Evidence for the efficacy and safety of anti-interleukin-5 treatment in the management of refractory eosinophilic asthma

[Burden and management of severe asthma in Russia: results from international observational study]

AIM

To assess clinical and demographic characteristics of severe asthma (SA) patients and their management in Russian Federation.

MATERIALS AND METHODS

This publication provides data for Russian part of population of the international observational study. In Phase I, retrospective analysis of medical records of patients with SA was performed with assessment of clinical and demographic data, medical history, comorbidities, treatment approaches and healthcare utilization. Phase II was a cross-sectional collection of patient-reported outcomes: level of asthma control assessed by ACT (Asthma Control Test) and health-related quality of life (HRQoL) measured using the EQ-5D-5L questionnaire. Phase I patients were enrolled into Phase II if they signed a written consent form.

RESULTS

A total of 315 patients were included in Phase I of the study, 106 (33.6%) of them entered Phase II. Majority of study participants were either obese (n=103; 39.8%) or overweight (n=94; 36.3%). The most common comorbidities were cardiovascular diseases (n=217; 71.4%), followed by chronic respiratory diseases (n=198; 68.8%). There were 268 (85.1%) patients who had at least one exacerbation during last 12 months. Data for blood eosinophil count were available in 176 patients; 81.3% of them (n=143) had only one test in the last 12 months. The mean (SD) last available blood eosinophil count was 161.2 (181.2) cells/mm3. Serum Immunoglobulin E (IgE) value was known for 88 patients, and the mean (SD) last measured IgE value was 254.3 (249.7) ng/mL. Only 4.7% of Phase II participants had ACT scores indicative of controlled asthma (>20). As much as 74.5% had scores ≤15 suggesting uncontrolled disease. Most patients also had impaired HRQoL.

CONCLUSION

Most SA patients had poor disease control with frequent exacerbations and high number of comorbidities. Blood eosinophils and IgE level measurements were not evaluated routinely which might be a barrier for appropriate phenotyping and treatment selection.

IL-5 antagonism reverses priming and activation of eosinophils in severe eosinophilic asthma

Eosinophils are key effector cells mediating airway inflammation and exacerbation in patients with severe eosinophilic asthma. They are present in increased numbers and activation states in the airway mucosa and lumen. Interleukin-5 (IL-5) is the key eosinophil growth factor that is thought to play a role in eosinophil priming and activation. However, the mechanism of these effects is still not fully understood. The anti-IL-5 antibody mepolizumab reduces eosinophil counts in the airway modestly but has a large beneficial effect on the frequency of exacerbations of severe eosinophilic asthma, suggesting that reduction in eosinophil priming and activation is of central mechanistic importance. In this study, we used the therapeutic effect of mepolizumab and single-cell ribonucleic acid sequencing to investigate the mechanism of eosinophil priming and activation by IL-5. We demonstrated that IL-5 is a dominant driver of eosinophil priming and plays multifaceted roles in eosinophil function. It enhances eosinophil responses to other stimulators of migration, survival, and activation by activating phosphatidylinositol-3-kinases, extracellular signal-regulated kinases, and p38 mitogen-activated protein kinases signaling pathways. It also enhances the pro-fibrotic roles of eosinophils in airway remodeling via transforming growth factor-β pathway. These findings provide a mechanistic understanding of eosinophil priming in severe eosinophilic asthma and the therapeutic effect of anti-IL-5 approaches in the disease.

Intravesical Ty21a treatment of non-muscle invasive bladder cancer induces immune responses that correlate with safety and may be associated to therapy potential

BACKGROUND

Standard of care treatment of non-muscle invasive bladder cancer (NMIBC) with intravesical Bacillus Calmette Guérin (BCG) is associated with side effects, disease recurrence/progression and supply shortages. We recently showed in a phase I trial (NCT03421236) that intravesical instillation in patients with NMIBC with the maximal tolerated dose of Ty21a/Vivotif, the oral vaccine against typhoid fever, might have a better safety profile. In the present report, we assessed the immunogenicity of intravesical Ty21a in patients of the clinical trial that had received the maximal tolerated dose and compared it with data obtained in patients that had received standard BCG.

METHODS

Urinary cytokines and immune cells of patients with NMIBC treated with intravesical instillations of Ty21a (n=13, groups A and F in NCT03421236) or with standard BCG in a concomitant observational study (n=12, UROV1) were determined by Luminex and flow cytometry, respectively. Serum anti-lipopolysaccharide Typhi antibodies and circulating Ty21a-specific T-cell responses were also determined in the Ty21a patients. Multiple comparisons of different paired variables were performed with a mixed-effect analysis, followed by Sidak post-test. Single comparisons were performed with a paired or an unpaired Student's t-test.

