The Role of Neutrophil Elastase Inhibitors in Lung Diseases

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Commentary Ahead of the Curve

]

The Role of Neutrophil Elastase Inhibitors in Lung Diseases Eva Polverino, MD, PhD; Edmundo Rosales-Mayor, MD; Glenn E. Dale, PhD; Klaus Dembowsky, MD, PhD; and Antoni Torres, MD, PhD

In many respiratory diseases characterized by an intense inflammatory response, the balance between proteolytic enzymes (proteases, including elastases) and their inhibitors (proteinases inhibitors) is not neutral. Excess activity of neutrophil elastase (NE) and similar proteases has been reported to cause tissue damage and to alter the remodeling process in many clinical conditions such as pneumonia, respiratory distress, and acute lung injury (ALI). Several experimental NE inhibitors have been tested in preclinical and clinical studies of different conditions of inflammatory lung injury such as ALI and pneumonia, with contrasting results. This study reviews the literature regarding NE inhibitors in the field of respiratory diseases and reflects on possible future developments. In particular, we highlight potential gaps in the scientific evidence and discuss potential strategies for focusing investigation on antielastases in clinical practice through the selection of targeted populations and proper outcomes. CHEST 2017; 152(2):249-262 KEY WORDS: airways inflammation; ARDS; bronchiectasis; cystic fibrosis; neutrophil biology; neutrophil elastase; pneumonia

Neutrophil elastase (NE) is one of the physiologic proteolytic enzymes (serine proteases) that are required for neutrophil function and are involved in the inflammatory response to tissue injury such as sepsis or arthritis. Certain proteases, for example E and cathepsin G, have a clear intracellular and extracellular antibacterial or antifungal activity.1-3 NE is a destructive elastase that attacks the extracellular matrix and modulates inflammation and tissue remodeling. Its involvement may be direct (tissue damage) or indirect (proinflammatory or proapoptotic), or ABBREVIATIONS: ALI = acute lung injury; a1-AT = alpha1 antitrypsin; CF = cystic fibrosis; EPI-hNE4 = engineered protease inhibitor, human neutrophil elastase 4; MNEI = monocyte neutrophil elastase inhibitor; NE = neutrophil elastase; PA = Pseudomonas aeruginosa; QoL = quality of life; RCT = randomized controlled trial AFFILIATIONS: From the Department of Pneumology (Dr Torres) and Institut Clínic Respiratori (Drs Polverino, Rosales-Mayor, and Torres), Hospital Clinic of Barcelona, Institut d’Investigacions Biomèdiques August Pi i Sunyer, University of Barcelona, Ciber de Enfermedades

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it may just be a marker of leukocyte activation. The tissue damage and remodeling after an injury is the result of an imbalance between proteases and their inhibitors (Fig 1).4 Numerous studies have investigated the potential therapeutic role of NE inhibitors (endogenous or synthetic) in different models of inflammatory tissue damage, with contrasting results. The transfer of these findings to clinical practice remains a challenge. Here we present a critical analysis of the literature on NE inhibitors in different respiratory conditions that may contribute to guide future investigations.

Respiratorias, Barcelona, Spain; and Drug Discovery and Development (Drs Dale and Dembowsky), Polyphor Ltd., Allschwil, Switzerland. CORRESPONDENCE TO: Antoni Torres, MD, PhD, Department of Pneumology, Hospital Clinic, Calle Villarroel 170, Barcelona 08036, Spain; e-mail: [email protected] Copyright Ó 2017 American College of Chest Physicians. Published by Elsevier Inc. All rights reserved. DOI: http://dx.doi.org/10.1016/j.chest.2017.03.056

249

Innate immune defense neutrophils, macrophages and epithelial cells

serine proteases (NE) cathepsin metalloproteases (MMP) Proteinase 3

Proteases

α1-AT α1-macroglobulin Elafin SLPI

Proteaseinhibitors

• Inflammatory response (local and systemic) • Intercellular signelling & Neutrophil migration Cleavege of adhesion molecules Citokine modification (processing and degradation) Cell-surface receptor activation and chemotactic activity • Matrix and tissue remodelling • Up regulation of NE inhibitors • Bacterial clearance (neutrophil azurophil granules) Tissue repair Infection clearance Injury resolution

Progressive tissue damage

Figure 1 – Innate immune defense. a1-AT ¼ alpha1 antitrypsin; MMP ¼ matrix metalloproteinase; NE ¼ neutrophil elastase; SLPI ¼ secretory leukocyte protease inhibitor.

Search Methodology A broad search strategy was used to find English language publications indexed in PubMed and in the abstract books from the American Thoracic Society and European Respiratory Society congresses between 1996 and 2016. Relevant publications were selected manually from the following searches: human elastases in respiratory diseases and elastase inhibitors in respiratory diseases.

