Phase 2, randomised placebo-controlled trial to evaluate the efficacy and safety of an anti-GM-CSF antibody (KB003) in patients with inadequately controlled asthma

Treatment with onion bulb extract both prevents and reverses allergic inflammation in a murine model of asthma

CONTEXT

Asthma presents a global health challenge. The main pharmacotherapy is synthetic chemicals and biological-based drugs that are costly, and have significant side effects. In contrast, use of natural products, such as onion (Allium cepa L., Amaryllidaceae) in the treatment of airway diseases has increased world-wide because of their perceived efficacy and little safety concerns. However, their pharmacological actions remain largely uncharacterized.

OBJECTIVE

We investigated whether onion bulb extract (OBE) can (1) reverse established asthma phenotype (therapeutic treatment) and/or (2) prevent the development of the asthma phenotype, if given before the immunization process (preventative treatment).

MATERIALS AND METHODS

Six groups of male Balb/c mice were established for the therapeutic (21 days) and five groups for the preventative (19 days) treatment protocols; including PBS and house dust mite (HDM)-challenged mice treated with vehicle or OBE (30, 60, and 100 mg/kg/i.p.). Airways inflammation was determined using cytology, histology, immunofluorescence, Western blot, and serum IgE.

RESULTS

Therapeutic (60 mg/kg/i.p.) and preventative (100 mg/kg/i.p.) OBE treatment resulted in down-regulation of HDM-induced airway cellular influx, histopathological changes and the increase in expression of pro-inflammatory signaling pathway EGFR, ERK1/2, AKT, pro-inflammatory cytokines and serum IgE.

DISCUSSION AND CONCLUSION

Our data show that OBE is an effective anti-inflammatory agent with both therapeutic and preventative anti-asthma effects. These findings imply that onion/OBE may be used as an adjunct therapeutic agent in established asthma and/or to prevent development of allergic asthma. However, further studies to identify the active constituents, and demonstrate proof-of-concept in humans are needed.

IL-5 and GM-CSF, but Not IL-3, Promote the Proliferative Properties of Inflammatory-like and Lung Resident-like Eosinophils in the Blood of Asthma Patients

Blood eosinophils can be described as inflammatory-like (iEOS-like) and lung-resident-like (rEOS-like) eosinophils. This study is based on the hypothesis that eosinophilopoetins such as interleukin (IL)-3 and IL-5 and granulocyte-macrophage colony-stimulating factor (GM-CSF) alter the proliferative properties of eosinophil subtypes and may be associated with the expression of their receptors on eosinophils. We investigated 8 individuals with severe nonallergic eosinophilic asthma (SNEA), 17 nonsevere allergic asthma (AA), and 11 healthy subjects (HS). For AA patients, a bronchial allergen challenge with Dermatophagoides pteronyssinus was performed. Eosinophils were isolated from peripheral blood using high-density centrifugation and magnetic separation methods. The subtyping of eosinophils was based on magnetic bead-conjugated antibodies against L-selectin. Preactivation by eosinophilopoetins was performed by incubating eosinophil subtypes with IL-3, IL-5, and GM-CSF, and individual combined cell cultures were prepared with airway smooth muscle (ASM) cells. ASM cell proliferation was assessed using an Alamar blue assay. The gene expression of eosinophilopoetin receptors was analyzed with a qPCR. IL-5 and GM-CSF significantly enhanced the proliferative properties of iEOS-like and rEOS-like cells on ASM cells in both SNEA and AA groups compared with eosinophils not activated by cytokines (p < 0.05). Moreover, rEOS-like cells demonstrated a higher gene expression of the IL-3 and IL-5 receptors compared with iEOS-like cells in the SNEA and AA groups (p < 0.05). In conclusion: IL-5 and GM-CSF promote the proliferative properties of iEOS-like and rEOS-like eosinophils; however, the effect of only IL-5 may be related to the expression of its receptors in asthma patients.

An exploratory study investigating biomarkers associated with autoimmune pulmonary alveolar proteinosis (aPAP)

Autoimmune pulmonary alveolar proteinosis (aPAP) is a rare lung disorder involving production of autoantibodies against endogenous granulocyte–macrophage colony-stimulating factor (GM-CSF). This study aimed to identify biomarkers that could be used to monitor for aPAP, particularly in patients treated with anti-GM-CSF antibodies. This was an exploratory, prospective, observational, single-center study. Pre-specified biomarkers were evaluated between baseline and Day 120 in serum/plasma, whole blood, sputum and exhaled breath condensate from patients with aPAP, healthy volunteers, and patients with chronic obstructive pulmonary disease (COPD) and asthma (not treated with anti-GM-CSF and with no evidence of aPAP). Pulmonary function tests were also performed. Overall, 144 individuals were enrolled (aPAP: n = 34, healthy volunteers: n = 24, COPD: n = 40 and asthma: n = 46). Plasma GM-CSF levels were lower, and Krebs von den Lungen 6 and GM-CSF autoantibody ranges were higher, in patients with aPAP compared with other populations. Surfactant proteins-A and -D, lactate dehydrogenase and carcinoembryonic antigen ranges partially or completely overlapped across populations. Most plasma biomarkers showed high sensitivity and specificity for detection of aPAP; GM-CSF and GM-CSF autoantibody concentrations demonstrated equivalent sensitivity for differentiating aPAP. In addition to characteristic GM-CSF autoantibodies, assessment of plasma GM-CSF may identify individuals at risk of developing aPAP.

Trial registration: EudraCT, 2012-003475-19. Registered 23 July 2012—https://eudract.ema.europa.eu/.

T2-low: what do we know?: Past, present, and future of biologic therapies in noneosinophilic asthma

T2-low asthma is an often severe asthma subtype with limited treatment options and biologic therapeutics are lacking. Several monoclonal antibodies (mAbs) targeting non-T2 cytokines were previously reported to be ineffective in asthma. These trials often investigated heterogeneous asthma populations and negative outcomes could be related to unsuitable study cohorts. More tailored approaches in selecting participants based on specific biomarkers have been beneficial in treating severe T2-high asthma. Similarly, mAbs previously deemed ineffective bear the potential to be useful when administered to the correct target population. Here, we review individual clinical trials conducted between 2005 and 2021 and assess the suitability of the selected cohorts, whether study end points were met, and whether outcome measures were appropriate to investigate the effectiveness of the respective drug. We discuss potential target groups within the T2-low asthma population and suggest biomarkers that may predict a treatment response. Furthermore, we assess whether biomarker-guided approaches or subgroup analyses were associated with more positive study outcomes. The mAbs directed against alarmins intervene early in the inflammatory cascade and are the first mAbs found to have efficacy in T2-low asthma. Several randomized controlled trials performed predefined subgroup analyses that included T2-low asthma. Subgroup analyses were associated with positive outcomes and were able to reveal a stronger response in at least 1 subgroup. A better understanding of T2-low subgroups and specific biomarkers is necessary to identify the most responsive target population for a given mAb.

