Postinfectious Bronchiolitis Obliterans

Childhood bronchiolitis obliterans (BO) is an uncommon complication that is characterized clinically by persistent and continuous obstructive respiratory symptoms, and has been described secondary to various etiologic factors, including drugs, exposure to toxic fumes, allergic reactions, collagen vascular disease or infections. BO occurs most commonly in children after an episode of acute bronchiolitis and is considered a long-term sequela of viral infection.Postinfectious Bronchiolitis Obliterans (PIBO) is characterized by persistent airway obstruction with functional and radiological evidence of small airway involvement that is in general unresponsive to bronchodilator treatment.Although the condition is relatively rare, and its exact incidence is unknown, it is important to keep it in mind. PIBO is complication of lower respiratory tract epithelial injury, and is often misdiagnosed, delaying recognition and potential treatment. A PIBO diagnosis is usually based on a few factors, including a good medical history, positive clinical findings, and lung function test and imaging results, although biopsy and histopathology remain as the optimum diagnostic approach. There have to date been few studies proposing treatments for the condition, and no accepted protocol exists in literature. There is usually a fixed airway obstruction in PIBO. Various treatment approaches have been extrapolated from studies of post bone marrow transplantations and lung transplant BO. The clinical course is variable, and good supportive therapy is essential, with anti-inflammatory therapy often being employed.

Beyond Bronchiolitis Obliterans: In-Depth Histopathologic Characterization of Bronchiolitis Obliterans Syndrome after Lung Transplantation

Bronchiolitis obliterans syndrome (BOS) is considered an airway-centered disease, with bronchiolitis obliterans (BO) as pathologic hallmark. However, the histologic spectrum of pure clinical BOS remains poorly characterized. We provide the first in-depth histopathologic description of well-characterized BOS patients and patients without chronic lung allograft dysfunction (CLAD), defined according to the recent consensus guidelines. Explant lung tissue from 52 clinically-defined BOS and 26 non-CLAD patients (collected 1993–2018) was analyzed for histologic parameters, including but not limited to airway lesions, vasculopathy and fibrosis. In BOS, BO lesions were evident in 38 (73%) patients and varied from concentric sub-epithelial fibrotic BO to inflammatory BO, while 10/14 patients without BO displayed ‘vanishing airways’, defined by a discordance between arteries and airways. Chronic vascular abnormalities were detected in 22 (42%) patients. Ashcroft fibrosis scores revealed a median of 43% (IQR: 23–69) of normal lung parenchyma per patient; 26% (IQR: 18–37) of minimal alveolar fibrous thickening; and 11% (IQR: 4–18) of moderate alveolar thickening without architectural damage. Patchy areas of definite fibrotic damage to the lung structure (i.e., Ashcroft score ≥ 5) were present in 28 (54%) patients. Fibrosis was classified as bronchocentric (n = 21/28, 75%), paraseptal (n = 17/28, 61%) and subpleural (n = 15/28, 54%). In non-CLAD patients, BO lesions were absent, chronic vascular abnormalities present in 1 (4%) patient and mean Ashcroft scores were significantly lower compared to BOS (p = 0.0038) with 78% (IQR:64–88) normally preserved lung parenchyma. BOS explant lungs revealed evidence of various histopathologic findings, including vasculopathy and fibrotic changes, which may contribute to the pathophysiology of BOS.

Effects of Alvelestat, an Oral Neutrophil Elastase Inhibitor, on Elevated Elastase and Collagen Turnover Biomarkers in Patients with Bronchiolitis Obliterans Syndrome after Hematopoietic Cell Transplantation

