Prostaglandin D2 metabolites activate asthmatic patient-derived type 2 innate lymphoid cells and eosinophils via the DP2 receptor.

BACKGROUND: Prostaglandin D2 (PGD2) signaling via prostaglandin D2 receptor 2 (DP2) contributes to atopic and non-atopic asthma. Inhibiting DP2 has shown therapeutic benefit in certain subsets of asthma patients, improving eosinophilic airway inflammation. PGD2 metabolites prolong the inflammatory response in asthmatic patients via DP2 signaling. The role of PGD2 metabolites on eosinophil and ILC2 activity is not fully understood. METHODS: Eosinophils and ILC2s were isolated from peripheral blood of atopic asthmatic patients. Eosinophil shape change, ILC2 migration and IL-5/IL-13 cytokine secretion were measured after stimulation with seven PGD2 metabolites in presence or absence of the selective DP2 antagonist fevipiprant. RESULTS: Selected metabolites induced eosinophil shape change with similar nanomolar potencies except for 9α,11ß-PGF2. Maximal values in forward scatter of eosinophils were comparable between metabolites. ILC2s migrated dose-dependently in the presence of selected metabolites except for 9α,11ß-PGF2 with EC50 values ranging from 17.4 to 91.7 nM. Compared to PGD2, the absolute cell migration was enhanced in the presence of Δ12-PGD2, 15-deoxy-Δ12,14-PGD2, PGJ2, Δ12-PGJ2 and 15-deoxy-Δ12,14-PGJ2. ILC2 cytokine production was dose dependent as well but with an average sixfold reduced potency compared to cell migration (IL-5 range 108.1 to 526.9 nM, IL-13 range: 125.2 to 788.3 nM). Compared to PGD2, the absolute cytokine secretion was reduced in the presence of most metabolites. Fevipiprant dose-dependently inhibited eosinophil shape change, ILC2 migration and ILC2 cytokine secretion with (sub)-nanomolar potencies. CONCLUSION: Prostaglandin D2 metabolites initiate ILC2 migration and IL-5 and IL-13 cytokine secretion in a DP2 dependent manner. Our data indicate that metabolites may be important for in vivo eosinophil activation and ILC2 migration and to a lesser extent for ILC2 cytokine secretion.

The Roles of Type 2 Cytotoxic T Cells in Inflammation, Tissue Remodeling, and Prostaglandin (PG) D2 Production Are Attenuated by PGD2 Receptor 2 Antagonism.

Human type 2 cytotoxic T (Tc2) cells are enriched in severe eosinophilic asthma and can contribute to airway eosinophilia. PGD2 and its receptor PGD2 receptor 2 (DP2) play important roles in Tc2 cell activation, including migration, cytokine production, and survival. In this study, we revealed novel, to our knowledge, functions of the PGD2/DP2 axis in Tc2 cells to induce tissue-remodeling effects and IgE-independent PGD2 autocrine production. PGD2 upregulated the expression of tissue-remodeling genes in Tc2 cells that enhanced the fibroblast proliferation and protein production required for tissue repair and myofibroblast differentiation. PGD2 stimulated Tc2 cells to produce PGD2 using the routine PGD2 synthesis pathway, which also contributed to TCR-dependent PGD2 production in Tc2 cells. Using fevipiprant, a specific DP2 antagonist, we demonstrated that competitive inhibition of DP2 not only completely blocked the cell migration, adhesion, proinflammatory cytokine production, and survival of Tc2 cells triggered by PGD2 but also attenuated the tissue-remodeling effects and autocrine/paracrine PGD2 production in Tc2 induced by PGD2 and other stimulators. These findings further confirmed the anti-inflammatory effect of fevipiprant and provided a better understanding of the role of Tc2 cells in the pathogenesis of asthma.

A Study of the Effect of Cyclosporine on Fevipiprant Pharmacokinetics and its Absolute Bioavailability Using an Intravenous Microdose Approach.

