Update on the Pathogenic Mechanisms of Isocyanate-induced Asthma

Background The pathogenic mechanisms of toluene diisocyanate (TDI)-induced asthma are not understood clearly.Methods In this review, we summarized recent data to further understand the pathogenic mechanisms through recent approach of molecular genetic studies, and specific antibody responses to cellular mechanisms.Results Genetic polymorphism studies suggested the involvement of oxidant/antioxidant-related genes and neurogenic inflammatory response genes. A high-resolution technique of HLA allele suggested some HLA genetic markers presenting the phenotype of TDI-induced asthma. The new volatile type of TDI-human serum albumin conjugate could improve specific immunoglobulin E and immunoglobulin G bindings in enzyme-linked immunosorbent assay studies for identifying TDI-induced asthma patients. The role of bronchial epithelial cells and cytokeratins derived from epithelial cells could be involved in autoantibody productions, suggesting that an autoimmune mechanism may be involved in airway inflammation. Neutrophil activation and oxidant/antioxidant-related mechanisms were also suggested.Conclusion The pathogenic mechanism of TDI-induced asthma is complicated as various humoral and cellular mechanisms are combined and involved differently on an individual basis. Therefore, additional efforts for further elucidation should follow. Keywords: asthma, genetic polymorphism, HLA, specific IgE, specific IgG, toluene diisocyanat

Clinical predictors of treatment response to tiotropium add-on therapy in adult asthmatic patients: From multicenter real-world cohort data in Korea

Background: Tiotropium, a long-acting muscarinic antagonist, is recommended for add-on therapy to inhaled corticosteroids (ICS)-long-acting beta 2 agonists (LABA) for severe asthma. However, real-world studies on the predictors of response to tiotropium are limited. We investigated the real-world use of tiotropium in asthmatic adult patients in Korea and we identified predictors of positive response to tiotropium add-on. Methods: We performed a multicenter, retrospective, cohort study using data from the Cohort for Reality and Evolution of Adult Asthma in Korea (COREA). We enrolled asthmatic participants who took ICS-LABA with at least 2 consecutive lung function tests at 3-month intervals. We compared tiotropium users and non-users, as well as tiotropium responders and non-responders to predict positive responses to tiotropium, defined as 1) increase in forced expiratory volume in 1 s (FEV1) ≥ 10% or 100 mL; and 2) increase in asthma control test (ACT) score ≥3 after 3 months of treatment. Results: The study included 413 tiotropium users and 1756 tiotropium non-users. Tiotropium users had low baseline lung function and high exacerbation rate, suggesting more severe asthma. Clinical predictors for positive response to tiotropium add-on were 1) positive bronchodilator response (BDR) [odds ratio (OR) = 6.8, 95% confidence interval (CI): 1.6–47.4, P = 0.021] for FEV1 responders; 2) doctor-diagnosed asthma-chronic obstructive pulmonary disease overlap (ACO) [OR = 12.6, 95% CI: 1.8–161.5, P = 0.024], and 3) initial ACT score <20 [OR = 24.1, 95% CI: 5.45–158.8, P < 0.001] for ACT responders. FEV1 responders also showed a longer exacerbation-free period than those with no FEV1 increase (P = 0.014), yielding a hazard ratio for the first asthma exacerbation of 0.5 (95% CI: 0.3–0.9, P = 0.016). Conclusions: The results of this study suggest that tiotropium add-on for uncontrolled asthma with ICS-LABA would be more effective in patients with positive BDR or ACO. Additionally, an increase in FEV1 following tiotropium may predict a lower risk of asthma exacerbation

A comparison of treatment response to biologics in asthma-COPD overlap and pure asthma: Findings from the PRISM study