RESULTS

As compared with BCG, Ty21a induced lower levels of inflammatory urinary cytokines, which correlated to the milder adverse events (AEs) observed in Ty21a patients. However, both Ty21a and BCG induced a Th1 tumor environment. Peripheral Ty21a-specific T-cell responses and/or antibodies were observed in most Ty21a patients, pointing the bladder as an efficient local immune inductive site. Besides, Ty21a-mediated stimulation of unconventional Vδ2 T cells was also observed, which turned out more efficient than BCG. Finally, few Ty21a instillations were sufficient for increasing urinary infiltration of dendritic cells and T cells, which were previously associated with therapeutic efficacy in the orthotopic mouse model of NMIBC.

CONCLUSIONS

Ty21a immunotherapy of patient with NMIBC is promising with fewer inflammatory cytokines and mild AE, but induction of immune responses with possible antitumor potentials. Future phase II clinical trials are necessary to explore possible efficacy of intravesical Ty21a.

Long-Term Weight Changes After Starting Anti-IL-5/5Ra Biologics in Severe Asthma: The Role of Oral Corticosteroids

BACKGROUND

Many patients with severe asthma are overweight or obese, often attributed to unintentional weight gain as a side effect of oral corticosteroids (OCSs). Anti-IL-5/5Ra biologics significantly reduce OCS use, but their long-term effects on weight are unknown.

OBJECTIVES

To examine (1) weight change up to 2 years after anti-IL-5/5Ra initiation in subgroups on the basis of maintenance OCS use at start of treatment and (2) whether cumulative OCS exposure before or changes in OCS exposure during treatment are related to weight change.

METHODS

Real-world data on weight and cumulative OCS dose from adults included in the Dutch Registry of Adult Patients with Severe asthma for Optimal DIsease management before and at least 2 years after starting anti-IL-5/5Ra were analyzed using linear mixed models and linear regression analyses.

RESULTS

For the included 389 patients (55% female; mean body mass index, 28 ± 5 kg/m2; 58% maintenance OCS), mean weight decreased -0.27 kg/y (95% CI, -0.51 to -0.03; P = .03), with more weight loss in patients with maintenance OCS use than in those without maintenance OCS use (-0.87 kg/y [95% CI, -1.21 to -0.52; P < .001] vs +0.54 kg/y [0.26 to 0.82; P < .001]). Greater weight loss at 2 years was associated with higher cumulative OCS dose in the 2 years before anti-IL-5/5Ra initiation (β = -0.24 kg/g; 95% CI, -0.38 to -0.10; P < .001) and, independently, greater reduction in cumulative OCS dose during follow-up (β = 0.27 kg/g; 95% CI, 0.11 to 0.43; P < .001).

CONCLUSIONS

Anti-IL-5/5Ra therapy is associated with long-term weight reduction, especially in patients with higher OCS exposure before treatment and those able to reduce OCS use during treatment. However, the effect is small and does not apply to all patients, and so additional interventions seem necessary if weight change is desired.

Diagnosis and Assessment of the Asthmas

Optimizing asthma diagnosis is an essential part of global strategies to reduce the excessive illness burden from asthma. New understanding about how to address the complexity and heterogeneity of the different forms of asthma means that asthma diagnosis now requires a compound diagnostic approach and label. Eliciting the typical symptoms and abnormal physiology of variable airflow limitation permits the recognition of asthma, and the identification of further features, such as eosinophilic or type 2 inflammation, allows a compound diagnostic label of eosinophilic asthma. This conveys key information about future exacerbation risk and likely treatment responsiveness. Treatable traits are a useful way to implement this new approach to diagnosis. Targeted assessment is used to inform a specific treatment plan in a pragmatic and iterative process.

Improved intratumoral penetration of IL12 immunocytokine enhances the antitumor efficacy

Tumor-targeting antibody (Ab)-fused cytokines, referred to as immunocytokines, are designed to increase antitumor efficacy and reduce toxicity through the tumor-directed delivery of cytokines. However, the poor localization and intratumoral penetration of immunocytokines, especially in solid tumors, pose a challenge to effectively stimulate antitumor immune cells to kill tumor cells within the tumor microenvironment. Here, we investigated the influence of the tumor antigen-binding kinetics of a murine interleukin 12 (mIL12)-based immunocytokine on tumor localization and diffusive intratumoral penetration, and hence the consequent antitumor activity, by activating effector T cells in immunocompetent mice bearing syngeneic colon tumors. Based on tumor-associated antigen HER2-specific Ab Herceptin (HCT)-fused mIL12 carrying one molecule of mIL12 (HCT-mono-mIL12 immunocytokine), we generated a panel of HCT-mono-mIL12 variants with different affinities (K D) mainly varying in their dissociation rates (k off) for HER2. Systemic administration of HCT-mono-mIL12 required an anti-HER2 affinity above a threshold (K D = 130 nM) for selective localization and antitumor activity to HER2-expressing tumors versus HER2-negative tumors. However, the high affinity (K D = 0.54 or 46 nM) due to the slow k off from HER2 antigen limited the depth of intratumoral penetration of HCT-mono-mIL12 and the consequent tumor infiltration of T cells, resulting in inferior antitumor activity compared with that of HCT-mono-mIL12 with moderate affinity of (K D = 130 nM) and a faster k off. The extent of intratumoral penetration of HCT-mono-mIL12 variants was strongly correlated with their tumor infiltration and intratumoral activation of CD4+ and CD8+ T cells to kill tumor cells. Collectively, our results demonstrate that when developing antitumor immunocytokines, tumor antigen-binding kinetics and affinity of the Ab moiety should be optimized to achieve maximal antitumor efficacy.