This drug-drug interaction study determined the effect of cyclosporine, an inhibitor of organic anion transporting polypeptide (OATP) 1B3 and P-gp, on the pharmacokinetics (PK) of fevipiprant, an oral, highly selective, competitive antagonist of the prostaglandin D2 receptor 2 and a substrate of the two transporters. The concomitant administration of an intravenous microdose of stable isotope-labeled fevipiprant provided the absolute bioavailability of fevipiprant as well as mechanistic insights into its PK and sensitivity to drug interactions. Liquid chromatography-mass spectrometry/mass spectrometry was used to measure plasma and urine concentrations. Geometric mean ratios [90% confidence interval (CI)] for oral fevipiprant with or without cyclosporine were 3.02 (2.38, 3.82) for C max, 2.50 (2.17, 2.88) for AUClast, and 2.35 (1.99, 2.77) for AUCinf The geometric mean ratios (90% CI) for fevipiprant intravenous microdose with or without cyclosporine were 1.04 (0.86, 1.25) for C max, 2.04 (1.83, 2.28) for AUClast, and 1.95 (1.76, 2.16) for AUCinf The absolute bioavailability for fevipiprant was approximately 0.3 to 0.4 in the absence and 0.5 in the presence of cyclosporine. The intravenous microdose allowed differentiation between systemic and presystemic effects of cyclosporine on fevipiprant, demonstrating a small (approximately 1.2-fold) presystemic effect of cyclosporine and a larger (approximately twofold) effect on systemic elimination of fevipiprant. Uptake by OATP1B3 appears to be the rate-limiting step in the hepatic elimination of fevipiprant, whereas P-gp does not have a relevant effect on oral absorption. SIGNIFICANCE STATEMENT: The drug interaction investigated here with cyclosporine, an inhibitor of several drug transporters, provides a refined quantitative understanding of the role of active transport processes in liver and intestine for the absorption and elimination of fevipiprant as well as the basis to assess the need for dose adjustment in the presence of transporter inhibitors. The applied intravenous microdose approach presents a strategy to maximize learnings from a trial, limit the number and duration of clinical trials, and enhance mechanistic drug-drug interaction understanding.

Increased type 2 inflammation post rhinovirus infection in patients with moderate asthma.

Rhinovirus (RV) infections are a major cause of exacerbations in patients with asthma. Experimental RV challenges can provide insight into the pathophysiology of viral exacerbations. Previous reports, investigating mild or moderate asthma patients, have shown an upregulation in type 2 inflammation post RV infection, however, studies specifically involving asthma patients taking inhaled corticosteroids have concentrated on symptoms and lung function, rather than the inflammatory response. Eleven moderate asthma patients were inoculated with RV. Cold symptoms and asthma control were assessed at baseline and post infection. Nasal epithelial lining fluid and bronchial alveolar lavage (BAL) fluid were collected at baseline and 4 days post infection for assessment of inflammatory proteins. Patients suffered increased cold symptoms and decreased asthma control within 7 days of infection. Antiviral mechanisms were induced following inoculation, with increases in interferon -α, ß, γ and λ, as well as CXCL10 and CXCL11. Type 2 inflammatory cytokines were also significantly elevated post RV infection in both nasal and bronchial samples. In BAL, epithelial derived IL-25 and IL-33 levels strongly correlated with Th2 cytokines, IL-4, IL-5 and IL-13. We show how experimental rhinovirus challenge regulates lung and nasal biomarkers in asthma patients taking inhaled corticosteroids. These biomarkers could be used to evaluate the effects of novel drugs for asthma.

Omalizumab normalizes the gene expression signature of lesional skin in patients with chronic spontaneous urticaria: A randomized, double-blind, placebo-controlled study.

