Preclinical evaluation of the epithelial sodium channel inhibitor AZD5634 and implications on human translation.

Airway dehydration causes mucus stasis and bacterial overgrowth in cystic fibrosis (CF), resulting in recurrent respiratory infections and exacerbations. Strategies to rehydrate airway mucus including inhibition of the epithelial sodium channel (ENaC) have the potential to improve mucosal defense by enhancing mucociliary clearance (MCC) and reducing the risk of progressive decline in lung function. In the current work, we evaluated the effects of AZD5634, an ENaC inhibitor that shows extended lung retention and safety profile as compared with previously evaluated candidate drugs, in healthy and CF preclinical model systems. We found that AZD5634 elicited a potent inhibition of amiloride-sensitive current in non-CF airway cells and airway cells derived from F508del-homozygous individuals with CF that effectively increased airway surface liquid volume and improved mucociliary transport (MCT) rate. AZD5634 also demonstrated efficacious inhibition of ENaC in sheep bronchial epithelial cells, translating to dose-dependent improvement of mucus clearance in healthy sheep in vivo. Conversely, nebulization of AZD5634 did not notably improve airway hydration or MCT in CF rats that exhibit an MCC defect, consistent with findings from a first single-dose evaluation of AZD5634 on MCC in people with CF. Overall, these findings suggest that CF animal models demonstrating impaired mucus clearance translatable to the human situation may help to successfully predict and promote the successful translation of ENaC-directed therapies to the clinic.

AZD5634, an inhaled ENaC inhibitor, in healthy subjects and patients with cystic fibrosis.

BACKGROUND: Epithelial sodium channel (ENaC) inhibitors may offer clinical benefit in cystic fibrosis (CF); however, data are limited. We report the outcomes of a Phase I (NCT02679729) and a Phase Ib (NCT02950805) study of AZD5634, a novel inhaled ENaC inhibitor. METHODS: A Phase I, first-in-human, single-blind, placebo-controlled, single ascending dose, sequential dose group study assessed the safety, tolerability, and pharmacokinetics of AZD5634 in healthy subjects (n=53) in part A following inhaled doses up to 1700 µg, and, in part B, following administration of single inhaled (1700 µg) and intravenous (65 µg) doses. A Phase Ib, randomized, double-blind, placebo-controlled, single-dose, 2-way cross-over study assessed the effects of a single dose (600 µg) of inhaled AZD5634 on mucociliary clearance (MCC), pharmacokinetics and safety and tolerability in patients with CF (n=11). Nasal potential difference (NPD) was assessed as an in situ target engagement exploratory biomarker. RESULTS: Absolute bioavailability of AZD5634 after inhalation was approximately 3%, indicating minimal distribution into the systemic circulation. Urinary excretion was a minor elimination pathway. Administration of inhaled AZD5634 did not improve MCC in CF patients, but AZD5634 inhibited ENaC in the nasal epithelium, as measured by NPD. AZD5634 was safe and well tolerated in both studies. CONCLUSIONS: AZD5634 showed favorable pharmacokinetics and safety in healthy subjects and patients with CF. However, despite achieving target engagement, proof of mechanism was not achieved after a single dose in patients with CF. Further evaluation into multiple dose studies is warranted to explore its therapeutic potential.

New generation ENaC inhibitors detach cystic fibrosis airway mucus bundles via sodium/hydrogen exchanger inhibition.

Cystic fibrosis (CF) is a recessive inherited disease caused by mutations affecting anion transport by the epithelial ion channel cystic fibrosis transmembrane conductance regulator (CFTR). The disease is characterized by mucus accumulation in the airways and intestine, but the major cause of mortality in CF is airway mucus accumulation, leading to bacterial colonization, inflammation and respiratory failure. Several drug targets are under evaluation to alleviate airway mucus obstruction in CF and one of these targets is the epithelial sodium channel ENaC. To explore effects of ENaC inhibitors on mucus properties, we used two model systems to investigate mucus characteristics, mucus attachment in mouse ileum and mucus bundle transport in piglet airways. We quantified mucus attachment in explants from CFTR null (CF) mice and tracheobronchial explants from newborn CFTR null (CF) piglets to evaluate effects of ENaC or sodium/hydrogen exchanger (NHE) inhibitors on mucus attachment. ENaC inhibitors detached mucus in the CF mouse ileum, although the ileum lacks ENaC expression. This effect was mimicked by two NHE inhibitors. Airway mucus bundles were immobile in untreated newborn CF piglets but were detached by the therapeutic drug candidate AZD5634 (patent WO, 2015140527). These results suggest that the ENaC inhibitor AZD5634 causes detachment of CF mucus in the ileum and airway via NHE inhibition and that drug design should focus on NHE instead of ENaC inhibition.

