US Food and Drug Administration-mandated trials of long-acting β-agonists safety in asthma: will we know the answer?

Emulation of Randomized Clinical Trials With Nonrandomized Database Analyses: Results of 32 Clinical Trials

Importance

Nonrandomized studies using insurance claims databases can be analyzed to produce real-world evidence on the effectiveness of medical products. Given the lack of baseline randomization and measurement issues, concerns exist about whether such studies produce unbiased treatment effect estimates.

Objective

To emulate the design of 30 completed and 2 ongoing randomized clinical trials (RCTs) of medications with database studies using observational analogues of the RCT design parameters (population, intervention, comparator, outcome, time [PICOT]) and to quantify agreement in RCT-database study pairs.

Design, Setting, and Participants

New-user cohort studies with propensity score matching using 3 US claims databases (Optum Clinformatics, MarketScan, and Medicare). Inclusion-exclusion criteria for each database study were prespecified to emulate the corresponding RCT. RCTs were explicitly selected based on feasibility, including power, key confounders, and end points more likely to be emulated with real-world data. All 32 protocols were registered on ClinicalTrials.gov before conducting analyses. Emulations were conducted from 2017 through 2022.

Exposures

Therapies for multiple clinical conditions were included.

Main Outcomes and Measures

Database study emulations focused on the primary outcome of the corresponding RCT. Findings of database studies were compared with RCTs using predefined metrics, including Pearson correlation coefficients and binary metrics based on statistical significance agreement, estimate agreement, and standardized difference.

Results

In these highly selected RCTs, the overall observed agreement between the RCT and the database emulation results was a Pearson correlation of 0.82 (95% CI, 0.64-0.91), with 75% meeting statistical significance, 66% estimate agreement, and 75% standardized difference agreement. In a post hoc analysis limited to 16 RCTs with closer emulation of trial design and measurements, concordance was higher (Pearson r, 0.93; 95% CI, 0.79-0.97; 94% meeting statistical significance, 88% estimate agreement, 88% standardized difference agreement). Weaker concordance occurred among 16 RCTs for which close emulation of certain design elements that define the research question (PICOT) with data from insurance claims was not possible (Pearson r, 0.53; 95% CI, 0.00-0.83; 56% meeting statistical significance, 50% estimate agreement, 69% standardized difference agreement).

Conclusions and Relevance

Real-world evidence studies can reach similar conclusions as RCTs when design and measurements can be closely emulated, but this may be difficult to achieve. Concordance in results varied depending on the agreement metric. Emulation differences, chance, and residual confounding can contribute to divergence in results and are difficult to disentangle.

Metallothionein-2 is associated with the amelioration of asthmatic pulmonary function by acupuncture through protein phosphorylation

BACKGROUND

Acupuncture has long been used for asthma treatment but the underlying mechanism remains unclear. Previous study showed that metallothionein-2 (MT-2) was significantly decreased in asthmatic lung tissue. However, the relationship between acupuncture treatment and MT-2 expression during asthma is still unknown, and the detailed effect analysis of MT-2 on phosphorylation in airway smooth muscle cells (ASMCs) is also unclear.

METHODS

The acupuncture effect on pulmonary resistance (RL) was investigated in a rat model of asthma, and the mRNA and protein levels of MT-2 in lung tissue were detected. Primary ASMCs were isolated and treated with MT-2 recombinant protein to study the MT-2 effects on ASMC relaxation. A Phospho Explorer antibody microarray was applied to detect protein phosphorylation changes associated with MT-2-induced ASMC relaxation. Bioinformatic analysis were performed with PANTHER database, DAVID and STRING. Phosphorylation changes in key proteins were confirmed by Western blot.

RESULTS

Acupuncture significantly reduced RL at 2-5 min (P < 0.05 vs asthma) in asthmatic rats. Acupuncture continued to increase MT-2 mRNA expression in lung tissue for up to 14 days (P < 0.05 vs asthma). The MT-2 protein expression was significantly decreased in the asthmatic rats (P < 0.05 vs control), while MT-2 protein expression was significantly increased in the asthmatic model group treated with acupuncture (P < 0.05 vs asthma). Primary ASMCs were successfully isolated and recombinant MT-2 protein (100, 200, 400 ng/ml) significantly relaxed ASMCs (P < 0.05 vs control). MT-2 induced phosphorylation changes in 51 proteins. Phosphorylation of 14 proteins were upregulated while 37 proteins were downregulated. PANTHER classification revealed eleven functional groups, and the phosphorylated proteins were identified as transferases (27.8 %), calcium-binding proteins (11.1 %), etc. DAVID functional classification showed that the phosphorylated proteins could be attributed to eight functions, including protein phosphorylation and regulation of GTPase activity. STRING protein-protein interaction network analysis showed that Akt1 was one of the most important hubs for the phosphorylated proteins. The phosphorylation changes of Akt1 and CaMK2β were consistent in both the Phospho Explorer antibody microarray and Western blot.