Decreased expression of airway epithelial Axl is associated with eosinophilic inflammation in severe asthma

BACKGROUND

Airway epithelium-derived cytokines are critical to provoke and perpetuate type 2 inflammation in asthma. Yet it is poorly understood how this epithelial cell-driven inflammatory response is negatively regulated. We previously reported that Axl receptor tyrosine kinase was expressed by basal cells in the airway epithelium and had a role in defining their stem cell identity. However, whether and how Axl regulates airway type 2 inflammation remains unknown.

METHODS

We performed immunofluorescence staining to compare Axl expression in airway epithelium between non-asthmatic subjects, mild-moderate asthma and severe asthma. We confirmed this result by interrogating public databases of global gene expression in endobronchial biopsies. We then quantified eosinophil numbers infiltrating into the trachea of wild-type or Axl-knockout mice that were intranasally treated with house dust mite extracts (HDM). Cell-based assays using siRNA targeting Axl were further performed to identify molecules involved in Axl-mediated regulation of inflammation.

RESULTS

Histological assessments and transcriptome analyses revealed decreases in protein and mRNA of Axl in airway basal cells of severe asthmatics. This reduction of Axl expression was correlated with infiltration of eosinophils and mast cells in severe asthmatics. Eosinophil infiltration was more evident in the trachea of Axl-knockout mice in response to repetitive HDM administration. siRNA-mediated knockdown of Axl increased mRNA and protein expression of granulocyte macrophage-colony stimulating factor (GM-CSF) in human bronchial epithelial cells.

CONCLUSIONS

Axl kinase expressed by basal cells may suppress excessive eosinophilic inflammation via inhibition of GM-CSF in the airway. Axl reduction has clinical implications for the pathogenesis of severe asthma.

Human autoantibodies underlying infectious diseases

The vast interindividual clinical variability observed in any microbial infection—ranging from silent infection to lethal disease—is increasingly being explained by human genetic and immunological determinants. Autoantibodies neutralizing specific cytokines underlie the same infectious diseases as inborn errors of the corresponding cytokine or response pathway. Autoantibodies against type I IFNs underlie COVID-19 pneumonia and adverse reactions to the live attenuated yellow fever virus vaccine. Autoantibodies against type II IFN underlie severe disease caused by environmental or tuberculous mycobacteria, and other intra-macrophagic microbes. Autoantibodies against IL-17A/F and IL-6 are less common and underlie mucocutaneous candidiasis and staphylococcal diseases, respectively. Inborn errors of and autoantibodies against GM-CSF underlie pulmonary alveolar proteinosis; associated infections are less well characterized. In individual patients, autoantibodies against cytokines preexist infection with the pathogen concerned and underlie the infectious disease. Human antibody-driven autoimmunity can interfere with cytokines that are essential for protective immunity to specific infectious agents but that are otherwise redundant, thereby underlying specific infectious diseases.

Lenzilumab in hospitalised patients with COVID-19 pneumonia (LIVE-AIR): a phase 3, randomised, placebo-controlled trial

Background

The pathophysiology of COVID-19 includes immune-mediated hyperinflammation, which could potentially lead to respiratory failure and death. Granulocyte-macrophage colony-stimulating factor (GM-CSF) is among cytokines that contribute to the inflammatory processes. Lenzilumab, a GM-CSF neutralising monoclonal antibody, was investigated in the LIVE-AIR trial to assess its efficacy and safety in treating COVID-19 beyond available treatments.

Methods

In LIVE-AIR, a phase 3, randomised, double-blind, placebo-controlled trial, hospitalised adult patients with COVID-19 pneumonia not requiring invasive mechanical ventilation were recruited from 29 sites in the USA and Brazil and were randomly assigned (1:1) to receive three intravenous doses of lenzilumab (600 mg per dose) or placebo delivered 8 h apart. All patients received standard supportive care, including the use of remdesivir and corticosteroids. Patients were stratified at randomisation by age and disease severity. The primary endpoint was survival without invasive mechanical ventilation to day 28 in the modified intention-to-treat population (mITT), comprising all randomised participants who received at least one dose of study drug under the documented supervision of the principal investigator or sub-investigator. Adverse events were assessed in all patients who received at least one dose of study drug. This trial is registered with ClinicalTrials.gov, NCT04351152, and is completed.

Findings

Patients were enrolled from May 5, 2020, until Jan 27, 2021. 528 patients were screened, of whom 520 were randomly assigned and included in the intention-to-treat population. 479 of these patients (n=236, lenzilumab; n=243, placebo) were included in the mITT analysis for the primary outcome. Baseline demographics were similar between groups. 311 (65%) participants were males, mean age was 61 (SD 14) years at baseline, and median C-reactive protein concentration was 79 (IQR 41–137) mg/L. Steroids were administered to 449 (94%) patients and remdesivir to 347 (72%) patients; 331 (69%) patients received both treatments. Survival without invasive mechanical ventilation to day 28 was achieved in 198 (84%; 95% CI 79–89) participants in the lenzilumab group and in 190 (78%; 72–83) patients in the placebo group, and the likelihood of survival was greater with lenzilumab than placebo (hazard ratio 1·54; 95% CI 1·02–2·32; p=0·040). 68 (27%) of 255 patients in the lenzilumab group and 84 (33%) of 257 patients in the placebo group experienced at least one adverse event that was at least grade 3 in severity based on CTCAE criteria. The most common treatment-emergent adverse events of grade 3 or higher were related to respiratory disorders (26%) and cardiac disorders (6%) and none led to death.

Interpretation

Lenzilumab significantly improved survival without invasive mechanical ventilation in hospitalised patients with COVID-19, with a safety profile similar to that of placebo. The added value of lenzilumab beyond other immunomodulators used to treat COVID-19 alongside steroids remains unknown.

Funding

Humanigen.

Clinical characteristics, cytokine profiles and plasma IgE in adults with asthma

Asthma is a disease with complicated network of inflammatory responses of cytokines and ImmunoglobulinE (IgE). The aim of this study was to explore the clinical characteristics, cytokine profile and plasma IgE in the Malaysian population. This is a cross-sectional study involving physician-diagnosed asthma patients (n = 287) recruited from the Chest Clinic, University of Malaya Medical Centre (UMMC). Blood (8 mL) was taken after consent was obtained. The peripheral blood leucocytes (PBL) were cultured in presence of a mitogen for 72 h to quantify cytokines [Interleukin-5(IL-5), Interleukin-9 (IL-9), Interleukin-12 Beta (IL-12ꞵ) and granulocyte-macrophage colony-stimulating factor (GM-CSF)] and plasma was used to quantify IgE levels with commercial ELISA kits. Results were compared against the same biomarkers in healthy subjects (n = 203). In addition, the amount of the biomarkers in the asthma patients were compared with their disease severity and clinical characteristics. Statistical tests in the SPSS software (Mann-Whitney U test and the Kruskal Wallis) were used to compare cytokine production and plasma IgE levels. The mean plasma IgE level was markedly higher (p < 0.0001) in asthmatics compared to controls. There were higher levels of IL-5, IL-9, IL-12ꞵ and GM-CSF (p < 0.0001) produced by cultured PBL from asthma patients compared to controls. However, our results did not expose a significant association between these cytokine levels and severity and clinical symptoms of asthma. However, there was a marked association between asthma severity and blood lymphocyte count [ꭓ²(2) = 6.745, p < 0.05]. These findings support the roles played by cytokines and IgE in the airway inflammation in asthma. The findings of this study provide new information about inflammatory cytokines in Malaysian asthma patients.