Imbalance Between Proteases and Antiproteases in Respiratory Diseases Different conditions of inflammatory lung injury such as pneumonia and cystic fibrosis (CF) are often characterized by a local imbalance between proteases (serine proteases, cathepsins, metalloproteases) and antiproteases (alpha1 antitrypsin [a1-AT], a2-macroglobulin, cystatins, tissue inhibitors of metalloproteinases). The proinflammatory imbalance is usually associated with tissue damage and systemic involvement.5-7 NE is one of the major proteases involved in a range of conditions such as communityacquired pneumonia,8 ventilator-associated pneumonia,9 acute lung injury (ALI) and ARDS,5,10 exacerbated COPD,11 CF,12 and bronchiectasis.13,14

250 Commentary

A number of NE inhibitors such as elafin and secretory leukocyte protease inhibitor are physiologically produced at sites of tissue injury or by the liver (in the case of a1-AT), and their production is upregulated in response to inflammatory stimuli. They are produced by neutrophils, macrophages, and epithelial cells,15,16 but some organs, such as the myocardium and the brain, are less prepared to counteract increased NE activity and are thus more predisposed to develop neutrophil-mediated injury.4 To reduce the excess inflammatory response, various inhibitors of the neutrophilic elastase, ranging from nebulized a1-AT to systemic (oral or intravenous) or nebulized NE inhibitors (ONO-5046 [sivelestat]; AZD9668; engineered protease inhibitor, human NE 4 [EPI-hNE4 (depelstat; Debiopharm S.A.)]; monocyte NE inhibitor (MNEI); KRP-109, pre-elafin; BAY 85-8501; POL6014; and DX-890) have been tested in different diseases (Table 1).17,18

Severe Pneumonia In acute infections, an appropriate balance between proinflammatory and antiinflammatory mediators is required to resolve the inflammatory process.19 Several studies in humans with severe community-acquired pneumonia or ventilator-associated pneumonia have

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TABLE 1

] NE Inhibitors in Preclinical Studies of Respiratory Diseases

NE Inhibitor EPI-hNE4 (depelestat; Debiopharm S. A.)

Pathologic Condition

Type of Study

Positive Results .

Negative Results

PA lung infection (Honorè et al22/2004)

Animal model (rats) NE inhibitor before infection

Bleomycin-induced ALI (Honorè et al22/2004)

Animal model (rats) NE inhibitor during and after bleomycin

Decrease of alveolar inflammation (treatment during and after that of ALI group) Trend toward an improvement of static lung compliance (treatment during that of ALI group)

No significant improvement in lung edema or in static lung compliance (treatment after that of ALI group)

Repeated lung injury with LPS and bleomycin (Honorè et al22/2004)

Animal model (rats) NE inhibitor during bleomycin

Significant inhibition of alveolar inflammation Partial but significant reversal of the impairment of lung compliance

.

Prolastin

PA lung chronic infection (Cantin and Woods23/1999)

Animal model (rats) NE inhibitor after infection

Lower NE activity Decrease in the amount of inflammatory infiltration of lung Enhanced clearance of bacteria

No difference in total cell counts in BAL, but a decrease in neutrophil numbers

KRP-109

SPn lung infection (Yamada et al17/2011)

Animal model (mice) NE inhibitor after infection

Trend toward a higher survival rate Less inflammation at histopathologic examination, and reductions in inflammatory cells and markers in BAL

No significant differences in viable bacteria numbers between groups No difference in NE activity in BAL

Sivelestat

SPn lung infection (Hagio et al25/2008)

Animal model (hamsters) NE inhibitor after infection

Reduction in the increase in NE activity and inflammatory markers Enhanced clearance of bacteria Decreased levels of MIP-2 and surfactant protein D in BAL

No effect of leukocyte influx into lung interstitial tissue and BAL

SPn lung infection (Yanagihara et al26/ 2007)

Animal model (mice) NE inhibitor after infection

Delayed mortality Decrease in inflammatory cells in lung histopathologic specimens and in BAL Decrease levels of viable bacteria in blood

No difference in number of viable bacteria in lungs

LPS-induced ALI (Iba et al37/2006)

Animal model (hamsters) NE inhibitor before and after LPS

Protective effect on intravascular and extravascular damage in the lung, suppression of morphologic lung injury, and decreased expression of inflammatory markers (NE inhibitor before LPS group) Partial suppression of extravascular damage and widening of interstitium (latter damage) (NE inhibitor after LPS group)

No change in alveolar neutrophil recruitment No change in bacterial clearance

.

(Continued) chestjournal.org

251

TABLE 1

] (Continued)

NE Inhibitor

DX-890

Pathologic Condition

Type of Study

Positive Results

Negative Results

LPS-induced ALI (Inoue et al7/2005)

Animal model (rats) NE inhibitor after LPS

Lower NE activity in BAL, serum, and homogenate supernatant of lung Decreased leukocyte adhesion in the pulmonary capillary bed Prevention of deterioration of tissue hemoglobin oxygenation and the development of LPSinduced acute dysfunction of pulmonary microcirculation

.

