Beth E. Davis

Effects of an Anti-TSLP Antibody on Allergen-Induced Asthmatic Responses

BACKGROUND Thymic stromal lymphopoietin (TSLP) is an epithelial-cell-derived cytokine that may be important in initiating allergic inflammation. AMG 157 is a human anti-TSLP monoclonal immunoglobulin G2λ that binds human TSLP and prevents receptor interaction. METHODS In this double-blind, placebo-controlled study, we randomly assigned 31 patients with mild allergic asthma to receive three monthly doses of AMG 157 (700 mg) or placebo intravenously. We conducted allergen challenges on days 42 and 84 to evaluate the effect of AMG 157 in reducing the maximum percentage decrease in the forced expiratory volume in 1 second (FEV1). We also measured the fraction of nitric oxide in exhaled air, blood and sputum eosinophils, and airway hyperresponsiveness. The primary end point was the late asthmatic response, as measured 3 to 7 hours after the allergen challenge. RESULTS AMG 157 attenuated most measures of allergen-induced early and late asthmatic responses. The maximum percentage decrease in the FEV1 during the late response was 34.0% smaller in the AMG-157 group than in the placebo group on day 42 (P=0.09) and 45.9% smaller on day 84 (P=0.02). In addition, patients receiving AMG 157 had significant decreases in levels of blood and sputum eosinophils before and after the allergen challenge and in the fraction of exhaled nitric oxide. There were 15 adverse events in the AMG-157 group, as compared with 12 in the placebo group; there were no serious adverse events. CONCLUSIONS Treatment with AMG 157 reduced allergen-induced bronchoconstriction and indexes of airway inflammation before and after allergen challenge. These findings are consistent with a key role for TSLP in allergen-induced airway responses and persistent airway inflammation in patients with allergic asthma. Whether anti-TSLP therapeutics will have clinical value cannot be determined from these data. (Funded by Amgen; ClinicalTrials.gov number, NCT01405963.).

Effects of Interleukin-13 Blockade on Allergen-induced Airway Responses in Mild Atopic Asthma

RATIONALE Extensive evidence in animal models supports a role for IL-13 in the pathobiology of asthma. IMA-638 and IMA-026 are fully humanized IgG(1) antibodies that bind to different epitopes and neutralize IL-13 bioactivity. OBJECTIVES We hypothesized that anti-IL-13 treatment would inhibit allergen-induced late-phase asthmatic responses, airway hyperresponsiveness, and inflammation in subjects with asthma. METHODS Fifty-six subjects with mild, atopic asthma were recruited for two double-blind, randomized, placebo-controlled, parallel group trials to compare IMA-638 and IMA-026 IL-13 antibody treatments with placebo treatment. Drug was administered on Days 1 and 8, and allergen challenges were performed on Days 14 and 35. The primary outcome variable was the late-phase area under the curve (AUC), and secondary outcome variables were the early- and late-phase maximum percent fall in FEV(1), early AUC, allergen-induced shift in airway hyperresponsiveness, and sputum eosinophils. MEASUREMENTS AND MAIN RESULTS The treatment difference with IMA-638 on Day 14 was -19.1 FEV(1) × hour (95% confidence interval: -36.2, -1.9) for the allergen-induced early AUC and -23.8 FEV(1) × hour (95% confidence interval: -46.4, -1.2) for the late AUC (both P < 0.05), but this effect was lost by Day 35. Treatment with IMA-026 did not attenuate the asthmatic responses on Day 14 or Day 35. There was no effect of either antibody on allergen-induced airway hyperresponsiveness or sputum eosinophils. The frequency of adverse events after administration of the IL-13 antibodies was similar to placebo. CONCLUSIONS IL-13 has a role in allergen-induced airway responses in humans. Further study is required to determine whether anti-IL-13 monoclonal antibodies will be beneficial clinically.