CONCLUSION

Acupuncture can significantly ameliorate RL, and the MT-2 mRNA and protein levels in lung tissue are increased during treatment. MT-2 significantly relaxes ASMCs and induces a series of protein phosphorylation. These phosphorylation changes, including Akt1 and CaMK2β, may play important roles in the therapeutic effects of acupuncture on asthma.

Transgelin-2 as a therapeutic target for asthmatic pulmonary resistance

There is a clinical need for new bronchodilator drugs in asthma, because more than half of asthmatic patients do not receive adequate control with current available treatments. We report that inhibition of metallothionein-2 protein expression in lung tissues causes the increase of pulmonary resistance. Conversely, metallothionein-2 protein is more effective than β₂-agonists in reducing pulmonary resistance in rodent asthma models, alleviating tension in tracheal spirals, and relaxing airway smooth muscle cells (ASMCs). Metallothionein-2 relaxes ASMCs via transgelin-2 (TG2) and induces dephosphorylation of myosin phosphatase target subunit 1 (MYPT1). We identify TSG12 as a nontoxic, specific TG2-agonist that relaxes ASMCs and reduces asthmatic pulmonary resistance. In vivo, TSG12 reduces pulmonary resistance in both ovalbumin- and house dust mite-induced asthma in mice. TSG12 induces RhoA phosphorylation, thereby inactivating the RhoA-ROCK-MYPT1-MLC pathway and causing ASMCs relaxation. TSG12 is more effective than β₂-agonists in relaxing human ASMCs and pulmonary resistance with potential clinical advantages. These results suggest that TSG12 could be a promising therapeutic approach for treating asthma.

Combined Analysis of Asthma Safety Trials of Long-Acting β2-Agonists

BACKGROUND

Safety concerns regarding long-acting β₂-agonists (LABAs) in asthma management were initially identified in a large postmarketing trial in which the risk of death was increased. In 2010, the Food and Drug Administration (FDA) mandated that the four companies marketing LABAs for asthma perform prospective, randomized, controlled trials comparing the safety of combination therapy with a LABA plus an inhaled glucocorticoid with that of an inhaled glucocorticoid alone in adolescents (12 to 17 years of age) and adults. In conjunction with the FDA, the manufacturers harmonized their trial methods to allow an independent joint oversight committee to provide a final combined analysis of the four trials.

METHODS

As members of the joint oversight committee, we performed a combined analysis of the four trials comparing an inhaled glucocorticoid plus a LABA (combination therapy) with an inhaled glucocorticoid alone. The primary outcome was a composite of asthma-related intubation or death. Post hoc secondary outcomes included serious asthma-related events and asthma exacerbations.

RESULTS

Among the 36,010 patients in the intention-to-treat study, there were three asthma-related intubations (two in the inhaled-glucocorticoid group and one in the combination-therapy group) and two asthma-related deaths (both in the combination-therapy group) in 4 patients. In the secondary analysis of serious asthma-related events (a composite of hospitalization, intubation, or death), 108 of 18,006 patients (0.60%) in the inhaled-glucocorticoid group and 119 of 18,004 patients (0.66%) in the combination-therapy group had at least one composite event (relative risk in the combination-therapy group, 1.09; 95% confidence interval [CI], 0.83 to 1.43; P=0.55); 2100 patients in the inhaled-glucocorticoid group (11.7%) and 1768 in the combination-therapy group (9.8%) had at least one asthma exacerbation (relative risk, 0.83; 95% CI, 0.78 to 0.89; P<0.001).

CONCLUSIONS

Combination therapy with a LABA plus an inhaled glucocorticoid did not result in a significantly higher risk of serious asthma-related events than treatment with an inhaled glucocorticoid alone but resulted in significantly fewer asthma exacerbations.