LPS-induced ALI (Yuan et al38/2014)

Animal model (rats) NE inhibitor before LPS

Suppression of lung injury assessed by means of morphologic examination Inhibition of LPS elicited increase of MPO Decreased expression of ICAM-1, ICAM-1 mRNA, and NF-kB p65

.

LPS-induced ALI (Yasui et al36/1995)

Animal model (hamsters) NE inhibitor before LPS

Decrease in inflammatory cells, albumin concentration, and elastase-like activity in BAL Decrease in inflammatory cells in alveolar spaces Inhibition of neutrophil migration in vitro

.

Ventilator-induced lung injury (Sakashita et al42/ 2007)

Animal model (mice) NE inhibitor before injury

Inhibition of NE activity and MPO activity Attenuation of histologic lung damage, neutrophil accumulation, and lung water Decreased levels of MIP-2, IL-6, and TNF-a in BAL and serum

.

Ventilator-induced lung injury (Kim et al41/2014)

Animal model (rats) NE inhibitor before and during injury

Attenuation of lung edema and neutrophil count and proteins in BAL in the early sivelestat group (NE inhibitor before injury) compared with that in the sivelestat group (NEI during injury)

.

Lung injury induced after hemorrhagic shock followed by resuscitation (Toda et al18/2007)

Animal model (rats) NE inhibitor at the start of resuscitation

Suppression of lung injury (histologic damage) and reduction of MPO activity; decrease in TNF-a, iNOS, and ICAM-1 expression in the lung; attenuation of DNA binding activity of NF-kB

.

CF (Dunlevy et al53/2012)

In vitro study of neutrophils from subjects with CF and those who were healthy

Pretreatment reduced NE activity from neutrophils (CF and healthy), IL-8 secretion, and neutrophil transmigration

.

(Continued)

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TABLE 1

] (Continued)

NE Inhibitor

Pathologic Condition

Type of Study

Positive Results

Negative Results

Pre-elafin

LPS-induced ALI (Vachon et al39/2002)

Animal model (mice) NE inhibitor before LPS

Decrease in the neutrophil influx in alveolar spaces and also neutrophil attractant and activators levels Antiinflammatory protective effect

.

MNEI

PA lung chronic infection (Woods et al24/2005)

Animal model (rats) NE inhibitor after infection

Decrease in the extent of inflammatory infiltrate of lung Enhanced clearance of bacteria

No difference in total cell counts or neutrophils in BAL

BAY 85-8501

NE-induced or PPEinduced ALI (von Nussbaum et al35/ 2015)

Animal model (mice) NE inhibitor before injury

Prevention of the development of lung injury and subsequent inflammation induced by NE but no effect on PPE

.

POL6014

CF (Lacey et al54/2016)

In vitro study (BAL fluid from patients with CF)

Inhibition of NE activity while preserving neutrophil function

.

a1-AT

a1-AT deficiency

Single-dose aerosol administration of a1-AT (15 patients with deficiency)

Significant increase in lung anti-NE defenses with a single-dose aerosol administration of a1-AT No adverse clinical effects

.

(Hubbard et al63/ 1989)

ALI ¼ acute lung injury; a1-AT ¼ alpha1 antitrypsin; CF ¼ cystic fibrosis; EPI-hNE4 ¼ engineered protease inhibitor, human neutrophil elastase 4; ICAM1 ¼ anti-intercellular adhesion molecule 1; iNOS ¼ inducible nitric oxide synthase; LPS ¼ lipopolysaccharide; MIP-2 ¼ macrophage inflammatory protein 2; MNEI ¼ monocyte neutrophil elastase inhibitor; MPO ¼ myeloperoxidase; mRNA ¼ messenger RNA; NE ¼ neutrophil elastase; NF ¼ nuclear factor; PA ¼ Pseudomonas aeruginosa; PPE ¼ porcine pancreatic elastase; SPn ¼ Streptococcus pneumoniae; TNF ¼ tumor necrosis factor.

demonstrated a reduced inhibition of NE, which may result in excessive proteolytic damage and worse outcome.8,9,20 Studies of the potential role of NE inhibitors in modulating the inflammatory balance in severe pneumonia have provided contrasting results. Animal Models of NE Inhibitors

In the transgenic a1-ATþ/þ mice strain expressing this protein, mortality due to pneumonia caused by Pseudomonas aeruginosa (PA) was reduced by 90% compared with that in nontransgenic mice.21 Infected mice had reduced lung tissue inflammation and damage, as well as decreased bacterial load. Similarly, EPI-hNE4 (depelestat; Debiopharm S. A.), MNEI (human monocyte/ neutrophil elastase inhibitor), and a1-proteinase inhibitor (prolastin; Talecris Biotherapeutics, Inc) showed reduced alveolar inflammation22 and enhanced bacterial clearance.23,24 In animal models of severe Streptococcus pneumoniae pneumonia, KRP-1093 and sivelestat25,26 showed higher survival rates and less inflammation in BAL. Human Studies With NE Inhibitors