BACKGROUND: Omalizumab, a humanized recombinant monoclonal anti-IgE antibody, proved to be effective in patients with chronic spontaneous urticaria (CSU), including severe and treatment-refractory CSU. Here, we report omalizumab's effect on gene expression in skin biopsies from CSU patients enrolled in a double-blind, placebo-controlled study. METHODS: Chronic spontaneous urticaria patients (18-75 years) were randomized to either 300 mg omalizumab (n = 20) or placebo (n = 10) administered s.c. every 4 weeks for 12 weeks (NCT01599637). Lesional and nonlesional skin biopsies were collected from the same area of consenting patients and assessed at baseline and on Day 85 compared with skin biopsies from the same area of 10 untreated healthy volunteers (HVs). Gene expression data were generated using Affymetrix HG-U133Plus2.0 microarrays. Statistical analyses were performed using R packages. RESULTS: At baseline, 63 transcripts were differentially expressed between lesional and nonlesional skin. Two-thirds of these lesional signatures were also differentially expressed between lesional and HV skin. Upon treatment with omalizumab, >75% of lesional signatures changed to reflect nonlesional skin expression levels (different vs placebo, P < 0.01). Transcripts upregulated in lesional skin (vs nonlesional and/or HV skin) suggested increased mast cell/leukocyte infiltration (FCER1G, C3AR1, CD93, S100A8, and S100A9), increased oxidative stress, vascularization (CYR61), and skin repair events (KRT6A, KRT16). Lesional signatures were not modulated by treatment in nonresponders (defined based on UAS7 longitudinal changes ≥16). CONCLUSION: Omalizumab, in treatment responders, reverted transcriptional signatures associated with CSU lesion phenotype to reflect nonlesional/HV expression levels; this is consistent with observed omalizumab-mediated clinical improvement observed in patients with CSU.

The prostaglandin D2 receptor 2 pathway in asthma: a key player in airway inflammation.

Asthma is characterised by chronic airway inflammation, airway obstruction and hyper-responsiveness. The inflammatory cascade in asthma comprises a complex interplay of genetic factors, the airway epithelium, and dysregulation of the immune response.Prostaglandin D2 (PGD2) is a lipid mediator, predominantly released from mast cells, but also by other immune cells such as TH2 cells and dendritic cells, which plays a significant role in the pathophysiology of asthma. PGD2 mainly exerts its biological functions via two G-protein-coupled receptors, the PGD2 receptor 1 (DP1) and 2 (DP2). The DP2 receptor is mainly expressed by the key cells involved in type 2 immune responses, including TH2 cells, type 2 innate lymphoid cells and eosinophils. The DP2 receptor pathway is a novel and important therapeutic target for asthma, because increased PGD2 production induces significant inflammatory cell chemotaxis and degranulation via its interaction with the DP2 receptor. This interaction has serious consequences in the pulmonary milieu, including the release of pro-inflammatory cytokines and harmful cationic proteases, leading to tissue remodelling, mucus production, structural damage, and compromised lung function. This review will discuss the importance of the DP2 receptor pathway and the current understanding of its role in asthma.

U-BIOPRED: evaluation of the value of a public-private partnership to industry.

Unbiased Biomarkers for the Prediction of Respiratory Disease Outcomes (U-BIOPRED) was initiated in the first year of the Innovative Medicines Initiative (IMI). It was an ambitious plan to tackle the understanding of asthma through an integration of clinical and multi-'omics approaches that necessitated the bringing together of industry, academic, and patient representatives because it was too large to be managed by any one of the partners in isolation. It was a novel experience for all concerned. In this review, we describe the main features of the U-BIOPRED experience from the industry perspective. We list some of the key advantages and learnings from the perspective of the authors, and also improvements that we feel could be made in future projects.

Absorption, Distribution, Metabolism, and Excretion of the Oral Prostaglandin D2 Receptor 2 Antagonist Fevipiprant (QAW039) in Healthy Volunteers and In Vitro.