Targeting the γ-Aminobutyric Acid A Receptor α4 Subunit in Airway Smooth Muscle to Alleviate Bronchoconstriction

We previously demonstrated that airway smooth muscle (ASM) cells express γ-aminobutyric acid A receptors (GABA(A)Rs), and that GABA(A)R agonists acutely relax ASM. Among the GABA(A)R α subunits, human ASM cells express only α4 and α5, providing the opportunity for selective pharmacologic targeting. Novel GABA(A)R-positive allosteric modulators designed for enhanced α4/α6 subunit selectivity were synthesized using iterative computational analyses (CMD-45 and XHe-III-74). Studies using oocyte heterologous expression systems confirmed that CMD-45 and XHe-III-74 led to significantly greater augmentation of currents induced by a 3% maximal effective concentration (EC3) of GABA [EC3]-induced currents in oocytes expressing α4 or α6 subunits (along with β3 and γ2) compared with other α subunits. CMD-45 and XHe-III-74 also led to greater ex vivo relaxation of contracted wild-type mouse tracheal rings compared with tracheal rings from GABA(A)R α4 subunit (Gabra4) knockout mice. Furthermore, CMD-45 and XHe-III-74 significantly relaxed precontracted human ASM ex vivo, and, at a low concentration, both ligands led to a significant leftward shift in albuterol-mediated ASM relaxation. In vivo, inhaled XHe-III-74 reduced respiratory system resistance in an asthmatic mouse model. Pretreatment of human ASM cells with CMD-45 and XHe-III-74 inhibited histamine-induced increases in intracellular calcium concentrations in vitro, an effect that was lost when calcium was omitted from the extracellular buffer, suggesting that inhibition of calcium influx due to alterations in plasma membrane potential may play a role in the mechanism of ASM relaxation. Selective targeting of the GABA(A)R α4 subunit with inhaled ligands may be a novel therapeutic pathway to treat bronchoconstriction, while avoiding sedative central nervous system effects, which are largely mediated by α1-3 subunit-containing GABA(A)Rs in the brain.

Antagonists of the TMEM16A calcium-activated chloride channel modulate airway smooth muscle tone and intracellular calcium

BACKGROUND

Perioperative bronchospasm refractory to β agonists continues to challenge anesthesiologists and intensivists. The TMEM16A calcium-activated chloride channel modulates airway smooth muscle (ASM) contraction. The authors hypothesized that TMEM16A antagonists would relax ASM contraction by modulating membrane potential and calcium flux.

METHODS

Human ASM, guinea pig tracheal rings, or mouse peripheral airways were contracted with acetylcholine or leukotriene D4 and then treated with the TMEM16A antagonists: benzbromarone, T16Ainh-A01, N-((4-methoxy)-2-naphthyl)-5-nitroanthranilic acid, or B25. In separate studies, guinea pig tracheal rings were contracted with acetylcholine and then exposed to increasing concentrations of isoproterenol (0.01 nM to 10 μM) ± benzbromarone. Plasma membrane potential and intracellular calcium concentrations were measured in human ASM cells.

RESULTS

Benzbromarone was the most potent TMEM16A antagonist tested for relaxing an acetylcholine -induced contraction in guinea pig tracheal rings (n = 6). Further studies were carried out to investigate the clinical utility of benzbromarone. In human ASM, benzbromarone relaxed either an acetylcholine- or a leukotriene D4-induced contraction (n = 8). Benzbromarone was also effective in relaxing peripheral airways (n = 9) and potentiating relaxation by β agonists (n = 5 to 10). In cellular mechanistic studies, benzbromarone hyperpolarized human ASM cells (n = 9 to 12) and attenuated intracellular calcium flux from both the plasma membrane and the sarcoplasmic reticulum (n = 6 to 12).

CONCLUSION

TMEM16A antagonists work synergistically with β agonists and through a novel pathway of interrupting ion flux at both the plasma membrane and sarcoplasmic reticulum to acutely relax human ASM.

