4 overlapping actions in asthma pathophysiology.

Antigen-specific immunoreactivity and clinical outcome following vaccination with glioma-associated antigen peptides in children with recurrent high-grade gliomas: results of a pilot study.

Recurrent high-grade gliomas (HGGs) of childhood have an exceedingly poor prognosis with current therapies. Accordingly, new treatment approaches are needed. We initiated a pilot trial of vaccinations with peptide epitopes derived from glioma-associated antigens (GAAs) overexpressed in these tumors in HLA-A2+ children with recurrent HGG that had progressed after prior treatments. Peptide epitopes for three GAAs (EphA2, IL13Rα2, survivin), emulsified in Montanide-ISA-51, were administered subcutaneously adjacent to intramuscular injections of poly-ICLC every 3 weeks for 8 courses, followed by booster vaccines every 6 weeks. Primary endpoints were safety and T-cell responses against the GAA epitopes, assessed by enzyme-linked immunosorbent spot (ELISPOT) analysis. Treatment response was evaluated clinically and by magnetic resonance imaging. Twelve children were enrolled, 6 with glioblastoma, 5 with anaplastic astrocytoma, and one with malignant gliomatosis cerebri. No dose-limiting non-CNS toxicity was encountered. ELISPOT analysis, in ten children, showed GAA responses in 9: to IL13Rα2 in 4, EphA2 in 9, and survivin in 3. One child had presumed symptomatic pseudoprogression, discontinued vaccine therapy, and responded to subsequent treatment. One other child had a partial response that persisted throughout 2 years of vaccine therapy, and continues at >39 months. Median progression-free survival (PFS) from the start of vaccination was 4.1 months and median overall survival (OS) was 12.9 months. 6-month PFS and OS were 33 and 73 %, respectively. GAA peptide vaccination in children with recurrent malignant gliomas is generally well tolerated, and has preliminary evidence of immunological and modest clinical activity.

Chitinase 3-Like 1 Promotes Candida albicans Killing and Preserves Corneal Structure and Function by Controlling Host Antifungal Responses.

Chitinase 3-like 1 (CHI3L1) has been shown to play a role in promoting antibacterial responses, decreasing tissue injury, and enhancing pulmonary repair. This study sought to elucidate the role of CHI3L1 in augmenting the corneal innate immune response to Candida albicans infection in an animal model of fungal keratitis. Flagellin applied topically 24 h prior to C. albicans inoculation significantly protected the corneal from C. albicans and induced CHI3L1 expression in C57BL/6 mouse corneas. CHI3L1, however, played a detectable but minor role in flagellin-induced protection. While C. albicans keratitis was more severe in the corneas treated with Chi3l1 small interfering RNA (siRNA), corneas treated with recombinant CHI3L1 before C. albicans inoculation had markedly ameliorated keratitis, reduced fungal load, and decreased polymorphonucleocyte (PMN) infiltration in an interleukin 13 receptor α2 (IL-13Rα2)-dependent manner. CHI3L1 treatment resulted in the induction of the antimicrobial peptides ß-defensin 3, CRAMP, and chemokine CXCL10 and its receptor CXCR3 in corneal epithelial cells. Importantly, CHI3L1 administered after C. albicans inoculation also had strong protection against fungal keratitis, suggesting a therapeutic window. This is the first report demonstrating that CHI3L1 is induced during fungal infection, where it acts as an immunomodulator to promote fungal clearance and to regulate antifungal innate immune responses in the cornea.

Antigen-specific immune responses and clinical outcome after vaccination with glioma-associated antigen peptides and polyinosinic-polycytidylic acid stabilized by lysine and carboxymethylcellulose in children with newly diagnosed malignant brainstem and nonbrainstem gliomas.