Engineering of Humanized Antibodies Against Human Interleukin 5 Receptor Alpha Subunit That Cause Potent Antibody-Dependent Cell-Mediated Cytotoxicity

Patients with severe eosinophilic asthma (SEA; characterized by persistent eosinophilia in blood and airway tissues) experience frequent asthma exacerbations with poor clinical outcomes. Interleukin 5 (IL-5) and IL-5 receptor alpha subunit (IL-5α) play key roles in eosinophilia maintenance, and relevant therapeutic strategies include the development of antibodies (Abs) against IL-5 or IL-5α to control eosinophilia. Benralizumab, an anti–IL-5α Ab that depletes eosinophils mainly via Ab-dependent cell-mediated cytotoxicity and through blockage of IL-5 function on eosinophils, has been clinically approved for patients with SEA. Here, we report engineering of a new humanized anti–IL-5Rα Ab with potent biological activity. We first raised murine Abs against human IL-5Rα, humanized a leading murine Ab, and then further engineered the humanized Abs to enhance their affinity for IL-5Rα using the yeast surface display technology. The finally engineered version of the Ab, 5R65.7, with affinity (K_D ≈ 4.64 nM) stronger than that of a clinically relevant benralizumab analogue (K_D ≈ 26.8 nM) showed improved neutralizing activity toward IL-5–dependent cell proliferation in a reporter cell system. Domain level Ab epitope mapping revealed that 5R65.7 recognizes membrane-proximal domain 3 of IL-5Rα, distinct from domain I epitope of the benralizumab analogue. In ex vivo assays with peripheral eosinophils from patients with SEA and healthy donors, 5R65.7 manifested more potent biological activities than the benralizumab analogue did, including inhibition of IL-5–dependent proliferation of eosinophils and induction of eosinophil apoptosis through autologous natural-killer-cell–mediated Ab-dependent cell-mediated cytotoxicity. Our study provides a potent anti–IL-5Rα Ab, 5R65.7, which is worthy of further testing in preclinical and clinical trials against SEA as a potential alternative to the current therapeutic arsenal.

The pharmacological management of asthma-chronic obstructive pulmonary disease overlap syndrome (ACOS)

Introduction: Asthma-chronic obstructive pulmonary disease overlap syndrome (ACOS) is a disease phenotype that shares T helper lymphocyte cell Th1/neutrophilic/non-Type-2 Inflammation pathways thought to be key in COPD and Th2/eosinophilic/Type-2 inflammatory pathways of asthma. The pharmacology of treating ACOS is challenging in severe circumstances.Areas covered: This review evaluates the stepwise treatment of ACOS using pharmacological treatments used in both COPD and asthma. The most common medications involve the same inhalers used to treat COPD and asthma patients. Advanced stepwise therapies for ACOS patients are based on patient characteristics and biomarkers. Very few clinical trials exist that focus specifically on ACOS patients.Expert opinion: After inhalers, advanced therapies including phosphodiesterase inhibitors, macrolides, N-acetylcysteine and statin therapy for those ACOS patients with a COPD appearance and exacerbations are available. In atopic ACOS patients with exacerbations, advanced asthma therapies (leukotriene receptor antagonists and synthesis blocking agents.) are used. ACOS patients with elevated blood eosinophil/IgE levels are considered for immunotherapy or therapeutic monoclonal antibodies blocking specific Th2/Type-2 interleukins or IgE. Symptom control, stabilization/improvement in pulmonary function and reduced exacerbations are the metrics of success. More pharmacological trials of ACOS patients are needed to better understand which patients benefit from specific treatments.Abbreviations: 5-LOi: 5-lipoxygenase inhibitor; ACOS: asthma - COPD overlap syndrome; B₂AR: Beta₂ adrenergic receptors; cAMP: cyclic adenosine monophosphate; cGMP: cyclic guanosine monophosphate; CI: confidence interval; COPD: chronic obstructive pulmonary disease; CRS : chronic rhinosinusitis; cys-LT: cysteinyl leukotrienes; DPI: dry powder inhaler; EMA: European Medicines Agency; FDA: US Food and Drug Administration; FDC: fixed-dose combination; FeNO: exhaled nitric oxide; FEV₁: forced expiratory volume in one second; FVC: forced vital capacity; GM-CSF: granulocyte-macrophage colony-stimulating factor; ICS : inhaled corticosteroids; IL: interleukin; ILC2: Type 2 innate lymphoid cells; IP₃: Inositol triphosphate; IRR: incidence rate ratio; KOLD: Korean Obstructive Lung Disease; LABA: long-acting B₂ adrenergic receptor agonist; LAMA: long-acting muscarinic receptor antagonist; LRA: leukotriene receptor antagonist; LT: leukotrienes; MDI: metered-dose inhalers; M_N: M-subtype muscarinic receptors; MRA: muscarinic receptor antagonist; NAC: N-acetylcysteine; NEB: nebulization; OR: odds ratio; PDE: phosphodiesterase; PEFR: peak expiratory flow rate; PGD2: prostaglandin D2; PRN: as needed; RR: risk ratio; SABA: short-acting B₂ adrenergic receptor agonist; SAMA: short-acting muscarinic receptor antagonist; SDMI: spring-driven mist inhaler; Th1: T helper cell 1 lymphocyte; Th2: T helper cell 2 lymphocytes; TNF-α: tumor necrosis factor alpha; US : United States.