Pharmacotherapy of critical asthma syndrome: current and emerging therapies

The critical asthma syndrome (CAS) encompasses the most severe, persistent, refractory asthma patients for the clinician to manage. Personalized pharmacotherapy is necessary to prevent the next acute severe asthma exacerbation, not just the control of symptoms. The 2007 National Asthma Education and Prevention Program Expert Panel 3 provides guidelines for the treatment of uncontrolled asthma. The patient's response to recommended pharmacotherapy is highly variable which risks poor asthma control leading to frequent exacerbations that can deteriorate into CAS. Controlling asthma symptoms and preventing acute exacerbations may be two separate clinical activities with their own unique demands. Clinicians must be prepared to use the entire spectrum of asthma medications available but must concurrently be aware of potential drug toxicities some of which can paradoxically worsen asthma control. Medications normally prescribed for COPD can potentially be useful in the CAS patient, particularly those with asthma-COPD overlap syndrome. Immunomodulation with drugs like omalizumab in IgE-mediated asthma syndromes is one important approach. New and emerging drugs address unique aspects of airway inflammation and biology but at a significant financial cost. The pharmacology and toxicities of the agents that may be used in the treatment of CAS to control asthma symptoms and prevent severe exacerbations are reviewed.

Safety of β2-Agonists in Asthma: Linking Mechanisms, Meta-Analyses and Regulatory Practice

An epidemic of asthma fatalities in the 1970s prompted a series of case-control studies which indicated that short acting β-agonists increased the risk of death. Subsequent mechanistic and pharmacodynamic studies have suggested that β-agonist monotherapy facilitates airway inflammation, although when co-administered with inhaled corticosteroids (ICSs), similar evidence is lacking. The Salmeterol Multicenter Asthma Research Trial, which revealed a fourfold increase in asthma-related deaths in salmeterol-treated patients, prompted a paradigm shift in the evidential assessment of β-agonist safety. The FDA's meta-analysis of over 60,000 patients ultimately concluded that long-acting β-agonist (LABA) therapy increased the risk of serious asthma-related events. However, this meta-analysis itself raised questions given a large body of omitted data and a limited emphasis on the risk of ICS-LABA co-administration. Subsequently, the FDA mandated the conduct of five large studies to definitively ascertain whether ICS-LABAs increase asthma-related risk. Whether this ambitious programme will provide certainty remains to be seen given issues of multiplicity, the very low frequency of fatal and near-fatal asthma, and the administration of a free combination of ICS and LABA in one trial. The FDA's de facto use of FEV1 as a safety parameter, based on findings from the Foradil NDA, is a further topical issue: subsequent clinical study data, considerations relating to regional pulmonary drug deposition and pharmacological differences between different β-agonists suggest that FEV1 may be a suboptimal safety metric. Models evaluating airway inflammation and bronchial reactivity may be more appropriate to assess the relative risk of asthma-related events.

Clinical utility and development of the fluticasone/formoterol combination formulation (Flutiform(®)) for the treatment of asthma

Pharmacologic treatment of asthma should be done with a stepwise approach recommended in treatment guidelines. If inhaled corticosteroids (ICSs) alone are not adequate, ICSs in combination with long-acting β-agonists (LABAs) are now established and widely used as the next step in effective controller therapy. Fixed-dose ICS/LABA combinations in a single device are the preferred form of delivery and improve compliance by enabling patients to get symptom relief from the LABA while receiving the anti-inflammatory benefits of ICSs. Fluticasone propionate/formoterol fumarate is one of the newest fixed-dose combinations. It has been in use in Europe in 2012, but is still under regulatory review in the US. Fluticasone is a synthetic ICS with potent anti-inflammatory effects, while formoterol is a selective β2-adrenergic receptor agonist with a rapid onset of bronchodilation within 5-10 minutes and a 12-hour duration of action. Fluticasone/formoterol has shown superior efficacy when compared to fluticasone or formoterol alone in multiple well-designed studies. The combination has shown comparable or "noninferior" benefits in lung function, clinical symptoms, and asthma control when compared with fluticasone and formoterol administered concurrently in separate inhalers. Fluticasone/formoterol provides similar efficacy with fluticasone/salmeterol, but with more rapid symptom relief. It has been compared directly with budesonide/formoterol with comparable results. Fluticasone/formoterol is well tolerated, with no unusual or increased safety concerns versus each individual component or other available ICS/LABA combinations. Fluticasone/formoterol is the latest entry into a relatively crowded market of branded fixed-dose preparations. Upcoming generic fixed-dose combinations and once-daily agents pose significant market challenges. In clinical practice, most practitioners consider all the currently available fixed-dose preparations to be of comparable efficacy and safety.

