A Mathematical Modeling Approach to Understanding the Effect of Anti-Interleukin Therapy on Eosinophils

Emerging T‐helper type 2 (Th₂) cytokine‐based asthma therapies, such as tralokinumab, lebrikizumab (anti‐interleukin (IL)‐13), and mepolizumab (anti‐IL‐5), have shown differences in their blood eosinophil (EOS) response. To better understand these effects, we developed a mathematical model of EOS dynamics. For the anti‐IL‐13 therapies, lebrikizumab and tralokinumab, the model predicted an increase of 30% and 10% in total and activated EOS in the blood, respectively, and a decrease in the total and activated EOS in the airways. The model predicted a rapid decrease in total and activated EOS levels in blood and airways for the anti‐IL‐5 therapy mepolizumab. All model‐based predictions were consistent with published clinical observations. The modeling approach provided insights into EOS response after treatment with Th₂‐targeted therapies, and supports the hypothesis that an increase in blood EOS after anti‐IL‐13 therapy is part of the pharmacological action of these therapies.

Structural Characterisation Reveals Mechanism of IL-13-Neutralising Monoclonal Antibody Tralokinumab as Inhibition of Binding to IL-13Rα1 and IL-13Rα2

Interleukin (IL)-13 is a pleiotropic T helper type 2 cytokine frequently associated with asthma and atopic dermatitis. IL-13-mediated signalling is initiated by binding to IL-13Rα1, which then recruits IL-4Rα to form a heterodimeric receptor complex. IL-13 also binds to IL-13Rα2, considered as either a decoy or a key mediator of fibrosis. IL-13-neutralising antibodies act by preventing IL-13 binding to IL-13Rα1, IL-4Rα and/or IL-13Rα2. Tralokinumab (CAT-354) is an IL-13-neutralising human IgG4 monoclonal antibody that has shown clinical benefit in patients with asthma. To decipher how tralokinumab inhibits the effects of IL-13, we determined the structure of tralokinumab Fab in complex with human IL-13 to 2 Å resolution. The structure analysis reveals that tralokinumab prevents IL-13 from binding to both IL-13Rα1 and IL-13Rα2. This is supported by biochemical ligand-receptor interaction assay data. The tralokinumab epitope is mainly composed of residues in helices D and A of IL-13. It is mostly light chain complementarity-determining regions that are driving paratope interactions; the variable light complementarity-determining region 2 plays a key role by providing residue contacts for a network of hydrogen bonds and a salt bridge in the core of binding. The key residues within the paratope contributing to binding were identified as Asp50, Asp51, Ser30 and Lys31. This study demonstrates that tralokinumab prevents the IL-13 pharmacodynamic effect by binding to IL-13 helices A and D, thus preventing IL-13 from interacting with IL-13Rα1 and IL-13Rα2.

Asthma control with extrafine-particle hydrofluoroalkane-beclometasone vs. large-particle chlorofluorocarbon-beclometasone: a real-world observational study

BACKGROUND

The extrafine-particle formulation of hydrofluoroalkane-beclometasone (EF HFA-BDP; Qvar®) demonstrates improved total and small airway deposition compared with large-particle chlorofluorocarbon (CFC)-BDP. In some short-term studies, EF HFA-BDP provides greater effects on lung function than CFC-BDP, and hence is recommended to be prescribed at a lower dose, but whether there are differences in asthma outcomes during long-term treatment is unknown.

OBJECTIVE

To compare the effectiveness of EF HFA-BDP vs. CFC-BDP over 1 year.

METHODS

This retrospective matched cohort study examined outcomes in a large primary care database for patients aged 5-60 years with asthma receiving their first inhaled corticosteroid (ICS) prescription (initiation population) or first ICS dose increase (step-up population) by a pressurized metered-dose inhaler (pMDI) as EF HFA-BDP or CFC-BDP. Patients were matched on baseline demographic and asthma severity measures in EF HFA-BDP:CFC-BDP ratios of 1:3 and 1:2 for initiation and step-up populations, respectively. Step-up patients were matched also on ICS dose during a baseline year. Co-primary endpoints were asthma control (composite measure comprising no recorded hospital attendance for asthma, oral corticosteroids, or antibiotics for lower respiratory infection) and exacerbation rate during the outcome year.

RESULTS

For the initiation population (EF HFA-BDP n=2882; CFC-BDP n=8646), adjusted odds of achieving asthma control with EF HFA-BDP vs. CFC-BDP was 1.15 (95% CI 1.02-1.28). For the step-up population (n=258 and 516), adjusted odds of asthma control with EF HFA-BDP was 1.72 (95% CI 1.14-2.56). EF HFA-BDP was prescribed at a median dose half that of CFC-BDP.