There are few descriptive studies of NE inhibitors in humans with pneumonia (Table 2).27,28 In a

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retrospective study in 28 patients with severe bacterial pneumonia receiving sivelestat, this inhibitor was administered earlier in survivors than in fatal cases.29 Some case reports of acute pneumonia with respiratory failure caused by Legionella pneumophila or Pneumocystis jirovecii suggest that sivelestat could improve outcomes.30,31

ALI and ARDS ARDS is an acute, diffuse inflammatory lung injury, characterized by hypoxemia, bilateral infiltrates, and decreased lung compliance.32 For the purposes of this review, we will use the terms “ALI” and “ARDS” interchangeably. The pathophysiologic aspects of ALI include unregulated NE activity,33 and Lengas et al34 demonstrated a correlation between NE concentration in BAL and the intensity of alveolar inflammation in ALI. Animal Models of NE Inhibitors

A mouse model of NE-induced ALI demonstrated that pretreatment with BAY 85-8501 (a selective inhibitor of human NE) was able to prevent the development of lung injury.35

253

TABLE 2

] NE Inhibitors in Clinical Studies of Respiratory Diseasesa

NE Inhibitor Sivelestat

Pathologic Condition

Type of Study

Positive Results

Negative Results .

Severe bacterial pneumonia (PSI class V) (Nakamura et al27/ 2008)

Retrospective study 28 patients

Sivelestat had been administered earlier in the survival cases

ALI and ARDS associated with SIRS requiring MV (Hashimoto et al5/ 2008)

Observational study 32 patients (all treated with NE inhibitor)

NE activity decrease after sivelestat administration and return to baseline after cessation of sivelestat

ALI and ARDS associated with SIRS requiring MV (Miyoshi et al45/2013)

Retrospective study NE inhibitor at the time of ALI diagnosis 110 patients: 70 sivelestat and 40 control subjects

Trend toward higher survival (P ¼ .064), VFDs (P ¼ .031), and PaO2/FIO2 ratio (P ¼ .018) NE inhibitor effective for survival in patients with PaO2/FIO2 ratio $ 140 mm Hg and sepsis NE inhibitor significantly prolonged survival, leading to higher VFDs and increased PaO2/FIO2 ratio in patients with sepsis and procalcitonin level $ 0.5 ng/mL

.

ARDS and MV with lung water > 10 mL/kg (Tagami et al43/2014)

Post hoc analysis of a cohort study (PiCCO study) NE inhibitor after ICU admission 164 patients: 87 sivelestat and 77 control subjects

.

No significant difference in 28-day mortality (24.7% vs 29.5%) No increase in VFDs (9.6 vs 9.7 d)

Aspiration lung injury (Shime and Hashimoto28/2006)

Retrospective study 28 patients: 23 sivelestat and 5 control subjects

Fewer ventilator days Increase in PaO2/FIO2 ratio and better response if drug was administered within 24 h for patients with background of neurologic disease

.

Patients undergoing esophagectomy (Wang et al47/2015)

Systematic review and meta-analysis 13 trials with 484 patients: 266 sivelestat and 218 control subjects

Decrease in the incidence of ALI after surgery (RR, 0.27; CI, 0.08-0.93) MV duration decreased in patients with drug administration until postoperative day 5 (standardized mean difference, 1.41; CI, 2.63 to 0.19) No difference in postoperative complications

Incidence of pneumonia and ICU and hospital stay decreased without reaching statistical significance

No difference in NEa1-AT complex Outcome and prognosis not evaluated

MV ¼ mechanical ventilation; PiCCO ¼ Pulse Contour Cardiac Output; PSI ¼ pneumonia severity index; RR ¼ relative risk; SIRS ¼ systemic inflammatory response syndrome; VFD ¼ ventilator-free day. See Table 1 legend for expansion of other abbreviations. a Clinical trials not included.

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Several animal models of lipopolysaccharide-induced ALI have shown that sivelestat and pre-elafin have protective effects on lung damage.36-39 The combination of sivelestat with a free radical scavenger (edaravone) in a rat model of lipopolysaccharide-induced ALI showed a potential protective effect against neutrophilic tissue injury.40 Two mouse models of lung injury induced by mechanical ventilation showed that sivelestat inhibited NE and myeloperoxidase activities and reduced local and systemic inflammatory interleukins and lung damage.41,42

In vitro Studies With NE Inhibitors

DX-890, an NE inhibitor, reduced NE activity from activated neutrophils (in both patients with CF and healthy control subjects), IL-8 secretion, and neutrophil transmigration.53 An NE inhibitor (POL6014) was tested in the BAL of six patients with CF and showed comparable NE inhibitory action as that of a1-AT.54 Finally, aerosolized EPI-hNE4 (depelestat; Debiopharm S. A.) has also been tested, but little information is available.55,56 Human Studies With NE Inhibitors