INEXAS: A Phase 2 Randomized Trial of On-demand Inhaled Interferon Beta-1a in Severe Asthmatics.

BACKGROUND: Upper respiratory tract infections (URTIs) are important triggers for asthma exacerbations. We hypothesized that inhalation of the anti-viral cytokine, interferon (IFN)-ß, during URTI, could prevent these exacerbations. OBJECTIVE: To evaluate the efficacy of on-demand inhaled IFN-ß1a (AZD9412) to prevent severe asthma exacerbations following symptomatic URTI. METHODS: This was a randomized, double-blind, placebo-controlled trial in which patients with severe asthma (GINA 4-5; n = 121) reporting URTI symptoms were randomized to 14 days of once-daily nebulized AZD9412 or placebo. The primary endpoint was severe exacerbations during treatment. Secondary endpoints included 6-item asthma control questionnaire (ACQ-6) and lung function. Exploratory biomarkers included IFN-response markers in serum and sputum, blood leucocyte counts and serum inflammatory cytokines. RESULTS: Following a pre-planned interim analysis, the trial was terminated early due to an unexpectedly low exacerbation rate. Asthma worsenings were generally mild and tended to peak at randomization, possibly contributing to the lack of benefit of AZD9412 on other asthma endpoints. Numerically, AZD9412 did not reduce severe exacerbation rate, ACQ-6, asthma symptom scores or reliever medication use. AZD9412 improved lung function (morning peak expiratory flow; mPEF) by 19.7 L/min. Exploratory post hoc analyses indicated a greater mPEF improvement by AZD9412 in patients with high blood eosinophils (>0.3 × 109 /L) at screening and low serum interleukin-18 relative change at pre-treatment baseline. Pharmacodynamic effect of AZD9412 was confirmed using IFN-response markers. CONCLUSIONS & CLINICAL RELEVANCE: Colds did not have the impact on asthma patients that was expected and, due to the low exacerbation rate, the trial was stopped early. On-demand AZD9412 treatment did not numerically reduce the number of exacerbations, but did attenuate URTI-induced worsening of mPEF. Severe asthma patients with high blood eosinophils or low serum interleukin-18 response are potential subgroups for further investigation of inhaled IFN-ß1a.

NETopathic Inflammation in Chronic Obstructive Pulmonary Disease and Severe Asthma.

Neutrophils play a central role in innate immunity, inflammation, and resolution. Unresolving neutrophilia features as a disrupted inflammatory process in the airways of patients with chronic obstructive pulmonary disease (COPD) and severe asthma. The extent to which this may be linked to disease pathobiology remains obscure and could be further confounded by indication of glucocorticoids or concomitant respiratory infections. The formation of neutrophil extracellular traps (NETs) represents a specialized host defense mechanism that entrap and eliminate invading microbes. NETs are web-like scaffolds of extracellular DNA in complex with histones and neutrophil granular proteins, such as myeloperoxidase and neutrophil elastase. Distinct from apoptosis, NET formation is an active form of cell death that could be triggered by various microbial, inflammatory, and endogenous or exogenous stimuli. NETs are reportedly enriched in neutrophil-dominant refractory lung diseases, such as COPD and severe asthma. Evidence for a pathogenic role for respiratory viruses (e.g., Rhinovirus), bacteria (e.g., Staphylococcus aureus) and fungi (e.g., Aspergillus fumigatus) in NET induction is emerging. Dysregulation of this process may exert localized NET burden and contribute to NETopathic lung inflammation. Disentangling the role of NETs in human health and disease offer unique opportunities for therapeutic modulation. The chemokine CXCR2 receptor regulates neutrophil activation and migration, and small molecule CXCR2 antagonists (e.g., AZD5069, danirixin) have been developed to selectively block neutrophilic inflammatory pathways. NET-stabilizing agents using CXCR2 antagonists are being investigated in proof-of-concept studies in patients with COPD to provide mechanistic insights. Clinical validation of this type could lead to novel therapeutics for multiple CXCR2-related NETopathologies. In this Review, we discuss the emerging role of NETs in the clinicopathobiology of COPD and severe asthma and provide an outlook on how novel NET-stabilizing therapies via CXCR2 blockade could be leveraged to disrupt NETopathic inflammation in disease-specific phenotypes.

Pharmacokinetics of the Oral Selective CXCR2 Antagonist AZD5069: A Summary of Eight Phase I Studies in Healthy Volunteers.