CONCLUSION AND CLINICAL RELEVANCE

During 1 year after initiating or stepping up ICS therapy by pMDI, patients who received EF HFA-BDP were more likely to achieve asthma control than those receiving CFC-BDP. These findings suggest that ICS formulation, particle size, and deposition characteristics play important roles in real-life effectiveness of asthma therapy. This study shows that an EF-particle formulation of beclometasone can be used at half the dose of the large-particle formulation with at least as good clinical outcomes.

Healthcare and workloss costs associated with patients with persistent asthma in a privately insured population

OBJECTIVE

The objective of this study was to estimate annual healthcare and workloss costs of patients with persistent asthma by severity.

METHODS

A persistent asthma patient sample (<65 years) was selected from an employer claims database. Asthma persistence and severity were determined by a novel algorithm based on Health Plan Employer Data and Information Set criteria, Leidy's Reliever and Oral Steroid Method, and Global Initiative for Asthma guidelines. Healthcare costs were compared between asthma patients and demographically matched controls and by asthma severity.

RESULTS

Average annual excess costs for persistent patients were $4412 for health care and $924 for workloss (P < 0.01). Although costs for severe patients were higher than moderate patients (P < 0.05), moderate patients' costs were similar to that for mild patients. Persistent use of inhaled corticosteroids was lower in mild (9.0%) relative to moderate (78.1%) and severe (86.4%) patients.

CONCLUSIONS

Persistent asthma is expensive. Underutilization of inhaled corticosteroids is higher in patients with mild persistent asthma.

Development of a COPD severity score

OBJECTIVE

Treatment of chronic obstructive pulmonary disease (COPD) is based on symptom control. This suggests that COPD severity can be determined by analyzing treatment intensity. The objective of this analysis was to develop and validate a severity score for adult COPD based on treatments.

RESEARCH DESIGN

Using principal components analysis, a COPD severity score was developed using data based on treatments extracted from an employer claims database (development group). Variables included were identified from literature review and clinical expert opinion. External validity was tested in a separate group of adult chronic bronchitis patients in whom principal components analysis was re-conducted and factor loadings were compared to the development group. Construct validity was tested by comparing the incidence of acute exacerbations of chronic bronchitis (AECB) in patients with high and lower severity scores. To illustrate the use of the COPD severity score, effectiveness of alternative AECB antibiotic treatments was compared in a separate patient sample categorized by severe versus mild/moderate COPD.

RESULTS

In the development group (n = 2068), principal components analysis produced a single main factor for severity scoring. Of the 12 variables contributing to this factor, the 6 with the highest factor loadings were treatment related. The factor performed similarly in the external validity group (n = 9127) as it did in the development group. In construct validity testing, severe COPD patients were 4 times more likely to have AECB episodes than mild/moderate patients. Patients with severe COPD and an AECB were more likely to fail treatment with antibiotics than those with mild/moderate COPD. Based on the COPD severity score developed, we found that treatment of patients with severe COPD and an AECB with fluoroquinolones was more likely to result in treatment failure than treatment with macrolides (OR = 2.01; p = 0.03).

CONCLUSIONS

The analysis was successful in developing and validating a method to score COPD severity based on treatments. This method may prove useful in providing insights about the benefits of COPD treatments.

Influenza pneumonia: a descriptive study

OBJECTIVE

To describe the clinical features and complications of patients hospitalized with influenza during the 1999-2000 influenza season.

METHODS

We reviewed all cases of patients with influenza admitted to a large metropolitan referral hospital during the 1999-2000 season.

RESULTS

Thirty-five adult patients (15 men and 20 women) tested positive for influenza A by direct enzyme immunoassay. A fourfold to sevenfold increase in the number of influenza cases was observed over previous years. Most patients had serious comorbid illnesses (88%), such as diabetes and chronic respiratory and heart disease. Seventeen patients developed pneumonia; these patients tended to be older (mean +/- SD, 63 +/- 13 years vs 51 +/- 19 years, respectively; p = 0.04) and had a higher incidence of chronic lung disease (41% vs 6%, respectively; p = 0.02) than the patients without pneumonia. Shortness of breath was the only symptom that distinguished patients with pneumonia from those with an upper respiratory tract illness alone. Antiviral treatment was begun 4 +/- 3 days from initiation of symptoms in patients with pneumonia and consisted of oseltamivir (35.2%), rimantadine (5.8%), or a combination of both (17.6%). Respiratory and/or blood culture results were positive in five patients (29%), Staphylococcus aureus was isolated in five patients, and Streptococcus pneumoniae was isolated in one patient. Ten of the patients with pneumonia (58.8%) were admitted to the ICU, and 5 patients (29%) died. The length of ICU stay and mechanical ventilation were 28 +/- 26 days and 21.5 +/- 20.5 days, respectively. Death in most pneumonia patients was attributed to respiratory failure.

