β(2) -adrenoceptor agonists: current and future direction

An overview of the efficacy and safety of β2-adrenoceptor antagonists for the treatment of chronic obstructive pulmonary disease

INTRODUCTION

The safety of β2-AR antagonists in the treatment of patients with COPD continues to be a topic of research and discussion within the medical community. Emerging evidence suggests potentially benefits in the management of this complex respiratory condition. However, antagonists that display a preference for β2-AR over β1-AR present a complex therapeutic challenge in COPD management, necessitating an understanding of differences in their pharmacological profiles and clinical implications.

AREAS COVERED

An overview of the mechanisms of action of β2-AR antagonists and their potential impact on respiratory function, their pharmacological interactions, clinical implications, and future perspectives in COPD.

EXPERT OPINION

β-Blockers have the potential to become a versatile class of therapeutic agents with benefits beyond their original cardiovascular use. However, the one-size-fits-all approach of prescribing β-blockers regardless of their receptor selectivity to COPD patients with concomitant heart disease may not be appropriate. Instead, it is advisable to develop an individualized treatment strategy based on a thorough assessment of the patient's overall health. The use of non selective β2-AR antagonists, functioning as inverse agonists at β2-ARs, has garnered interest and debate, but further research efforts should focus on elucidating the optimal use of β-AR antagonists in COPD, balancing cardiovascular benefits with potential respiratory risks to enhance outcomes and quality of life for individuals living with this debilitating respiratory condition.

Stability-indicating UPLC assay coupled with mass spectrometry for the analysis of vilanterol degradation products in human urine

Vilanterol is a once-daily dose inhaler prescribed for asthma and chronic obstructive pulmonary disease. This study involved an investigation of vilanterol stability under acidic, basic, oxidative, thermal, and photolytic stress conditions. UPLC method was developed and validated for the analysis of vilanterol with its degradants. The drug was stable under photolytic and thermal stress conditions and degraded under acidic, basic, and oxidative stress conditions. Degradation kinetics was performed for acidic, basic and oxidative stress conditions. Kinetics parameters, K, half-life time (t1/2) and shelf-life time (t90) were assessed, and the degradation followed first order reaction. The method was linear from 0.10 to 100.00 µg mL-1 with accuracy, inter-day and intra-day precision from 99.45 to 100.02%, 0.391-0.694 and 0.041-0.345, respectively. Mass spectrometry was employed to elucidate the structure of the degradants, and the results revealed that certain degradation products were comparable to vilanterol metabolites. The World Anti-Doping Agency has prohibited the presence of vilanterol and its metabolites in athletes' urine except for exercise bronchoconstriction with limited dose. So, quantification of vilanterol in the presence of its degradants was performed in human urine. The results revealed that the method was linear in range of 1.00 to 100.00 µg mL-1. Samples collection and experimental protocol was performed according to the guidelines of the Research Ethics Committee of the Faculty of Pharmacy, the British University in Egypt with approval No. CH-2305.

Predicting the duration of action of β2-adrenergic receptor agonists: Ligand and structure-based approaches

Agonists of the β2 adrenergic receptor (ADRB2) are an important class of medications used for the treatment of respiratory diseases. They can be classified as short acting (SABA) or long acting (LABA), with each class playing a different role in patient management. In this work we explored both ligand-based and structure-based high-throughput approaches to classify β2-agonists based on their duration of action. A completely in-silico prediction pipeline using an AlphaFold generated structure was used for structure-based modelling. Our analysis identified the ligands' 3D structure and lipophilicity as the most relevant features for the prediction of the duration of action. Interaction-based methods were also able to select ligands with the desired duration of action, incorporating the bias directly in the structure-based drug discovery pipeline without the need for further processing.

Is it preferable to administer a bronchodilator once- or twice-daily when treating COPD?

Nocturnal and early morning symptoms are common and uncomfortable in many patients with COPD, and are likely to affect their long-term outcomes. However, it is still debated whether it is better to give long-acting bronchodilators once- or twice-daily to symptomatic COPD patients. The functional link between circadian rhythms of autonomic tone and airway calibre explains why the timing of administration of bronchodilators in chronic airway diseases can induce different effects when taken at different biological (circadian) times. However, the timing also depends on the pharmacological characteristics of the bronchodilator to be used. Because the profile of bronchodilation produced by once-daily vs. twice-daily long-acting bronchodilators differs throughout 24 h, selecting long-acting bronchodilators may be customized to specific patient preferences based on the need for further bronchodilation in the evening. This is especially helpful for people who experience respiratory symptoms at night or early morning. Compared to placebo, evening bronchodilator administration is consistently linked with persistent overnight improvements in dynamic respiratory mechanics and inspiratory neural drive. The current evidence indicates that nocturnal and early morning symptoms control is best handled by a LAMA taken in the evening. In contrast, it seems preferable to use a LABA for daytime symptoms. Therefore, it can be speculated that combining a LAMA with a LABA can improve bronchodilation and control symptoms better. Both LAMA and LABA must be rapid in their onset of action. Aclidinium/formoterol, a twice-daily combination, is the most studies of the available LAMA/LABA combinations in terms of impact on daytime and nocturnal symptoms.

Advances in adrenergic receptors for the treatment of chronic obstructive pulmonary disease: 2023 update

INTRODUCTION

Strong scientific evidence and large experience support the use of β2-agonists for the symptomatic alleviation of COPD. Therefore, there is considerable effort in discovering highly potent and selective β2-agonists.

AREAS COVERED

Recent research on novel β2-agonists for the treatment of COPD. A detailed literature search was performed in two major databases (PubMed/MEDLINE and Scopus) up to September 2023."

EXPERT OPINION

Compounds that preferentially activate a Gs- or β-arrestin-mediated signaling pathway via β- adrenoceptors (ARs) are more innovative. Pepducins, which target the intracellular region of β2-AR to modulate receptor signaling output, have the most interesting profile from a pharmacological point of view. They stabilize the conformation of the β2-AR and influence its signaling by interacting with the intracellular receptor-G protein interface. New bifunctional drugs called muscarinic antagonist-β2 agonist (MABA), which have both muscarinic receptor (mAChR) antagonism and β2-agonist activity in the same molecule, are a new opportunity. However, all tested compounds have been shown to act predominantly as mAChR antagonists or β2-agonists. An intriguing idea is to utilize allosteric modulators that bind to β2-ARs at sites different than those bound by orthosteric ligands to augment or reduce the signaling transduced by the orthosteric ligand.

Beta2-adrenoreceptor agonists and long-term risk of Parkinson's disease

INTRODUCTION

There is limited information on how the association between Parkinson's disease and the use of beta2-adrenoreceptor (β2AR) agonists varies among groups of short-, long-, and ultra-long-acting β2AR agonists (SABA, LABA and ultraLABA).

METHODS

In this prospective study of the Norwegian population, we estimated the incidence of Parkinson's disease according to exposure to β2AR agonists as a time-dependent variable by means of Cox regression. We adjusted for educational level, comorbidity and performed a sensitivity analysis excluding individuals with chronic obstructive pulmonary disease (COPD), all factors associated with smoking. Anticholinergics and corticosteroids as drugs with the same indication were analyzed for comparison.

RESULTS

In the follow-up period from 2005 to 2019, 15,807 incident Parkinson's cases were identified. After adjustments for sex, education and age as the timescale, SABA (Hazard ratio (HR) = 0.84; 95%CI: 0.79, 0.89; p < 0.001), LABA (HR = 0.85; 95%CI: 0.81, 0.90; p < 0.001) and ultraLABA (HR = 0.6; 95%CI: 0.49, 0.73; p < 0.001) were all associated with a lower risk of Parkinson's disease. After exclusion of COPD patients, corticosteroids and anticholinergics were no longer inversely associated, whereas β2AR agonists remained associated.

CONCLUSION

Of drugs with the same indication of use, only β2AR agonists remained inversely associated with PD risk after all adjustments, with ultraLABA displaying the overall strongest association. Although the precision of the estimate is limited by the modest number of exposed PD cases without COPD, the association is intriguing and suggest that longer-acting, more lipophilic, and thus likely more brain-penetrant β2AR agonists could be prioritized for further studies.

