Single inhaler extrafine triple therapy in uncontrolled asthma (TRIMARAN and TRIGGER): two double-blind, parallel-group, randomised, controlled phase 3 trials

Randomized controlled trial of triple versus dual inhaler therapy on small airways in smoking asthmatics

BACKGROUND

Smoking worsens underlying asthma inflammation and also induces resistance to inhaled corticosteroids (ICS). Small airways dysfunction measured by impulse oscillometry (IOS) is associated with worse control.

OBJECTIVES

We investigated the effects on small airways of adding long-acting beta-agonist (LABA) alone or with long-acting muscarinic antagonist (LAMA) to ICS in asthmatic smokers.

METHODS

Sixteen current smokers were enrolled: mean age 44 year, FEV1 84%, FEF25-75 47%, R5 158%, ACQ 1.69, 20 pack year . Patients were converted to a reference ICS as HFA-BDP during initial run-in at median dose of 800 µg/day. Open label olodaterol 5 µg od (OLO) or olodaterol 5 µg/tiotropium 5 µg od (OLO/TIO) was added to HFA-BDP for median duration of 3 weeks in a randomized cross over design, including run-in and washout periods on HFA-BDP. IOS and spirometry were measured after each treatment (BDP/OLO/TIO or BDP/OLO) and at baseline after run-in and washout (BDP).

RESULTS

After chronic dosing, IOS outcomes at trough except for R20 were all significantly improved with OLO/TIO compared to OLO. For the primary end-point of total airway resistance (as R5), the mean difference (95%CI) at trough was 0.06 (0.015-0.10) kPa/l/s, peripheral airways resistance (as R5-R20) 0.03 (0.003-0.06) kPa/l/s, peripheral lung reactance area (as AX) 0.38 (0.08-0.68) kPa/l and resonant frequency (as RF) 2.28 (0.45-4.12) Hz. FEF25-75 at trough was also better with OLO/TIO vs TIO: 0.93 (0.86 - 0.95) l/s while FEV1 was not different.

CONCLUSIONS

ICS/LABA/LAMA was superior to ICS/LABA on trough small airway outcomes in asthma patients who smoke.

Pharmacotherapeutic management of asthma in the elderly patient

INTRODUCTION

Asthma is a heterogeneous syndrome with variable phenotypes. Reversible airway obstruction and airway hyper-responsiveness often with an atopic or eosinophilic component is common in the elderly asthmatic. Asthma chronic obstructive pulmonary disease overlap syndrome (ACOS), a combination of atopy-mediated airway hyper-responsiveness and a history of smoking or other environmental noxious exposures, can lead to some fixed airway obstruction and is also common in elderly patients. Little specific data exist for the treating the elderly asthmatic, thus requiring the clinician to extrapolate from general adult data and asthma treatment guidelines.

AREAS COVERED

A stepwise approach to pharmacotherapy of the elderly patient with asthma and ACOS is offered and the literature supporting the use of each class of drugs reviewed.

EXPERT OPINION

Inhaled, long-acting bronchodilators in combination with inhaled corticosteroids represent the backbone of treatment for the elderly patient with asthma or ACOS . Beyond these medications used as direct bronchodilators and topical anti-inflammatory agents, a stepwise approach to escalation of therapy includes multiple options such as oral leukotriene receptor antagonist or 5-lipoxygense inhibitor therapy, oral phosphodiesterase inhibitors, systemic corticosteroids, oral macrolide antibiotics and if evidence of eosinophilic/atopic component disease exists then modifying monoclonal antibody therapies.

Once-daily, single-inhaler mometasone-indacaterol-glycopyrronium versus mometasone-indacaterol or twice-daily fluticasone-salmeterol in patients with inadequately controlled asthma (IRIDIUM): a randomised, double-blind, controlled phase 3 study

BACKGROUND

Patients with asthma who are inadequately controlled on inhaled corticosteroid-long-acting β₂-adrenoceptor agonist (ICS-LABA) combinations might benefit from the addition of a long-acting muscarinic receptor antagonist. The aim of the IRIDIUM study was to assess the efficacy and safety of a once-daily, single-inhaler combination of mometasone furoate, indacaterol acetate, and glycopyrronium bromide (MF-IND-GLY) versus ICS-LABA in patients with inadequately controlled asthma.