Targeting GM-CSF in inflammatory and autoimmune disorders

Granulocyte macrophage-colony stimulating factor (GM-CSF) was originally identified as a growth factor for its ability to promote the proliferation and differentiation in vitro of bone marrow progenitor cells into granulocytes and macrophages. Many preclinical studies, using GM-CSF deletion or depletion approaches, have demonstrated that GM-CSF has a wide range of biological functions, including the mediation of inflammation and pain, indicating that it can be a potential target in many inflammatory and autoimmune conditions. This review provides a brief overview of GM-CSF biology and signaling, and summarizes the findings from preclinical models of a range of inflammatory and autoimmune disorders and the latest clinical trials targeting GM-CSF or its receptor in these disorders.

Asthma phenotypes and endotypes: a systematic review

INTRODUCTION

Asthma is a complex disorder characterized by expiratory airflow limitation, wheeze, shortness of breath, chest tightness and cough, which can vary over time and in intensity. Being highly heterogeneous, asthma was characterized and classified in several asthma phenotypes and endotypes from 1947 until today. The present systematic review aims to summarize and describe evidence that was published in the last ten years in the field of asthma phenotyping and endotyping.

EVIDENCE ACQUISITION

The systematic review resumed high-quality evidence (clinical trials and randomized control trials) retrieved on MEDLINE and EMBASE databanks and involving adult asthmatic populations. Analyses of literature were conducted according to PRISMA and CASP guidelines.

EVIDENCE SYNTHESIS

Querying MEDLINE and EMBASE databanks, 5019 and 12261 entries were retrieved, respectively. Applying limitations for year of publication, age of participants, and type of publication, the search results were reduced to 98 and 132 articles, respectively. After data abstraction and resolution of duplications, only 50 articles were further evaluated. The research products were then classified first in macro-areas of interest (phenotypes or endotypes) and then in detailed micro-areas.

CONCLUSIONS

This systematic review overviews the principal findings available from high-quality literature in the last decade concerning asthma phenotypes and endotypes. Asthma has been described from different points of view, characterizing symptoms, microbiota composition, comorbidities, viral infections, and airway and/or systemic inflammatory status. The comprehension of precise mechanisms underlying asthma pathogenesis is thereby the basis for the development of novel therapeutic strategies, likely essential to the development of precision medicine.

Phase 1 study of lenzilumab, a recombinant anti-human GM-CSF antibody, for chronic myelomonocytic leukemia

In this phase 1 trial, inhibition of granulocyte-macrophage colony-stimulating factor (GM-CSF) was associated with clinically meaningful responses in 5 of 15 patients with relapsed or refractory chronic myelomonocytic leukemia (CMML). Preliminary data suggest that this approach may be tractable in CMML bearing activating NRAS mutations.

GM-CSF instigates a dendritic cell-T-cell inflammatory circuit that drives chronic asthma development

BACKGROUND

Steroid-resistant asthma is often characterized by high levels of neutrophils and mixed T_H2/T_H17 immune profiles. Indeed, neutrophils are key drivers of chronic lung inflammation in multiple respiratory diseases. Their numbers correlate strongly with disease severity, and their presence is often associated with exacerbation of chronic lung inflammation.

OBJECTIVE

What factors drive development of neutrophil-mediated chronic lung disease remains largely unknown, and we sought to study the role of GM-CSF as a potential regulator in chronic asthma.

METHODS

Different experimental animal models of chronic asthma were used in combination with alveolar macrophage-reconstitution of global GM-CSF receptor knockout mice as well as cell-type-specific knockout animals to elucidate the role of GM-CSF signaling in chronic airway inflammation.

RESULTS

We identify GM-CSF signaling as a critical factor regulating pulmonary accumulation of neutrophils. We show that although being not required for intrinsically regulating neutrophil migration, GM-CSF controls lung dendritic cell function, which in turn promotes T-cell-dependent recruitment of neutrophils to the airways. We demonstrate that GM-CSF regulates lung dendritic cell antigen uptake, transport, and T_H2/T_H17 cell priming in an intrinsic fashion, which in turn drives pulmonary granulocyte recruitment and contributes to development of airway hyperresponsiveness in chronic disease.

CONCLUSIONS

We identify GM-CSF as a potentially novel therapeutic target in chronic lung inflammation, describing a GM-CSF-dependent lung conventional dendritic cell-T-cell-neutrophil axis that drives chronic lung disease.

Salt-inducible kinases are required for the IL-33-dependent secretion of cytokines and chemokines in mast cells

Cytokines and chemokines are important regulators of airway hyper-responsiveness, immune cell infiltration, and inflammation and are produced when mast cells are stimulated with interleukin-33 (IL-33). Here, we establish that the salt-inducible kinases (SIKs) are required for the IL-33-stimulated transcription of il13, gm-csf and tnf and hence the production of these cytokines. The IL-33-stimulated secretion of IL-13, granulocyte-macrophage colony stimulating factor, and tumor necrosis factor was strongly reduced in fetal liver-derived mast cells from mice expressing a kinase-inactive mutant of SIK3 and abolished in cells expressing kinase-inactive mutants of SIK2 and SIK3. The IL-33-dependent secretion of these cytokines and several chemokines was also abolished in SIK2/3 double knock-out bone marrow-derived mast cells (BMMC), reduced in SIK3 KO cells but little affected in BMMC expressing kinase-inactive mutants of SIK1 and SIK2 or lacking SIK2 expression. In SIK2 knock-out BMMC, the expression of SIK3 was greatly increased. Our studies identify essential roles for SIK2 and SIK3 in producing inflammatory mediators that trigger airway inflammation. The effects of SIKs were independent of IκB kinase β, IκB kinase β-mediated NF-κB-dependent gene transcription, and activation of the mitogen-activated protein kinase family members p38α and c-jun N-terminal kinases. Our results suggest that dual inhibitors of SIK2 and SIK3 may have therapeutic potential for the treatment of mast cell-driven diseases.

Emerging drugs for the treatment of chronic myelomonocytic leukemia

Introduction: Chronic myelomonocytic leukemia (CMML) is a clonal hematologic disorder with heterogenous prognosis, but with no curative therapies with exception of allogeneic transplant. Therapeutic options for patients with CMML are limited, and although hypomethylating agents such as azacitidine and decitabine are the standard of care, only 40% of patients achieve a response, and most responses are transient. Over the last 5 years, significant advances have been made in the understanding of the clonal landscape of CMML, some of the mechanisms associated to resistance to HMA, and other key biological processes involved in disease pathogenesis. Areas covered: The current article reviews the most relevant emerging therapies currently undergoing clinical trials for the treatment of previously untreated or relapsed CMML. Expert opinion: The presence of recurrent somatic mutations in CMML represents therapeutic opportunities to utilize specific small molecule inhibitors such as IDH, FLT3, MEK/ERK, PLK1, or splicing inhibitors and modulators. In addition, other novel agents such as immune therapies, BCL2 or MCL1 inhibitors and other monoclonal antibodies could lead to therapeutic advances. Identifying specific patient populations likely to benefit from some of these interventions, and development of optimal combinations will remain the challenge when determining their role in therapy.