PURPOSE: Diffuse brainstem gliomas (BSGs) and other high-grade gliomas (HGGs) of childhood carry a dismal prognosis despite current treatments, and new therapies are needed. Having identified a series of glioma-associated antigens (GAAs) commonly overexpressed in pediatric gliomas, we initiated a pilot study of subcutaneous vaccinations with GAA epitope peptides in HLA-A2-positive children with newly diagnosed BSG and HGG. PATIENTS AND METHODS: GAAs were EphA2, interleukin-13 receptor alpha 2 (IL-13Rα2), and survivin, and their peptide epitopes were emulsified in Montanide-ISA-51 and given every 3 weeks with intramuscular polyinosinic-polycytidylic acid stabilized by lysine and carboxymethylcellulose for eight courses, followed by booster vaccinations every 6 weeks. Primary end points were safety and T-cell responses against vaccine-targeted GAA epitopes. Treatment response was evaluated clinically and by magnetic resonance imaging. RESULTS: Twenty-six children were enrolled, 14 with newly diagnosed BSG treated with irradiation and 12 with newly diagnosed BSG or HGG treated with irradiation and concurrent chemotherapy. No dose-limiting non-CNS toxicity was encountered. Five children had symptomatic pseudoprogression, which responded to dexamethasone and was associated with prolonged survival. Only two patients had progressive disease during the first two vaccine courses; 19 had stable disease, two had partial responses, one had a minor response, and two had prolonged disease-free status after surgery. Enzyme-linked immunosorbent spot analysis in 21 children showed positive anti-GAA immune responses in 13: to IL-13Rα2 in 10, EphA2 in 11, and survivin in three. CONCLUSION: GAA peptide vaccination in children with gliomas is generally well tolerated and has preliminary evidence of immunologic and clinical responses. Careful monitoring and management of pseudoprogression is essential.

A search for novel cancer/testis antigens in lung cancer identifies VCX/Y genes, expanding the repertoire of potential immunotherapeutic targets.

Cancer/testis (CT) antigens are potential immunotherapeutic targets in cancer. However, the expression of particular antigens is limited to a subset of tumors of a given type. Thus, there is a need to identify antigens with complementary expression patterns for effective therapeutic intervention. In this study, we searched for genes that were distinctly expressed at a higher level in lung tumor tissue and the testes compared with other nontumor tissues and identified members of the VCX/Y gene family as novel CT antigens. VCX3A, a member of the VCX/Y gene family, was expressed at the protein level in approximately 20% of lung adenocarcinomas and 35% of squamous cell carcinomas, but not expressed in normal lung tissues. Among CT antigens with concordant mRNA and protein expression levels, four CT antigens, XAGE1, VCX, IL13RA2, and SYCE1, were expressed, alone or in combination, in about 80% of lung adenocarcinoma tumors. The CT antigen VCX/Y gene family broadens the spectrum of CT antigens expressed in lung adenocarcinomas for clinical applications.

Role of interleukin-13 in asthma.

Interleukin-13 is a pleiotropic TH2 cytokine that has been shown to be central to the pathogenesis of asthma. Some of the most prominent of the effects of IL-13 include increases in goblet cell differentiation, activation of fibroblasts, elevation of bronchial hyperresponsiveness, and switching of B cell antibody production from IgM to IgE. The relevances of these effects to asthma have been carefully studied in both animal models and more recently in human studies. As the role of IL-13 in asthma has become more defined, a number of potential biomarkers for TH2 airway inflammation, and hence IL-13 activity, have been identified, including blood and sputum eosinophils, total serum IgE, proteins derived from the bronchial epithelium (e.g., serum periostin), and exhaled nitric oxide. Most importantly, many of these markers for TH2 inflammation are strong predictors for positive responses to inhaled corticosteroid treatment. These biomarkers may also be useful in identifying patients who are most likely to benefit from specific IL-13 antagonism, as was demonstrated in a recent clinical trial of anti-IL-13 antibody therapy (lebrikizumab) in patients with poorly controlled asthma despite using inhaled corticosteroids. In that study, significant improvements in FEV1 were observed in patients with elevations of serum periostin but not in patients with normal periostin levels. These data indicate that IL-13 antagonists may fulfill an important unmet need in patients with poorly controlled asthma and biologic evidence of persistent IL-13 activity.

MAPK regulation of IL-4/IL-13 receptors contributes to the synergistic increase in CCL11/eotaxin-1 in response to TGF-ß1 and IL-13 in human airway fibroblasts.