METHODS

In this 52-week, double-blind, double-dummy, parallel-group, active-controlled phase 3 study, patients were recruited from 415 sites across 41 countries. Patients aged 18 to 75 years with symptomatic asthma despite treatment with medium-dose or high-dose ICS-LABA, at least one exacerbation in the previous year, and a percentage of predicted FEV₁ of less than 80% were included. Enrolled patients were randomly assigned (1:1:1:1:1) via interactive response technology to receive medium-dose or high-dose MF-IND-GLY (80 μg, 150 μg, 50 μg; 160 μg, 150 μg, 50 μg) or MF-IND (160 μg, 150 μg; 320 μg, 150 μg) once daily via Breezhaler, or high-dose fluticasone-salmeterol (FLU-SAL; 500 μg, 50 μg) twice daily via Diskus. The primary outcome was change from baseline in trough FEV₁ with MF-IND-GLY versus MF-IND at week 26 in patients in the full analysis set, analysed by means of a mixed model for repeated measures. Safety was assessed in all patients who received at least one dose of study drug. This study is registered with ClinicalTrials.gov, NCT02571777, and is completed.

FINDINGS

Between Dec 8, 2015, and Jun 14, 2019, 3092 of 4851 patients screened were randomly assigned (medium-dose MF-IND-GLY, n=620; high-dose MF-IND-GLY, n=619; medium-dose MF-IND, n=617; high-dose MF-IND, n=618; high-dose FLU-SAL, n=618). 2747 (88·8%) patients completed the 52-week treatment and 321 (10·4%) started but discontinued study treatment prematurely. Medium-dose MF-IND-GLY (treatment difference [Δ] 76 mL [95% CI 41-111]; p<0·001) and high-dose MF-IND-GLY (Δ 65 mL [31-99]; p<0·001) showed superior improvement in trough FEV₁ versus corresponding doses of MF-IND at week 26. Improvements in trough FEV₁ were greater for both medium-dose MF-IND-GLY (99 mL [64-133]; p<0·001) and high-dose MF-IND-GLY (119 mL [85-154]; p<0·001) than for high-dose FLU-SAL at week 26. Overall, the incidence of adverse events was balanced across the treatment groups. Seven deaths were reported (one with medium-dose MF-IND-GLY, two with high-dose MF-IND-GLY, and four with high-dose MF-IND) during the study; none of these deaths was considered by the investigators to be caused by study drugs or other study-related factors.

INTERPRETATION

Once-daily, single-inhaler MF-IND-GLY improved lung function versus ICS-LABA combinations (MF-IND and FLU-SAL) in patients with inadequately controlled asthma. The safety profile was similar across treatment groups. MF-IND-GLY therefore constitutes a good treatment option in these patients.

FUNDING

Novartis Pharmaceuticals.

The evolving algorithm of biological selection in severe asthma

New therapeutic options for severe asthma have recently emerged, mostly in the form of monoclonal antibodies ("biologicals") targeting relevant inflammatory pathways. Currently available agents target different aspects of "Type 2" immunity, and their indications often include overlapping patient groups. We present a round-table discussion that took place during the Annual Meeting of the Respiratory Effectiveness Group (REG), on the reasoning behind the use of different add-on medications for severe asthma, and crucially, on selection strategies. The proposed rational is based on current evidence, including real-life studies, as well as on the appreciation of the relevant complexities. Direct head-to-head comparisons of biologicals are lacking; therefore, algorithms for initial choice and potential switch between agents should be based on understanding the key characteristics of different options and the development of a clear plan with predefined targets and shared decision-making, in a structured way.

Emerging muscarinic receptor antagonists for the treatment of asthma

INTRODUCTION

The increased acetylcholine signaling in asthma pathophysiology offers the rationale for the use of LAMAs in the treatment of asthmatic patients. Tiotropium is still the only LAMA approved for use in asthma but there is a real interest in developing novel LAMAs for the treatment of asthma, or at least to extend this indication to other LAMAs already on the market.

AREAS COVERED

We examined and discussed trials and research that have studied or are evaluating the role of LAMAs already on the market in asthma and possible novel muscarinic acetylcholine receptor antagonists.

EXPERT OPINION

Glycopyrronium and umeclidinium will soon be included in the GINA strategy with the same current indications of tiotropium. It is likely that the choice of the LAMA will be influenced not so much by its pharmacological profile as by the type of triple therapy chosen. It is extremely difficult to identify a new LAMA that is more effective than tiotropium, but is it plausible that new technologies that will allow delivering the drug in a more targeted way and with a lower risk of adverse effects may represent the real progress in the use of LAMAs in asthma in the coming years.