GM-CSF Neutralization With Lenzilumab in Severe COVID-19 Pneumonia: A Case-Cohort Study

OBJECTIVE

To assess the efficacy and safety of lenzilumab in patients with severe coronavirus disease 2019 (COVID-19) pneumonia.

METHODS

Hospitalized patients with COVID-19 pneumonia and risk factors for poor outcomes were treated with lenzilumab 600 mg intravenously for three doses through an emergency single-use investigational new drug application. Patient characteristics, clinical and laboratory outcomes, and adverse events were recorded. We also identified a cohort of patients matched to the lenzilumab patients for age, sex, and disease severity. Study dates were March 13, 2020, to June 18, 2020. All patients were followed through hospital discharge or death.

RESULTS

Twelve patients were treated with lenzilumab; 27 patients comprised the matched control cohort (untreated). Clinical improvement, defined as improvement of at least 2 points on the 8-point ordinal clinical endpoints scale, was observed in 11 of 12 (91.7%) patients treated with lenzilumab and 22 of 27 (81.5%) untreated patients. The time to clinical improvement was significantly shorter for the lenzilumab-treated group compared with the untreated cohort with a median of 5 days versus 11 days (P=.006). Similarly, the proportion of patients with acute respiratory distress syndrome (oxygen saturation/fraction of inspired oxygen<315 mm Hg) was significantly reduced over time when treated with lenzilumab compared with untreated (P<.001). Significant improvement in inflammatory markers (C-reactive protein and interleukin 6) and markers of disease severity (absolute lymphocyte count) were observed in patients who received lenzilumab, but not in untreated patients. Cytokine analysis showed a reduction in inflammatory myeloid cells 2 days after lenzilumab treatment. There were no treatment-emergent adverse events attributable to lenzilumab.

CONCLUSION

In high-risk COVID-19 patients with severe pneumonia, granulocyte-macrophage colony-stimulating factor neutralization with lenzilumab was safe and associated with faster improvement in clinical outcomes, including oxygenation, and greater reductions in inflammatory markers compared with a matched control cohort of patients hospitalized with severe COVID-19 pneumonia. A randomized, placebo-controlled clinical trial to validate these findings is ongoing (NCT04351152).

GM-CSF: A Promising Target in Inflammation and Autoimmunity

The cytokine, granulocyte macrophage-colony stimulating factor (GM-CSF), was firstly identified as being able to induce in vitro the proliferation and differentiation of bone marrow progenitors into granulocytes and macrophages. Much preclinical data have indicated that GM-CSF has a wide range of functions across different tissues in its action on myeloid cells, and GM-CSF deletion/depletion approaches indicate its potential as an important therapeutic target in several inflammatory and autoimmune disorders, for example, rheumatoid arthritis. In this review, we discuss briefly the biology of GM-CSF, raise some current issues and questions pertaining to this biology, summarize the results from preclinical models of a range of inflammatory and autoimmune disorders and list the latest clinical trials evaluating GM-CSF blockade in such disorders.

Targeting neutrophils in asthma: A therapeutic opportunity?

Suppression of airway inflammation with inhaled corticosteroids has been the key therapeutic approach for asthma for many years. Identification of inflammatory phenotypes in asthma has moreover led to important breakthroughs, e.g. with specific targeting of the IL-5 pathway as add-on treatment in difficult-to-treat eosinophilic asthma. However, the impact of interfering with the neutrophilic component in asthma is less documented and understood. This review provides an overview of established and recent insights with regard to the role of neutrophils in asthma, focusing on research in humans. We will describe the main drivers of neutrophilic responses in asthma, the heterogeneity in neutrophils and how they could contribute to asthma pathogenesis. Moreover we will describe findings from clinical trials, in which neutrophilic inflammation was targeted. It is clear that neutrophils are important actors in asthma development and play a role in exacerbations. However, more research is required to fully understand how modulation of neutrophil activity could lead to a significant benefit in asthma patients with airway neutrophilia.

GM-CSF in inflammation

GM-CSF is a potential therapeutic target in inflammation and autoimmunity. This study reviews the literature on the biology of GM-CSF, in particular that describing the research leading to clinical trials targeting GM-CSF and its receptor in numerous inflammatory/autoimmune conditions, such as rheumatoid arthritis.

Granulocyte–macrophage colony-stimulating factor (GM-CSF) has many more functions than its original in vitro identification as an inducer of granulocyte and macrophage development from progenitor cells. Key features of GM-CSF biology need to be defined better, such as the responding and producing cell types, its links with other mediators, its prosurvival versus activation/differentiation functions, and when it is relevant in pathology. Significant preclinical data have emerged from GM-CSF deletion/depletion approaches indicating that GM-CSF is a potential target in many inflammatory/autoimmune conditions. Clinical trials targeting GM-CSF or its receptor have shown encouraging efficacy and safety profiles, particularly in rheumatoid arthritis. This review provides an update on the above topics and current issues/questions surrounding GM-CSF biology.

GM-CSF-based treatments in COVID-19: reconciling opposing therapeutic approaches

Therapeutics against coronavirus disease 2019 (COVID-19) are urgently needed. Granulocyte–macrophage colony-stimulating factor (GM-CSF), a myelopoietic growth factor and pro-inflammatory cytokine, plays a critical role in alveolar macrophage homeostasis, lung inflammation and immunological disease. Both administration and inhibition of GM-CSF are currently being therapeutically tested in COVID-19 clinical trials. This Perspective discusses the pleiotropic biology of GM-CSF and the scientific merits behind these contrasting approaches.

Recombinant granulocyte–macrophage colony-stimulating factor (GM-CSF) as well as antibodies targeted at GM-CSF or its receptor are being tested in clinical trials for coronavirus disease 2019 (COVID-19). This Perspective introduces the pleiotropic functions of GM-CSF and explores the rationale behind these different approaches.

First Clinical Use of Lenzilumab to Neutralize GM-CSF in Patients with Severe COVID-19 Pneumonia

BACKGROUND

In COVID-19, high levels of granulocyte macrophage-colony stimulating factor (GM-CSF) and inflammatory myeloid cells correlate with disease severity, cytokine storm, and respiratory failure. With this rationale, we used lenzilumab, an anti-human GM-CSF monoclonal antibody, to treat patients with severe COVID-19 pneumonia.

METHODS

Hospitalized patients with COVID-19 pneumonia and risk factors for poor outcomes were treated with lenzilumab 600 mg intravenously for three doses through an emergency single-use IND application. Patient characteristics, clinical and laboratory outcomes, and adverse events were recorded. All patients receiving lenzilumab through May 1, 2020 were included in this report.

RESULTS

Twelve patients were treated with lenzilumab. Clinical improvement was observed in 11 out of 12 (92%), with a median time to discharge of 5 days. There was a significant improvement in oxygenation: The proportion of patients with SpO2/FiO2 < 315 at the end of observation was 8% vs. compared to 67% at baseline (p=0.00015). A significant improvement in mean CRP and IL-6 values on day 3 following lenzilumab administration was also observed (137.3 mg/L vs 51.2 mg/L, p = 0.040; 26.8 pg/mL vs 16.1 pg/mL, p = 0.035; respectively). Cytokine analysis showed a reduction in inflammatory myeloid cells two days after lenzilumab treatment. There were no treatment-emergent adverse events attributable to lenzilumab, and no mortality in this cohort of patients with severe COVID-19 pneumonia.