CCL11/eotaxin-1 is a potent eosinophilic CC chemokine expressed by primary human fibroblasts. The combination of TGF-ß1 and IL-13 synergistically increases CCL11 expression, but the mechanisms behind the synergy are unclear. To address this, human airway fibroblast cultures from normal and asthmatic subjects were exposed to IL-13 alone or TGF-ß1 plus IL-13. Transcriptional (nuclear run-on) and posttranscriptional (mRNA stability) assays confirmed that transcriptional regulation is critical for synergistic expression of CCL11. TGF-ß1 plus IL-13 synergistically increased STAT-6 phosphorylation, nuclear translocation, and binding to the CCL11 promoter as compared with IL-13 alone. STAT-6 small interfering RNA significantly knocked down both STAT-6 mRNA expression and phosphorylation and inhibited CCL11 mRNA and protein expression. Regulation of the IL-4Rα complex by TGF-ß1 augmented IL-13 signaling by dampening IL-13Rα2 expression, overcoming IL-13's autoregulation of its pathway and enhancing the expression of CCL11. Our data suggest that TGF-ß1 induced activation of the MEK/ERK pathway reduces IL-13Rα2 expression induced by IL-13. Thus, TGF-ß1, a pleiotropic cytokine upregulated in asthmatic airways, can augment eosinophilic inflammation by interfering with IL-13's negative feedback autoregulatory loop under MEK/ERK-dependent conditions.

Immune modulation for treatment of allergic disease.

Immune modulation for treatment of allergic diseases aims to decrease the pathologic immune response rather than to cause a return to an immunologically naive or unresponsive state. Our expanding knowledge of innate and adaptive immune responses at the molecular level has led to development of immunomodulators for several allergic diseases, particularly asthma, allergic rhinitis, and eosinophilic esophagitis. Although successful immune modulation in mouse models of allergic disease have often failed to translate into significant results in human clinical trials, much has been learned about the pleotropic nature of cytokines and their effector mechanisms and of the varied phenotypes of allergic disease. We examine strategies of immune modulation in allergic diseases that have undergone human clinical trials, all with the common goal of decreasing the T-helper 2 (Th2) response, but through different mechanisms: blocking critical Th2 cytokines, inhibiting Th2 cytokine synthesis, blocking critical Th2 effector molecules, inhibiting important cells in the Th2 response, and stimulating Th1 responses. Therapies directed against specific effector molecules, such as immunoglobulin E and prostaglandin D2, hold promise in immune modulation of allergic disease, as do targeting the IL-4/IL-13 receptor and augmenting Th1/Th2 balance with Toll-like receptor agonists.

Interleukin 13 receptors as biochemical markers in atopic patients.

BACKGROUND: Interleukin (IL) 13, a type 2 helper T cell (T(H)2), is an important regulator of inflammatory immune responses. It mediates its action through a receptor complex consisting of IL-13Ralpha1 and IL-4Ralpha. IL-13Ralpha2 binds IL-13 with high affinity and is thought to act primarily as a decoy receptor, sequestering IL-13 and thus inhibiting its action. Our aim was to clarify the role of these receptors in the diagnosis and follow-up of atopic patients. METHODS: We genotyped the 1398A>G polymorphism in the IL-13Ralpha1 gene using restriction fragment length polymorphism for causal genetic diversity and measured serum levels of IL-13Ralpha2 in 105 atopic patients suffering from atopic asthma, atopic dermatitis, and atopic rhinitis (35 each). We compared the results with those of 35 nonatopic control individuals. Total immunoglobulin (Ig) E and serum IL-13Ralpha2 were measured using enzyme-linked immunosorbent assay, and the eosinophil counts were recorded. RESULTS: A significant increase in serum IL-13Ralpha2 levels was recorded in the 3 atopic groups compared with the control group (P < .001), as well as a significant increase in total IgE levels and eosinophil counts. No significant association was found between 1398A>G and atopy other than a suggestive association between this polymorphism and raised total serum IgE levels in all 3 atopic groups (P < .001). CONCLUSIONS: These findings indicate that IL-13Ralpha2 plays an important role in atopy and that increased levels in different groups highlight its regulatory role in the development of atopic symptoms. The 1398A>G polymorphism might be involved in the production of IgE.

Histone modification enhances the effectiveness of IL-13 receptor targeted immunotoxin in murine models of human pancreatic cancer.