Human Studies With NE Inhibitors

Several retrospective or open-label studies have shown that sivelestat may increase ventilator-free days and 180day survival in patients with ALI or ARDS.5,43-46 The meta-analysis by Wang et al47 showed some benefit in preventing ALI after esophagectomy (relative risk, 0.27; 95% CI, 0.08 to 0.93), particularly if sivelestat was administered within the first 5 days after surgery. A review of case reports of aspiration-related lung injury showed some benefits in oxygenation and ventilator-free days with prompt administration of sivelestat in patients with neurologic comorbidities.45 Nonetheless, the only large multicenter, double-blind placebo-controlled trial in patients with ALI receiving mechanical ventilation (Staphylococcus aureus Surgical Inpatient Vaccine Efficacy, or STRIVE) showed a trend toward increased long-term mortality with sivelestat (sivelestat 40.2% vs placebo 31.3%; P ¼ .006) (Table 3).48 A subsequent meta-analysis of randomized controlled trials (RCTs) of sivelestat confirmed the absence of any benefit in ALI and ARDS.49

AZD9668, a reversible and selective inhibitor of human NE, was tested in a randomized, double-blind, placebocontrolled, parallel-group, phase IIa study in CF.57 Patients were assigned treatment with oral AZD9668 or placebo (28 days). AZD9668 was well tolerated and significantly reduced sputum inflammatory biomarkers (IL-6 and regulated on activation, normal T-cell expressed and secreted cytokine) (Fig 2). AZD9668 also decreased free and total urine desmosine, a biomarker of elastin degradation. It failed to achieve the primary end points (sputum neutrophil counts, NE activity, and lung function) and clinical outcomes (quality of life [QoL]); however, other factors may have contributed to the failure (eg, duration or dose of AZD9668, small sample size, or drug penetration). Another phase II clinical trial in CF with inhaled a1-AT showed no effect on lung function but reduced free NE activity, neutrophil count, PA bacterial load, IL-8 levels, and IgG levels.58 However, a limitation of this study was its single-arm, nonplacebo design.

Bronchiectasis Cystic Fibrosis CF is a multiorgan genetic disease characterized by abnormal ion transport (CF transmembrane conductance regulator mutations) that predisposes patients to infection and neutrophilic inflammation, altered airway clearance, and progressive bronchiectasis. Respiratory infections and bronchiectasis are the major determinants of disease progression and mortality. Various studies of CF have demonstrated an increasing accumulation of neutrophils, NE, and matrix metallopeptidase 9 and reduced levels of protease inhibitors such as secretory leukoproteinase inhibitor and a1-AT in sputum.12,50-52 This imbalance impairs bacterial clearance and contributes to local inflammation, bronchiectasis, and lung function decline.52

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Bronchiectasis is usually characterized by excessive neutrophilic airways inflammation. Airways infection, particularly by PA, is usually considered the trigger of this deregulated inflammatory pattern, which persists even after successful antibiotic treatment.14 Tsang et al59 demonstrated a strict relationship between elastase levels in sputum and relevant clinical data (sputum volume, radiologic extension, and lung function). Animal Models of NE Inhibitors

Nebulized MNEI was used in a rat model of chronic PA infection. The results showed significant decreases in the extent of inflammatory injury (histopathologic findings) and enhanced clearance of bacteria from infected lungs.24

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TABLE 3

] NE Inhibitors in Humans With Respiratory Diseases: Clinical Trials and Systematic Reviews and Meta-analyses

Disease ALI and ARDS

NE Inhibitor

Type of Study

Intervention

Principal Outcomes

Sivelestat (Zeiher et al48/ 2004)

Multicenter, doubleblind, placebocontrolled RCT (STRIVE study) 492 patients (of 620 patients planned) with ALI and MV (245 to sivelestat and 245 to placebo).

Randomized Sivelestat (0.16 mg/kg/h), or placebo, intravenous infusion for the duration of MV plus 24 h (maximum 14 d)

58.5% had an infectious cause of ALI Enrollment suspended due to a negative trend in long-term mortality on the interim analysis, 180-d all-cause mortality (40.2% vs 31.3%; P ¼ .006) greater in sivelestat vs placebo group No effect on primary end point (11.4 vs 11.9; P ¼ .536) or 28-d all-cause mortality (26.6% vs 26.0%; P ¼ .847)

Sivelestat (Akamoto et al46/2007)

Single-center, singleblind, placebocontrolled trial 13 patients undergoing major surgery: 6 sivelestat and 7 control subjects

Randomized Sivelestat (4.8 mg/kg/d) or saline, from the beginning of the operation for 3 d