CONCLUSIONS

In high-risk COVID-19 patients with severe pneumonia, GM-CSF neutralization with lenzilumab was safe and associated with improved clinical outcomes, oxygen requirement, and cytokine storm.

Regulating the development of pulmonary Group 2 innate lymphoid cells

Group 2 innate lymphoid cells (ILC2s) are members of the family of innate lymphoid cells and are innately committed to type 2 immune responses. In the lungs, ILC2s are the predominant population of innate lymphoid cells (ILCs) and their development is orchestrated by several different transcription factors ensuring lineage commitment by intrinsic regulation. ILC2s are present in the lungs from the foetal period onwards and are thus exposed to extrinsic regulation due to the airways' continuous morphological changes upon birth. In this review, we will briefly summarise the dependence of ILC2s on transcription factors and discuss recently described characteristics and function of early life ILC2s in the lungs.

Contributions of Eosinophils to Human Health and Disease

The human eosinophil has long been thought to favorably influence innate mucosal immunity but at times has also been incriminated in disease pathophysiology. Research into eosinophil biology has uncovered a number of interesting contributions by eosinophils to health and disease. However, it appears that not all eosinophils from all species are created equal. It remains unclear, for example, exactly how having eosinophils benefits the human host when helminth infections in the developed world have become scarce. This review focuses on our current state of knowledge as it relates to human eosinophils. When information is lacking, we discuss lessons learned from mouse studies that may or may not directly apply to human biology and disease. It is an exciting time to be an "eosinophilosopher" because the use of biologic agents that selectively target eosinophils provides an unprecedented opportunity to define the contribution of this cell to eosinophil-associated human diseases.

The Cytokines of Asthma

Asthma is a chronic inflammatory airway disease associated with type 2 cytokines interleukin-4 (IL-4), IL-5, and IL-13, which promote airway eosinophilia, mucus overproduction, bronchial hyperresponsiveness (BHR), and immunogloubulin E (IgE) synthesis. However, only half of asthma patients exhibit signs of an exacerbated Type 2 response. "Type 2-low" asthma has different immune features: airway neutrophilia, obesity-related systemic inflammation, or in some cases, few signs of immune activation. Here, we review the cytokine networks driving asthma, placing these in cellular context and incorporating insights from cytokine-targeting therapies in the clinic. We discuss established and emerging paradigms in the context of the growing appreciation of disease heterogeneity and argue that the development of new and improved therapeutics will require understanding the diverse mechanisms underlying the spectrum of asthma pathologies.

Targeting cytokines to treat asthma and chronic obstructive pulmonary disease

Cytokines play a key role in orchestrating and perpetuating the chronic airway inflammation in asthma and chronic obstructive pulmonary disease (COPD), making them attractive targets for treating these disorders. Asthma and some cases of COPD are mainly driven by type 2 immune responses, which comprise increased airway eosinophils, T helper 2 (T_H2) cells and group 2 innate lymphoid cells (ILC2s) and the secretion of IL-4, IL-5 and IL-13. Clinical trials of antibodies that block these interleukins have shown reduced acute exacerbations and oral corticosteroid use and improvements in lung function and symptoms in selected patients. More recent approaches that block upstream cytokines, such as thymic stromal lymphopoietin (TSLP), show promise in improving patient outcome. Importantly, the clinical trials in cytokine blockade have highlighted the crucial importance of patient selection for the successful use of these expensive therapies and the need for biomarkers to better predict drug responses.

Monoclonal antibodies in type 2 asthma: a systematic review and network meta-analysis

Since novel treatments to target eosinophilic inflammation in Type 2 asthma are emerging, we aimed to evaluate and meta-analyze the efficacy of monoclonal antibodies to reduce exacerbation rate. PubMed and Web of Science were searched for phase II and phase III randomized clinical trials with monoclonal antibodies targeting key mediators of type 2-associated asthma. Thirty trials were selected involving biologics that target the IL-5 pathway, IL-13, the common IL-4 and IL-13 receptor, IL-9, IL-2 and TSLP. As no head-to-head trials were retrieved from literature, we performed an arm-based network meta-analysis to compare effects on exacerbation rate between the different treatments.

Mepolizumab, reslizumab and benralizumab significantly reduced the risk of exacerbations compared to placebo (by 47–52%, 50–60%, and 28–51% respectively). Reslizumab and benralizumab also improved lung function. Dupilumab and tezepelumab improved lung function in frequent exacerbators. Lebrikizumab had no significant effect on the number of exacerbations, symptom control or health-related quality of life. Tralokinumab improved lung function compared to placebo. Network meta-analysis of all treatment and placebo arms, showed no superiority of one biologic over the others. Large reductions in exacerbation rates were observed compared to placebo, though only benralizumab was sufficiently powered (n = 2051) to demonstrate significantly decreased exacerbation rates in the subgroup analysis of IL-5 acting agents compared to placebo.

Monoclonal antibodies such as mepolizumab, reslizumab and benralizumab have proven their benefit to reduce exacerbation rates in severe persistent eosinophilic asthma in the published trials. However, no statistically significant superiority was observed of one biologic over the other in the network meta-analysis. More studies with direct head to head comparisons and better defined endotypes are required.

Challenges in the treatment of Rheumatoid Arthritis

Rheumatoid Arthritis (RA) is a chronic inflammatory disease characterized by a heterogeneous clinical response to the different treatments. Some patients are difficult to treat and do not reach the treatment targets as clinical remission or low disease activity. Known negative prognostic factors, such as the presence of auto-antiantibodies and joint erosion, the presence of a genetic profile, comorbidities and extra-articular manifestations, pregnancy or a pregnancy wish may concur to the treatment failure. In this review we aimed at identify difficult to treat RA patients and define the optimal therapeutic and environmental targets. Genetic markers of severity such as HLA-DRB1, TRAF1, PSORS1C1 and microRNA 146a are differently associated with joint damage; other gene polymorphisms seem to be associated with response to biologic disease modifying anti-rheumatic drugs (bDMARDs). The presence of comorbidities and/or extra-articular manifestations may influence the therapeutic choice; overweight and obese patients are less responsive to TNF inhibitors. In this context the patient profiling can improve the clinical outcome. Targeting different pathways, molecules, and cells involved in the pathogenesis of RA may in part justify the lack response of some patients. An overview of the future therapeutic targets, including bDMARDs (inhibitors of IL-6, GM-CSF, matrix metalloproteinases, chemokines) and targeted synthetic DMARDs (filgotinib, ABT-494, pefacitinib, decernotinib), and environmental targets is addressed. Environmental factors, such as diet and cigarette smoke, may influence susceptibility to autoimmune diseases and interfere with inflammatory pathways. Mediterranean diet, low salt intake, cocoa, curcumin, and physical activity seem to show beneficial effects, however studies of dose finding, safety and efficacy in RA need to be performed.