Combined docking and machine learning identify key molecular determinants of ligand pharmacological activity on β2 adrenoceptor

G protein‐coupled receptors (GPCRs) are valuable therapeutic targets for many diseases. A central question of GPCR drug discovery is to understand what determines the agonism or antagonism of ligands that bind them. Ligands exert their action via the interactions in the ligand binding pocket. We hypothesized that there is a common set of receptor interactions made by ligands of diverse structures that mediate their action and that among a large dataset of different ligands, the functionally important interactions will be over‐represented. We computationally docked ~2700 known β2AR ligands to multiple β2AR structures, generating ca 75 000 docking poses and predicted all atomic interactions between the receptor and the ligand. We used machine learning (ML) techniques to identify specific interactions that correlate with the agonist or antagonist activity of these ligands. We demonstrate with the application of ML methods that it is possible to identify the key interactions associated with agonism or antagonism of ligands. The most representative interactions for agonist ligands involve K97^2.68×67, F194^ECL2, S203^5.42×43, S204^5.43×44, S207^5.46×641, H296^6.58×58, and K305^7.32×31. Meanwhile, the antagonist ligands made interactions with W286^6.48×48 and Y316^7.43×42, both residues considered to be important in GPCR activation. The interpretation of ML analysis in human understandable form allowed us to construct an exquisitely detailed structure‐activity relationship that identifies small changes to the ligands that invert their pharmacological activity and thus helps to guide the drug discovery process. This approach can be readily applied to any drug target.

Review of potential medical treatments for middle ear cholesteatoma

Middle ear cholesteatoma (MEC), is a destructive, and locally invasive lesion in the middle ear driven by inflammation with an annual incidence of 10 per 100,000. Surgical extraction/excision remains the only treatment strategy available and recurrence is high (up to 40%), therefore developing the first pharmaceutical treatments for MEC is desperately required. This review was targeted at connecting the dysregulated inflammatory network of MEC to pathogenesis and identification of pharmaceutical targets. We summarized the numerous basic research endeavors undertaken over the last 30+ years to identify the key targets in the dysregulated inflammatory pathways and judged the level of evidence for a given target if it was generated by in vitro, in vivo or clinical experiments. MEC pathogenesis was found to be connected to cytokines characteristic for Th1, Th17 and M1 cells. In addition, we found that the inflammation created damage associated molecular patterns (DAMPs), which further promoted inflammation. Similar positive feedback loops have already been described for other Th1/Th17 driven inflammatory diseases (arthritis, Crohn’s disease or multiple sclerosis). A wide-ranging search for molecular targeted therapies (MTT) led to the discovery of over a hundred clinically approved drugs already applied in precision medicine. Based on exclusion criteria designed to enable fast translation as well as efficacy, we condensed the numerous MTTs down to 13 top drugs. The review should serve as groundwork for the primary goal, which is to provide potential pharmaceutical therapies to MEC patients for the first time in history.

An Add-On Treatment for Moderate COPD with Squill-Oxymel (a Traditional Formulation from Drimia maritima (L.) Stearn): A Pilot Randomized Triple-Blinded Placebo-Controlled Clinical Trial

Background. In traditional Persian medicine, Drimia maritima, with the popular name Squill, has been used to alleviate phlegm dyspnea. Squill has also been shown to have anti-inflammatory and anticholinergic properties. The goal of this research was to see how effective and safe Squill-Oxymel was in treating COPD patients. Method. Forty-two COPD patients were examined for eight weeks in two groups. Patients underwent a 6-minute walk test to assess the treatment’s effectiveness at the beginning and conclusion of the intervention. We utilized St. George’s Respiratory Questionnaire (SGRQ) to evaluate the subjective symptoms of patients in order to measure their quality of life. Results. Patients who received Squill-Oxymel showed a statistically significant increase in 6MWT distance ( $P=0.011$ ). The mean O2 saturation at the end of the 6MWT before the intervention was significantly greater in the placebo group. ( $P=0.008$ ). In terms of questionnaire variables, there was a significant difference between placebo and Squill-Oxymel groups in the mean presymptom score ( $P=0.009$ ) and the mean post-symptom score ( $P=0.004$ ). Conclusions. The findings of this research provide preliminary evidence for the effectiveness and safety of Squill-Oxymel as an add-on therapy in individuals with mild COPD.

Discovery of Environment-Sensitive Fluorescent Ligands of β-Adrenergic Receptors for Cell Imaging and NanoBRET Assay

By fusing several environment-sensitive fluorophores to the pharmacophore mirabegron, a series of new fluorescent ligands for β-adrenergic receptors (β-ARs) were produced with a turn-on mechanism and high binding affinity to β-ARs efficiently. Compound L5 with the pyridinium moiety possessed the most favorable combination of properties after systematic comparison and optimization, including high affinity and acceptable cytotoxicity, remarkable fluorescence enhancement (up to 30-fold) upon binding with β-ARs, and feasible visualizing ability of β-ARs in living cells under no-wash conditions. Furthermore, a NanoLuc-based bioluminescence resonance energy transfer (NanoBRET) binding assay based on compound L5 was developed and may be used in high-throughput screening (HTS) in the drug discovery of β-ARs due to its unique fluorescence spectroscopic features. Overall, as the first environment-sensitive fluorescent ligand, molecule L5 could be a useful tool for understanding the pharmacology of β-ARs.

A human relevant mixture of persistent organic pollutants induces reactive oxygen species formation in isolated human leucocytes: Involvement of the β2-adrenergic receptor

Exposure to chlorinated (Cl), brominated (Br) and perfluoroalkyl acid (PFAA) persistent organic pollutants (POPs) is associated with immunotoxicity and other adverse effects in humans and animals. Previous studies on POPs have mainly focused on single chemicals, while studies on complex mixtures are limited. Using DCF and luminol assays we examined effects on ROS generation in isolated human neutrophils, monocytes and lymphocytes, after in vitro exposure to a total mixture and sub-mixtures of 29 persistent compounds (Cl, Br, and PFAA). The mixtures were based on compounds prominent in blood, breast milk, and/or food. All mixture combinations induced ROS production in one or several of the cell models, and in some cases even at concentrations corresponding to human blood levels (compound range 1 pM - 16 nM). Whilst some interactions were detected (assessed using a mixed linear model), halogenated subgroups mainly acted additively. Mechanistic studies in neutrophils at 500× human levels (0.5 nM - 8 µM) indicated similar mechanisms of action for the Cl, PFAA, the combined PFAA + Cl and total (PFAA + Br + Cl) mixtures, and ROS responses appeared to involve β2-adrenergic receptor (β2AR) and Ca²⁺ signalling, as well as activation of NADPH oxidases. In line with this, the total mixture also increased cyclic AMP at levels comparable with the non-selective βAR agonist, isoproterenol. Although the detailed mechanisms involved in these responses remain to be elucidated, our data show that POP mixtures at concentrations found in human blood, may trigger stress responses in circulating immune cells. Mixtures of POPs, further seemed to interfere with adrenergic pathways, indicating a novel role of βARs in POP-induced effects.

OUP accepted manuscript

The content of this article derives from a Health and Environmental Sciences Institute (HESI) consortium with a focus to improve cardiac safety during drug development. A detailed literature review was conducted to evaluate the concordance between nonclinical repolarization assays and the clinical thorough QT (TQT) study. Food and Drug Administration and HESI developed a joint database of nonclinical and clinical data, and a retrospective analysis of 150 anonymized drug candidates was reviewed to compare the performance of 3 standard nonclinical assays with clinical TQT study findings as well as investigate mechanism(s) potentially responsible for apparent discrepancies identified. The nonclinical assays were functional (I_Kr) current block (Human ether-a-go-go related gene), action potential duration, and corrected QT interval in animals (in vivo corrected QT). Although these nonclinical assays demonstrated good specificity for predicting negative clinical QT prolongation, they had relatively poor sensitivity for predicting positive clinical QT prolongation. After review, 28 discordant TQT-positive drugs were identified. This article provides an overview of direct and indirect mechanisms responsible for QT prolongation and theoretical reasons for lack of concordance between clinical TQT studies and nonclinical assays. We examine 6 specific and discordant TQT-positive drugs as case examples. These were derived from the unique HESI/Food and Drug Administration database. We would like to emphasize some reasons for discordant data including, insufficient or inadequate nonclinical data, effects of the drug on other cardiac ion channels, and indirect and/or nonelectrophysiological effects of drugs, including altered heart rate. We also outline best practices that were developed based upon our evaluation.