Effect on tumor immunity and inflammatory mediator: serum IL-6, IL-12, C-reactive protein, and IAP significantly lower in the sivelestat group No difference in Th1/Th2 balance between two groups

Sivelestat (Aikawa et al44/ 2011)

Open-label, nonrandomized, multicenter, phase IV clinical study Patients with ALI associated with SIRS and MV 581 patients: 404 sivelestat and 177 control subjects

Nonrandomized Sivelestat (0.2 mg/kg/h) intravenous infusion for a maximum of 14 d

Sivelestat associated with more VFDs (15.7 vs 12.1; P ¼ .0022) and early weaning (28-day MV weaning rate 74.6% vs 61.2%; P ¼ .0028) Adjusted 180-day survival rate higher in sivelestat group (71.8% vs 56.3%; P ¼ .0022) Incidence of adverse events lower in sivelestat group (23.4% vs 33.7%; P ¼ .0073)

Sivelestat (Iwata et al49/ 2010)

Systematic review and meta-analysis of RCT 8 trials: 7 conducted in Japan, 1 multicenter trial (STRIVE study)

Sivelestat for the treatment of ALI and ARDS

No difference in mortality within 28 to 30 d after randomization (RR, 0.95; CI, 0.72-1.26) Sivelestat associated with a worse outcome for 180-d mortality (RR, 1.27; CI, 1.00-1.62) No difference in MV days (standardized mean difference, 0.43; 1.12 to 0.27), but sivelestat associated with a better short-term PaO2/FIO2 ratio (0.30, 0.05 to 0.56) (Continued)

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TABLE 3

] (Continued)

Disease

CF

NE Inhibitor

Intervention

Principal Outcomes

Sivelestat (Wang et al47/ 2015)

Systematic review and meta-analysis (RCT and high-quality comparative studies) 13 studies included in systematic review and 9 in meta-analysis

Sivelestat for the improvement of postoperative clinical course in patients with esophageal carcinoma undergoing esophagectomy

Sivelestat decreased the incidence of ALI after surgery (RR, 0.27; CI, 0.08-0.93) MV duration decreased in sivelestat group with administration until postoperative day 5 (standardized mean difference, 1.41; CI, 2.63 to 0.19) Incidence of pneumonia and ICU and hospital stay decreased in sivelestat group without reaching statistical significance No difference in postoperative complications

AZD9668 (Elborn et al57/ 2012)

Randomized, doubleblind, placebocontrolled, parallelgroup, phase IIa study 56 patients with a clinical diagnosis of CF: 27 AZD9668 and 29 placebo

Randomized AZD9668 (60 mg) or placebo, orally 2 times a day for 4 wk

No difference in lung function, respiratory symptoms, or use of reliever medication or in QoL between groups No difference in sputum NE activity Trend toward a reduction in sputum inflammatory biomarkers: TNF-a, IL-6, IL-8, IL-1b, RANTES, and monocyte chemoattractant protein-1 Reduction of free and total urinary desmosine and plasma desmosine Adverse events similar between groups

a1-AT (Griese

Multicenter, randomized, openlabel, parallel-group trial 52 patients with CF: 28 peripheral deposition and 24 bronchial deposition

Randomized Daily inhalation of 25 mg a1-AT for 4 wk comparing 2 different inhalation strategies (peripheral or bronchial compartment) No placebo control group

No difference in the measured variables between the peripheral and bronchial deposition groups; therefore, the overall effect of a1-AT was assessed Increase in a1-AT concentration No effect on lung function Decrease of free NE activity in sputum, neutrophil numbers, PA colony-forming units, IL8 and TNF-a levels, and intact IgG

AZD9668 (Stockley et al60/2013)

Randomized, doubleblind, placebocontrolled, parallelgroup, phase II, trial 38 patients with clinical

Randomized AZD9668 (60 mg) or placebo, orally 2 times a day for 4 wk

No difference in sputum neutrophil count, 24-h sputum weight, diary symptom scores, use of reliever medication, or

et al58/2007)

Bronchiectasis

Type of Study

(Continued)

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257

TABLE 3

] (Continued)

Disease

NE Inhibitor

Type of Study

Intervention

Principal Outcomes

diagnosis of idiopathic or postinfective bronchiectasis nonCF: 22 AZD9668 and 16 placebo

COPD

SGRQ scores Improvement in lung function (change in FEV1 from baseline: 100 mL) Trend toward reduction in sputum inflammatory markers (IL-6, IL-8) and NE activity

BAY 85-8501 (NCT01818544)

Phase II clinical trial 92 patients with idiopathic or postinfectious bronchiectasis non-CF

Randomized Oral BAY 85-8501 (1 mg) or placebo, orally once daily for 28 d

Phase II completed in June 2014, no data published yet

AZD9668 (Vogelmeier et al62/2012)

Randomized, doubleblind, placebocontrolled, phase IIb trial 838 patients with COPD plus ongoing tiotropium: 212 to 5 mg, 206 to 20 mg, 202 to 60 mg, and 218 to placebo