Immune Modulation in Asthma: Current Concepts and Future Strategies

Asthma treatment concepts have profoundly changed over the last 20 years, from standard therapeutic regimens for all patients with asthma towards individually tailored interventions targeting treatable traits ("precision medicine"). A precise and highly effective immune modulation with minimal adverse effects plays a central role in this new concept. Recently, there have been major advances in the treatment of asthma with immune-modulatory compounds. One example is the approval of several highly potent biologics for the treatment of severe asthma. New immune-modulatory strategies are expected to enter clinical practice in the future; these innovations will be especially important for patients with treatment-resistant asthma.

Bringing asthma care into the twenty-first century

Despite access to diagnostic tests and effective therapies, asthma often remains misdiagnosed and/or poorly controlled or uncontrolled. In this review, we address the key issues of asthma diagnosis and management, recent evidence for levels of asthma control, the consequences of poor control and, in line with that, explore the potential reasons for poor asthma control and acute exacerbations. Based on recent evidence and current guidelines, we also aim to provide practical answers to the key questions of how to improve asthma management, with the best possible prevention of exacerbations, addressing the basics-adherence, inhaler misuse, obesity and smoking-and how to facilitate a new era of asthma care in the twenty-first century. We hope this review will be useful to busy primary care clinicians in their future interactions with their patients with both suspected and proven asthma.

Fixed-dose combination of indacaterol/glycopyrronium/mometasone furoate once-daily versus salmeterol/fluticasone twice-daily plus tiotropium once-daily in patients with uncontrolled asthma: A randomised, Phase IIIb, non-inferiority study (ARGON)

BACKGROUND

The efficacy and safety of once-daily (o.d.) fixed-dose combination of indacaterol (IND), glycopyrronium (GLY) and mometasone furoate (MF) via Breezhaler® versus concurrent administration of salmeterol/fluticasone (SAL/FLU) twice-daily (b.i.d.) via Accuhaler®+Tiotropium (TIO) o.d. via Respimat® was evaluated in patients with uncontrolled asthma.

METHODS

Patients (aged ≥18 years), symptomatic (Asthma Control Questionnaire [ACQ]-7 ≥1.5) despite treatment with long-acting β₂-agonist/inhaled corticosteroid medium- or high-dose, received IND/GLY/MF high- (150/50/160 μg) or medium-dose (150/50/80 μg) o.d. or SAL/FLU high-dose (50/500 μg) b.i.d.+Tio 5 μg o.d. for 24 weeks. The primary objective was to confirm the non-inferiority of either dose of IND/GLY/MF to SAL/FLU high dose + TIO in terms of Asthma Quality of Life Questionnaire (AQLQ). Additional endpoints: ACQ-7, lung function, health status (St George's Respiratory Questionnaire [SGRQ]), exacerbations, and safety after 24 weeks.

RESULTS

IND/GLY/MF high- and medium-dose met the primary endpoint, confirming non-inferiority to SAL/FLU high dose + TIO for AQLQ (least square mean treatment difference [Δ]: 0.073 and -0.038, respectively; both p < 0.001). IND/GLY/MF high-dose improved ACQ-7 (Δ: -0.124; p = 0.004), trough FEV₁ (Δ: 96 mL; p < 0.001), peak expiratory flow (morning [Δ: 9.56 L/min; p = 0.005], evening [Δ: 9.15 L/min; p = 0.006]) and SGRQ (Δ: -2.00; p = 0.04) versus SAL/FLU high dose + TIO. Improvements in these endpoints were comparable for IND/GLY/MF medium-dose and SAL/FLU high dose + TIO. Adverse events were generally comparable across treatments.

CONCLUSIONS

IND/GLY/MF high- and medium-dose o.d. via a single inhaler were non-inferior to SAL/FLU high-dose b.i.d. + TIO o.d. via two inhalers for AQLQ. IND/GLY/MF high-dose o.d. improved lung function, asthma control and health status versus SAL/FLU high dose + TIO, while IND/GLY/MF medium-dose had comparable efficacy but at a corresponding lower steroid dose.

Health-Related Effects of Home Nebulization With Glycopyrronium on Difficult-to-Treat Asthma: Post-Hoc Analyses of an Observational Study

BACKGROUND

Bronchial asthma remains a clinical enigma with poorly controlled symptoms or exacerbations despite regular use of inhaled corticosteroids. Home nebulization offers a simplified solution for the delivery of rescue and maintenance bronchodilators, which is especially true for patients with frequent exacerbations during management of uncontrolled or difficult-to-treat asthma.