Safety of Reslizumab in Uncontrolled Asthma with Eosinophilia: A Pooled Analysis from 6 Trials

BACKGROUND

Intravenous reslizumab, a monoclonal IL-5 antibody, is approved for treating severe asthma with eosinophilia. Limited structured information is available on the safety of reslizumab in larger populations.

OBJECTIVE

To investigate the safety profile of intravenous reslizumab 3.0 mg/kg by analyzing data from 6 asthma clinical trials: 5 placebo-controlled (duration ≤52 weeks) and 1 open-label extension (up to 2 years of treatment).

METHODS

Patients were aged 12 to 75 years with inadequately controlled asthma with eosinophilia. In the placebo-controlled trials, 730 patients received placebo and 1028 received reslizumab 3.0 mg/kg.

RESULTS

Adverse events (AEs) and serious AEs occurred in higher percentages of patients in the placebo group (81% and 9%) than in the reslizumab group (67% and 6%). Asthma, nasopharyngitis, and upper respiratory tract infection were the most common AEs with placebo and reslizumab. Three cases of anaphylaxis, related to reslizumab, were successfully managed with standard therapies. No significant difference in the incidence of malignancies was seen when compared with placebo or the general population. Among 756 patients with more than 12 months of reslizumab exposure, the AE rate was lower than in the placebo-controlled trials (367.3 vs 433.9 events/100 patient-years). The incidence of AEs in patients on treatment for more than 12 months was no higher than in patients with shorter treatment durations.

CONCLUSIONS

This analysis confirms that treatment with intravenous reslizumab for more than 12 months is well tolerated in patients with asthma, with no evidence of rare safety events that were not detected in individual trials.

Recent developments in the use of biologics targeting IL-5, IL-4, or IL-13 in severe refractory asthma

INTRODUCTION

Severe or refractory asthma is seen in approximately 5% of asthmatic subjects who have unsatisfactory symptom control despite adherence to high-dose inhaled glucocorticoid therapies resulting in significant morbidity, reduced quality of life and health-care cost implications. Asthma exhibits marked heterogeneity both clinically and at the molecular phenotypic level requiring specifically targeted treatments to block the key pathways of the disease. Monoclonal antibody-based biologics targeted at inhibition of the type 2 cytokines IL-4, IL-5, and IL-13 have considerable potential as effective treatments for severe asthma. Areas covered: This review is based on recent English-language original articles in PubMed or Medline that reported significant clinical findings on the current status, therapeutic potential, and safety of biologics targeted at IL-4, IL-5, and IL-13 in the treatment of asthma together with the potential utility of simple reproducible non-invasive biomarkers to guide the effective use of biologic-based therapy that do not require direct sampling of the airways Expert commentary: The further development of reproducible and straightforward discriminatory non-invasive biomarkers may aid identification of those patients most likely to benefit from treatment with these interventions.

Synergistic activation of pro-inflammatory type-2 CD8+ T lymphocytes by lipid mediators in severe eosinophilic asthma

Human type-2 CD8⁺ T cells are a cell population with potentially important roles in allergic disease. We investigated this in the context of severe asthma with persistent airway eosinophilia-a phenotype associated with high exacerbation risk and responsiveness to type-2 cytokine-targeted therapies. In two independent cohorts we show that, in contrast to Th2 cells, type-2 cytokine-secreting CD8⁺CRTH2⁺ (Tc2) cells are enriched in blood and airways in severe eosinophilic asthma. Concentrations of prostaglandin D₂ (PGD₂) and cysteinyl leukotriene E₄ (LTE₄) are also increased in the airways of the same group of patients. In vitro PGD₂ and LTE₄ function synergistically to trigger Tc2 cell recruitment and activation in a TCR-independent manner. These lipids regulate diverse genes in Tc2 cells inducing type-2 cytokines and many other pro-inflammatory cytokines and chemokines, which could contribute to eosinophilia. These findings are consistent with an important innate-like role for human Tc2 cells in severe eosinophilic asthma and suggest a potential target for therapeutic intervention in this and other diseases.