Randomized AZD9668 (5, 20, or 60 mg) or placebo, orally 2 times a day for 12 wk

No effect on lung function, respiratory signs and symptoms, QoL, or biomarkers No change in mean prebronchodilator FEV1 for AZD9668 60 mg compared with placebo AZD9668 was well tolerated; numbers of patients with adverse events were similar in each of the 4 study groups

AZD9668 (Kuna et al61/ 2012)

Randomized, doubleblind, placebocontrolled, phase IIb, trial 615 patients with COPD plus ongoing budesonide and formoterol: 313 AZD9668 and 302 placebo

Randomized AZD9668 (60 mg) or placebo, orally 2 times a day for 12 wk

No difference in lung function, symptoms, QoL, SGRQ score, or incidence of exacerbation No difference in urine desmosine level between the 2 groups Number of adverse events was low and similar between the 2 groups.

a1-AT

Randomized, multicenter, doubleblind, parallel-group, placebo-controlled, phase III trial 177 patients with severe a1-AT deficiency: 92 a1-AT and 85 placebo

Randomized a1-AT (60 mg/kg/wk) or placebo, intravenously for 24 mo

No difference in primary end point (CT lung density at TLC and FRC combined) a1-AT augmentation treatment can slow progression of emphysema measured with CT at TLC alone Adverse events similar between groups Effect on exacerbation or survival not evaluated

(Chapman et al64/2015)

FRC ¼ functional residual capacity; IAP ¼ immunosuppressive acidic protein; QoL ¼ quality of life; RANTES ¼ regulated on activation, normal T-cell expressed and secreted; RCT ¼ randomized controlled trial; SGRQ ¼ St. George’s Respiratory Questionnaire; STRIVE ¼ Staphylococcus aureus Surgical Inpatient Vaccine Efficacy; Th1 ¼ type 1 T helper; Th2 ¼ type 2 T helper; TLC ¼ total lung capacity. See Table 1 and 2 legends for expansion of other abbreviations.

Human Studies With NE Inhibitors

The efficacy of AZD9668, a selective oral inhibitor of NE, was tested in a phase II RCT with 38 patients with

258 Commentary

bronchiectasis (22 AZD9668 vs 16 placebo) over a 28day period.60 AZD9668 improved FEV1 (100 mL) and showed a trend toward reduced sputum inflammatory

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Ratio (and 90% CI) of AZD9668 to placebo for sputum inflammatory markers Improvement

Deterioration

TNF alpha **

IL-6 IL-8 IL-1 beta LTB4 RANTES

*

MCP-1 0.00

0.25

0.50

0.75

1.00

1.25

1.50

1.75

2.00

*P = .10; **P = .006 vs placebo Figure 2 – Ratio and 90% CI of AZD9668 to placebo for changes in sputum inflammatory biomarkers. Compared with placebo, AZD9668 was associated with reductions in all sputum biomarkers (TNF-a, IL-6, IL-8, IL-1b, RANTES, MCP-1) except LTB4. Changes in IL-6 and RANTES were statistically significant. There were no changes in blood inflammatory biomarkers. LTB4 ¼ leukotriene B4; MCP-1 ¼ monocyte chemoattractant protein-1; RANTES ¼ regulated on activation, normal T-cell expressed and secreted; TNF ¼ tumor necrosis factor. (Adapted with permission from Elborn et al.57)

biomarkers (IL-6 and IL-8) but did not influence QoL (St. George’s Respiratory Questionnaire). Finally, an oral NE inhibitor (BAY 85-8501) has been tested in a 1-month, phase II clinical trial (ClinicalTrials. gov identifier NCT01818544) in 92 patients with bronchiectasis. The trial investigated safety, cardiovascular, and spirometric parameters, but the results are as yet unpublished.

COPD COPD is a chronic and progressive lung disease characterized by neutrophilic airways inflammation and airflow limitation.11 Two phase IIb RCTs investigated the effects of AZD9668 on exacerbation frequency, symptoms, lung function, and inflammatory biomarkers in patients with symptomatic COPD.61,62 Neither trial showed any positive results, despite good safety and tolerability data. Alpha-1 antitrypsin (a1-AT) deficiency is a genetic disorder and is a contributing risk factor for COPD. Aerosol administration of a1-AT significantly enhances lung anti-NE activity.63 The intravenous augmentation treatment and lung density in severe a1 antitrypsin deficiency (RAPID) trial compared intravenous a1-AT augmentation treatment vs placebo in 177 patients with emphysema and severe a1-AT deficiency. The a1-AT treatment slowed the loss of lung parenchyma (CTmeasured lung density),64 but there was no effect on exacerbations or survival. To our knowledge, this trial is the only study so far to show positive effects of an NE

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inhibitor in a selected population (a1-AT deficit) with a chronic respiratory disease (emphysema).