Background: Despite the increasing use of biologics in severe asthma, there is limited research on their use in asthma-chronic obstructive pulmonary disease overlap (ACO). We compared real-world treatment responses to biologics in ACO and asthma. Methods: We conducted a multicenter, retrospective, cohort study using data from the Precision Medicine Intervention in Severe Asthma (PRISM). ACO was defined as post-bronchodilator forced expiratory volume in 1 s (FEV1)/forced vital capacity (FVC) 10 pack-years. Physicians selected biologics (omalizumab, mepolizumab, reslizumab, benralizumab, and dupilumab) based on each United States Food &amp; Drug Administration (FDA) approval criteria. Results: After six-month treatment with biologics, both patients with ACO (N = 13) and asthma (N = 81) showed positive responses in FEV1 (10.69 ± 17.17 vs. 11.25 ± 12.87 %, P = 0.652), Asthma Control Test score (3.33 ± 5.47 vs. 5.39 ± 5.42, P = 0.290), oral corticosteroid use (−117.50 ± 94.38 vs. −115.06 ± 456.85 mg, P = 0.688), fractional exhaled nitric oxide levels (−18.62 ± 24.68 vs. −14.66 ± 45.35 ppb, P = 0.415), sputum eosinophils (−3.40 ± 10.60 vs. −14.48 ± 24.01 %, P = 0.065), blood eosinophils (−36.47 ± 517.02 vs. −363.22 ± 1294.59, P = 0.013), and exacerbation frequency (−3.07 ± 4.42 vs. −3.19 ± 5.11, P = 0.943). The odds ratio for exacerbation and time-to-first exacerbation showed no significant difference after full adjustments, and subgroup analysis according to biologic type was also showed similar results. Conclusions: Biologics treatment response patterns in patients with ACO and asthma were comparable, suggesting that biologics should be actively considered for ACO patients as well

Sparsentan in patients with IgA nephropathy: a prespecified interim analysis from a randomised, double-blind, active-controlled clinical trial

Background: Sparsentan is a novel, non-immunosuppressive, single-molecule, dual endothelin and angiotensin receptor antagonist being examined in an ongoing phase 3 trial in adults with IgA nephropathy. We report the prespecified interim analysis of the primary proteinuria efficacy endpoint, and safety. Methods: PROTECT is an international, randomised, double-blind, active-controlled study, being conducted in 134 clinical practice sites in 18 countries. The study examines sparsentan versus irbesartan in adults (aged ≥18 years) with biopsy-proven IgA nephropathy and proteinuria of 1·0 g/day or higher despite maximised renin-angiotensin system inhibitor treatment for at least 12 weeks. Participants were randomly assigned in a 1:1 ratio to receive sparsentan 400 mg once daily or irbesartan 300 mg once daily, stratified by estimated glomerular filtration rate at screening (30 to 1·75 g/day). The primary efficacy endpoint was change from baseline to week 36 in urine protein-creatinine ratio based on a 24-h urine sample, assessed using mixed model repeated measures. Treatment-emergent adverse events (TEAEs) were safety endpoints. All endpoints were examined in all participants who received at least one dose of randomised treatment. The study is ongoing and is registered with ClinicalTrials.gov, NCT03762850. Findings: Between Dec 20, 2018, and May 26, 2021, 404 participants were randomly assigned to sparsentan (n=202) or irbesartan (n=202) and received treatment. At week 36, the geometric least squares mean percent change from baseline in urine protein-creatinine ratio was statistically significantly greater in the sparsentan group (-49·8%) than the irbesartan group (-15·1%), resulting in a between-group relative reduction of 41% (least squares mean ratio=0·59; 95% CI 0·51-0·69; p<0·0001). TEAEs with sparsentan were similar to irbesartan. There were no cases of severe oedema, heart failure, hepatotoxicity, or oedema-related discontinuations. Bodyweight changes from baseline were not different between the sparsentan and irbesartan groups. Interpretation: Once-daily treatment with sparsentan produced meaningful reduction in proteinuria compared with irbesartan in adults with IgA nephropathy. Safety of sparsentan was similar to irbesartan. Future analyses after completion of the 2-year double-blind period will show whether these beneficial effects translate into a long-term nephroprotective potential of sparsentan. Funding: Travere Therapeutics