Type 2 immunity in asthma

Type 2-immunity represents the typical adaptive response to allergen exposure in atopic individuals. It mainly involves Th2 cells and immunoglobulin E, as the main orchestrators of type 2-inflammation. Recently, it has been highlighted that allergens may be responsible for a Th2 response beside specific IgE activation and that a number of other environmental stimuli, such as viruses and pollutants, can trigger the same pattern of inflammation beyond atopy. Emerging data sustain a substantial role of the so-called epithelial dysfunction in asthma pathogenesis, both from anatomic and functional point of view. Furthermore an increasing amount of evidence demonstrates the relevance of innate immunity in polarizing a Th2 impaired response in asthmatic patients. Under this perspective, the complex cross-talking between airway epithelium, innate and adaptive immunity is emerging as a major determinant of type 2-inflammation beyond allergens.

This review will include an update on the relevance of dysregulation of innate and adaptive type 2-immunity in asthma pathogenesis, particularly severe asthma, and on the role of the allergens that are associated with severe asthma. Type 2-immunity also will be reviewed in the light of the current and upcoming targeted treatments for severe asthma.

Targeted Therapy for Severe Asthma: Identifying the Right Patients

Asthma affects over 300 million people worldwide. Most asthmatics are well controlled with inhaled corticosteroids and long-acting beta-agonists; however, a proportion of patients are unresponsive and attain limited disease control. This group represents a considerable healthcare and financial burden, particularly patients who experience frequent exacerbations and require hospital admission. Development of new biological agents and disease biomarkers has provided novel avenues for treatment. These treatments have been highly successful, reducing exacerbations and yielding modest improvements in quality of life and lung function. However, only a proportion of severe asthmatics respond to this targeted treatment, highlighting the heterogeneity of severe asthma. One of the first biological therapies targeted immunoglobulin E (IgE) and demonstrated modest benefit but could only be used in a subgroup of patients. Recent research has shown that treatment aimed at the T helper-2-(Th₂)-high pathways and cytokines such as interleukin (IL)-5, IL-4, and IL-13 may also be effective in another partially overlapping subgroup. A blood eosinophil count over a defined threshold (generally ≥300 cells/μl) was a reliable biomarker and identified the majority of responders in this group. Further discovery and validation of biological markers to define asthmatic phenotypes that may benefit from biological treatments remain an area of intense interest and research. We review the latest information pertaining to biological agents and demonstrate how patient responders may potentially be identified for treatment.

Eosinophil Development, Disease Involvement, and Therapeutic Suppression

Human eosinophils have characteristic morphologic features, including a bilobed nucleus and cytoplasmic granules filled with cytotoxic and immunoregulatory proteins that are packaged in a specific manner. Eosinophil production in the bone marrow is exquisitely regulated by timely expression of a repertoire of transcription factors that work together via collaborative and hierarchical interactions to direct eosinophil development. In addition, proper granule formation, which occurs in a spatially organized manner, is an intrinsic checkpoint that must be passed for proper eosinophil production to occur. In eosinophil-associated disorders, eosinophils and their progenitors can be recruited in large numbers into tissues where they can induce proinflammatory organ damage in response to local signals. Eosinophils are terminally differentiated and do not proliferate once they leave the bone marrow. The cytokine IL-5 specifically enhances eosinophil production and, along with other mediators, promotes eosinophil activation. Indeed, eosinophil depletion with anti-IL-5 or anti-IL-5Rα is now proven to be clinically beneficial for several eosinophilic disorders, most notably severe asthma, and several therapeutics targeting eosinophil viability and production are now in development. Significant progress has been made in our understanding of eosinophil development and the consequences of tissue eosinophilia. Future research efforts focused on basic eosinophil immunobiology and translational efforts to assist in the diagnosis, treatment selection, and resolution of eosinophil-associated disorders will likely be informative and clinically helpful.

Efficacy and safety of benralizumab in patients with eosinophilic asthma: a meta-analysis of randomized placebo-controlled trials

Benralizumab is a monoclonal antibody that targets interleukin-5 receptor α to deplete blood eosinophils and improve the clinical outcomes of allergic asthma. We conducted a meta-analysis to evaluate the safety and efficacy of different doses of benralizumab in patients with eosinophilic asthma. All randomized controlled trials involving benralizumab treatment for patients with eosinophilic asthma, which were searched in PubMed, Embase, and the Cochrane Library published until January 2017, as well as the rate of asthmatic exacerbation, pulmonary functionality, asthma control, quality of life scores, and adverse events were included. Randomized-effect models were used in the meta-analysis to calculate the pooled mean difference, relative risks, and 95% confidence intervals. Five studies involving 1951 patients were identified. Compared with the placebo, benralizumab treatment demonstrated significant improvements in the forced expiratory volume in 1 s (FEV1), Asthma Quality of Life Questionnaire scores, decreased asthmatic exacerbation and Asthma Control Questionnaire-6 (ACQ-6) scores. Benralizumab treatment was also not associated with increased adverse events. These findings indicated that benralizumab can be safely used to improve FEV1, enhance patient symptom control and quality of life, and reduce the risk of exacerbations and ACQ-6 scores in patients with eosinophilic asthma. Furthermore, our meta-analysis showed that benralizumab with 30 mg (every eight weeks) dosage can improve the health-related quality of life and appear to be more effective than 30 mg (every four weeks) dosage. Overall, data indicated that the optimal dosing regimen for benralizumab was possibly 30 mg (every eight weeks).