Membrane-facilitated receptor access and binding mechanisms of long-acting β2-adrenergic receptor (β2-AR) agonists

The drugs salmeterol, formoterol, and salbutamol constitute the frontline treatment for asthma and other chronic pulmonary diseases. These drugs activate the β2-adrenergic receptors (β2-AR), a class A G-protein-coupled receptor (GPCR) and differ significantly in their clinical onset and duration of actions. According to the "microkinetic model," the long duration of action of salmeterol and formoterol compared to salbutamol were attributed, at least in part, to their high lipophilicity and increased local concentrations in the membrane near the receptor. However, the structural and molecular bases of how the lipophilic drugs reach the binding site of the receptor from the surrounding membrane remain unknown. Using a variety of classical and enhanced molecular dynamics simulation techniques, we investigated the membrane partitioning characteristics, binding, and unbinding mechanisms of the ligands. The obtained results offer remarkable insight into the functional role of membrane lipids in the ligand association process. Strikingly, salmeterol entered the binding site from the bilayer through transmembrane helices 1 and 7. The entry was preceded by membrane-facilitated rearrangement and presentation of its phenyl-alkoxy-alkyl tail as a passkey to an access route gated by F193, a residue known critical for salmeterol's affinity. Formoterol's access is through the aqueous path shared by other β2-AR agents. We observed a novel secondary path for salbutamol that is distinct from its primary route. Our study offers a mechanistic description for the membrane-facilitated access and binding of ligands to β2-AR and establishes a groundwork for recognizing membrane lipids as an integral component in the molecular recognition process. Significance Statement The cell membrane's functional role behind the duration of action of long-acting β2-adrenergic receptor (β2-AR) agonists such as salmeterol has been a subject of debate for a long time. We investigated the binding and unbinding mechanisms of the three commonly used β2-AR agonists, salmeterol, formoterol, and salbutamol, using advanced simulation techniques. The obtained results offer unprecedented insights into the active role of membrane lipids in facilitating access and binding of the ligands, affecting the molecular recognition process and their pharmacology.

Computer-aided understanding and engineering of enzymatic selectivity

Enzymes offering chemo-, regio-, and stereoselectivity enable the asymmetric synthesis of high-value chiral molecules. Unfortunately, the drawback that naturally occurring enzymes are often inefficient or have undesired selectivity toward non-native substrates hinders the broadening of biocatalytic applications. To match the demands of specific selectivity in asymmetric synthesis, biochemists have implemented various computer-aided strategies in understanding and engineering enzymatic selectivity, diversifying the available repository of artificial enzymes. Here, given that the entire asymmetric catalytic cycle, involving precise interactions within the active pocket and substrate transport in the enzyme channel, could affect the enzymatic efficiency and selectivity, we presented a comprehensive overview of the computer-aided workflow for enzymatic selectivity. This review includes a mechanistic understanding of enzymatic selectivity based on quantum mechanical calculations, rational design of enzymatic selectivity guided by enzyme-substrate interactions, and enzymatic selectivity regulation via enzyme channel engineering. Finally, we discussed the computational paradigm for designing enzyme selectivity in silico to facilitate the advancement of asymmetric biosynthesis.

Cardiac biomarkers and long-term outcomes of exacerbations of COPD: a long-term follow-up of two cohorts

Background

COPD patients often have cardiac comorbidities. Cardiac involvement at the time of a COPD exacerbation is associated with a high short-term mortality, but whether this influences long-term outcomes is unknown. We explored whether biomarkers of cardiac dysfunction at the time of a COPD exacerbation predict long-term outcomes.

Methods

Two prospective cohorts of patients admitted to Waikato Hospital for exacerbations of COPD were recruited during 2006-2007 and 2012-2013. N-terminal pro-B-type natriuretic peptide (NT-proBNP) and troponin T were measured on admission and were used to indicate cardiac stretch and myocardial injury, respectively. 5-year survival after discharge and subsequent admissions for cardiac disease and COPD exacerbations were analysed using Kaplan-Meier and Cox proportional hazards tests.

Results

The overall 5-year mortality was 61%. Patients with high NT-proBNP on admission had higher mortality than those with normal cardiac biomarkers (adjusted hazard ratio (aHR) 1.76, 95% CI 1.18-2.62). High NT-proBNP was also associated with a higher risk of future cardiac admissions (aHR 1.75, 95% CI 1.2-2.55). Troponin T levels were not associated with long-term survival (aHR 0.86, 95% CI 0.40-1.83) or future cardiac admissions (aHR 0.74, 95% CI 0.34-1.57). Neither biomarker predicted future COPD exacerbations.

Conclusion

The long-term prognosis following a hospitalisation for an exacerbation of COPD is poor with less than half of patients surviving for 5 years. Elevated NT-proBNP at the time of a COPD exacerbation is associated with higher long-term mortality and a greater likelihood of future cardiac admissions, but not future COPD exacerbations.

Recent Advances in β2-Agonists for Treatment of Chronic Respiratory Diseases and Heart Failure

β₂-Adrenoceptor (β₂-AR) agonists are widely used as bronchodilators. The emerge of ultralong acting β₂-agonists is an important breakthrough in pulmonary medicine. In this review, we will provide mechanistic insights into the application of β₂-agonists in asthma, chronic obstructive pulmonary disease (COPD), and heart failure (HF). Recent studies in β-AR signal transduction have revealed opposing functions of the β₁-AR and the β₂-AR on cardiomyocyte survival. Thus, β₂-agonists and β-blockers in combination may represent a novel strategy for HF management. Allosteric modulation and biased agonism at the β₂-AR also provide a theoretical basis for developing drugs with novel mechanisms of action and pharmacological profiles. Overlap of COPD and HF presents a substantial clinical challenge but also a unique opportunity for evaluation of the cardiovascular safety of β₂-agonists. Further basic and clinical research along these lines can help us develop better drugs and innovative strategies for the management of these difficult-to-treat diseases.

Activation of β2 adrenergic receptor signaling modulates inflammation: a target limiting the progression of kidney diseases

Beta 2 adrenergic receptor (β₂-AR)-agonists, widely used as bronchodilators, have demonstrated wide-spectrum anti-inflammatory properties in both immune and non-immune cells in various tissues. Their anti-inflammatory properties are mediated primarily, but not exclusively, via activation of the canonical β₂-AR signaling pathway (β₂-AR/cAMP/PKA). As non-canonical β₂-AR signaling also occurs, several inconsistent findings on the anti-inflammatory effect of β₂-agonists are notably present. Increasing amounts of evidence have unveiled the alternative mechanisms of the β₂-AR agonists in protecting the tissues against injuries, i.e., by augmenting mitochondria biogenesis and SIRT1 activity, and by attenuating fibrotic signaling. This review mainly covers the basic mechanisms of the anti-inflammatory effects of β₂-AR activation along with its limitations. Specifically, we summarized the role of β₂-AR signaling in regulating kidney function and in mediating the progression of acute and chronic kidney diseases. Given their versatile protective effects, β₂-agonists can be a promising avenue in the treatment of kidney diseases.

Ultra-LABAs for the treatment of asthma

The term ultra-LABA indicates once-daily β2-AR agonists (abediterol, indacaterol, olodaterol and vilanterol) that are single enantiomers of the (R)-configuration. All have a near full-agonist profile at human β2-AR. They can be prescribed in asthmatics only when associated with an with ICS, although further confirmations need to clarify what really these agents add if used in association to ICS and in what asthmatic patients this association may have more value. They are also under development in triple inhalers that include an ultra-LABA, a LAMA and an ICS. The once-daily posology might increase adherence in long-term treatment of asthma but superiority to twice-daily LABAs has not yet been fully demonstrated. In any case, still no ultra-LABA can be recommended as preferred.

Detailed insight on β-adrenoceptors as therapeutic targets

Human G protein-coupled receptors (GPCRs), especially adrenoceptors, play a crucial role in maintaining important physiological activities including cardiovascular and pulmonary functions. Among all adrenoceptors, β-adrenoceptors are the best characterized GPCRs and possess distinctive features as drug targets. Similarly, ligands that activate/deactivate β-adrenoceptors also hold a significant position in the field of biomarker identification and drug discovery. Several studies regarding molecular characterization of the β-adrenoceptor ligands have revealed that ligands with abilities to inhibit basal or intrinsic receptor activity or prevent receptor desensitization are particularly important to efficiently manage detrimental health conditions, including chronic heart failure, asthma, chronic obstructive pulmonary disease, obesity, and diabetes. Given the importance of β-adrenoceptors as molecular targets for many pathological conditions, this review aims to provide a detailed insight on the structural and functional aspects of β-adrenoceptors, with a particular emphasis on their importance as biomarkers and therapeutic targets.