BACKGROUND: Interleukin-13 Receptor α2 (IL-13Rα2) is a tumor-associated antigen and target for cancer therapy. Since IL-13Rα2 is heterogeneously overexpressed in a variety of human cancers, it would be highly desirable to uniformly upregulate IL-13Rα2 expression in tumors for optimal targeting. METHODS: We examined epigenetic regulation of IL-13Rα2 in a murine model of human pancreatic cancer by Bisulfite-PCR, sequencing for DNA methylation and chromatin immunoprecipitation for histone modification. Reverse transcription-PCR was performed for examining changes in IL-13Rα2 mRNA expression after treatment with histone deacetylase (HDAC) and c-jun inhibitors. In vitro cytotoxicity assays and in vivo testing in animal tumor models were performed to determine whether HDAC inhibitors could enhance anti-tumor effects of IL-13-PE in pancreatic cancer. Mice harboring subcutaneous tumors were treated with HDAC inhibitors systemically and IL-13-PE intratumorally. RESULTS: We found that CpG sites in IL-13Rα2 promoter region were not methylated in all pancreatic cancer cell lines studied including IL-13Rα2-positive and IL-13Rα2-negative cell lines and normal cells. On the other hand, histones at IL-13Rα2 promoter region were highly-acetylated in IL-13Rα2-positive but much less in receptor-negative pancreatic cancer cell lines. When cells were treated with HDAC inhibitors, not only histone acetylation but also IL-13Rα2 expression was dramatically enhanced in receptor-negative pancreatic cancer cells. In contrast, HDAC inhibition did not increase IL-13Rα2 in normal cell lines. In addition, c-jun in IL-13Rα2-positive cells was expressed at higher level than in negative cells. Two types of c-jun inhibitors prevented increase of IL-13Rα2 by HDAC inhibitors. HDAC inhibitors dramatically sensitized cancer cells to immunotoxin in the cytotoxicity assay in vitro and increased IL-13Rα2 in the tumors subcutaneously implanted in the immunodeficient animals but not in normal mice tissues. Combination therapy with HDAC inhibitors and immunotoxin synergistically inhibited growth of not only IL-13Rα2-positive but also IL-13Rα2-negative tumors. CONCLUSIONS: We have identified a novel function of histone modification in the regulation of IL-13Rα2 in pancreatic cancer cell lines in vitro and in vivo. HDAC inhibition provides a novel opportunity in designing combinatorial therapeutic approaches not only in combination with IL-13-PE but with other immunotoxins for therapy of pancreatic cancer and other cancers.

Overcoming dendritic cell tardiness to triumph over IL-13 receptor: a strategy for the development of effective pediatric vaccines.

Neonatal exposure to antigen gives rise to a primary response comprising both T helper 1 (Th1) and T helper 2 (Th2) lymphocytes. However, re-encounter with the same antigen yields an indubitably biased response with minimal Th1 but excessive Th2 cells. Since Th1 cells combat microbes while Th2 cells react to allergens, the neonate faces susceptibility to both microbial infections and allergic reactions. The Th1/Th2 imbalance of neonatal immunity stems from a delayed maturation of dendritic cells that yields limited IL-12 cytokine during the neonatal stage. Th1 cells developing under these circumstances up-regulate the IL-13Ralpha1 chain that physically associates with the IL-4Ralpha chain, forming a potentially hazardous heteroreceptor. During re-challenge with antigen, IL-4 from Th2 cells utilizes the heteroreceptor to signal the death of Th1 cells, leading to the Th2 bias of neonatal immunity. Our view to overcome Th1 deficiency is to supplement neonatal immunizations with toll-like receptor ligands that could stimulate maturation of dendritic cells and augment IL-12 production to counter IL-13Ralpha1 up-regulation. This regimen would yield Th1 cells devoid of the heteroreceptor and resistant to IL-4-induced apoptosis. Accordingly, the neonate would have balanced Th1/Th2 immunity and withstand both microbes and allergens. Such approaches could open new avenues for better pediatric vaccines and allergy therapies.

IL-13 and the IL-13 receptor as therapeutic targets for asthma and allergic disease.

It is widely accepted that T-helper 2 cell (Th2) cytokines play an important role in the maintenance of asthma and allergy. Emerging evidence has highlighted the role of IL-13 in the pathogenesis of these diseases. In particular, IL-13 is involved in the regulation of IgE synthesis, mucus hypersecretion, subepithelial fibrosis and eosinophil infiltration, and has been associated with the regulation of certain chemokine receptors, notably CCR5. Thus, targeting IL-13 and its associated receptors may be a therapeutic approach to the treatment of asthma and/or allergy. Pharmaceutical and biotechnology companies are researching various strategies, based on this approach, aimed at binding IL-13, increasing the level of the IL-13 decoy receptor, IL-13Ralpha2, or blocking the effect of the chemokine receptor CCR5. This review focuses on the therapeutic potential of anti-IL-13 agents and their role in the treatment of asthma and allergy.

Adapter-directed display: a modular design for shuttling display on phage surfaces.