Introduction Bronchiolitis Obliterans Syndrome (BOS) is a rare but devastating complication of chronic graft-versus-host disease (GVHD) after allogeneic hematopoietic cell transplantation (HCT) and is associated with a high morbidity and mortality. There is a dearth of treatment options for BOS and new strategies are needed. Airway neutrophilia is a hallmark of BOS, even in the absence of infection, and neutrophil elastase (NE) is an enzyme that has been implicated in the pathogenesis of BOS. We are conducting a phase 1b study of an oral NE inhibitor, alvelestat, in patients with BOS after HCT . Biomarkers, including the elastin breakdown peptides desmosine/isodesmosine (DES/IDES), and stimulated neutrophil elastase assess direct effect on NE activity. Neo-epitope by-products of collagen type 3 and 6 synthesis (PRO-C3 and PRO-C6) and degradation (C3M and C6M) are measured as biomarkers of fibrosis/tissue modelling Methods Patients age ≥18 years with BOS and chronic GVHD after HCT were recruited to the National Cancer Institute protocol (NCT02669251). This phase 1 study had 2 parts: 8-week intra-patient dose escalation period, followed by a continuation period that allowed for up to 6 months of treatment. Alvelestat was given orally starting at 60mg twice daily, increased every 2 weeks to 120mg twice daily, 180mg twice daily, and finally 240mg twice daily. Peripheral blood samples were collected at baseline and at the end of each dose-escalation stage. Plasma DES/IDES was measured by isotopic dilution liquid chromatography-tandem mass spectrometry (Huang et al Thorax 2012;67:502-508). Ex vivo zymosan stimulated neutrophil elastase activity was measured by ProteaseTag® immunoassay (ProAxsis Ltd, Northern Ireland). PRO-C3, PRO-C6, C3M and C6M were measured by competitive ELISA. (Nordic Biosciences, Denmark). Results are presented as Mean and Standard Error Mean (SEM). Results Between 2016 and 2018, 7 patients were enrolled (3 men and 4 women). Median FEV 1 after bronchodilator at time of enrollment was 44% predicted (range 38-74). All 7 patients were able to tolerate dose escalation of alvelestat up to the maximum dose 240mg twice daily. Preliminary clinical results were previously presented. DES/IDES was elevated at baseline (mean 0.464 (SEM 0.0508) ng/ml, with 6 of 7 subjects above the Upper Limit of Normal (ULN, 0.280 ng/ml)). Levels progressively declined during the dose escalation period to 0.380 (SEM 0.0419) ng/ml by week 8, representing a mean within subject % change from baseline (CFB) of -16.2% (SEM 6.794, Figure 1a) Ex vivo zymosan stimulated elastase activity also showed progressive decrease over the dose escalation period, with some subjects demonstrating 100% suppression (Figure 1b). Collagen synthesis as measured by PRO-C3 and PRO-C6 was increased above ULN at baseline and declined with alvelestat treatment (Figure 1c and 1d). There was no consistent change in collagen degradation biomarkers (C3M, C6M) There was consistency of a suppressive effect on biomarkers of elastase activity and collagen turnover in 6 of 7 treated patients, all of whom had improved or stable lung disease (ranging from change in FEV1 % predicted at end of treatment from +9% to -6%). Conclusion NE can damage lung tissue due to elastin breakdown, pro-inflammatory and pro-fibrotic effects (Sallenave J-M, J Leuk Biol 2015;98:137-139). This is the first evidence of elevated elastase activity as detected by elastin breakdown in patients with BOS and chronic GVHD. Treatment with the selective NE inhibitor, alvelestat was associated with progressive reduction of plasma desmosine levels over 8 weeks of within-subject dose escalation and reduction stimulated neutrophil elastase activity. The consistent suppression of elastase and of collagen synthesis/turnover biomarkers following alvelestat treatment is encouraging for its potential to impact progressive lung fibrosis in BOS and chronic GVHD. Disclosures Parkin: Mereo BioPharma Group: Current Employment. Moore: Mereo BioPharma Group: Current Employment. Pavletic: Center for Cancer Research: Research Funding; National Cancer Institute: Research Funding; National Institutes of Health: Research Funding; Celgene: Research Funding; Actelion: Research Funding; Eli Lilly: Research Funding; Pharmacyclics: Research Funding; Kadmon: Research Funding.

Retrospective Analysis of Bronchiolitis Obliterans Syndrome after Allogeneic Hematopoietic Stem Cell Transplantation

Objective: To explore the incidence, clinical features,risk factors and survival prognosis of bronchiolitis obliterans syndrome (BOS) after allogeneic hematopoietic stem cell transplantation (allo-HSCT) by using large samples form a single center.Provide a prerequisite for improving the early diagnosis of BOS after allo-HSCT. Methods: We retrospectively investigated the case data of 802 patients who underwent allo-HSCT in our institute in petiod of January 1, 2015 to December 31, 2019 and survived more than 100 days. Adopt a multidisciplinary discussion method in the Department of Hematology, Respiratory and Radiology,according to the 2014 National Institutes of Health (NIH) ,diagnose and assess the severity of patiencts with BOS.Describe the clinical characteristics of BOS, and then analyze the risk factors and survival prognosis. Result: Among the 802 patients，46 patients（5.74%), 26males and 20 females with a median age of 32 years was diagnosed BOS.The median time to first appearance of respiratory symptoms was 13.5 months after transplantation, and the median time to diagnosis was 14.4 months.The cumulative incidence rate for 1- year, 2- year, and 5 -year after allo-HSCT is 3.7%, 6.5%, and 8.4%,while the cumulative incidence rate for patients already diagnosed with cGVHD is 7.5%、12.4% and 15.0% . Univariate analysis showed several risk factors associated with the onset of BOS,including the presence of preoperative or postoperative pneumonia,free of ATG ,use of DLI,peripheral blood stem cell transplantation, occurrence of GVHD and the severity and number of these episodes .And multivariate analysis denotes :free of ATG ,use of DLI,and number of organs affected by cGVHD were the variables correlated with increased incidences of BOS. At the onset of BOS, FEV1, FEV1%pred, FEV1/FVC ,FEV1/FVC %pred were significantly lower than those before transplantation. Compare before and after onset, the average decrease rate of FEV1 is 0.17L/month, while FEV1%pred is 5.15%/month.We also recorded the last follow-up lung function to evaluate the treatment efficacy : after treatment, the average FEV1 was 2.46L, the average of FEV1%pred was 36.61%, the average of FEV1/FVC was 45.80%, and the average of FEV1/FVC%pred was 56.36%, before and after treatment., FEV1%pred has no statistical difference (P=0.455).Not only that, there was no statistical difference in the treatment effect among different severity of BOS.The median follow-up time after the diagnosis of BOS was 19 months, and there was no statistical difference in the survival rate between the BOS and non-BOS groups at the end of the follow-up. The analysis result shows that early-onset BOS is a independent risk factors for poor survival time of BOS.Compare BOS with other non-infectious lung complications,the severity of BOS and cGVHD involving extrapulmonary organs are statistically different. Conclusion: BOS is a serious refractory complication after allo-HSCT.Early detection of potential patients with BOS is very difficult , and because most of the BOS patients did not respond to the therapy well, eventually lead to the irreversibility of deterioration of PFT. Compared with other non-infectious lung complications, strong association with severe cGVHD and deterioration of lung function characterized by obstructive ventilation disorder，etc.It suggests that the clinical need to deepen the recognition of BOS, continue to explore the early diagnosis method of BOS , more importantly , strive to give effective treatment at the early stage to improve the prognosis. KEYWORDS Bronchiolitis obliterans Allogeneic hematopoietic stem cell transplantation Risk factors Non-infectious pulmonary complications Disclosures No relevant conflicts of interest to declare.