Antisense Therapy against CCR3 and the Common Beta Chain Attenuates Allergen-induced Eosinophilic Responses

RATIONALE The drug product TPI ASM8 contains two modified phosphorothioate antisense oligonucleotides designed to inhibit allergic inflammation by down-regulating human CCR3 and the common beta chain (beta(c)) of IL-3, IL-5, and granulocyte-macrophage colony-stimulating factor receptors. OBJECTIVES This study examined the effects of inhaled TPI ASM8 on sputum cellular influx, CCR3 and beta(c) mRNA and protein levels, and the airway physiologic response after inhaled allergen. METHODS Seventeen subjects with mild atopic asthma were randomized in a crossover study to inhale 1,500 microg TPI ASM8 or placebo by nebulizer, once daily for 4 days. On Day 3, subjects underwent allergen inhalation challenge. Sputum samples were collected before and after allergen. CCR3 and beta(c) protein levels were measured by flow cytometry, mRNA was measured using real-time quantitative polymerase chain reaction, and the FEV1 was measured over 7 hours after challenge. MEASUREMENTS AND MAIN RESULTS Compared with placebo, TPI ASM8 inhibited sputum eosinophil influx by 46% (P = 0.02) and blunted the increase in total cells (63%) after allergen challenge. TPI ASM8 significantly reduced the early asthmatic response (P = 0.04) with a trend for the late asthmatic response (P = 0.08). The allergen-induced (Day 2 to Day 3) levels of beta(c) mRNA and CCR3 mRNA in sputum-derived cells were inhibited by TPI ASM8 (P = 0.039 and P = 0.054, respectively), with no significant effects on the cell surface protein expression of CCR3 and beta(c) (P > 0.05). No serious adverse events were reported. CONCLUSIONS TPI ASM8 attenuates the allergen-induced increase in target gene mRNA and airway responses in subjects with mild asthma. Clinical trial registered with www.clinicaltrials.gov (NCT 00264966).

Direct and indirect challenges in the clinical assessment of asthma

OBJECTIVE To compare direct and indirect bronchoprovocation challenges in the clinical assessment of asthma. DATA SOURCES PubMed search using the keywords adenosine monophosphate, eucapnic voluntary hyperpnea, exercise, hypertonic saline, mannitol, and methacholine challenges and asthma. STUDY SELECTION Articles were selected based on their relevance to the topic of this review. RESULTS Methacholine is the most widely used direct challenge. Methacholine is highly sensitive, provided symptoms are clinically current and deep inhalations are avoided during inhalation. There are many causes of a false-positive test result. Specificity is increased if the pretest probability of asthma is greater, if the methacholine responsiveness is moderate or greater, and if the methacholine-induced symptoms mimic the natural symptoms. Indirect challenges are more specific for asthma but are insensitive, particularly for mild and/or well-controlled asthma. The lower sensitivity may relate to the fact that many indirect challenges (eg, exercise, eucapnic voluntary hyperpnea, adenosine monophosphate) are dose limited (ie, the dose of stimulus cannot be increased above a level based on physiology or solubility). Indirect challenges also correlate better with airway inflammation and are more responsive to anti-inflammatory treatments. CONCLUSIONS Direct challenges (ie, methacholine), because of the high sensitivity, function best to exclude clinically current asthma; a positive test result is consistent with but not diagnostic of asthma. By contrast, indirect challenges are superior for confirming asthma and are the challenges of choice when exercise bronchospasm is the question (eg, certification for international athletic competition, armed forces, scuba diving). Indirect challenges would be preferred for monitoring of asthma control and used serially to help diagnose occupational asthma.

The links between allergen skin test sensitivity, airway responsiveness and airway response to allergen

Background:  The allergen‐induced early asthmatic response [provocation concentration (PC)20, the concentration causing a 20% forced expiratory volume in 1 s (FEV)1 fall] depends on the level of IgE sensitivity and the degree of nonallergic airway hyperresponsiveness (AHR) and can be predicted from histamine PC20 and allergen skin test endpoint.