Effect of rare variants in ADRB2 on risk of severe exacerbations and symptom control during longacting β agonist treatment in a multiethnic asthma population: a genetic study

BACKGROUND

Severe adverse life-threatening events associated with longacting β agonist (LABA) use have caused the US Food and Drug Administration (FDA) to review the safety of these drugs, resulting in a boxed warning and a mandatory safety study in 46 800 patients with asthma. Identification of an at-risk, susceptible subpopulation on the basis of predictive biomarkers is crucial for understanding LABA safety. The β2-adrenergic receptor gene (ADRB2) contains a common, non-synonymous single nucleotide polymorphism, Gly16Arg, that is unlikely to account for the rare, life-threatening events seen with LABA use. We hypothesise that rare ADRB2 variants modulate therapeutic responses to LABA therapy and contribute to rare, severe adverse events.

METHODS

In this genetic study, ADRB2 was sequenced in 197 African American, 191 non-Hispanic white, and 73 Puerto Rican patients. Sequencing identified six rare variants, which were genotyped in 1165 patients with asthma. The primary hypothesis was that severe asthma exacerbations requiring hospital admission were associated with rare ADRB2 variants in patients receiving LABA therapy. This outcome was assessed overall and by ethnic group. Replication was done in 659 non-Hispanic white patients with asthma.

FINDINGS

Patients receiving LABA with a rare ADRB2 variant had increased asthma-related hospital admissions (15 [44%] of 34 patients with rare variant vs 121 [22%] of 553 patients with common ADRB2 alleles admitted to hospital in past 12 months; meta-analysis for all ethnic groups, p=0·0003). Specifically, increases in hospital admission rates were recorded in LABA-treated non-Hispanic white patients with the rare Ile 164 allele compared with non-Hispanic white patients with the common allele (odds ratio [OR] 4·48, 95% CI 1·40-13·96, p=0·01) and African American patients with a 25 bp promoter polynucleotide insertion, -376ins, compared with African American patients with the common allele (OR 13·43, 95% CI 2·02-265·42, p=0·006). The subset of non-Hispanic white and African American patients receiving LABAs with these rare variants had increased exacerbations requiring urgent outpatient health-care visits (non-Hispanic white patients with or without the rare Ile 164 allele, 2·6 [SD 3·5] vs 1·1 [2·1] visits, p<0·0001; and African American patients with or without the rare insertion, 3·7 [4·6] vs 2·4 [3·4] visits, p=0·01), and more frequently were treated with chronic systemic corticosteroids (OR 4·25, 95% CI 1·38-14·41, p=0·01, and 12·83, 1·96-251·93, p=0·006). Non-Hispanic white patients from the primary and replication cohorts with the rare Ile 164 allele were more than twice as likely as Thr 164 homozygotes to have uncontrolled, persistent symptoms during LABA treatment (p=0·008-0·04).

INTERPRETATION

The rare ADRB2 variants Ile164 and -376ins are associated with adverse events during LABA therapy and should be evaluated in large clinical trials including the current FDA-mandated safety study.

FUNDING

US National Institutes of Health.

Dispensation of long-acting β agonists with or without inhaled corticosteroids, and risk of asthma-related hospitalisation: a population-based study

BACKGROUND

The role of long-acting β-agonists (LABA) added to inhaled corticosteroids (ICS) in the management of asthma is extensively debated. We thought to assess the risk of asthma-related hospitalisation in individuals who regularly filled prescriptions for ICS+LABA compared to those who regularly filled prescriptions for ICS alone or LABA alone, and compared to those who did not regularly fill such medications.

METHODS

Using administrative health databases of the province of British Columbia (BC), Canada, from 1997 to 2012, we conducted a nested case-control analysis of a cohort of asthma patients. Cases were defined as those who experienced asthma-related hospitalisation after the first year of their entry into the cohort. For each case, up to 20 controls were matched based on age, sex, date of cohort entry, and several measures of asthma severity. We categorised individuals as regularly exposed, irregularly exposed, or non-exposed to ICS alone, LABA alone, or ICS+LABA based on dispensation records in the past 12 months. The primary outcome measures were the rate ratio (RR) of the asthma-related hospitalisation among categories of regular exposure.

RESULTS

3319 cases were matched to 43 023 controls. The RR for regular dispensation of ICS+LABA was 1.14 (95% CI 0.93 to 1.41) compared with regular dispensation of ICS alone and 0.45 (95% CI 0.29 to 0.70) compared with regular dispensation of LABA alone. Those who regularly dispensed LABA had to dispense an ICS for at least three quarters of a year to reduce their risk to that of those who did not dispense LABA.