Fevipiprant is a novel oral prostaglandin D2 receptor 2 (DP2; also known as CRTh2) antagonist, which is currently in development for the treatment of severe asthma and atopic dermatitis. We investigated the absorption, distribution, metabolism, and excretion properties of fevipiprant in healthy subjects after a single 200-mg oral dose of [14C]-radiolabeled fevipiprant. Fevipiprant and metabolites were analyzed by liquid chromatography coupled to tandem mass spectrometry and radioactivity measurements, and mechanistic in vitro studies were performed to investigate clearance pathways and covalent plasma protein binding. Biotransformation of fevipiprant involved predominantly an inactive acyl glucuronide (AG) metabolite, which was detected in plasma and excreta, representing 28% of excreted drug-related material. The AG metabolite was found to covalently bind to human plasma proteins, likely albumin; however, in vitro covalent binding to liver protein was negligible. Excretion was predominantly as unchanged fevipiprant in urine and feces, indicating clearance by renal and possibly biliary excretion. Fevipiprant was found to be a substrate of transporters organic anion transporter 3 (OAT3; renal uptake), multidrug resistance gene 1 (MDR1; possible biliary excretion), and organic anion-transporting polypeptide 1B3 (OATP1B3; hepatic uptake). Elimination of fevipiprant occurs via glucuronidation by several uridine 5'-diphospho glucuronosyltransferase (UGT) enzymes as well as direct excretion. These parallel elimination pathways result in a low risk of major drug-drug interactions or pharmacogenetic/ethnic variability for this compound.

Clinical efficacy of omalizumab in chronic spontaneous urticaria is associated with a reduction of FcεRI-positive cells in the skin.

Background. Treatment with omalizumab, a humanized recombinant monoclonal anti-IgE antibody, results in clinical efficacy in patients with Chronic Spontaneous Urticaria (CSU). The mechanism of action of omalizumab in CSU has not been elucidated in detail. Objectives. To determine the effects of omalizumab on levels of high affinity IgE receptor-positive (FcεRI+) and IgE-positive (IgE+) dermal cells and blood basophils. Treatment efficacy and safety were also assessed. Study design. In a double-blind study, CSU patients aged 18­75 years were randomized to receive 300 mg omalizumab (n=20) or placebo (n=10) subcutaneously every 4 weeks for 12 weeks. Changes in disease activity were assessed by use of the weekly Urticaria Activity Score (UAS7). Circulating IgE levels, basophil numbers and levels of expression of FcεRI+ and IgE+ cells in the skin and in blood basophils were determined. Results. Patients receiving omalizumab showed a significantly greater decrease in UAS7 compared with patients receiving placebo. At Week 12 the mean difference in UAS7 between treatment groups was -14.82 (p=0.0027), consistent with previous studies. Total IgE levels in serum were increased after omalizumab treatment and remained elevated up to Week 12. Free IgE levels decreased after omalizumab treatment. Mean levels of FcεRI+ skin cells in patients treated with omalizumab 300 mg were decreased at Week 12 compared with baseline in the dermis of both non-lesional and lesional skin, reaching levels comparable with those seen in healthy volunteers (HVs). There were no statistically significant changes in mean FcɛRI+ cell levels in the placebo group. Similar results were seen for changes in IgE+ cells, although the changes were not statistically significant. The level of peripheral blood basophils increased immediately after treatment start and returned to Baseline values after the follow-up period. The levels of FcεRI and IgE expression on peripheral blood basophils were rapidly reduced by omalizumab treatment up to Week 12. Conclusions. Treatment with omalizumab resulted in rapid clinical benefits in patients with CSU. Treatment with omalizumab was associated with reduction in FcɛRI+ and IgE+ basophils and intradermal cells.

Data on the oral CRTh2 antagonist QAW039 (fevipiprant) in patients with uncontrolled allergic asthma.

This article contains data on clinical endpoints (Peak Flow Expiratory Rate, fractional exhaled nitric oxide and total IgE serum levels) and plasma pharmacokinetic parameters concerning the use of the oral CRTh2 antagonist QAW039 (fevipiprant) in mild to moderate asthma patients. Information on experimental design and methods on how this data was obtained is also described. Further interpretation and discussion of this data can be found in the article "The oral CRTh2 antagonist QAW039 (fevipiprant): a phase II study in uncontrolled allergic asthma" (Erpenbeck et al., in press) [1].

Pharmacokinetics, Safety, and Tolerability of Fevipiprant (QAW039), a Novel CRTh2 Receptor Antagonist: Results From 2 Randomized, Phase 1, Placebo-Controlled Studies in Healthy Volunteers.