Targeting membrane-expressed IgE B cell receptor with an antibody to the M1 prime epitope reduces IgE production

A humanized monoclonal antibody that targets the membrane IgE B cell receptor was associated with improvements in asthmatic airway responses. Asthma Antibody Clears the Air A humanized antibody may be the key for treating allergic asthma. Gauvreau et al. report that quilizumab—a humanized monoclonal antibody that targets the membrane immunoglobulin E (IgE) B cell receptor—led to reductions in total and allergen-specific serum IgE that were sustained for 6 months after dosing and were associated with improvements in allergen-induced early and late asthmatic airway responses. A monoclonal antibody that neutralizes IgE can effectively treat asthma in the clinic; however, use is limited by dosing restrictions and it does not prevent new IgE production. Inhibiting IgE production by targeting membrane IgE–expressing cells may enable more subjects to be treated and less frequent dosing, and has the potential for sustained effects upon the cessation of therapy. Elevated serum levels of both total and allergen-specific immunoglobulin E (IgE) correlate with atopic diseases such as allergic rhinitis and allergic asthma. Neutralization of IgE by anti-IgE antibodies can effectively treat allergic asthma. Preclinical studies indicate that targeting membrane IgE–positive cells with antibodies against M1 prime can inhibit the production of new IgE and significantly reduce the levels of serum IgE. We report results from two trials that investigated the safety, pharmacokinetics, and activity of quilizumab, a humanized monoclonal antibody targeting specifically the M1 prime epitope of membrane IgE, in subjects with allergic rhinitis (NCT01160861) or mild allergic asthma (NCT01196039). In both studies, quilizumab treatment was well tolerated and led to reductions in total and allergen-specific serum IgE that lasted for at least 6 months after the cessation of dosing. In subjects with allergic asthma who were subjected to an allergen challenge, quilizumab treatment blocked the generation of new IgE, reduced allergen-induced early and late asthmatic airway responses by 26 and 36%, respectively, and reduced allergen-induced increases in sputum eosinophils by ~50% compared with placebo. These studies indicate that targeting of membrane IgE–expressing cells with anti-M1 prime antibodies can prevent IgE production in humans.

OX40L blockade and allergen‐induced airway responses in subjects with mild asthma

The OX40/OX40L interaction contributes to an optimal T cell response following allergic stimuli and plays an important role in the maintenance and reactivation of memory T effector cells.

Induction of Type 2 T Helper Cell Allergen Tolerance by IL-10–Differentiated Regulatory Dendritic Cells

In mouse models of asthma, therapeutic use of allergen-presenting IL-10-differentiated dendritic cells (DCs) can abrogate airway hyperresponsiveness, and reduce other asthma-related responses to near background. Analogous human DCs can suppress human T cell responses in vitro, but the operative mechanisms are poorly defined. We investigated the ability of IL-10-treated human DCs to induce tolerance among autologous T cells of subjects with asthma and the mechanisms by which they do this. CD14(+) monocyte-derived DCs were differentiated in the presence of IL-10 (DC10) ex vivo from 11 donors with asthma and 4 control donors, and characterized for relevant markers. They were pulsed with specific or irrelevant allergen, and cultured with autologous peripheral blood CD4(+) T cells, either alone or together with autologous immunostimulatory DCs (DC-TNF), and the impact of this treatment on the T-cell responses was assessed for each donor. The DC10 expressed reduced levels of some relevant markers (CD40, CD80, human leukocyte antigen-DR) and stimulatory cytokines (IL-6 and IL-12), but augmented levels of Ig-like transcript-22/CD85j and IL-10 relative to DC-TNF. In cocultures, they dampened DC-TNF-driven T helper (Th) type 2 cell proliferation and cytokine (IL-4, -5, and -13) secretion. They also drove the development from atopic CD4(+)CD25(lo)Foxp3(lo) cells of a population of IL-10-secreting CD25(+)Foxp3(+)LAG-3(+)CTLA-4(+) regulatory T cells (Tregs). These Tregs suppressed stimulatory DC-induced autologous Th2 cell proliferation and cytokine secretion in a contact-dependent manner. Our data indicate that IL-10-treated human DCs induce Th2 cell allergen tolerance ex vivo by driving the differentiation of Tregs.