Development of covalent antagonists for β1- and β2-adrenergic receptors

The selective covalent tethering of ligands to a specific GPCR binding site has attracted considerable interest in structural biology, molecular pharmacology and drug design. We recently reported on a covalently binding noradrenaline analog (FAUC37) facilitating crystallization of the β₂-adrenergic receptor (β₂AR^H2.64C) in an active state. We herein present the stereospecific synthesis of covalently binding disulfide ligands based on the pharmacophores of adrenergic β₁- and β₂ receptor antagonists. Radioligand depletion experiments revealed that the disulfide-functionalized ligands were able to rapidly form a covalent bond with a specific cysteine residue of the receptor mutants β₁AR^I2.64C and β₂AR^H2.64C. The propranolol derivative (S)-1a induced nearly complete irreversible blockage of the β₂AR^H2.64C within 30 min incubation. The CGP20712A-based ligand (S)-4 showed efficient covalent blocking of the β₂AR^H2.64C at very low concentrations. The analog (S)-5a revealed extraordinary covalent cross-linking at the β₁AR^I2.64C and β₂AR^H2.64C mutant while retaining a 41-fold selectivity for the β₁AR wild type over β₂AR. These compounds may serve as valuable molecular tools for studying β₁/β₂ subtype selectivity or investigations on GPCR trafficking and dimerization.

Hybridization of β-Adrenergic Agonists and Antagonists Confers G Protein Bias

Starting from the β-adrenoceptor agonist isoprenaline and beta-blocker carvedilol, we designed and synthesized three different chemotypes of agonist/antagonist hybrids. Investigations of ligand-mediated receptor activation using bioluminescence resonance energy transfer biosensors revealed a predominant effect of the aromatic head group on the intrinsic activity of our ligands, as ligands with a carvedilol head group were devoid of agonistic activity. Ligands composed of a catechol head group and an antagonist-like oxypropylene spacer possess significant intrinsic activity for the activation of Gα_s, while they only show weak or even no β-arrestin-2 recruitment at both β₁- and β₂-AR. Molecular dynamics simulations suggest that the difference in G protein efficacy and β-arrestin recruitment of the hybrid ( S)-22, the full agonist epinephrine, and the β₂-selective, G protein-biased partial agonist salmeterol depends on specific hydrogen bonding between Ser^5.46 and Asn^6.55, and the aromatic head group of the ligands.

Does the Lipid Bilayer Orchestrate Access and Binding of Ligands to Transmembrane Orthosteric/Allosteric Sites of G Protein-Coupled Receptors?

The ligand-binding sites of many G protein-coupled receptors (GPCRs) are situated around and deeply embedded within the central pocket formed by their seven transmembrane-spanning α-helical domains. Generally, these binding sites are assumed accessible to endogenous ligands from the aqueous phase. Recent advances in the structural biology of GPCRs, along with biophysical and computational studies, suggest that amphiphilic and lipophilic molecules may gain access to these receptors by first partitioning into the membrane and then reaching the binding site via lateral diffusion through the lipid bilayer. In addition, several crystal structures of class A and class B GPCRs bound to their ligands offer unprecedented details on the existence of lipid-facing allosteric binding sites outside the transmembrane helices that can only be reached via lipid pathways. The highly organized structure of the lipid bilayer may direct lipophilic or amphiphilic drugs to a specific depth within the bilayer, changing local concentration of the drug near the binding site and affecting its binding kinetics. Additionally, the constraints of the lipid bilayer, including its composition and biophysical properties, may play a critical role in "pre-organizing" ligand molecules in an optimal orientation and conformation to facilitate receptor binding. Despite its clear involvement in molecular recognition processes, the critical role of the membrane in binding ligands to lipid-exposed transmembrane binding sites remains poorly understood and warrants comprehensive investigation. Understanding the mechanistic basis of the structure-membrane interaction relationship of drugs will not only provide useful insights about receptor binding kinetics but will also enhance our ability to take advantage of the apparent membrane contributions when designing drugs that target transmembrane proteins with improved efficacy and safety. In this minireview, we summarize recent structural and computational studies on membrane contributions to binding processes, elucidating both lipid pathways of ligand access and binding mechanisms for several orthosteric and allosteric ligands of class A and class B GPCRs.

iPSC- and mesenchymoangioblast-derived mesenchymal stem cells provide greater protection against experimental chronic allergic airways disease compared with a clinically used corticosteroid

The airway remodeling (AWR) associated with chronic allergic airways disease (AAD)/asthma contributes to irreversible airway obstruction. This study compared and combined the antiremodeling and other effects of induced pluripotent stem cell and mesenchymoangioblast-derived mesenchymal stem cells (MCA-MSCs) with the corticosteroid dexamethasone (Dex) in experimental chronic AAD/asthma. Female BALB/c mice subjected to 11 wk of ovalbumin (Ova)-induced chronic AAD were intranasally administered MCA-MSCs (1 × 10⁶ cells/mouse; once weekly on wk 10 and 11), Dex (0.5 mg/ml; once daily for 2 wk), or both combined. MCA-MSC detection and changes in airway inflammation (AI), AWR, and airway hyperresponsiveness (AHR) were measured at the end of wk 11. Mice with chronic AAD had significant AI, goblet cell metaplasia, epithelial damage/thickening, aberrant TGF-β1 levels, subepithelial myofibroblast accumulation, airway/lung fibrosis, and AHR (all P < 0.001 vs. healthy controls). MCA-MSCs were detected in the lungs up to 5-7 d postadministration and demonstrated modest anti-inflammatory but striking antifibrotic effects against Ova-induced AAD, effectively decreasing AHR by 70-75% (all P < 0.05 vs. Ova alone). In comparison, Dex predominantly demonstrated anti-inflammatory effects, decreasing AHR by ∼30%. Combining MCA-MSCs with Dex provided equivalent protection to that offered by either therapy alone. MCA-MSCs reduce chronic AAD-induced AWR and AHR to a greater extent than Dex and may act as a suitable adjunct therapy to corticosteroid treatment of asthma.-Royce, S. G., Mao, W., Lim, R., Kelly, K., Samuel, C. S. iPSC- and mesenchymoangioblast-derived mesenchymal stem cells provide greater protection against experimental chronic allergic airways disease compared with a clinically used corticosteroid.

Structural insights into binding specificity, efficacy and bias of a β2AR partial agonist

Salmeterol is a partial agonist for the β2 adrenergic receptor (β2AR) and the first long-acting β2AR agonist to be widely used clinically for the treatment of asthma and chronic obstructive pulmonary disease. Salmeterol's safety and mechanism of action have both been controversial. To understand its unusual pharmacological action and partial agonism, we obtained the crystal structure of salmeterol-bound β2AR in complex with an active-state-stabilizing nanobody. The structure reveals the location of the salmeterol exosite, where sequence differences between β1AR and β2AR explain the high receptor-subtype selectivity. A structural comparison with the β2AR bound to the full agonist epinephrine reveals differences in the hydrogen-bond network involving residues Ser2045.43 and Asn2936.55. Mutagenesis and biophysical studies suggested that these interactions lead to a distinct active-state conformation that is responsible for the partial efficacy of G-protein activation and the limited β-arrestin recruitment for salmeterol.

Prolonged stimulation of β2-adrenergic receptor with β2-agonists impairs insulin actions in H9c2 cells

Insulin resistance is a condition in which there is a defect in insulin actions to induce glucose uptake into the cells. Overstimulation of β₂-adrenergic receptors (β₂ARs) is associated with the pathogenesis of insulin resistance in the heart. However, the mechanisms by which β₂-agonists affect insulin resistance in the heart are incompletely understood. The β₂-agonists are used for treatment of asthma due to bronchodilating effects. We also investigated the effects of β₂-agonists in human bronchial smooth muscle (HBSM) cells. In this study, we demonstrate that chronic treatment with salbutamol, salmeterol, and formoterol inhibited insulin-induced glucose uptake and GLUT4 synthesis in H9c2 myoblast cells. Sustained β₂AR stimulation also attenuated GLUT4 translocation to the plasma membrane, whereas short-term stimulation had no effect. In HBSM cells, prolonged treatment with β₂-agonists had no effect on insulin-induced glucose uptake and did not alter insulin-induced expressions of GLUT1, GLUT4, and GLUT10. In addition, genetic polymorphisms at amino acid positions 16 and 27 of β₂AR are linked to insulin resistance by significant suppression of GLUT4 translocation compared to wild-type. Thus, prolonged β₂AR stimulation by β₂-agonists impairs insulin actions through suppression of GLUT synthesis and translocation only in H9c2 cells.