CONCLUSIONS

Regular dispensation of ICS+LABA was not associated with an increased risk of asthma-related hospitalisation compared with regular dispensation of ICS alone. Adherence to ICS in patients who regularly receive ICS+LABA seems to be an important factor in the prevention of adverse asthma-related outcomes.

Safety of bronchodilators and corticosteroids for asthma during pregnancy: what we know and what we need to do better

Asthma is a common medical condition complicating pregnancy with potentially serious effects on pregnancy outcome. The aim of this review is to provide an update on efficacy and safety of asthma medications, primarily bronchodilators and corticosteroids, used during pregnancy with focus on pregnancy outcome, and, furthermore, to discuss limitations of available studies and point to possible improvements in future studies. A planned series of systematic searches was conducted using the PubMed database. Use of short-acting β2-agonists has generally been established as safe, and the few studies stating otherwise appear to have, perhaps critical, methodological limitations. The safety of long-acting β2-agonists remains to be further investigated, and the few available studies have methodological limitations and, therefore, provide no definite answers, although a very recent study supports the safety of add-on long-acting β2-agonists to inhaled corticosteroids. Inhaled corticosteroids are generally found to be safe, although further research is needed to investigate both the efficacy and safety of high dose therapy with inhaled corticosteroids. Studies have reported associations between the use of systemic corticosteroids and adverse perinatal outcomes, such as preterm birth, low birth weight, and pre-eclampsia. This must, however, be weighed against the potential serious impact of severe, uncontrolled asthma itself on pregnancy outcome. The main obstacle to a valid interpretation of several of the available studies is the inadequate stratification for asthma severity and control. Overall, asthma in itself and not just poor asthma control poses a greater risk to pregnancy outcomes than asthma medication. Nonetheless, more studies focusing on disentangling the effects of asthma alone and asthma medications are needed. Increased use of stratified risk assessments, taking the concept of asthma severity into greater consideration, is much warranted in future studies.

Inhaled long-acting β2 agonists enhance glucocorticoid receptor nuclear translocation and efficacy in sputum macrophages in COPD

BACKGROUND

Combination inhaled therapy with long-acting β2 agonists (LABAs) and corticosteroids is beneficial in treating asthma and chronic obstructive pulmonary disease (COPD).

OBJECTIVE

In asthma, LABAs enhance glucocorticoid receptor (GR) nuclear translocation in the presence of corticosteroids. Whether this biological mechanism occurs in COPD, a relatively corticosteroid-resistant disease, is uncertain.

METHODS

Eight patients with mild/moderate COPD participated in a double-blind, placebo-controlled, crossover study and inhaled single doses of fluticasone propionate (FP) 100 μg, FP 500 μg, salmeterol xinafoate (SLM) 50 μg, and combination FP 100 μg + SLM 50 μg. One hour postinhalation, sputum was induced, nuclear proteins isolated from purified macrophages, and levels of activated nuclear GR quantified by using a GR-glucocorticoid response element ELISA-based assay.

RESULTS

Nuclear GR significantly increased after the inhalation of FP 500 μg (P < .01), but not after the inhalation of FP 100 μg or SLM 50 μg, compared with placebo. Interestingly, SLM in combination with FP 100 μg increased nuclear GR levels equivalent to those of FP 500 μg alone. This was significantly greater than either FP 100 μg (P < .05) or SLM 50 μg (P < .01) alone. In vitro in a human macrophage cell line, SLM (10(-8) mol/L) enhanced FP (10(-9) mol/L)-induced mitogen-activated protein kinase phosphatase-1 mRNA (5.8 ± 0.6 vs 8.4 ± 1.1 × 10(-6) copies, P < .05) and 2 × glucocorticoid response element-luciferase reporter gene activity (250.1 ± 15.6 vs 103.1 ± 23.6-fold induction, P < .001). Addition of SLM (10(-9) mol/L) to FP (10(-11) mol/L) significantly enhanced FP-mediated suppression of IL-1β-induced CXCL8 (P < .05).

CONCLUSIONS

Addition of SLM 50 μg to FP 100 μg enhanced GR nuclear translocation equivalent to that seen with a 5-fold higher dose of FP in sputum macrophages from patients with COPD. This may account for the superior clinical effects of combination LABA/corticosteroid treatment compared with either as monotherapy observed in COPD.