CONCLUSION

The recognized number of hospital admissions for influenza increased fourfold to sevenfold over previous years, most likely due to the implementation of rapid diagnostic tests for influenza. Patients with signs and symptoms of influenza and shortness of breath should undergo chest radiography. Hospitalization of patients with influenza pneumonia occurred in both previously healthy and immunocompromised patients and had a high mortality. S aureus was the most common bacterial isolate in patients with influenza pneumonia. Empiric antibiotics with staphylococcal activity should be used pending culture results in patients with influenza pneumonia. The effectiveness of oseltamivir and rimantadine in treating patients with influenza pneumonia remains to be determined.

An open-label dose escalation study of the nitric oxide synthase inhibitor, N(G)-methyl-L-arginine hydrochloride (546C88), in patients with septic shock. Glaxo Wellcome International Septic Shock Study Group

OBJECTIVE

To assess the effects of the nitric oxide synthase inhibitor, 546C88, in patients with septic shock and to evaluate the range of dose rates that sustain mean arterial pressure (MAP) of > or =70 mmHg.

DESIGN

Multicenter, open-label, uncontrolled, dose range finding study.

SETTING

Ten intensive care units in Europe and the United States.

PATIENTS

Thirty-two patients with septic shock diagnosed within <24 hrs.

INTERVENTIONS

Patients received a fixed dose rate of 546C88 at either 1(n = 6), 2.5 (n = 6), 5 (n = 4), 10 (n = 5), or 20 mg/kg/hr (n = 11) by intravenous infusion for up to 8 hrs. Conventional vasoactive therapy was restricted to norepinephrine and/or dobutamine. During 546C88 therapy, MAP was to be maintained between 70 and 90 mm Hg, while attempting to withdraw any concurrent norepinephrine.

MEASUREMENTS AND MAIN RESULTS

Systemic and pulmonary hemodynamics, blood gases, and plasma nitrate were assessed. Infusion of 546C88 (1-20 mg/kg/hr) for up to 8 hrs enabled a 60 to 80% reduction of the norepinephrine dose rate in all cohorts, while MAP was sustained at >70 mm Hg. There was an increase in vascular tone and a decrease in cardiac index within the 1st hr of therapy. Systemic vascular resistance returned toward baseline with reduction of concomitant administration of norepinephrine. The decline in oxygen delivery was associated with an increase in extraction and, therefore, the maintenance of oxygen consumption. There was a sustained reduction of venous admixture within the 1st hr of therapy. 546C88 was not associated with any major or dose-dependent adverse effect on pulmonary, hepatic, or renal function.

CONCLUSIONS

Treatment with the nitric oxide synthase inhibitor, 546C88, can restore the balance of vasomotor tone, thereby, maintaining blood pressure and reducing or eliminating the requirement for norepinephrine therapy in patients with septic shock. Infusion of 546C88 (1-20 mg/kg/hr) appears to have a satisfactory overall safety profile.

Pharmacokinetics of the nitric oxide synthase inhibitor L-NG-methylarginine hydrochloride in patients with septic shock. Glaxo Wellcome International Septic Shock Study Group

OBJECTIVES

To characterize the pharmacokinetics of L-NG-methylarginine in patients with septic shock.

METHODS

This was an international, uncontrolled, open-label study of L-NG-methylarginine (546C88) therapy given to 32 patients with septic shock. It was conducted in hospital-based intensive care units that admit general surgical and medical patients. Patient cohorts received an infusion of L-NG-methylarginine at fixed dose rates of 1, 2.5, 5, 10, and 20 mg/kg/h for up to 8 hours. The 5 dosing regimens were administered sequentially to separate groups of patients.