β2-Adrenoceptor signalling bias in asthma and COPD and the potential impact on the comorbidities associated with these diseases

Inhaled selective β2-agonists are the most widely used treatment for obstructive airway diseases. The classical mechanism of action of these drugs is considered as their ability to activate β2-adrenergic receptors (β2-AR) on airway smooth muscle leading to G-protein activation and subsequent generation of c-AMP causing bronchodilation. However, there is now growing evidence to suggest that binding of β2-agonists to β2-AR is pleotropically coupled to many intracellular pathways whereby depending on the state of the β2-AR when activated, a subset of different intracellular responses can be triggered. This is called biased agonism (or functional selectivity) and this type of activity has now been observed with different types of G protein-coupled receptor (GPCR), not just β2-AR. Accordingly, drug efficacy for many agonists binding to GPCRs can no longer be solely described in terms of a single relationship between binding of a ligand to a receptor and the subsequent magnitude of the cellular response, but is often far more complex reflecting a specific complement of signals following binding of a ligand to its receptor. These differences in responses depending on what state the receptor is in when the ligand binds to it can subsequently influence the intracellular signalling that in turn can influence the efficacy of β2-AR ligands. Such findings suggest that in the future it may be possible to develop new synthetic β2-agonists that could preferentially confine their activity in stabilizing/activating the receptor to a certain conformation which could lead to improved drugs either to reduce adverse responses or to avoid drugs that activate certain conformations of the receptors that may lead to tolerance or desensitization following repeated activation.

Drug delivery to the lungs: challenges and opportunities

Pulmonary drug delivery is relatively complex because the respiratory tract has evolved defense mechanisms to keep inhaled drug particles out of the lungs and to remove or inactivate them once deposited. In addition to these mechanical, chemical and immunological barriers, pulmonary drug delivery is adversely affected by the behavioral barriers of poor adherence and poor inhaler technique. Strategies to mitigate the effects of these barriers include use of inhaler devices and formulations that deliver drug to the lungs efficiently, appropriate inhaler technique and improved education of patients. Owing to the advantages offered by the pulmonary route, the challenges that the route poses are worth addressing, and if successfully addressed, the pulmonary route offers huge opportunities, often fulfilling unmet clinical needs.

Synthesis, biological evaluation and molecular modeling of 2-amino-2-phenylethanol derivatives as novel β2-adrenoceptor agonists

A novel series of 2-amino-2-phenylethanol derivatives were developed as β₂-adrenoceptor agonists. Among them, 2-amino-3-fluoro-5-(2-hydroxy-1-(isopropylamino)ethyl)benzonitrile (compound 2f) exhibited the highest activity (EC₅₀ = 0.25 nM) in stimulating β₂-adrenoceptor-mediated cellular cAMP production with a 763.6-fold selectivity over the β₁-adrenoceptor. The (S)-isomer of 2f was subsequently found to be 8.5-fold more active than the (R)-isomer. Molecular docking was performed to determine the putative binding modes of this new class of β₂-adrenoceptor agonists. Taken together, these data show that compound 2f is a promising lead compound worthy of further study for the development of β₂-adrenoceptor agonists.

Inhaled therapies in patients with moderate COPD in clinical practice: current thinking

COPD is a complex, heterogeneous condition. Even in the early clinical stages, COPD carries a significant burden, with breathlessness frequently leading to a reduction in exercise capacity and changes that correlate with long-term patient outcomes and mortality. Implementation of an effective management strategy is required to reduce symptoms, preserve lung function, quality of life, and exercise capacity, and prevent exacerbations. However, current clinical practice frequently differs from published guidelines on the management of COPD. This review focuses on the current scientific evidence and expert opinion on the management of moderate COPD: the symptoms arising from moderate airflow obstruction and the burden these symptoms impose, how physical activity can improve disease outcomes, the benefits of dual bronchodilation in COPD, and the limited evidence for the benefits of inhaled corticosteroids in this disease. We emphasize the importance of maximizing bronchodilation in COPD with inhaled dual-bronchodilator treatment, enhancing patient-related outcomes, and enabling the withdrawal of inhaled corticosteroids in COPD in well-defined patient groups.

Next generation beta adrenoreceptor agonists for the treatment of asthma

INTRODUCTION

A fixed-dose inhalation of a long-acting β-agonist (LABA) and inhaled corticosteroids (ICS) is commonly recommended for moderate to severe asthmatic patients not adequately controlled by an ICS only. In order to improve the patients' adherence and the control of disease there is a noteworthy interest for the next generation inhaled β adrenoreceptor agonists maintaining an over 24 hours bronchodilatation and used once-daily (ultra-LABAs). This review focuses on the currently available evidences on the clinical role of any single ultra-LABAs in the treatment of asthmatic patients. Areas covered: New ultra-LABAs have been developed in recent years for the treatment of asthma. In particular, several evidences in asthmatic patients include indacaterol, vilanterol, olodaterol, and abediterol. Expert opinion: Pharmacologically, all new ultra-LABAs considered have demonstrated a good ability to maintain a true bronchodilatation for over 24 hours and a good safety profile. This aspect could be a key point to improve the patient's perspective, the adherence to the treatment regimens and therefore the control of disease. At this time, however, limited data are available and no ultra-LABA+ICS may be recommended as preferred.

Pharmacological treatments in asthma-affected horses: A pair-wise and network meta-analysis

BACKGROUND

Equine asthma is a disease characterised by reversible airflow obstruction, bronchial hyper-responsiveness and airway inflammation following exposure of susceptible horses to specific airborne agents. Although clinical remission can be achieved in a low-airborne dust environment, repeated exacerbations may lead to irreversible airway remodelling. The available data on the pharmacotherapy of equine asthma result from several small studies, and no head-to-head clinical trials have been conducted among the available medications.

OBJECTIVES

To assess the impact of the pharmacological interventions in equine asthma and compare the effect of different classes of drugs on lung function.

STUDY DESIGN

Pair-wise and network meta-analysis.

METHODS

Literature searches for clinical trials on the pharmacotherapy of equine asthma were performed. The risk of publication bias was assessed by funnel plots and Egger's test. Changes in maximum transpulmonary or pleural pressure, pulmonary resistance and dynamic lung compliance vs. control were analysed via random-effects models and Bayesian networks.

RESULTS

The results obtained from 319 equine asthma-affected horses were extracted from 32 studies. Bronchodilators, corticosteroids and chromones improved maximum transpulmonary or pleural pressure (range: -8.0 to -21.4 cmH₂ O; P<0.001). Bronchodilators, corticosteroids and furosemide reduced pulmonary resistance (range: -1.2 to -1.9 cmH₂ O/L/s; P<0.001), and weakly increased dynamic lung compliance. Inhaled β₂ -adrenoreceptor (β₂ -AR) agonists and inhaled corticosteroids had the highest probability of being the best therapies. Long-term treatments were more effective than short-term treatments.

MAIN LIMITATIONS

Weak publication bias was detected.

CONCLUSIONS

This study demonstrates that long-term treatments with inhaled corticosteroids and long-acting β₂ -AR agonists may represent the first choice for treating equine asthma. Further high quality clinical trials are needed to clarify whether inhaled bronchodilators should be preferred to inhaled corticosteroids or vice versa, and to investigate the potential superiority of combination therapy in equine asthma.

Pharmacological Profile of GPD-1116, an Inhibitor of Phosphodiesterase 4

We have previously reported that GPD-1116, an inhibitor of phosphodiesterase (PDE) 4, exhibits anti-inflammatory effects in a model of cigarette smoke-induced emphysema in senescence-accelerated P1 mice. In the present study, we further characterized the pharmacological profile of GPD-1116 in several experiments in vitro and in vivo. GPD-1116 and its metabolite GPD-1133 predominantly inhibited not only human PDE4, but also human PDE1 in vitro. Moreover, GPD-1116 was effective in several disease models in animals, including acute lung injury, chronic obstructive pulmonary disease (COPD), asthma and pulmonary hypertension; the effective doses of GPD-1116 were estimated to be 0.3-2 mg/kg in these models. With regard to undesirable effects known as class effects of PDE4 inhibitors, GPD-1116 showed suppression of gastric emptying in rats and induction of emesis in dogs, but showed no such suppression of rectal temperature in rats, and these side effects of GPD-1116 seemed to be less potent than those of roflumilast. These results suggested that GPD-1116 could be a promising therapeutic agent for the treatment of inflammatory pulmonary diseases. Furthermore, the inhibitory effects of GPD-1116 for PDE1 might be associated with its excellent pharmacological profile. However, the mechanisms through which PDE1 inhibition contributes to these effects should be determined in future studies.