A novel adapter-directed phage display system was developed with modular features. In this system, the target protein is expressed as a fusion protein consisting of adapter GR1 from the phagemid vector, while the recombinant phage coat protein is expressed as a fusion protein consisting of adapter GR2 in the helper phage vector. Surface display of the target protein is accomplished through specific heterodimerization of GR1 and GR2 adapters, followed by incorporation of the heterodimers into phage particles. A series of engineered helper phages were constructed to facilitate both display valency and formats, based on various phage coat proteins. As the target protein is independent of a specific phage coat protein, this modular system allows the target protein to be displayed on any given phage coat protein and allows various display formats from the same vector without the need for reengineering. Here, we demonstrate the shuttling display of a single-chain Fv antibody on phage surfaces between multivalent and monovalent formats, as well as the shuttling display of an antigen-binding fragment molecule on phage coat proteins pIII, pVII, and pVIII using the same phagemid vectors combined with different helper phage vectors. This adapter-directed display concept has been applied to eukaryotic yeast surface display and to a novel cross-species display that can shuttle between prokaryotic phage and eukaryotic yeast systems.

Impact of molecular processing in the hinge region of therapeutic IgG4 antibodies on disposition profiles in cynomolgus monkeys.

The IgG4 isotype antibody is a potential candidate for immunotherapy when reduced effector functions are desirable. However, antigen binding fragment (Fab) arm exchange leads to functional monovalency with potentially reduced therapeutic efficacy. Mutagenesis studies suggested that the CH3 domain and not the core hinge is dominantly involved in in vivo molecular processing. This work investigated whether stabilization of the core hinge of a therapeutic IgG4 antibody by mutation of Ser228 to Pro (S228P) would be sufficient to prevent in vivo Fab arm exchange. In vitro experiments evaluated the influence of different levels of oxidation-reduction conditions in buffer and serum on Fab arm exchange (swapping) of wild-type (WT) IgG4 and IgG1 and of IgG4 S228P, which included a sterically neutral second mutation (Leu235 replaced by Glu). The objective of single-dose pharmacokinetic experiments in cynomolgus monkeys was to determine whether the mutation reduced IgG4 swapping in vivo. The results indicated that S228P mutation did not completely prevent Fab arm exchange in vitro in buffer under reducing conditions relative to IgG4 WT. The immunoassay findings were confirmed by mass spectrometry measurements. Results of the in vivo studies suggested that the therapeutic IgG4 WT antibody exchanged Fab arms with endogenous cynomolgus monkey IgG4, resulting in bispecific IgG4 antibodies with monovalency for the therapeutic target. In contrast, serum from cynomolgus monkeys dosed with the IgG4 mutant was virtually free of swapped IgG4. In conclusion, the results indicated that IgG4 swapping in vivo was markedly attenuated by S228P mutation.

Interleukin-13 promoter gene polymorphism -1112C/T is associated with the systemic form of mastocytosis.

BACKGROUND: Mastocytosis is a heterogenous disease involving mast cells (MC) and their progenitors. Cutaneous and systemic variants of the disease have been reported. In contrast to cutaneous mastocytosis (CM), patients with systemic mastocytosis (SM) are at risk to develop disease progression or a nonMC-lineage haematopoietic neoplasm. Little is known, however, about factors predisposing for the development of SM. One factor may be cytokine regulation of MC progenitors. METHODS: We examined the role of the interleukin-13 (IL-13) promoter gene polymorphism -1112C/T, known to be associated with increased transcription, in mastocytosis using allele-specific polymerase chain reaction method. Serum tryptase and IL-13 levels were determined by immunoassay, and expression of the IL-13 receptor in neoplastic MC by reverse transcription-polymerase chain reaction and flow cytometry. RESULTS: The frequency of the -1112T allele of the IL-13 promoter was significantly higher in patients with SM compared with CM (P < 0.008) and in mastocytosis patients compared with healthy controls (P < 0.0001). Correspondingly, the polymorphism was found to correlate with an elevated serum tryptase level (P = 0.004) and with adult-onset of the disease (P < 0.0015), both of which are almost invariably associated with SM. Serum IL-13 levels were also higher in SM patients compared with CM (P = 0.011), and higher in CT- than in CC carriers (P < 0.05). Finally, we were able to show that neoplastic human MC display IL-13 receptors and grow better in IL-13-containing medium. CONCLUSIONS: The -1112C/T IL-13 gene polymorphism and the resulting 'hypertranscription' may predispose for the development of SM.