Tolerance to the bronchoprotective effect of β2 -agonists: Comparison of the enantiomers of salbutamol with racemic salbutamol and placebo

BACKGROUND Regular use of racemic salbutamol results in the partial loss of its bronchoprotective effect. The 2 enantiomers of salbutamol, the bronchodilator R-salbutamol and nonbronchodilator S-salbutamol, are now available. OBJECTIVE We sought to compare the effect of regular use of S-salbutamol, R-salbutamol, racemic salbutamol, and placebo on the bronchoprotective effect of a single dose of racemic salbutamol against methacholine-induced bronchoconstriction. METHODS Eleven of 13 well-controlled beta2 -agonist-free asthmatic subjects completed a double-blind, randomized study comparing racemic salbutamol 2.5 mg, S-salbutamol 1. 25 mg, R-salbutamol 1.25 mg, and diluent placebo nebulized and inhaled 3 times daily for 6 days (>/=6-day washout period). Ten to 12 hours after the last dose, the subjects performed measurement of FEV1, methacholine PC20, and a repeat methacholine PC20 done 1 hour after the first methacholine test and 10 minutes after 2 puffs (200 microgram) of racemic salbutamol administered from a metered-dose inhaler. The primary endpoint was the methacholine PC20 dose shift (Deltalog PC20/log 2) from before to after administration of 200 microgram of racemic salbutamol. RESULTS The methacholine dose shift was 3.2 doubling doses (9-fold increase in methacholine PC20 after 200 microgram of racemic salbutamol) during the placebo treatment and was unaltered (3.2) after administration of S-salbutamol. The dose shift was significantly lower after both the R-salbutamol and racemic salbutamol treatments (2.2 and 2.6 doubling doses, respectively); there was no significant difference between R-salbutamol and racemic salbutamol. There was no treatment effect on baseline FEV1, baseline methacholine PC20, or bronchodilation. CONCLUSION Regular treatment with racemic salbutamol or R-salbutamol, but not S-salbutamol, results in a partial loss of bronchoprotection, without loss of bronchodilation, compared with placebo.

Single-dose desloratadine and montelukast and allergen-induced late airway responses

Montelukast and desloratadine synergistically inhibit the allergen-induced early asthmatic response. Montelukast also suppresses the allergen-induced late asthmatic response, but there are no reports on the effect of desloratadine or the combination on the allergen-induced late asthmatic response. Atopic asthmatics (n = 10) completed a multicentric randomised double-blind crossover study comparing single-dose placebo, 5 mg desloratadine, 10 mg montelukast and the combination administered 2 h prior to allergen inhalation challenge. Methacholine challenges were performed 24 h before and after allergen challenge. Exhaled nitric oxide measurements and sputum inflammatory cell counts were also carried out. All active treatments significantly decreased the late asthmatic response area under the curve. Combination therapy provided the greatest inhibition compared to desloratadine and montelukast. Montelukast was nonsignificantly better than desloratadine but not as effective as the combination. There was a trend towards a decrease in airway responsiveness following montelukast and combination. Montelukast, but not desloratadine or the combination, decreased exhaled NO levels 24 h after allergen. The allergen-induced increase in sputum eosinophil numbers was significantly suppressed at 7 h with desloratadine and combination therapy, and at 24 h with montelukast and combination therapy. Single-dose co-administration of desloratadine and montelukast 2 h prior to allergen inhalation clinically abolished the late asthmatic response and eosinophil recruitment.