Anti-Interleukin 5 (IL-5) and IL-5Ra Biological Drugs: Efficacy, Safety, and Future Perspectives in Severe Eosinophilic Asthma

The definition of asthma has changed considerably in recent years, to the extent that asthma is no longer considered a single disease but a heterogeneous disorder that includes several phenotypes and, possibly, endotypes. A more detailed analysis of the immunological mechanisms underlying the pathogenesis of asthma shows interleukin 5 (IL-5) to be a crucial cytokine in several asthma phenotypes. In fact, IL-5 exerts selective action on eosinophils, which, in turn, sustain airway inflammation and worsen asthma symptoms and control. Clinical trials have shown drugs targeting IL-5 or its receptor alpha subunit (IL-5Ra) to be a promising therapeutic approach to severe asthma, whose characteristics render standard therapy of little use: systemic corticosteroids only partially control the disease and have well-known adverse effects, and omalizumab is used for allergic subtypes. Analysis of the design process of clinical trials reveals the importance of patient selection, taking into account both clinical data (e.g., exacerbations, lung function, and quality of life) and biomarkers (e.g., eosinophils, which are predictive of therapeutic response).

Biomarkers and asthma management: an update

PURPOSE OF REVIEW

Asthma is heterogeneous with different endotypes/phenotypes. Response to corticosteroids is variable and novel biological therapies are proving useful. Biomarkers allow individualization of treatment. This review provides an update on available data regarding asthma biomarkers with focus on their utility for prediction of response to steroidal and new biological therapies.

RECENT FINDINGS

Blood eosinophils are a biomarker with acceptable accuracy as a surrogate for sputum eosinophilia, are associated with relevant outcomes, and are more readily measureable. New evidence supports fraction of exhaled nitric oxide (FENO)-based treatment algorithms for cost-effective maintenance of asthma control/quality of life. Serum and sputum-derived periostin are biomarkers of lung function decline and associated with eosinophilic airway inflammation. Transcriptomics show promise for endotyping; their role in management remains to be determined. Biomarker panels may improve predictive value as shown for the combination of FENO/urinary bromotyrosine in prediction of steroid responsiveness. Novel biological therapies are proving effective in biomarker-selected populations.

SUMMARY

Biomarkers including blood eosinophils and FENO are proving to have utility for the effective administration of steroidal and novel biological therapies in asthma, allowing individualized treatment. Transcriptomics can discriminate subtypes of asthma and may have a role in delivery of individualized therapy.

B7-DC (PD-L2) costimulation of CD4+ T-helper 1 response via RGMb

The role of B7-DC in T-cell responses remains controversial because both coinhibitory and costimulatory functions have been reported in various experimental systems in vitro and in vivo. In addition to interacting with the coinhibitory receptor PD-1, B7-DC has also been shown to bind repulsive guidance molecule b (RGMb). The functional consequences of the B7-DC/RGMb interaction, however, remain unclear. More than a decade ago, we reported that replacement of a murine B7-DC mutant lysine with serine (K113S) at positive 113 resulted in a loss of binding capacity to PD-1. Nevertheless, K113S remained costimulatory for T cells in vitro, implicating a dual functionality for B7-DC in T-cell responses. Here we show that recombinant K113S protein interacts with RGMb with a similar affinity to wild-type B7-DC. More importantly, K113S costimulates CD4⁺ T-cell responses via RGMb and promotes Th1 polarization. RGMb is expressed on the surface of naive mouse T cells, macrophages, neutrophils and dendritic cells. Finally, K113S/RGMb costimulation suppresses Th2-mediated asthma and ameliorates small airway inflammation and lung pathology in an experimental mouse model. Our findings indicate that RGMb is a costimulatory receptor for B7-DC. These findings from the K113S variant provide not only a possible explanation for the B7-DC-triggered contradictory effects on T-cell responses, but also a novel approach to investigate the B7-DC/PD-1/RGMb axis. Recombinant K113S or its derivatives could potentially be developed as an agonist for RGMb to costimulate the Th1 response without triggering PD-1-mediated T-cell inhibition.