RESULTS

Of the 32 patients studied, 23 received complete 8-hour infusions. In the other 9 patients, the infusion was terminated prematurely within the first 1/2 to 4 hours. Median clearance of L-NG-methylarginine averaged 485 mL/h/kg for the 1 and 2.5 mg/kg/h dosing cohorts combined but decreased to 283, 181, and 98 mL/h/kg for the 5, 10, and 20 mg/kg/h dosing cohorts, respectively. Median renal clearance was similar at 9 to 26 mL/h for the 1, 2.5, and 5 mg/kg/h dosing cohorts but increased to 156 and 284 mL/h for the 10 and 20 mg/kg/h dosing cohorts, respectively. Median steady-state volume of distribution was similar in all 5 dosing cohorts, averaging 0.66 to 0.82 L/kg.

CONCLUSIONS

The 80% decrease in clearance from 485 to 98 mL/h/kg with the increase in dose suggests that a predominant metabolic pathway(s) of L-NG-methylarginine, accounting for at least 80% of clearance, is becoming progressively saturable in association with L-NG-methylarginine infusion rates > or = 5 mg/kg/h. Therefore the use of L-NG-methylarginine infusion rates > or = 5 mg/kg/h are typically expected to result in progressive inhibition of nitric oxide synthase activity. Consequently, patient hemodynamics should be monitored closely to avoid an excessive increase in vasomotor tone, which would be manifest by either an increase in mean arterial pressure or a decrease in cardiac output. The infusion rates of conventional vasopressor(s) (eg, norepinephrine [BAN, noradrenaline]) or L-NG-methylarginine or both may need to be reduced accordingly.

Comparison of the Maxair Autohaler to wet nebulizer in patients with acute asthma

STUDY OBJECTIVE

Patients with acute asthma often have difficulty using a conventional metered-dose inhaler. The Maxair Autohaler (3M Pharmaceuticals; St. Paul, MN) is a hand-held breath-actuated device developed to help patients coordinate drug administration. The study objective is to compare the efficacy of the Autohaler with inhaled beta-agonist administered by wet nebulizer in treating acute asthma exacerbations.

DESIGN

Parallel, randomized, placebo-controlled clinical trial.

SETTING

Emergency department (ED) of a university-affiliated hospital.

PARTICIPANTS

Patients aged 18 to 55 years presenting to the ED with acute asthma and an FEV1 40 to 70% on hospital arrival.

INTERVENTIONS AND MEASUREMENTS

Patients were given either six puffs of the Maxair Autohaler (1,200 microg pirbuterol) plus saline solution by nebulizer (active Autohaler group) or six puffs placebo by Autohaler plus 2,500 microg albuterol via nebulizer (active nebulizer group). Treatment was repeated at 30 and 60 min, with clinical evaluation performed before each treatment and again at 120 min. At 120 min, the protocol was completed.

RESULTS

Twenty-four patients were enrolled, with 5 excluded because of protocol violations. Baseline FEV1 percent predicted values for the active Autohaler group were 53% vs 51% for the active nebulizer group (p=not significant [NS]). At time 120 min, values were 66% for Autohaler and 64% for nebulizer (p=NS). The average time to administer Autohaler was 2.9 min, vs 9.1 min for nebulizer. No patient was excluded because of the inability to use the Autohaler device adequately.

CONCLUSION

In patients with moderate asthma exacerbations, similar improvements in pulmonary function are obtained when beta-agonists are given by either the Maxair Autohaler or a wet nebulizer device.

Effects of aerosolized surfactant in patients with stable chronic bronchitis: a prospective randomized controlled trial

CONTEXT

Chronic bronchitis, estimated to affect more than 13 million adults in the United States, is characterized in part by retention of airway secretions, but no approved or effective therapy for airway mucus retention in patients with chronic bronchitis has been established. Surfactant reduces sputum adhesiveness, which contributes to difficulty in clearing secretions, but surfactant has not been tested in patients with chronic bronchitis.

OBJECTIVE

To examine the effects of exogenous surfactant on sputum clearance and pulmonary function in patients with stable chronic bronchitis.

DESIGN

A prospective, multicenter, randomized, double-blind, parallel-group, placebo-controlled comparison of the effects of 2 weeks of treatment with 3 doses of aerosolized surfactant (palmitoylphosphadidylcholine [DPPC]) or saline (placebo).

SETTING

Four US teaching hospitals.

PARTICIPANTS

A total of 87 adult patients with the diagnosis of stable chronic bronchitis.

MAIN OUTCOME MEASURES

Pulmonary function, respiratory symptoms, and sputum properties before treatment (day 0), after 2 weeks of treatment (day 14), and 7 days after stopping treatment (day 21).