OBJECTIVE

We aimed to assess the clinical impact and outcomes associated with home nebulization-delivered long-acting bronchodilators for uncontrolled or difficult-to-treat asthma.

METHODS

This observational, concurrent study was conducted with 60 patients at 2 centers during November 2018. Statistical analyses for prebronchodilator forced expiratory volume in one second (FEV1) and Global Initiative for Asthma (GINA) asthma control score in patients on long-acting bronchodilators and corticosteroids were conducted, with two-tailed P values <.05 considered statistically significant.

RESULTS

Per protocol analyses (53/60) for consecutive cases receiving home nebulization with long-acting bronchodilators and corticosteroids were conducted. The baseline demographics included a male-to-female ratio of 30:23 and mean values of the following: age, 60.3 years (SD 11.8 years); weight, 64 kg (SD 16.8 kg); FEV1, 43% (SD 16%); GINA asthma control score, 3.0 points (SD 0.8 points); serum eosinophil level, 4% (SD 3%); fractional exhaled nitric oxide (FeNO), 12.1 ppb (SD 6 ppb). Of the patients, 100% (53/53) had uncontrolled symptoms, 69.8% (37/53) had prior exacerbations, 100% (53/53) used formoterol/budesonide, and 75.5% (40/53) used glycopyrronium. The per protocol group (n=53) had significantly improved mean prebronchodilator FEV1 (23.7%, SD 29.8%; 0.46 L, SD 0.58 L; P<.001) and GINA asthma control score (2.1 points, SD 0.8 points, P<.001). At baseline, patients (n=40) receiving glycopyrronium/formoterol/budesonide (25/20/500 mcg) nebulization admixture had the following mean values: prebronchodilator FEV1, 38% (SD 15%); GINA asthma control score, 3.0 points (SD 0.8 points); reversibility, 12% (SD 6%); peripheral eosinophil level, 4% (SD 3%); FeNO, 12 ppb (SD 5.7 ppb). In the post hoc analyses, these patients had significantly improved mean prebronchodilator FEV1 of 27.7% (SD 26.2%; 0.54 L, SD 0.51 L; P<.001) at 8 weeks compared with baseline. At baseline, patients (n=13) receiving formoterol/budesonide (20/500 mcg) nebulization had the following mean values: FEV1, 55% (SD 12%); GINA asthma control score, 3.0 points (SD 1.2 points); reversibility, 14% (SD 7%); serum eosinophil level, 4% (SD 3%); FeNO, 13.3 ppb (SD 6.8 ppb). In the post hoc analyses, these patients showed a significant improvement in prebronchodilator FEV1 of 11.2% (SD 13.1%; 0.22 L, SD 0.25 L; P<.001) from baseline. Breathlessness of mild to moderate intensity was reported by 10 cases (10/53, 18.9%), with no other treatment-emergent adverse events or serious adverse events.

CONCLUSIONS

Home nebulization remains a viable option for symptomatic difficult-to-treat asthma cases with frequent use of rescue medications. Glycopyrronium as add-on therapy offers a synergistic response in patients on corticosteroids with difficult-to-treat asthma.

TRIAL REGISTRATION

Clinical Trial Registry of India CTRI/2018/11/016319; https://tinyurl.com/y78cctm3.

New perspectives on the role of muscarinic antagonists in asthma therapy

INTRODUCTION

There is increasing evidence that tiotropium, a long-acting muscarinic agent (LAMA), is useful in the presence of severe-uncontrolled asthma despite the optimization of therapy with inhaled corticosteroids (ICSs) and long-acting β₂ agonists (LABAs) as recommended by the current guidelines. Furthermore, in recent years there have been several  preclinical and clinical studies on the pharmacological and therapeutic impact of other LAMAs in asthma.

AREAS COVERED

We have conducted an extensive search on muscarinic antagonists in asthma therapy throughout several sources and discuss what has emerged in the last 3 years (January 2017-March 2020).

EXPERT OPINION

New evidence indicates that the effectiveness of adding a LAMA, at least tiotropium, is independent of the degree of the type 2 inflammation and age of patient. Therefore, tiotropium can be administered without the need for patient phenotyping. Umeclidinium and glycopyrronium also appear effective in asthma. Initial treatment with LAMA+ICS for those with mild asthma may be an equally effective therapeutic option as LABA+ICS but this hypothesis should be confirmed by statistically powered trials.