Benralizumab for the treatment of asthma

INTRODUCTION

The classification of asthma into phenotypes and endotoypes allows for the use of targeted therapies, including three biologics which target interleukin 5 (IL-5) signaling in eosinophilic asthma. Areas covered: As of December 2016, two monoclonal antibodies, mepolizumab and reslizumab, are approved by U.S. Food and Drug Administration and one, benralizumab, is in clinical development. Two phase 3 trials for benralizumab, SIROCCO and CALIMA, were published in September 2016. Although there are no direct comparisons among these three anti-IL-5 therapies, the goal of this review is to summarize the current data and discuss their potential similarities and differences, with a focus on benralizumab. Expert commentary: Compared to mepolizumab and reslizumab, the possible advantages of benralizumab are less frequent dosing and a potential to reduce exacerbations irrespective of the blood eosinophil count. Some improvements in asthma symptom scores and quality of life occur with all three biologics, but the clinical meaningfulness of these improvements is less clear. A more defined reference range for eosinophil levels is necessary to determine which subjects will best benefit from these medications. Until quality randomized controlled trials directly compare the three, choosing among them for the treatment of eosinophilic asthma remains difficult.

Can serum cytokine profile discriminate irritant-induced and allergen-induced symptoms? A cross-sectional study in workers mostly exposed to laboratory animals

BACKGROUND

In workers exposed mostly to laboratory animals (LA), symptoms may be due to irritants or allergens. Correct aetiological diagnosis is important for health surveillance.

OBJECTIVES

This study aims to test whether work-related (WR) allergen-induced symptoms are associated with a cytokine profile distinct from that due to irritants.

METHODS

In a cross-sectional study (n=114), WR respiratory and/or skin symptoms were assessed through a standardised clinical examination and sensitisation to rat and/or mouse allergen determined by serum immunoglobulin E. Serum cytokine concentrations were measured by multiplex assays. The predefined cytokine profiles 'sensitiser' (interleukin (IL)-4, IL-5, IL-13, eotaxin-1) and 'irritation' (IL-8, IL-17A, IL-17F, IL-22) were considered positive, when ≥3 concentrations exceeded the 95th percentile of the asymptomatic non-sensitised group. Results were examined by hierarchical clustering analyses (HCA) and multiple linear regression. Explorative analyses were carried out for nine additional cytokines. Exposure to allergens and endotoxin was assessed in a subpopulation.

RESULTS

The prevalence of the profile 'irritation' was comparable in 28 symptomatic non-sensitised workers and 71 asymptomatic non-sensitised workers. HCA showed that nearly all symptomatic non-sensitised workers were gathered in two subclusters, characterised by high IL-17A levels, but different IL-8 levels. Multiple linear regression identified drug consumption and current complaints as confounders. Sensitised subjects were too few (n=14) for testing the profile 'sensitiser'.

CONCLUSIONS

In this unselected population of LA workers, the profile 'irritation' did not prove to be a valuable health surveillance tool. Low power precluded assessment of the profile 'sensitiser'. The increased IL-17A concentration may originate from irritative constituents of organic dust.

Improving the diagnosis of eosinophilic asthma

INTRODUCTION

Diagnosing eosinophilic asthma is important, because uncontrolled eosinophilic airway inflammation is associated with reduced response to glucocorticoids and increased risk of severe exacerbations.

AREAS COVERED

Currently, the diagnosis of eosinophilic asthma is based on measurements of sputum eosinophils, which is time consuming and requires specific technical expertise. Therefore, biomarkers such as blood eosinophils, FeNO, serum IgE and periostin are being used as surrogates. These biomarkers can be used separately or in combination, and their accuracy to detect sputum eosinophilia depends on cut-off values. The demonstration of eosinophils in sputum is no guarantee for response to treatment with current biological agents targeting Type 2 inflammation, because several molecular pathways may lead to eosinophilic inflammation. In the near future, the results of large trials using 'omics' technologies will certainly identify new, more 'upstream' biomarkers of eosinophilic inflammation, that will ultimately lead to the ideal targeted treatment for patients with eosinophilic asthma. Expert commentary: Of currently used surrogate markers to diagnose eosinophilic asthma, blood eosinophils and FeNO have the highest diagnostic accuracy, in particular if used in combination to rule in or rule out eosinophilic asthma. For patients who cannot be classified by these biomarkers alone, the clinical profile may be of help.

Biologics targeting IL-5, IL-4 or IL-13 for the treatment of asthma - an update

INTRODUCTION

The development of monoclonal antibody-based biologics targeted at inhibition of the Th2 cytokines IL-4, IL-5 and IL-13 represent potentially effective treatments for patients with the glucocorticoid refractory eosinophilic asthma phenotype. Areas covered: Asthma exhibits marked heterogeneity both clinically and at the molecular phenotypic level, requiring specifically targeted treatments to block the key pathways of the disease. It is becoming apparent that significant clinical effects with anti-cytokine-based biologic therapies are more likely in carefully selected patient populations that take asthma phenotypes into account. The development of reproducible and straightforward discriminatory biomarkers may aid identification of those patients most likely to benefit from treatment with these expensive interventions. This narrative review is based on English-language original articles in PubMed or Med-Line that reported significant clinical findings published in the last two years on the evidence demonstrating the effectiveness or otherwise of the targeting of IL-4, IL-5, or IL-13 in carefully selected patients with severe refractory asthma. Expert commentary: The use of a baseline peripheral blood eosinophilia as a simple reproducible biomarker to identify patients with particular sub-phenotypes of asthma to guide the effective use of biologic therapy represents a significant step forward.