Relationship between various cytokines implicated in asthma

Asthma is a complex disorder involving immunologic, environmental, genetic and other factors. Today, asthma is the most common disease encountered in clinical medicine in both children and adults worldwide. Asthma is characterized by increased responsiveness of the tracheobronchial tree resulting in chronic swelling and inflammation of the airways recognized to be controlled by the T-helper 2 (Th2) lymphocytes, which secrete cytokines to increase the production of IgE by B cells. There are many cytokines implicated in the development of the chronic inflammatory processes that are often observed in asthma. Ultimately, these cytokines cause the release of mediators such as histamine and leukotrienes (LT), which in turn promote airway remodeling, bronchial hyperresponsiveness and bronchoconstriction. The CD4⁺ T-lymphocytes from the airways of asthmatics express a panel of cytokines that represent the Th2 cells. The knowledge derived from numerous experimental and clinical studies have allowed physicians and scientists to understand the normal functions of these cytokines and their roles in the pathogenesis of asthma. The main focus of this review is to accentuate the relationship between various cytokines implicated in human asthma. However, some key findings from animal models will be highlighted to support the discoveries from clinical studies.

GM-CSF inhibition reduces cytokine release syndrome and neuroinflammation but enhances CAR-T cell function in xenografts

Chimeric antigen receptor T (CAR-T) cell therapy is a new pillar in cancer therapeutics; however, its application is limited by the associated toxicities. These include cytokine release syndrome (CRS) and neurotoxicity. Although the IL-6R antagonist tocilizumab is approved for treatment of CRS, there is no approved treatment of neurotoxicity associated with CD19-targeted CAR-T (CART19) cell therapy. Recent data suggest that monocytes and macrophages contribute to the development of CRS and neurotoxicity after CAR-T cell therapy. Therefore, we investigated neutralizing granulocyte-macrophage colony-stimulating factor (GM-CSF) as a potential strategy to manage CART19 cell–associated toxicities. In this study, we show that GM-CSF neutralization with lenzilumab does not inhibit CART19 cell function in vitro or in vivo. Moreover, CART19 cell proliferation was enhanced and durable control of leukemic disease was maintained better in patient-derived xenografts after GM-CSF neutralization with lenzilumab. In a patient acute lymphoblastic leukemia xenograft model of CRS and neuroinflammation (NI), GM-CSF neutralization resulted in a reduction of myeloid and T cell infiltration in the central nervous system and a significant reduction in NI and prevention of CRS. Finally, we generated GM-CSF–deficient CART19 cells through CRISPR/Cas9 disruption of GM-CSF during CAR-T cell manufacturing. These GM-CSFk/o CAR-T cells maintained normal functions and had enhanced antitumor activity in vivo, as well as improved overall survival, compared with CART19 cells. Together, these studies illuminate a novel approach to abrogate NI and CRS through GM-CSF neutralization, which may potentially enhance CAR-T cell function. Phase 2 studies with lenzilumab in combination with CART19 cell therapy are planned.

Systematic literature review of the clinical, humanistic, and economic burden associated with asthma uncontrolled by GINA Steps 4 or 5 treatment

OBJECTIVE

This study sought to characterize the epidemiologic, clinical, humanistic, and economic burden of patients with asthma uncontrolled by GINA Steps 4 or 5 treatment (severe, uncontrolled asthma [SUA]).

METHODS

A systematic literature review adhering to PRISMA guidelines was performed. Relevant publications were searched for in MEDLINE and EMBASE from January 2004 to September 2016 and in a conference proceedings database from January 2012 to October 2016. Studies were screened using the Population, Intervention, Comparator, Outcomes, Study Design, and Time (PICOS-T) framework. Studies of SUA with observational (prospective and retrospective), randomized, or nonrandomized study designs; adult patient populations; sample sizes ≥20 patients; epidemiologic or clinical outcomes, patient-reported outcomes (PROs), or economic outcomes were included. For our analysis, SUA was defined as inadequate control of asthma, despite the use of medium- to high-dosage inhaled corticosteroids and at least one additional treatment.

RESULTS

A total of 195 articles reporting unique study populations were included. Prevalence of SUA was as great as 87.4% for patients with severe asthma, although values varied depending on the criteria used to define asthma control. Compared with patients with severe asthma who were controlled, patients with SUA experienced more symptoms, night-time awakenings, rescue medication use, and worse PROs. SUA-associated costs were 3-times greater than costs for patients with severe, controlled disease.

CONCLUSION

Despite the availability of approved asthma treatments, this literature analysis confirms that SUA poses a substantial epidemiologic, clinical, humanistic, and economic burden. Published data are limited for certain aspects of SUA, highlighting a need for further research.

GM-CSF inhibition reduces cytokine release syndrome and neuroinflammation but enhances CAR-T cell function in xenografts

Chimeric antigen receptor T (CAR-T) cell therapy is a new pillar in cancer therapeutics; however, its application is limited by the associated toxicities. These include cytokine release syndrome (CRS) and neurotoxicity. Although the IL-6R antagonist tocilizumab is approved for treatment of CRS, there is no approved treatment of neurotoxicity associated with CD19-targeted CAR-T (CART19) cell therapy. Recent data suggest that monocytes and macrophages contribute to the development of CRS and neurotoxicity after CAR-T cell therapy. Therefore, we investigated neutralizing granulocyte-macrophage colony-stimulating factor (GM-CSF) as a potential strategy to manage CART19 cell-associated toxicities. In this study, we show that GM-CSF neutralization with lenzilumab does not inhibit CART19 cell function in vitro or in vivo. Moreover, CART19 cell proliferation was enhanced and durable control of leukemic disease was maintained better in patient-derived xenografts after GM-CSF neutralization with lenzilumab. In a patient acute lymphoblastic leukemia xenograft model of CRS and neuroinflammation (NI), GM-CSF neutralization resulted in a reduction of myeloid and T cell infiltration in the central nervous system and a significant reduction in NI and prevention of CRS. Finally, we generated GM-CSF-deficient CART19 cells through CRISPR/Cas9 disruption of GM-CSF during CAR-T cell manufacturing. These GM-CSF^k/o CAR-T cells maintained normal functions and had enhanced antitumor activity in vivo, as well as improved overall survival, compared with CART19 cells. Together, these studies illuminate a novel approach to abrogate NI and CRS through GM-CSF neutralization, which may potentially enhance CAR-T cell function. Phase 2 studies with lenzilumab in combination with CART19 cell therapy are planned.

Pathogenic Role of Immune Cells in Rheumatoid Arthritis: Implications in Clinical Treatment and Biomarker Development

Rheumatoid arthritis (RA) is a chronic, autoimmune, systemic, inflammatory disorder that affects synovial joints, both small and large joints, in a symmetric pattern. This disorder usually does not directly cause death but significantly reduces the quality of life and life expectancy of patients if left untreated. There is no cure for RA but, patients are usually on long-term disease modifying anti-rheumatic drugs (DMARDs) to suppress the joint inflammation, to minimize joint damage, to preserve joint function, and to keep the disease in remission. RA is strongly associated with various immune cells and each of the cell type contributes differently to the disease pathogenesis. Several types of immunomodulatory molecules mainly cytokines secreted from immune cells mediate pathogenesis of RA, hence complicating the disease treatment and management. There are various treatments for RA depending on the severity of the disease and more importantly, the patient’s response towards the given drugs. Early diagnosis of RA and treatment with (DMARDs) are known to significantly improve the treatment outcome of patients. Sensitive biomarkers are crucial in early detection of disease as well as to monitor the disease activity and progress. This review aims to discuss the pathogenic role of various immune cells and immunological molecules in RA. This review also highlights the importance of understanding the immune cells in treating RA and in exploring novel biomarkers.