OBJECTIVE: The aim of this study was to summarise the pharmacokinetic findings from eight phase I studies in healthy volunteers given oral AZD5069, a selective small-molecule CXCR2 antagonist. METHODS: 240 healthy volunteers across eight phase I studies received single (0.1-200 mg) or multiple once- or twice-daily (10-120 mg) oral AZD5069 as solution, suspension, capsules or tablets. Pharmacokinetics were evaluated using non-compartmental analysis methods. RESULTS: AZD5069 was rapidly absorbed (time to maximum concentration ~ 2 h) under fasting conditions. A high-fat, high-calorie meal delayed and reduced the peak plasma AZD5069 concentration (Cmax) by 50%, but total exposure (AUC) was unchanged (fed:fasting geometric mean ratio 90% confidence interval within 0.80-1.25). The plasma concentration of AZD5069 declined with an initial half-life of 4 h and terminal half-life of 11 h. Steady-state plasma concentrations were achieved within 2-3 days and accumulation was ~ 1.1-fold with twice-daily dosing. Systemic exposure was approximately proportional to dose. Intra- and inter-subject variability in AUC was 3-11 and 29-64%, respectively. Less than 5% of the AZD5069 dose was excreted as parent drug in the urine. Elderly subjects had 39% higher AZD5069 AUC and 21% higher Cmax than younger adults. Japanese subjects had similar or slightly higher exposure to AZD5069 than Caucasian subjects. Co-administration with ketoconazole resulted in 2.1-fold higher AUC and 1.6-fold higher Cmax. All formulations had similar bioavailability. CONCLUSIONS: AZD5069 demonstrated predictive linear pharmacokinetics with low intra- and moderate inter-subject variability and no major influences from ethnicity, age, food or formulation. Half-life data indicated suitability for twice-daily dosing. CLINICALTRIALS. GOV IDENTIFIERS: NCT00953888, NCT01051505, NCT01083238, NCT01100047, NCT01332903, NCT01480739, NCT01735240, NCT01989520.

Targets of Neutrophil Influx and Weaponry: Therapeutic Opportunities for Chronic Obstructive Airway Disease.

Neutrophils are important effector cells of antimicrobial immunity in an acute inflammatory response, with a primary role in the clearance of extracellular pathogens. However, in respiratory diseases such as asthma and chronic obstructive pulmonary disease (COPD), there is excessive infiltration and activation of neutrophils, subsequent production of reactive oxygen species, and release of serine proteases, matrix metalloproteinases, and myeloperoxidase-resulting in collateral damage as the cells infiltrate into the tissue. Increased neutrophil survival through dysregulated apoptosis facilitates continued release of neutrophil-derived mediators to perpetuate airway inflammation and tissue injury. Several target mechanisms have been investigated to address pathologic neutrophil biology and thereby provide a novel therapy for respiratory disease. These include neutrophil influx through inhibition of chemokine receptors CXCR2, CXCR1, and PI3Kγ signaling and neutrophil weaponry by protease inhibitors, targeting matrix metalloproteinases and neutrophil serine proteases. In addition, neutrophil function can be modulated using selective PI3Kδ inhibitors. This review highlights the latest advances in targeting neutrophils and their function, discusses the opportunities and risks of neutrophil inhibition, and explores how we might better develop future strategies to regulate neutrophil influx and function for respiratory diseases in dire need of novel effective therapies.

Indications for percutaneous endoscopic gastrostomy and survival in old adults.

BACKGROUND: Many diseases striking old adults result in eating difficulties. Indications for selecting individuals for percutaneous endoscopic gastrostomy (PEG) are unclear and everybody may not benefit from the procedure. OBJECTIVE: The aim of this study was to evaluate indications for and survival after PEG insertion in patients older than 65 years. DESIGN AND METHODS: A retrospective analysis including age, gender, diagnosis, indication, and date of death was made in 201 consecutive individuals, 94 male, mean age 79±7 years, who received a nutritional gastrostomy. RESULTS: Dysphagia was present in 86% of the patients and stroke was the most common diagnosis (49%). Overall median survival was 123 days and 30-day mortality was 22%. Patients with dementia and Mb Parkinson had the longest survival (i.e. 244 and 233 days), while those with other neurological diseases, and head and neck malignancy had the shortest (i.e. 75 and 106 days). There was no difference in mortality in patients older or younger than 80 years, except in patients with dementia. CONCLUSIONS: Old age should not be a contraindication for PEG. A high 30-day mortality indicates that there is a need of better criteria for selection and timing of PEG insertion in the elderly.