Mepolizumab for the reduction of exacerbations in severe eosinophilic asthma

Asthma affects over 300 million people worldwide and is severe in 10% of sufferers. Severe asthma is associated with greater morbidity and mortality particularly as a consequence of frequent exacerbations. Advances in approaches to phenotype the heterogeneity of severe asthma has established the importance of eosinophilic inflammation and emerging new therapies are broadly designed to target T2-mediated eosinophilic inflammation with the aim to reduce exacerbation frequency. Here, we summarize the evidence that eosinophilic asthma is an important pheno(endo)type and identifies a group at risk of exacerbations; that established therapies reduce exacerbations, particularly in eosinophilic severe asthma; and discuss the role of mepolizumab, an IL-5 neutralising monoclonal antibody therapy, in reducing exacerbations in severe eosinophilic asthma compared to established and other emerging therapies.

CSL311, a novel, potent, therapeutic monoclonal antibody for the treatment of diseases mediated by the common β chain of the IL-3, GM-CSF and IL-5 receptors

The β common-signaling cytokines interleukin (IL)-3, granulocyte-macrophage colony stimulating factor (GM-CSF) and IL-5 stimulate pro-inflammatory activities of haematopoietic cells via a receptor complex incorporating cytokine-specific α and shared β common (βc, CD131) receptor. Evidence from animal models and recent clinical trials demonstrate that these cytokines are critical mediators of the pathogenesis of inflammatory airway disease such as asthma. However, no therapeutic agents, other than steroids, that specifically and effectively target inflammation mediated by all 3 of these cytokines exist. We employed phage display technology to identify and optimize a novel, human monoclonal antibody (CSL311) that binds to a unique epitope that is specific to the cytokine-binding site of the human βc receptor. The binding epitope of CSL311 on the βc receptor was defined by X-ray crystallography and site-directed mutagenesis. CSL311 has picomolar binding affinity for the human βc receptor, and at therapeutic concentrations is a highly potent antagonist of the combined activities of IL-3, GM-CSF and IL-5 on primary eosinophil survival in vitro. Importantly, CSL311 inhibited the survival of inflammatory cells present in induced sputum from human allergic asthmatic subjects undergoing allergen bronchoprovocation. Due to its high potency and ability to simultaneously suppress the activity of all 3 β common cytokines, CSL311 may provide a new strategy for the treatment of chronic inflammatory diseases where the human βc receptor is central to pathogenesis. The coordinates for the βc/CSL311 Fab complex structure have been deposited with the RCSB Protein Data Bank (PDB 5DWU).

IL-3 Maintains Activation of the p90S6K/RPS6 Pathway and Increases Translation in Human Eosinophils

IL-5 is a major therapeutic target to reduce eosinophilia. However, all of the eosinophil-activating cytokines, such as IL-5, IL-3, and GM-CSF, are typically present in atopic diseases, including allergic asthma. As a result of the functional redundancy of these three cytokines on eosinophils and the loss of IL-5R on airway eosinophils, it is important to take IL-3 and GM-CSF into account to efficiently reduce tissue eosinophil functions. Moreover, these three cytokines signal through a common β-chain receptor but yet differentially affect protein production in eosinophils. Notably, the increased ability of IL-3 to induce the production of proteins, such as semaphorin-7A, without affecting mRNA levels suggests a unique influence of IL-3 on translation. The purpose of this study was to identify the mechanisms by which IL-3 distinctively affects eosinophil function compared with IL-5 and GM-CSF, with a focus on protein translation. Peripheral blood eosinophils were used to study intracellular signaling and protein translation in cells activated with IL-3, GM-CSF, or IL-5. We establish that, unlike GM-CSF or IL-5, IL-3 triggers prolonged signaling through activation of ribosomal protein S6 (RPS6) and the upstream kinase 90-kDa ribosomal S6 kinase (p90S6K). Blockade of p90S6K activation inhibited phosphorylation of RPS6 and IL-3-enhanced semaphorin-7A translation. Furthermore, in an allergen-challenged environment, in vivo phosphorylation of RPS6 and p90S6K was enhanced in human airway compared with circulating eosinophils. Our findings provide new insights into the mechanisms underlying differential activation of eosinophils by IL-3, GM-CSF, and IL-5. These observations identify IL-3 and its downstream intracellular signals as novel targets that should be considered to modulate eosinophil functions.