The mechanism of GM-CSF inhibition by human GM-CSF auto-antibodies suggests novel therapeutic opportunities

Granulocyte-macrophage colony-stimulating factor (GM-CSF) is a hematopoietic growth factor that can stimulate a variety of cells, but its overexpression leads to excessive production and activation of granulocytes and macrophages with many pathogenic effects. This cytokine is a therapeutic target in inflammatory diseases, and several anti-GM-CSF antibodies have advanced to Phase 2 clinical trials in patients with such diseases, e.g., rheumatoid arthritis. GM-CSF is also an essential factor in preventing pulmonary alveolar proteinosis (PAP), a disease associated with GM-CSF malfunction arising most typically through the presence of GM-CSF neutralizing auto-antibodies. Understanding the mechanism of action for neutralizing antibodies that target GM-CSF is important for improving their specificity and affinity as therapeutics and, conversely, in devising strategies to reduce the effects of GM-CSF auto-antibodies in PAP. We have solved the crystal structures of human GM-CSF bound to antigen-binding fragments of two neutralizing antibodies, the human auto-antibody F1 and the mouse monoclonal antibody 4D4. Coordinates and structure factors of the crystal structures of the GM-CSF:F1 Fab and the GM-CSF:4D4 Fab complexes have been deposited in the RCSB Protein Data Bank under the accession numbers 6BFQ and 6BFS, respectively. The structures show that these antibodies bind to mutually exclusive epitopes on GM-CSF; however, both prevent the cytokine from interacting with its alpha receptor subunit and hence prevent receptor activation. Importantly, identification of the F1 epitope together with functional analyses highlighted modifications to GM-CSF that would abolish auto-antibody recognition whilst retaining GM-CSF function. These results provide a framework for developing novel GM-CSF molecules for PAP treatment and for optimizing current anti-GM-CSF antibodies for use in treating inflammatory disorders.

Insights in particulate matter-induced allergic airway inflammation: Focus on the epithelium

Outdoor air pollution is a major environmental health problem throughout the world. In particular, exposure to particulate matter (PM) has been associated with the development and exacerbation of several respiratory diseases, including asthma. Although the adverse health effects of PM have been demonstrated for many years, the underlying mechanisms have not been fully identified. In this review, we focus on the role of the lung epithelium and specifically highlight multiple cytokines in PM-induced respiratory responses. We describe the available literature on the topic including in vitro studies, findings in humans (ie observations in human cohorts, human controlled exposure and ex vivo studies) and in vivo animal studies. In brief, it has been shown that exposure to PM modulates the airway epithelium and promotes the production of several cytokines, including IL-1, IL-6, IL-8, IL-25, IL-33, TNF-α, TSLP and GM-CSF. Further, we propose that PM-induced type 2-promoting cytokines are important mediators in the acute and aggravating effects of PM on airway inflammation. Targeting these cytokines could therefore be a new approach in the treatment of asthma.

Role of the β Common (βc) Family of Cytokines in Health and Disease

The β common ([βc]/CD131) family of cytokines comprises granulocyte macrophage colony-stimulating factor (GM-CSF), interleukin (IL)-3, and IL-5, all of which use βc as their key signaling receptor subunit. This is a prototypic signaling subunit-sharing cytokine family that has unveiled many biological paradigms and structural principles applicable to the IL-2, IL-4, and IL-6 receptor families, all of which also share one or more signaling subunits. Originally identified for their functions in the hematopoietic system, the βc cytokines are now known to be truly pleiotropic, impacting on multiple cell types, organs, and biological systems, and thereby controlling the balance between health and disease. This review will focus on the emerging biological roles for the βc cytokines, our progress toward understanding the mechanisms of receptor assembly and signaling, and the application of this knowledge to develop exciting new therapeutic approaches against human disease.

Diagnosis and Novel Approaches to the Treatment of Hypereosinophilic Syndromes

PURPOSE OF REVIEW

Hypereosinophilic syndrome (HES) is characterized by persistent hypereosinophilia associated with end-organ damage. As our understanding of the pathogenesis of various forms of HES broadens, so does our ability to tailor steroid-sparing therapies for each subtype. The purpose of this review is to summarize recent literature related to the etiology, diagnosis, and management of HES.

RECENT FINDINGS

Mutations involved in subsets of HES can guide the choice of tyrosine kinase inhibitors beyond just imatinib. Several biologics that target interleukin-5 or its receptor have shown beneficial and selective eosinophil-reducing effects in clinical trials for asthma and other disorders including HES. Early clinical data with emerging therapies such as dexpramipexole and anti-Siglec-8 antibody show promise, but need to be confirmed in randomized trials. Several new biologics and tyrosine kinase inhibitors have been shown to lower eosinophil numbers, but more randomized trials are needed to confirm efficacy in HES.

Therapeutic antibodies: A new era in the treatment of respiratory diseases?

Respiratory diseases affect millions of people worldwide, and account for significant levels of disability and mortality. The treatment of lung cancer and asthma with therapeutic antibodies (Abs) is a breakthrough that opens up new paradigms for the management of respiratory diseases. Antibodies are becoming increasingly important in respiratory medicine; dozens of Abs have received marketing approval, and many more are currently in clinical development. Most of these Abs target asthma, lung cancer and respiratory infections, while very few target chronic obstructive pulmonary disease - one of the most common non-communicable causes of death - and idiopathic pulmonary fibrosis. Here, we review Abs approved for or in clinical development for the treatment of respiratory diseases. We notably highlight their molecular mechanisms, strengths, and likely future trends.

Investigational therapies targeting the granulocyte macrophage colony-stimulating factor receptor-α in rheumatoid arthritis: focus on mavrilimumab

Mavrilimumab (formerly CAM-3001) is a high-affinity, immunoglobulin G4 monoclonal antibody (mAb) against the granulocyte macrophage colony-stimulating factor (GM-CSF) receptor-α chain. Phase I and II trials in patients with rheumatoid arthritis (RA) treated with mavrilimumab have shown encouraging results with respect to both safety and efficacy. No significant adverse events have so far been noted. The trials have demonstrated significant clinical benefit, meeting primary endpoints. Furthermore, for RA patients treated with mavrilimumab, who were tumour necrosis factor (TNF) inhibitor-inadequate responders, there are encouraging preliminary data indicating benefit and identifying potential biomarkers predictive of patients likely to find benefit. Here, we review the clinical trial data for mavrilimumab and discuss its potential as a treatment for RA in light of the competitive landscape in which it resides.