A randomized, seven-day study to assess the efficacy and safety of a glycopyrrolate/formoterol fumarate fixed-dose combination metered dose inhaler using novel Co-Suspension™ Delivery Technology in patients with moderate-to-very severe chronic obstructive pulmonary disease

BACKGROUND

Long-acting muscarinic antagonist/long-acting β₂-agonist combinations are recommended for patients whose chronic obstructive pulmonary disease (COPD) is not managed with monotherapy. We assessed the efficacy and safety of glycopyrrolate (GP)/formoterol fumarate (FF) fixed-dose combination delivered via a Co-Suspension™ Delivery Technology-based metered dose inhaler (MDI) (GFF MDI).

METHODS

This was a Phase IIb randomized, multicenter, placebo-controlled, double-blind, chronic-dosing (7 days), crossover study in patients with moderate-to-very severe COPD ( NCT01085045 ). Treatments included GFF MDI twice daily (BID) (GP/FF 72/9.6 μg or 36/9.6 μg), GP MDI 36 μg BID, FF MDI 7.2 and 9.6 μg BID, placebo MDI, and open-label formoterol dry powder inhaler (FF DPI) 12 μg BID or tiotropium DPI 18 μg once daily. The primary endpoint was forced expiratory volume in 1 s area under the curve from 0 to 12 h (FEV₁ AUC_0-12) on Day 7 relative to baseline FEV₁. Secondary endpoints included pharmacokinetics and safety.

RESULTS

GFF MDI 72/9.6 μg or 36/9.6 μg led to statistically significant improvements in FEV₁ AUC_0-12 after 7 days' treatment versus monocomponent MDIs, placebo MDI, tiotropium, or FF DPI (p ≤ 0.0002). GFF MDI 36/9.6 μg was non-inferior to GFF MDI 72/9.6 μg and monocomponent MDIs were non-inferior to open-label comparators. Pharmacokinetic results showed glycopyrrolate and formoterol exposure were decreased following administration via fixed-dose combination versus monocomponent MDIs; however, this was not clinically meaningful. GFF MDI was well tolerated.

CONCLUSIONS

GFF MDI 72/9.6 μg and 36/9.6 μg BID improve lung function and are well tolerated in patients with moderate-to-very severe COPD.

TRIAL REGISTRATION

ClinicalTrials.gov NCT01085045 . Registered 9 March 2010.

The Principles of Ligand Specificity on beta-2-adrenergic receptor

G protein-coupled receptors are recognized as one of the largest families of membrane proteins. Despite sharing a characteristic seven-transmembrane topology, G protein-coupled receptors regulate a wide range of cellular signaling pathways in response to various physical and chemical stimuli, and prevail as an important target for drug discovery. Notably, the recent progress in crystallographic methods led to a breakthrough in elucidating the structures of membrane proteins. The structures of β₂-adrenergic receptor bound with a variety of ligands provide atomic details of the binding modes of agonists, antagonists and inverse agonists. In this study, we selected four representative molecules from each functional class of ligands and investigated their impacts on β₂-adrenergic receptor through a total of 12 × 100 ns molecular dynamics simulations. From the obtained trajectories, we generated molecular fingerprints exemplifying propensities of protein-ligand interactions. For each functional class of compounds, we characterized and compared the fluctuation of the protein backbone, the volumes in the intracellular pockets, the water densities in the receptors, the domain interaction networks as well as the movements of transmembrane helices. We discovered that each class of ligands exhibits a distinct mode of interactions with mainly TM5 and TM6, altering the shape and eventually the state of the receptor. Our findings provide insightful prospective into GPCR targeted structure-based drug discoveries.

Vilanterol and fluticasone furoate for asthma

BACKGROUND

Vilanterol (VI) is a long-acting beta2-agonist (LABA) that binds to the beta2-adrenoceptor on the airway smooth muscle, producing bronchodilation. LABA therapy, which is well established in adults as part of the British Thoracic Society (BTS) Guidelines for the Management of Asthma, leads to improvement in symptoms and lung function and reduction in exacerbations. At present, the commonly used LABAs licensed for use in asthma management (formoterol and salmeterol) require twice-daily administration, whereas VI is a once-daily therapy.Fluticasone furoate (FF) is an inhaled corticosteroid (ICS), and ICS therapy is recommended by the BTS asthma guidelines. ICSs, the mainstay of asthma treatment, lead to a reduction in both airway inflammation and airway hyper-responsiveness. Regular use leads to improvement in symptoms and lung function. ICSs are currently recommended as 'preventer' therapy for patients who use a 'reliever' medication (e.g. short-acting beta2 agonist (SABA), salbutamol) three or more times per week. Most of the commonly used ICS treatments are twice-daily medications, although two once-daily products are currently licensed (ciclesonide and mometasone).At the present time, only one once-daily ICS/LABA combination (FF/VI) is available, and several other combination inhalers are recommended for twice-daily administration.

OBJECTIVES

To compare effects of VI and FF in combination versus placebo, or versus other ICSs and/or LABAs, on acute exacerbations and on health-related quality of life (HRQoL) in adults and children with chronic asthma.

SEARCH METHODS

We searched the Cochrane Airways Group Register of trials, clinical trial registries, manufacturers' websites and reference lists of included studies up to June 2016.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) of adults and children with a diagnosis of asthma. Included studies compared VI and FF combined versus placebo, or versus other ICSs and/or LABAs. Our primary outcomes were health-related quality of life, severe asthma exacerbation, as defined by hospital admissions or treatment with a course of oral corticosteroids, and serious adverse events.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data and analysed outcomes using a fixed-effect model. We used standard Cochrane methods.

MAIN RESULTS

We identified 14 studies that met our inclusion criteria, with a total of 6641 randomised participants, of whom 5638 completed the study. All studies lasted between two and 78 weeks and showed good methodological quality overall.We included 10 comparisons in this review, seven for which the dose of VI and FF was 100/25 mcg (VI/FF 100/25 mcg vs placebo; VI/FF 100/25 mcg vs same dose of FF; VI/FF 100/25 mcg vs same dose of VI; VI/FF 100/25 mcg vs fluticasone propionate (FP) 500 mcg twice-daily; VI/FF 100/25 mcg vs fluticasone propionate/salmeterol (FP/SAL) 250/50 mcg twice-daily; VI/FF 100/25 mcg vs FP/SAL 250/25 mcg twice-daily; FF/VI 100/25 vs FP/SAL500/50) and three for which the dose of VI and FF was 200/25 mcg (VI/FF 200/25 mcg vs placebo; VI/FF 200/25 mcg vs FP 500 mcg; VI/FF 200/25 mcg vs same dose of FF).We found very few opportunities to combine results from the 14 included studies in meta-analyses. We tabulated the data for our pre-specified primary outcomes. In particular, we found insufficient information to assess whether once-daily VI/FF was better or worse than twice-daily FP/SAL in terms of efficacy or safety.Only one of the 14 studies looked at health-related quality of life when comparing VI and FF 100/25 mcg versus placebo and identified a significant advantage of VI/FF 100/25 mcg (mean difference (MD) 0.30, 95% confidence interval (CI) 0.14 to 0.46; 329 participants); we recognised this as moderate-quality evidence. Only two studies compared VI/FF 100/25 mcg versus placebo with respect to exacerbations; both studies reported no exacerbations in either treatment arm. Five studies (VI/FF 100/25 mcg vs placebo) sought information on serious adverse events; all five studies reported no serious adverse events in the VI/FF 100/25 mcg or placebo arms. We found no comparison relevant to our primary outcomes for VI/FF at a higher dose (200/25 mcg) versus placebo.The small number of studies contributing to each comparison precludes the opportunity to draw robust conclusions for clinical practice. These studies were not of sufficient duration to allow conclusions about long-term side effects.

AUTHORS' CONCLUSIONS

Some evidence suggests clear advantages for VI/FF, in combination, compared with placebo, particularly for forced expiratory volume in one second (FEV1) and peak expiratory flow; however, the variety of questions addressed in the included studies did not allow review authors to draw firm conclusions. Information was insufficient for assessment of whether once-daily VI/FF was better or worse than twice-daily FP/SAL in terms of efficacy or safety. It is clear that more research is required to reduce the uncertainties that surround interpretation of these studies. It will be necessary for these findings to be replicated in other work before more robust conclusions are revealed. Only five of the 13 included studies provided data on health-related quality of life, and only six recorded asthma exacerbations. Only one study focused on paediatric patients, so no conclusions can be drawn for the paediatric population. More research is needed, particularly in the primary outcome areas selected for this review, so that we can draw firmer conclusions in the next update of this review.

Efficacy and safety of aclidinium/formoterol versus salmeterol/fluticasone: a phase 3 COPD study

The efficacy and safety of twice-daily aclidinium bromide/formoterol fumarate was compared with that of salmeterol/fluticasone propionate in patients with stable, moderate-to-severe chronic obstructive pulmonary disease (COPD).