Letter to the editor: indacaterol/glycopyrronium/mometasone furoate compared with salmeterol/fluticasone propionate in patients with asthma: a randomized controlled cross-over study

Abstract

Indacaterol (IND; 150 μg), glycopyrronium (GLY; 50 μg) and mometasone furoate (MF; 160 μg [high-dose ICS] and 80 μg [medium-dose ICS]) have been formulated as a once-daily (o.d.) fixed-dose combination treatment delivered via the Breezhaler® device for the treatment of patients with asthma. In this randomized (n = 116), double-blind, double-dummy, active comparator-controlled, three-period cross-over study we evaluated the benefit of o.d. IND/GLY/MF versus twice daily (b.i.d.) salmeterol/fluticasone propionate combination (SFC; 50/500 μg; high-dose ICS) treatment (NCT03063086). Overall, 107 patients completed the study. The study met its primary objective by demonstrating superiority of o.d. IND/GLY/MF at medium and high-dose ICS over b.i.d. SFC (high-dose ICS) in peak FEV₁ after 21 days of treatment (+ 172 mL with high-dose and + 159 mL with medium-dose IND/GLY/MF versus SFC, p < 0.0001 for each comparison). We also observed that a higher percentage of patients did not need rescue medicine with IND/GLY/MF (high-dose ICS, 58%; medium-dose ICS, 52%) compared with SFC (45%) during the last week of each treatment period. Study treatments were well-tolerated with no relevant differences in tolerability between both IND/GLY/MF doses and SFC. In conclusion, both doses of IND/GLY/MF provided superior lung function benefits compared with twice-daily, standard-of-care SFC at the highest approved dose.

Trial registration

ClinicalTrials.gov, (Identifier: NCT03063086),

EudraCT start date: May 11, 2017; First patient first visit / study initiation date: May 31, 2017.

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

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

Triple Therapy with Budesonide/Glycopyrrolate/Formoterol Fumarate Improves Inspiratory Capacity in Patients with Asthma-Chronic Obstructive Pulmonary Disease Overlap

Purpose

Asthma-chronic obstructive pulmonary disease overlap (ACO), characterized by airway limitation, is an important condition with high incidence and mortality. Although some guidelines recommend triple therapy with inhaled corticosteroids/long-acting muscarinic antagonists/long-acting β2 agonists, this treatment approach is based on the extrapolation of data from studies of asthma or chronic obstructive pulmonary disease (COPD) alone.

Methods

A 12-week, randomized, open-label cross-over pilot study was conducted in 19 patients with ACO to investigate the effect of triple therapy with glycopyrrolate (GLY) 50 µg/day on budesonide/formoterol fumarate (BUD/FORM) 640/18 µg/day. The study period included a 4-week wash-out, 4-week run-in, and 4-week treatment period. Respiratory function tests, fractional exhaled nitric oxide (FeNO), a COPD assessment test (CAT) and an asthma control questionnaire (ACQ) were carried out 0, 4, and 8 weeks after randomization.

Results

A total of 19 patients with stable ACO (19 males and no females) with a mean age of 70.7 ± 7.6 years (± standard deviation, SD; range 55-83 years) participated in this study. All patients were ex-smokers with a smoking history of 63.1 ± 41.1 pack-years (± SD). Mean values for inspiratory capacity (IC), an index of hyperinflation of the lung that causes exertional dyspnea and reduced exercise, were 1.93 L (± 0.47 L) after the run-in, 1.85 L (± 0.51 L) after the BUD/FORM dual therapy period and 2.11 L (± 0.58 L) after the BUD/GLY/FORM triple therapy period. IC values after the BUD/GLY/FORM triple therapy were significantly higher than those after the run-in (p < 0.02). FeNO values, ACQ, and CAT scores were not significantly different among the run-in, wash-out, and triple-therapy periods.

Conclusion

The present pilot study showed that triple therapy with BUD/GLY/FORM results in an improvement in lung function parameters including IC, indicating the potential value of triple therapy as standard treatment for ACO.

ERS International Congress, Madrid, 2019: highlights from the Airway Diseases, Asthma and COPD Assembly

The European Respiratory Society (ERS) International Congress 2019 in Madrid, Spain, was a platform for scientific discussion of the highest quality scientific research, cutting-edge techniques and innovative new therapies within the respiratory field. This article discusses some of the high-quality research studies presented at that Congress, with a focus on airway diseases, including asthma, COPD, small airways, bronchiectasis and cough, presented through the Airway Diseases, Asthma and COPD Assembly (Assembly 5) of the ERS. The authors establish the key take-home messages of these studies, compare their findings and place them into context of current understanding.