Biologic Therapy and Novel Molecular Targets of Severe Asthma

Treatment options for severe or uncontrolled asthma are increasing, especially pertaining to novel biologic therapies. The 2 primary asthma endotypes, T2 high and T2 low, are defined by the level of type 2 T helper and innate lymphoid cell activity and mediators. Most therapies for severe asthma target T2 high asthma, including the 3 biologics approved for use in the United States and Europe: omalizumb, mepolizumb, and reslizumab. Other biologics, with various molecular targets, are under investigation. Unfortunately, treatment options for T2 low asthma are limited. Although these therapies may improve asthma symptoms, exacerbation rates, and lung function parameters, they have not been shown to modify the disease process or provide lasting benefits after discontinuation. Biomarkers identified thus far to help guide individualized therapy in severe asthma are helpful, but imperfect discriminators for picking the best option for individual patients. This review will discuss the mechanisms of action, indications, and therapeutic effects of currently available and emerging biologics for the treatment of severe or uncontrolled asthma.

Monoclonal Antibody Therapies for Hematological Malignancies: Not Just Lineage-Specific Targets

Today, monoclonal antibodies (mAbs) are a widespread and necessary tool for biomedical science. In the hematological cancer field, since rituximab became the first mAb approved by the Food and Drug Administration for the treatment of B-cell malignancies, a number of effective mAbs targeting lineage-specific antigens (LSAs) have been successfully developed. Non-LSAs (NLSAs) are molecules that are not restricted to specific leukocyte subsets or tissues but play relevant pathogenic roles in blood cancers including the development, proliferation, survival, and refractoriness to therapy of tumor cells. In consequence, efforts to target NLSAs have resulted in a plethora of mAbs-marketed or in development-to achieve different goals like neutralizing oncogenic pathways, blocking tumor-related chemotactic pathways, mobilizing malignant cells from tumor microenvironment to peripheral blood, modulating immune-checkpoints, or delivering cytotoxic drugs into tumor cells. Here, we extensively review several novel mAbs directed against NLSAs undergoing clinical evaluation for treating hematological malignancies. The review focuses on the structure of these antibodies, proposed mechanisms of action, efficacy and safety profile in clinical studies, and their potential applications in the treatment of hematological malignancies.

The barrier hypothesis and Oncostatin M: Restoration of epithelial barrier function as a novel therapeutic strategy for the treatment of type 2 inflammatory disease

Mucosal epithelium maintains tissue homeostasis through many processes, including epithelial barrier function, which separates the environment from the tissue. The barrier hypothesis of type 2 inflammatory disease postulates that epithelial and epidermal barrier dysfunction, which cause inappropriate exposure to the environment, can result in allergic sensitization and development of type 2 inflammatory disease. The restoration of barrier dysfunction once it's lost, or the prevention of barrier dysfunction, have the potential to be exciting new therapeutic strategies for the treatment of type 2 inflammatory disease. Neutrophil-derived Oncostatin M has been shown to be a potent disrupter of epithelial barrier function through the induction of epithelial-mesenchymal transition (EMT). This review will discuss these events and outline several points along this axis at which therapeutic intervention could be beneficial for the treatment of type 2 inflammatory diseases.

Neutrophils are a major source of the epithelial barrier disrupting cytokine oncostatin M in patients with mucosal airways disease

BACKGROUND

We have previously shown that oncostatin M (OSM) levels are increased in nasal polyps (NPs) of patients with chronic rhinosinusitis (CRS), as well as in bronchoalveolar lavage fluid, after segmental allergen challenge in allergic asthmatic patients. We also showed in vitro that physiologic levels of OSM impair barrier function in differentiated airway epithelium.

OBJECTIVE

We sought to determine which hematopoietic or resident cell type or types were the source of the OSM expressed in patients with mucosal airways disease.

METHODS

Paraffin-embedded NP sections were stained with fluorescence-labeled specific antibodies against OSM, GM-CSF, and hematopoietic cell-specific markers. Live cells were isolated from NPs and matched blood samples for flow cytometric analysis. Neutrophils were isolated from whole blood and cultured with the known OSM inducers GM-CSF and follistatin-like 1, and OSM levels were measured in the supernatants. Bronchial biopsy sections from control subjects, patients with moderate asthma, and patients with severe asthma were stained for OSM and neutrophil elastase.

RESULTS

OSM staining was observed in NPs, showed colocalization with neutrophil elastase (n = 10), and did not colocalize with markers for eosinophils, macrophages, T cells, or B cells (n = 3-5). Flow cytometric analysis of NPs (n = 9) showed that 5.1% ± 2% of CD45+ cells were OSM+, and of the OSM+ cells, 56% ± 7% were CD16+Siglec-8-, indicating neutrophil lineage. Only 0.6 ± 0.4% of CD45+ events from matched blood samples (n = 5) were OSM+, suggesting that increased OSM levels in patients with CRS was locally stimulated and produced. A majority of OSM+ neutrophils expressed arginase 1 (72.5% ± 12%), suggesting an N2 phenotype. GM-CSF levels were increased in NPs compared with those in control tissue and were sufficient to induce OSM production (P < .001) in peripheral blood neutrophils in vitro. OSM+ neutrophils were also observed at increased levels in biopsy specimens from patients with severe asthma. Additionally, OSM protein levels were increased in induced sputum from asthmatic patients compared with that from control subjects (P < .05).

CONCLUSIONS

Neutrophils are a major source of OSM-producing cells in patients with CRS and severe asthma.

Inflammatory Disorders Associated with Allergy: Overview of Immunopathogenesis and Implications for Treatment

A number of chronic inflammatory diseases are associated with IgE-mediated immunologic hypersensitivity, including atopic dermatitis, chronic rhinosinusitis, and asthma. Pathogenetic studies of well-characterized patient groups has allowed investigators to more precisely define the molecular pathways involved in these diseases. Specific cytokines and chemokines, as well as other unique proteins, have now been identified in each of these common disorders and a number of medications are currently in development for inhibiting their actions. Continual refinement of our understanding of the pathogenesis of these diseases will undoubtedly yield increasingly precise, and potentially more effective, treatments.

The epithelial barrier and immunoglobulin A system in allergy

Airway and intestinal epithelial layers represent first-line physical barriers, playing a key role in mucosal immunity. Barrier dysfunction, characterized by alterations such as disruption of cell-cell apical junctions and aberrant epithelial responses, probably constitutes early and key events for chronic immune responses to environmental antigens in the skin and in the gut. For instance, barrier dysfunction drives Th2 responses in atopic disorders or eosinophilic esophagitis. Such epithelial impairment is also a salient feature of allergic asthma and growing evidence indicates that barrier alterations probably play a driving role in this disease. IgA has been identified as the most abundant immunoglobulin in mucosa, where it acts as an active barrier through immune exclusion of inhaled or ingested antigens or pathogens. Historically, it has been thought to represent the serum factor underlying reaginic activity before IgE was discovered. Despite several studies about regulation and major functions of IgA at mucosal surfaces, its role in allergy remains largely unclear. This review aims at summarizing findings about epithelial functions and IgA biology that are relevant to allergy, and to integrate the emerging concepts and the recent developments in mucosal immunology, and how these could translate to clinical observations in allergy.