AFFIRM COPD (Aclidinium and Formoterol Findings in Respiratory Medicine COPD) was a 24-week, double-blind, double-dummy, active-controlled study. Patients were randomised (1:1) to aclidinium/formoterol 400/12 µg twice-daily via Genuair/Pressair or salmeterol/fluticasone 50/500 µg twice-daily via Accuhaler. The primary end-point was peak forced expiratory volume in 1 s (FEV1) at week 24. Other end-points included Transition Dyspnoea Index (TDI) focal score at week 24, TDI and St George's Respiratory Questionnaire (SGRQ) responders, COPD Assessment Test and SGRQ scores, assessment of COPD symptoms and exacerbations, use of reliever medication, and device preference. Adverse events were monitored throughout.

In total, 933 patients were eligible (mean age 63.4 years, 65.1% male). Aclidinium/formoterol was superior to salmeterol/fluticasone in peak FEV1 and noninferior in TDI. Health status and reduction in exacerbation risk were similar in both groups. While both treatments were well tolerated, pneumonia occurred less frequently with aclidinium/formoterol than salmeterol/fluticasone.

In stable COPD, aclidinium/formoterol significantly improved bronchodilation versus salmeterol/fluticasone, with equivalent benefits in symptom control and reduction in exacerbation risk. Both treatments were well tolerated and treatment-related adverse events were less common with aclidinium/formoterol.

Abediterol, a novel long-acting β2-agonist: bronchodilation, safety, tolerability and pharmacokinetic results from a single-dose, dose-ranging, active-comparator study in patients with COPD

BACKGROUND

Abediterol is a novel, once-daily long-acting β2-agonist in development for the treatment of chronic obstructive pulmonary disease (COPD) and asthma in combination with an anti-inflammatory agent. This Phase IIa, randomised, double-blind, crossover study investigated the bronchodilation, safety, tolerability and pharmacokinetics of abediterol in patients with moderate to severe COPD.

METHODS

Seventy patients (aged ≥40 years, Global initiative for chronic Obstructive Lung Disease Stage II/III) were randomised (1:1:1:1:1:1) to single doses of abediterol 0.625, 2.5, 5 or 10 μg, indacaterol 150 μg or placebo. Spirometry was performed up to 36 h post-dose. Pharmacokinetics were assessed in a subset of patients (N = 20). Safety and tolerability were evaluated throughout the study.

RESULTS

Abediterol (all doses) significantly improved change from baseline in trough forced expiratory volume in 1 s (FEV1) compared with placebo (0.102, 0.203, 0.233 and 0.259 L for abediterol 0.625, 2.5, 5 and 10 μg, respectively; all p < 0.0001; primary endpoint). Abediterol 2.5, 5 and 10 μg significantly improved trough FEV1 compared with indacaterol 150 μg (0.092, 0.122 and 0.148 L, respectively; all p < 0.0001). Improvements in bronchodilation were maintained at all time points post-dose versus placebo (all abediterol doses) and from 15 or 30 min post-dose versus indacaterol 150 μg with abediterol 2.5, 5 and 10 μg (all p < 0.05). Abediterol had low systemic exposure; incidence of treatment-emergent adverse events was similar between treatment groups.

CONCLUSIONS

All doses of abediterol (0.625-10 μg) provided clinically and statistically significant, dose-dependent improvements in bronchodilation versus placebo, and abediterol 2.5, 5 and 10 μg gave significant improvements versus indacaterol. All doses of abediterol were safe and well tolerated in patients with COPD.

TRIAL REGISTRATION

Clinicaltrials.gov NCT01425814 . Registered 29 August 2011.

Olodaterol for the treatment of chronic obstructive pulmonary disease

PURPOSE

Published data on the pharmacology, pharmacokinetics, efficacy, and safety of the once-daily, long-acting β2-agonist (LABA) olodaterol are reviewed.

SUMMARY

Olodaterol (Striverdi Respimat, Boehringer Ingelheim), a LABA with high selectivity for β2-adrenergic receptors, is indicated for the treatment of chronic obstructive pulmonary disease (COPD); the recommended dose is 5 μg, to be delivered once daily via the Respimat inhaler. In 48- and 6-week Phase III clinical trials of olodaterol evaluating various lung function and symptomatic outcomes in patients with moderate to very severe COPD, olodaterol use was associated with significant improvements in spirometry outcomes, such as postbronchodilator forced expiratory volume in one second (FEV1), as well as dyspnea severity and quality-of-life measures. Other clinical trials demonstrated that olodaterol produced beneficial effects on FEV1 measures throughout the 24-hour dosing interval. A meta-analysis of data from 20 published research reports indicated that olodaterol's efficacy was comparable to that of the once-daily LABA indacaterol and that the combination of olodaterol and tiotropium provided improvements in lung function greater than those provided by tiotropium alone. Analysis of pooled data from four long-term trials showed that olodaterol's safety profile was comparable to that of formoterol; the most frequently reported adverse effects associated with olodaterol use were bronchitis, nasopharyngitis, and upper respiratory tract infection.

CONCLUSION

Once-daily olodaterol 5 μg is an effective therapy in improving lung function and symptomatic outcomes in patients with moderate to very severe COPD receiving other maintenance therapy, with a satisfactory safety profile.

The Therapeutic Potential of Targeting Cytokine Alarmins to Treat Allergic Airway Inflammation

Asthma is a heterogeneous disorder that results in recurrent attacks of breathlessness, coughing, and wheezing that affects millions of people worldwide. Although the precise causes of asthma are unclear, studies suggest that a combination of genetic predisposition and environmental exposure to various allergens and pathogens contribute to its development. Currently, the most common treatment to control asthma is a dual combination of β2-adrenergic receptor agonists and corticosteroids. However, studies have shown that some patients do not respond well to these medications, while others experience significant side effects. It is reported that the majority of asthmas are associated with T helper type 2 (TH2) responses. In these patients, allergen challenge initiates the influx of TH2 cells in the airways leading to an increased production of TH2-associated cytokines and the promotion of allergy-induced asthma. Therefore, biologics that target this pathway may provide an alternative method to treat the allergic airway inflammation associated with asthma. As of now, only two biologics (omalizumab and mepolizumab), which target immunoglobulin E and interleukin-5, respectively, are FDA-approved and being prescribed to asthmatics. However, recent studies have reported that targeting other components of the TH2 response also show great promise. In this review, we will briefly describe the immunologic mechanisms underlying allergic asthma. Furthermore, we will discuss the current therapeutic strategies used to treat asthma including their limitations. Finally, we will highlight the benefits of using biologics to treat asthma-associated allergic airway inflammation with an emphasis on the potential of targeting cytokine alarmins, especially thymic stromal lymphopoietin.

Vilanterol trifenatate for the treatment of COPD

INTRODUCTION

Currently the treatment of chronic obstructive pulmonary disease (COPD) has limited effectiveness and there is a need to develop new drugs. International guidelines recommend the use of long-acting bronchodilators (β2 agonists and anti-cholinergics/muscarinics), inhaled steroids and associations between these drugs in the maintenance treatment of moderate-to-severe COPD.

AREA COVERED

Vilanterol trifenate is a new once-daily highly selective β2-agonist available in USA and Europe in association with umeclidinium bromide (a long-acting anti-muscarnic agent) and fluticasone furoate (an inhaled corticosteroid) for the once-daily maintenance treatment of COPD. Vilanterol combined in fixed-dose treatments has been tested in numerous clinical trials involving thousands of patients. Expert commentary: These new once-daily formulations have the potential to improve compliance to long-term inhaled therapy. This paper will review the clinical and experimental data regarding vilanterol use in the regular treatment of COPD as well as provide a critical discussion of possible future treatment settings.

Olodaterol for the treatment of asthma

INTRODUCTION

Long-acting β-agonist (LABA)/inhaled corticosteroid (ICS) combinations are still the mainstay of asthma therapy but there is a pressing need to increase adherence to the prescribed treatment achievable in general by reducing the dose frequency. Consequently, there is considerable interest within the pharmaceutical industry in the discovery of once-daily β2-agonists (ultra-LABAs) to be used as a part of a combination therapy for treating asthma.

AREAS COVERED

The authors review the preclinical and clinical development of olodaterol, a new ultra-LABA characterized by an improved selectivity for β2-adrenoceptors and a rather high intrinsic efficacy profile, in asthma. The clinical results were generated by 4 Phase 2 trials, which have enrolled 731 asthmatic patients.