Discussion Acute Respiratory Diseases

Numerous animal models of severe pneumonia show benefits in inflammatory response; bacterial clearance; and, in some cases, survival rates with different NE inhibitors. To our knowledge, the only retrospective studies carried out to date and case reports in humans do not allow us to draw any conclusions regarding their use. RCTs of NE inhibitors in severe pneumonia are now needed. Severity of pneumonia and the microbiologic cause underlying patients’ conditions must surely influence the inflammatory response to injury.65 All these elements should be taken into account in the design of future studies in pneumonia. Similarly, in ALI and ARDS, the few clinical trials investigating NE inhibitors in humans do not show positive results despite the clear benefit in inflammatory response indicated in numerous animal studies. However, in selected populations (eg, perioperative patients) sivelestat has shown some clinical benefits and reduced inflammation. The wide variability observed between animal and human studies suggests that more targeted investigations are needed in the future. Many factors, such as patients’ baseline conditions, underlying causes

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of ALI and ARDS, ventilation mode, comedication, and fluid therapy management, can influence final outcomes in this fragile population. The ability to identify patients whose inflammatory response to injuries (eg, pneumonia) is more harmful than beneficial will be crucial in future trials. An example may come from the use of steroids in severe pneumonia and sepsis. Only in patients with severe pneumonia and sepsis or in patients with high inflammatory markers does the use of corticosteroids appear justified as adjunctive antiinflammatory treatment.66-69 Similarly, in the future, specific biomarkers of excessive inflammation (eg, serum C-reactive protein levels) or elastase activity in BAL can guide the use of antielastases. Equally, identification of risk factors of excessive elastase activity in acute respiratory conditions might allow the prophylactic use of antielastase drugs in selected conditions (eg, surgical interventions).

Chronic Respiratory Diseases The use of NE inhibitors in chronic respiratory disease (CF, bronchiectasis, or COPD) is still not supported by sufficient scientific evidence from clinical studies. However, AZD9668 induced a reduction in sputum inflammation in CF and an improvement in lung function in bronchiectasis. Both CF and bronchiectasis are characterized by progressive lung damage due to dysregulated neutrophilic inflammation. In 2016, blood desmosine was confirmed to be a good marker of sputum elastase activity and correlated with severe bronchiectasis exacerbations (hazard ratio, 2.7; 95% CI, 1.42-5.29; P ¼ .003).70 Because exacerbations are a crucial prognostic factor of bronchiectasis,71 desmosine could be used to select patients with frequent exacerbations who may benefit from antielastase treatment. Another key issue in both CF and bronchiectasis is chronic PA bronchial infection, which is a constant inflammatory trigger.14,59 Conceivably, future diagnostic tests such as specific antibodies or exhaled air markers of active PA infection72-74 may help to identify patients at increased risk of disease progression due to NE hyperactivation. Conversely, COPD does not seem suited to treatment with NE inhibitors, with the exception of a1-AT deficit. Its pathophysiologic aspects probably are less related to airway infections, so NE activity may play a lesser role.

260 Commentary

In conclusion, there is still a gap between the promising results of preclinical trials and the results in humans, which have mostly failed to achieve primary end points. Several factors may influence this variability: the dose, duration, or formulation of NE inhibitors; the target population that might realistically benefit from their use; or the outcomes used in some clinical trials, which may have been inappropriate to describe the potential benefits. For instance, in the case of CF or bronchiectasis, the long-term exacerbation rate, days of antibiotics, QoL, and lung function decline may be better outcomes than short-term evaluations or inflammatory biomarkers. Therefore, we consider that: 1) More RCTs in humans are needed to follow up the preliminary in vitro or animal data on NE inhibitors. 2) More targeted studies in homogeneous populations are needed in acute respiratory diseases (pneumonia, ALI, and ARDS). The identification of specific biomarkers could help to define the target population for both therapeutic and prophylactic interventions in these severe conditions. 3) Longer studies and different clinical outcomes should possibly be considered for CF and bronchiectasis in the future. Serum desmosine may be a cheap and useful marker of excessive elastase activity in the airways, whereas other molecular or immunologic markers of PA infection may facilitate identification of appropriate candidates for future clinical trials with antielastases.

Acknowledgments Author contributions: All authors contributed equally to the manuscript. E. P. is the main author of the manuscript in charge of literature review, writing, and revising the manuscript. E. R. M. has actively contributed to literature review, writing, and revising the manuscript. G. E. D. and K. D. have contributed to developing the idea of this manuscript and to writing and revising the manuscript. A. T. is the supervisor of the entire work and guarantor of its content and quality. Financial/nonfinancial disclosures: The authors have reported to CHEST the following: G. E. D. and K. D. have potential conflicts of interest regarding this publication because they are employees at Polyphor Ltd., a firm that is investigating new antielastase drugs. None declared (E. P., E. R. M., A. T.).

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262 Commentary

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