We evaluated the pharmacokinetics (PK), safety, and tolerability of a novel oral CRTh2 antagonist, fevipiprant (QAW039), in healthy subjects. Peak concentrations of fevipiprant in plasma were observed 1-3 hours postdosing. Concentrations declined in a multiexponential manner, followed by an apparent terminal phase (t1/2 , ∼20 hours). Steady state was achieved in 4 days with <2-fold accumulation. Elimination was partly by renal excretion (≤30% of the dose) and glucuronidation. Food had minimal impact on the PK of fevipiprant, and it was well tolerated at single and multiple oral doses up to 500 mg/day. No dose-dependent adverse events were observed, and all the events were mild or moderate in severity. Systemic concentrations were sufficiently high to achieve relevant target occupancy, considering in vitro pharmacology data. In summary, the data support further development as a once-daily oral therapy for allergic diseases.

The oral CRTh2 antagonist QAW039 (fevipiprant): A phase II study in uncontrolled allergic asthma.

BACKGROUND: There is an unmet medical need for allergic asthma patients who are uncontrolled on conventional therapies. The aim of this study was to collect efficacy and safety data for QAW039, an oral chemoattractant receptor-homologous molecule expressed on Th2 cells (CRTh2) receptor antagonist, for the treatment of asthma. METHODS: This was an exploratory phase II, double-blind, randomized, placebo-controlled multi-center study. Patients with mild-to-moderate uncontrolled allergic asthma (N = 170) were either without or weaned off inhaled corticosteroids (ICS) and long-acting ß-agonists (LABA) and randomized (1:1) to QAW039 (500 mg once daily) or to placebo for 28 days. RESULTS: Overall, 157 patients completed the study. There were no significant differences between QAW039 and placebo for trough forced expiratory volume in 1 s (FEV1) or Asthma control questionnaire (ACQ) in the total population. Subgroup analyses demonstrated that patients with a FEV1 <70% of predicted at baseline treated with QAW039 had significant improvement compared with placebo in trough FEV1 (QAW039- Placebo [Δ] = 207 mL; 90% confidence interval [CI]: 96, 319; P = 0.002) and ACQ7 (Δ = -0.41; 90%CI: -0.69, -0.13; P = 0.009). QAW039 reached a mean maximum concentration (Cmax) of 3440 ng/mL on day 28 at a median Tmax of 1 h (range 0.5-4 h). Most adverse events (AEs) were mild/moderate and balanced between both groups, with no serious AEs. CONCLUSIONS: In the general study population, no improvement in lung function was observed with QAW039. However, a subgroup analysis revealed that patients with greater severity of airflow limitation (FEV1 < 70%) had improved lung function and asthma control when treated with QAW039. QAW039 also demonstrated a favorable safety profile. TRIALS REGISTRATION: ClinicalTrials.govNCT01253603.

Clinical and inflammatory characteristics of the European U-BIOPRED adult severe asthma cohort.

U-BIOPRED is a European Union consortium of 20 academic institutions, 11 pharmaceutical companies and six patient organisations with the objective of improving the understanding of asthma disease mechanisms using a systems biology approach.This cross-sectional assessment of adults with severe asthma, mild/moderate asthma and healthy controls from 11 European countries consisted of analyses of patient-reported outcomes, lung function, blood and airway inflammatory measurements.Patients with severe asthma (nonsmokers, n=311; smokers/ex-smokers, n=110) had more symptoms and exacerbations compared to patients with mild/moderate disease (n=88) (2.5 exacerbations versus 0.4 in the preceding 12 months; p<0.001), with worse quality of life, and higher levels of anxiety and depression. They also had a higher incidence of nasal polyps and gastro-oesophageal reflux with lower lung function. Sputum eosinophil count was higher in severe asthma compared to mild/moderate asthma (median count 2.99% versus 1.05%; p=0.004) despite treatment with higher doses of inhaled and/or oral corticosteroids.Consistent with other severe asthma cohorts, U-BIOPRED is characterised by poor symptom control, increased comorbidity and airway inflammation, despite high levels of treatment. It is well suited to identify asthma phenotypes using the array of "omic" datasets that are at the core of this systems medicine approach.