EXPERT OPINION

The available results indicate that olodaterol is able to induce an effective 24-h bronchodilation and is safe. However, one cannot formulate a solid conclusion on the best dose and/or dose frequency to be used in asthma because trials were not powered to assess the differences between doses and dose frequencies. Apparently, there is no Phase 3 trial planned or ongoing for olodaterol monotherapy in patients with asthma and also no attempt to combine olodaterol with an ICS, which is surprising.

Fixed-Dose combination of the inhaled corticosteroid and long-acting beta2-agonist therapy in adults with persistent asthma

INTRODUCTION

Asthma is a respiratory condition characterized by airway inflammation, airflow obstruction, and bronchial hyperresponsiveness. The standard treatment of asthma comprises inhaled corticosteroid and beta2-agonist. Inhaled short-acting-beta2-agonists have been used as rescue medication for exacerbation. However, long-acting-beta2-agonists (LABA) used as monotherapy for asthma had been reported for having a safety concern. Consequently, it had been recommended as an add-on treatment to inhaled corticosteroid (ICS) in moderate to severe persistent asthma. The fixed-dose combination (FDC) of ICS and LABA has been approved since the year 2000. Evidences revealed using the combination of these medications is more effective in asthma control.

AREAS COVERED

The rational and phase III onward randomized-controlled studies were reviewed. Sources of evidences were from studies published in Medline until November 2015.

EXPERT OPINION

There are six FDC inhaler regimens approved worldwide. The significant synergistic effects of ICS and LABA in one device are well evidenced. A FDC reduces the daily dosage of ICS and asthma exacerbation. It is safe to use regularly as controller. The efficacy of each individual combination on asthma treatment is generally similar. Clinical experience, ease of use, cost and side effects of medication would guide the clinician's preferences.

Differential pharmacology and clinical utility of long-acting bronchodilators in COPD - focus on olodaterol

Olodaterol (BI 1744 CL) is a novel, once-daily long-acting β₂-agonist (LABA) designed with the aim of improving β₂-adrenoreceptor selectivity and intrinsic activity. Phase III pivotal trials have documented that olodaterol Respimat Soft Mist inhaler 5 μg induces fast onset of bronchodilation, comparable with formoterol at day 1. Moreover, significant lung function improvements have been documented up to 48 weeks in patients with moderate to very severe chronic obstructive pulmonary disease (COPD). Olodaterol was generally well tolerated and had an acceptable cardiovascular and respiratory adverse event profile. Regrettably, the clinical development of olodaterol is however still too partial to draw any firm conclusions on the positioning of this ultra-LABA as monotherapy in the management of COPD. Waiting for further data on the impact of olodaterol on different patient-reported outcomes, which however are widely available for indacaterol, and mainly for a head-to-head comparison between these two ultra-LABAs and between olodaterol long-acting antimuscarinic antagonists other than tiotropium, we believe it is correct to follow the clinical indications of indacaterol also for olodaterol. In any case, the parallel bronchodilating modes of action of olodaterol and tiotropium make them an attractive combination in COPD. The results from the ongoing large TOviTO Phase III trial program have documented the efficacy and safety of olodaterol/tiotropium fixed-dose combination as maintenance therapy in patients with moderate to very severe COPD. In particular, olodaterol/tiotropium fixed-dose combination provides a convincing alternative for patients remaining symptomatic with olodaterol monotherapy.

Bronchodilators, receptors and cross-talk: Together is better?

The most widely used maintenance therapies in chronic obstructive pulmonary disease (COPD) are long-acting muscarinic antagonists (LAMAs), and a number of these drugs are now available in combination with long-acting β2-agonists (LABAs). LAMAs inhibit the parasympathetic muscarinic pathway, while LABAs, as sympathomimetics, reduce airway smooth muscle (ASM) tone. As well as directly controlling the constriction and relaxation of ASM, muscarinic and adrenergic receptors are found on inflammatory cells, and drugs that target these receptors may also reduce inflammation in COPD. Evidence suggests that the muscarinic and adrenergic pathways cross-talk at the level of neuronal input to the ASM via second-messenger pathways within ASM cells. Although the cross-talk is not completely understood, pharmacologically targeting both pathways in COPD can maximize bronchodilation. Combining LAMAs and LABAs demonstrated improved efficacy compared with the individual therapies and so, for greater convenience, several fixed-dose combinations for once-daily use have been developed. These fixed-dose combinations demonstrate improvements in both lung-function and patient-reported outcomes compared with well-established monotherapies, with similar tolerability profiles to the individual agents.

Dose-finding evaluation of once-daily treatment with olodaterol, a novel long-acting β2-agonist, in patients with asthma: results of a parallel-group study and a crossover study

BACKGROUND

Olodaterol is a novel, inhaled long-acting β2-agonist (LABA) with >24-hour duration of action investigated in asthma and chronic obstructive pulmonary disease.

METHODS

Two multicentre studies examined the efficacy and safety of 4 weeks' once-daily (QD) olodaterol (2, 5, 10 and 20 μg, with background inhaled corticosteroids) in patients with asthma. One randomised, double-blind, parallel-group study (1222.6; 296 patients) administered treatment in the morning. Pulmonary function tests (PFTs) were performed pre-dose (trough) and ≤3 hours post-dose (weeks 1 and 2), and ≤6 hours post-dose after 4 weeks; primary end point was trough forced expiratory volume in 1 second (FEV1) response (change from baseline mean FEV1) after 4 weeks. A second randomised, double-blind, placebo- and active-controlled (formoterol 12 μg twice-daily) incomplete-block crossover study (1222.27; 198 patients) administered QD treatments in the evening. PFTs were performed over a 24-hour dosing interval after 4 weeks; primary end point was FEV1 area under the curve from 0-24 hours (AUC0-24) response (change from study baseline [mean FEV1] after 4 weeks).

RESULTS

Study 1222.6 showed a statistically significant increase in trough FEV1 response with olodaterol 20 μg (0.147 L; 95 % confidence interval [CI]: 0.059, 0.234; p = 0.001) versus placebo, with more limited efficacy and no evidence of dose response compared to placebo across the other olodaterol doses (2, 5 and 10 μg). Study 1222.27 demonstrated increases in FEV1 AUC0-24 responses at 4 weeks with all active treatments (p < 0.0001); adjusted mean (95 % CI) differences from placebo were 0.140 (0.097, 0.182), 0.182 (0.140, 0.224), 0.205 (0.163, 0.248) and 0.229 (0.186, 0.272) L for olodaterol 2, 5, 10 and 20 μg, respectively, and 0.169 (0.126, 0.211) for formoterol, providing evidence of increased efficacy with higher olodaterol dose. Olodaterol was generally well tolerated, with a few events associated with known sympathomimetic effects, mainly with 20 μg.

CONCLUSIONS

The LABA olodaterol has >24-hour duration of action. In patients with asthma, evidence of bronchodilator efficacy was demonstrated with statistically and clinically significant improvements in the primary end point of trough FEV1 response measured in clinics over placebo for the highest administered dose of 20 μg in Study 1222.6, and statistically and clinically significant improvements versus placebo in FEV1 AUC0-24 responses at 4 weeks for all doses tested in Study 1222.27, which also exhibited a dose response. Bronchodilator efficacy was seen over placebo for all olodaterol doses for morning and evening peak expiratory flow in both studies. All doses were well tolerated.

TRIAL REGISTRATIONS

NCT00467740 (1222.6) and NCT01013753 (1222.27).

Positioning new pharmacotherapies for COPD

COPD imposes considerable worldwide burden in terms of morbidity and mortality. In recognition of this, there is now extensive focus on early diagnosis, secondary prevention, and optimizing medical management of the disease. While established guidelines recognize different grades of disease severity and offer a structured basis for disease management based on symptoms and risk, it is becoming increasingly evident that COPD is a condition characterized by many phenotypes and its control in a single patient may require clinicians to have access to a broader spectrum of pharmacotherapies. This review summarizes recent developments in COPD management and compares established pharmacotherapy with new and emerging pharmacotherapies including long-acting muscarinic antagonists, long-acting β-2 sympathomimetic agonists, and fixed-dose combinations of long-acting muscarinic antagonists and long-acting β-2 sympathomimetic agonists as well as inhaled cortiocosteroids, phosphodiesterase inhibitors, and targeted anti-inflammatory drugs. We also review the available oral medications and new agents with novel mechanisms of action in early stages of development. With several new pharmacological agents intended for the management of COPD, it is our goal to familiarize potential prescribers with evidence relating to the efficacy and safety of new medications and to suggest circumstances in which these therapies could be most useful.