Ruxolitinib for Bronchiolitis Obliterans Syndrome after Allogeneic Hematopoietic Stem Cell Transplantation

Introduction: Bronchiolitis obliterans syndrome (BOS) is an extremely unfavorable chronic GVHD manifestation with limited therapeutic options. Recent small retrospective series and the only prospective randomized trial have demonstrated different response rates (8.6 - 66.7%) in patients with BOS to JAK1/2 inhibitor ruxolitinib (Streiler C. et al. BMT 2020, Zhao Y. et al. Front. Pharmacol. 2021, Zeiser R. et al. NEJM 2021). Here we report a single-center study of the ruxolitinib efficacy for BOS in adults after HSCT. Methods: The study included 52 patients (median age 33 years (18-58), female 48%) diagnosed with BOS according to the NIH (2014) criteria between 2008 and 2020. The median %FEV1 at BOS diagnosis was 41.6% (20.0-74.1). Severe BOS was present in 44% patients. Due to the previous extrapulmonary cGVHD, the vast majority of patients (81%) had a history of various treatment options, including calcineurin inhibitors, systemic steroids, extracorporeal photopheresis (ECP), tyrosine kinase inhibitors (TKIs imatinib, dasatinib) and ruxolitinib. After BOS diagnosis the following treatments were administered: a FAM-like regimen (fluticasone, azithromycin and montelukast) (94%), CNIs (50%), mTOR inhibitor (35%), systemic corticosteroids (52%), ECP (25%) or low-dose rIL-2 (19%) as the first and subsequent lines of therapy. Seventeen patients (33%) received TKIs. A total of 20 BOS patients received ruxolitinib (median dose of 15 mg/day). The remaining 32 patients were included in the control group. The response was assessed by the dynamics of FEV1 according to the NIH scale (2014): partial response (PR, ≥10% increase in FEV1), stabilization (<10% change), progression (≥10% decrease) (n=45), as well as clinically by the degree of dyspnea according to the NIH symptom-based lung score and mMRC scale with PR defined as a decrease in dyspnea by at least 1 point (n=52). The overall survival (OS) was assessed with the Kaplan-Meier method from the moment of BOS diagnosis. Results: At a median follow up of 27 months (5-102) in the ruxolitinib group, 5 (26%) patients achieved PR criteria, while BOS stabilization and progression was observed in 7 (37%) cases each. In the control group, PR, stabilization and progression were documented in 3 (12%, p=0.253), 17 (65%) and 6 (23%) cases respectively (Fig.1). The clinical evaluation of dyspnea also did not reveal statistically significant differences in PR rate: 15% vs 19% according to NIH-CC and 30% vs 31% according to mMRC scale (p = 1.0). Systemic steroids were used less frequently in the ruxolitinib group (35% versus 63%, p = 0.049). As of July 1, 2021, 32 (62%) patients were alive. Twenty patients died due to cGVHD and infectious complications (n = 16, 80%) or underlying disease relapse (n = 4, 20%). As a result, the 5-year OS was 54.4% (95% CI, 36.7-69.1) with no statistically significant differences between ruxolitinib and control groups: 59.1% (95% CI, 25.6-81.6) vs 50.2 (95% CI, 29.5-67.7) (p=0.387). Conclusions: In comparison with the retrospective control group, ruxolitinib showed no significant benefit in FEV1-based and clinical response rate in patients with BOS after HSCT. However, ruxolitinib therapy provides a more frequent systemic steroid-free strategy. These data are consistent with the results of REACH3 (Zeiser R. et al. NEJM 2021). Despite very positive results of ruxolitinib in the general cGVHD population, BOS remains an unsolved problem. Novel approaches are required. Figure 1 Figure 1. Disclosures No relevant conflicts of interest to declare. OffLabel Disclosure: Ruxolitinib for BOS in the settings of cGVHD