Exacerbation of atopic dermatitis on grass pollen exposure in an environmental challenge chamber.

BACKGROUND: It has frequently been speculated that pruritus and skin lesions develop after topical exposure to aeroallergens in sensitized patients with atopic dermatitis (AD). OBJECTIVE: We sought to study cutaneous reactions to grass pollen in adult patients with AD with accompanying clear IgE sensitization to grass allergen in an environmental challenge chamber using a monocenter, double-blind, placebo-controlled study design. METHODS: Subjects were challenged on 2 consecutive days with either 4000 pollen grains/m(3) of Dactylis glomerata pollen or clean air. The severity of AD was assessed at each study visit up to 5 days after challenge by (objective) scoring of AD (SCORAD). Additionally, air-exposed and non-air-exposed skin areas were each scored using local SCORAD scoring and investigator global assessments. Levels of a series of serum cytokines and chemokines were determined by using a Luminex-based immunoassay. The primary end point of the study was the change in objective SCORAD scores between prechallenge and postchallenge values. RESULTS: Exposure to grass pollen induced a significant worsening of AD. A pronounced eczema flare-up of air-exposed rather than covered skin areas occurred. In grass pollen-exposed subjects a significantly higher increase in CCL17, CCL22, and IL-4 serum levels was observed. CONCLUSIONS: This study demonstrates that controlled exposure to airborne allergens of patients with a so-called extrinsic IgE-mediated form of AD induced a worsening of cutaneous symptoms.

Omalizumab in asthma: an update on recent developments.

IgE is central to the pathophysiology of allergic asthma. Omalizumab, a humanized anti-IgE mAb, specifically binds free IgE and interrupts the allergic cascade by preventing binding of IgE with its high-affinity FcεRI receptors on mast cells, antigen-presenting cells, and other inflammatory cells. The clinical efficacy of omalizumab has been well documented in a number of clinical trials that involve adults, adolescents, and children with moderate-to-severe and severe allergic asthma. In these studies, omalizumab reduced exacerbations, asthma symptoms, inhaled corticosteroid and rescue medication use, and improved quality of life relative to placebo or best standard of care. Similar benefits have been reported in observational studies in "real-world" populations of patients. Results from recent pooled data from randomized clinical trials and from a large prospective cohort study provide reassurance about the long-term safety of omalizumab. Omalizumab dosing is individualized according to body weight and serum-IgE level, and recent adjustments to the dosing algorithm in Europe have enabled more patients to be eligible for treatment. Ongoing and future research is investigating the optimal duration of therapy, accurate predictors of response to treatment, and efficacy in nonatopic asthma as well as other IgE-mediated conditions.

Omalizumab in patients with allergic (IgE-mediated) asthma and IgE/bodyweight combinations above those in the initially approved dosing table.

BACKGROUND: When first approved in the European Union (EU), the omalizumab dosing table had upper bodyweight and IgE limits of 150 kg and 700 IU/mL, respectively. In this study, we assessed the safety, pharmacokinetics (PK) and pharmacodynamics (PD) of omalizumab in patients with IgE/bodyweight combinations above those in the original dosing table. METHODS: A multicentre, open-label, parallel-group study assessed the safety, PK and PD of omalizumab in 32 patients with mild-to-moderate allergic (IgE-mediated) asthma. Patients received two subcutaneous injections of omalizumab at one of three dosage levels (450, 525, or 600 mg), chosen according to baseline IgE (300-2000 IU/mL) and bodyweight (40-150 kg), with a 14-day interval between injections. RESULTS: Overall, 69 adverse events (AEs), none of them serious, were reported by 26 (81.3%) patients. Analysis of laboratory measurements, vital signs and ECG data revealed no adverse findings of clinical relevance. The PK profile was consistent with previous data for lower doses. Mean maximum decrease of free IgE from screening was ≥99% for all three doses, and mean free IgE concentrations remained <25 ng/mL for at least 2 weeks after the second dose. The reductions in free IgE were consistent with levels previously associated with clinical improvements. CONCLUSIONS: The safety and PK/PD findings from this study are consistent with previous data, and supported the extension of the omalizumab dosing table to include those patients with higher IgE/bodyweight combinations. Clinical trial registry and registration number: clinicaltrials.gov (NCT00546143).