RESULTS

A total of 66 patients were randomized to surfactant treatment and 21 to saline treatment. Patient demographic characteristics between groups were similar at baseline. In patients who received a DPPC dose of 607.5 mg/d for 2 weeks, prebronchodilator forced expiratory volume in 1 second (FEV1) increased from 1.22 L (SEM, 0.08 L) at day 0 to 1.33 L (SEM, 0.09 L) at day 21 (P=.05), an improvement of 11.4%; postbronchodilator FEV1 improved 10.4% by days 14 and 21 (P=.02); and the ratio of residual volume to total lung capacity, a measure of thoracic gas trapping, decreased 6.2% by day 21 (P=.009). In the surfactant groups, there was a dose-dependent increase in the ability of sputum to be transported by cilia in vitro.

CONCLUSION

Aerosolized surfactant improved pulmonary function and resulted in a dose-related improvement in sputum transport by cilia in patients with stable chronic bronchitis.

Blood types in cattle of Iberian ancestry and in Holsteins at various altitudes

Gene frequencies of RBC antigens were determined in Holsteins and Colombian (criollas) cattle living at 3,000 m, and in cattle descended from fighting bulls (Vacas de lidia) living at 2,500 m. These frequencies were compared with those of Holsteins, cattle native to Florida (scrub cattle), longhorns, and native cattle from Brazil (caracu cattle) living at sea level. The criollas, Vacas de lidia, scrub cows, longhorns, and caracu are descendants of original Iberian stock introduced to the Americas. We found that despite common ancestry (scrub cattle, long-horns, criollas, and caracu), genetic differences may have been derived through years of demographic isolation. The most remarkable blood-group differences were found in the high prevalence of the B system phenogroup (heritable group of antigenic factors) BQA'G'34 in the Vacas de lidia, and of the S system phenogroup U1H' in these cattle and in caracu. Furthermore, the gene frequencies differed in the Holsteins maintained at moderately high altitude (descended from Holsteins kept at sea level), and may have been reflective of the need to adapt to moderately high altitude and chronic hypoxemic conditions. Blood group polymorphism was found in all groups of cattle, although it was reduced in the Vacas de lidia, possibly because their breeding has been carefully controlled and they appear to be highly inbred.

Respiratory symptoms associated with sulfur dioxide exposure

Exposures to sulfur dioxide (SO2) have been associated with progressive, dose-dependent bronchoconstriction in sensitive individuals. The clinical significance of such changes remains poorly characterized. We studied subjective responses following exposure to low level concentrations of SO2 (less than 1 ppm) in a group of 10 healthy and 10 asthmatic subjects. The number and severity of complaints associated with SO2 increased with concentrations in both healthy and asthmatic subjects. Asthmatics indicated progressive lower respiratory complaints, such as wheezing, chest tightness, dyspnea and cough with increasing levels of SO2 while healthy subjects complained more frequently of upper airway complaints such as taste and odor with increasing levels of SO2. Exercise increased the frequency of lower airway symptoms in asthmatics but led to no increases in symptoms in healthy subjects.

Airway effects of low concentrations of sulfur dioxide: dose-response characteristics

The acute respiratory effects of exposure to low-level, short-term sulfur dioxide (SO2) were studied in ten asthmatic and ten healthy subjects. Subjects were exposed in an environmental chamber in a double-blind, random sequence to SO2) levels of 0.00, 0.25, 0.50, 0.75, and 1.00 ppm for 40 min. During the first 10 min subjects exercised on a cycloergometer at a level of 450 kpm/min. On separate days, subjects were exposed to 0 and 1.0 ppm SO2 in the absence of exercise. In exercising asthmatic subjects, breathing 1 ppm SO2 resulted in significant changes from baseline in airway resistance (Raw), forced expiratory volume in 1 sec (FEV1.0), maximal expiratory flow at 60% of the vital capacity (VC) below total lung capacity on the partial flow volume curve [MEF40% (P)] as well as reductions in flows at 50% of VC (Vmax50%). None of these parameters showed significant changes for exposures to 0.5 ppm or less, with the exception of small decreases (i.e., less than 0.2 L/sec) in Vmax50% at 0.25 and 0.5 ppm. Ten minutes after the end of exercise, there were no statistically significant differences from baseline, even though SO2 was still present in the chamber atmosphere. For asthmatic subjects, the average changes in Raw, FEV1.0, MEF40%(P), and Vmax50% increased as SO2 levels increased, suggestive of a dose-response relationship with a consistent effect first seen at 0.75 ppm. In individual exercising asthmatics, responses may occur at levels of SO2 below 0.75 ppm. No changes were seen in healthy individuals on any day, or in asthmatic subjects at rest.(ABSTRACT TRUNCATED AT 250 WORDS)