Cell counting in human endobronchial biopsies--disagreement of 2D versus 3D morphometry.

QUESTION: Inflammatory cell numbers are important endpoints in clinical studies relying on endobronchial biopsies. Assumption-based bidimensional (2D) counting methods are widely used, although theoretically design-based stereologic three-dimensional (3D) methods alone offer an unbiased quantitative tool. We assessed the method agreement between 2D and 3D counting designs in practice when applied to identical samples in parallel. MATERIALS AND METHODS: Biopsies from segmental bronchi were collected from healthy non-smokers (n = 7) and smokers (n = 7), embedded and sectioned exhaustively. Systematic uniform random samples were immunohistochemically stained for macrophages (CD68) and T-lymphocytes (CD3), respectively. In identical fields of view, cell numbers per volume unit (NV) were assessed using the physical disector (3D), and profiles per area unit (NA) were counted (2D). For CD68+ cells, profiles with and without nucleus were separately recorded. In order to enable a direct comparison of the two methods, the zero-dimensional CD68+/CD3+-ratio was calculated for each approach. Method agreement was tested by Bland-Altmann analysis. RESULTS: In both groups, mean CD68+/CD3+ ratios for NV and NA were significantly different (non-smokers: 0.39 and 0.68, p<0.05; smokers: 0.49 and 1.68, p<0.05). When counting only nucleated CD68+ profiles, mean ratios obtained by 2D and 3D counting were similar, but the regression-based Bland-Altmann analysis indicated a bias of the 2D ratios proportional to their magnitude. This magnitude dependent deviation differed between the two groups. CONCLUSIONS: 2D counts of cell and nuclear profiles introduce a variable size-dependent bias throughout the measurement range. Because the deviation between the 3D and 2D data was different in the two groups, it precludes establishing a 'universal conversion formula'.

Omalizumab protects against allergen- induced bronchoconstriction in allergic (immunoglobulin E-mediated) asthma.

BACKGROUND: Omalizumab has been shown to suppress responses to inhaled allergens in allergic asthma patients with pretreatment immunoglobulin E (IgE) ≤700 IU/ml. To extend current dosing tables, we evaluated the potential of high omalizumab doses to block allergen-induced bronchoconstriction in patients with higher IgE levels. METHODS: Asthmatic adults (18-65 years; body weight 40-150 kg) were divided into groups according to screening IgE (group 1: 30-300 IU/ml; group 2: 700-2,000 IU/ml) and randomized 2:1 to omalizumab/placebo every 2 or 4 weeks for 12-14 weeks. Allergen bronchoprovocation (ABP) testing was performed before treatment and at weeks 8 and 16. The primary efficacy endpoint, the early-phase allergic response (EAR), was defined as the maximum percentage drop in forced expiratory volume in 1 s during the first 30 min after ABP. Serum free IgE was determined as a pharmacodynamic endpoint, and the exhaled fractional concentration of nitric oxide (FE(NO)) was an exploratory endpoint. RESULTS: Fifty patients were included in the study. Omalizumab improved EAR; at week 8, EAR was 23.1% for placebo, 9.3% in group 1 (p = 0.018 versus placebo) and 5.6% in group 2 (p < 0.001). At week 16, EAR was 20%, 11.8% (p = 0.087) and 5.1% (p < 0.001), respectively. Free IgE decreased in groups 1 and 2 and remained <50 ng/ml in all patients during weeks 6-16. Omalizumab completely suppressed FE(NO) increases after ABP in both groups. CONCLUSIONS: Omalizumab blocked early asthmatic responses over a broad range of IgE/body weight combinations. Extending the dosing tables enables omalizumab to benefit a wider range of patients.