Lung histology predicts outcome of bronchiolitis obliterans syndrome after hematopoietic stem cell transplantation

Current Approaches for the Prevention and Treatment of Acute and Chronic GVHD

Whereas aGVHD has strong inflammatory components, cGVHD displays autoimmune and fibrotic features; incidence and risk factors are similar but not identical; indeed, the aGVHD is the main risk factor for cGVHD. Calcineurin Inhibitors (CNI) with either Methotrexate (MTX) or Mycophenolate (MMF) still represent the standard prophylaxis in HLA-matched allogeneic stem cell transplantation (HSCT); other strategies focused on ATG, Post-Transplant Cyclophosphamide (PTCy), Abatacept and graft manipulation. Despite the high rate, first-line treatment for aGVHD is represented by corticosteroids, and Ruxolitinib is the standard second-line therapy; investigational approaches include Microbiota transplant and the infusion of Mesenchymal stem cells. GVHD is a pleiotropic disease involving any anatomical district; also, Ruxolitinib represents the standard for steroid-refractory cGVHD in this setting. It is a pleiotropic disease involving any anatomical district; also, Ruxolitinib represents the standard for steroid-refractory cGVHD in this setting. Extracorporeal Photopheresis (ECP) is still an option used for steroid refractoriness or to achieve a steroid-sparing. For Ruxolitinib-refractory cGVHD, Belumosudil and Axatilimab represent the most promising agents. Bronchiolitis obliterans syndrome (BOS) still represents a challenge; among the compounds targeting non-immune effectors, Alvelestat, a Neutrophil elastase inhibitor, seems promising in BOS. Finally, in both aGVHD and cGVHD, the association of biological markers with specific disease manifestations could help refine risk stratification and the availability of reliable biomarkers for specific treatments.

Lung biopsy in the diagnosis and management of chILD

Children's interstitial and diffuse lung disease (chILD) comprises a large number of diverse entities ranging from disorders of lung development, maturation and function unique in infancy to immune-mediated, environmental, vascular and other conditions overlapping with adult disease. Pathologic evaluation of the lung has played a central role in characterizing many of these disorders, resulting in revised nomenclature and classifications to help guide clinical management(1-4). Technological advancements are rapidly uncovering genetic and molecular underpinnings of these conditions, as well as widening the phenotypes which bridge adult disease, often reducing the perceived need for diagnostic lung biopsy. As such the decision to get a lung biopsy in chILD is frequently for rapid ascertainment of disease in a critically ill child or when clinical presentation, imaging and laboratory studies fail to provide a cohesive diagnosis needed for treatment. While there have been modifications in surgical procedures for lung biopsy that minimize postoperative morbidity, it remains a high-risk invasive procedure, especially in a medically complex patient(5). Thus, it is essential that the lung biopsy be handled properly to maximize diagnostic yield, including close communication between the clinician, radiologist, surgeon, and pathologist before biopsy to determine best sampling site(s) and prioritization of tissue utilization. This review provides an overview of optimal handling and evaluation of a surgical lung biopsy for suspected chILD, with emphasis on specific conditions in which pathologic features play a critical role in providing an integrated diagnosis and guiding management.

Detection of Bronchiolitis Obliterans Syndrome after Pediatric Hematopoietic Stem Cell Transplantation: An Official American Thoracic Society Clinical Practice Guideline

Background: Many children undergo allogeneic hematopoietic stem cell transplantation (HSCT) for the treatment of malignant and nonmalignant conditions. Unfortunately, pulmonary complications occur frequently post-HSCT, with bronchiolitis obliterans syndrome (BOS) being the most common noninfectious pulmonary complication. Current international guidelines contain conflicting recommendations regarding post-HSCT surveillance for BOS, and a recent NIH workshop highlighted the need for a standardized approach to post-HSCT monitoring. As such, this guideline provides an evidence-based approach to detection of post-HSCT BOS in children. Methods: A multinational, multidisciplinary panel of experts identified six questions regarding surveillance for, and evaluation of, post-HSCT BOS in children. A systematic review of the literature was undertaken to answer each question. The Grading of Recommendations, Assessment, Development, and Evaluation approach was used to rate the quality of evidence and the strength of recommendations. Results: The panel members considered the strength of each recommendation and evaluated the benefits and risks of applying the intervention. In formulating the recommendations, the panel considered patient and caregiver values, the cost of care, and feasibility. Recommendations addressing the role of screening pulmonary function testing and diagnostic tests in children with suspected post-HSCT BOS were made. Following a Delphi process, new diagnostic criteria for pediatric post-HSCT BOS were also proposed. Conclusions: This document provides an evidence-based approach to the detection of post-HSCT BOS in children while also highlighting considerations for the implementation of each recommendation. Further, the document describes important areas for future research.

Diagnosis of Post-Hematopoietic Stem Cell Transplantation Bronchiolitis Obliterans Syndrome in Children: Time for a Rethink?

Hematopoietic stem cell transplantation (HSCT) is undertaken in children with the aim of curing a range of malignant and nonmalignant conditions. Unfortunately, pulmonary complications, especially bronchiolitis obliterans syndrome (BOS), are significant sources of morbidity and mortality post-HSCT. Currently, criteria developed by a National Institutes of Health (NIH) working group are used to diagnose BOS in children post-HSCT. Unfortunately, during the development of a recent American Thoracic Society (ATS) Clinical Practice Guideline on this topic, it became apparent that the NIH criteria have significant limitations in the pediatric population, leading to late diagnosis of BOS. Specific limitations include use of an outdated pulmonary function testing reference equation, a reliance on spirometry, use of a fixed forced expiratory volume in 1 second (FEV1) threshold, focus on obstructive defects defined by FEV1/vital capacity, and failure to acknowledge that BOS and infection can coexist. In this review, we summarize the evidence regarding the limitations of the current criteria. We also suggest potential evidence-based ideas for improving these criteria. Finally, we highlight a new proposed criteria for post-HSCT BOS in children that were developed by the authors of the recently published ATS clinical practice guideline, along with a pathway forward for improving timely diagnosis of BOS in children post-HSCT.

Multiple breath washout and oscillometry after allogenic HSCT: a scoping review

Pulmonary chronic graft-versus-host disease (cGVHD) is a substantial cause of pulmonary morbidity and mortality post-haematopoietic stem cell transplantation (HSCT). Current spirometry-based monitoring strategies have significant limitations. Understanding the utility of novel peripheral airway function tests - multiple breath washout (MBW) and oscillometry - is critical in efforts to improve detection, facilitate earlier intervention and improve outcomes. In this scoping review, we identified 17 studies investigating MBW or oscillometry, or both, after allogenic HSCT. Despite small study numbers limiting the ability to draw firm conclusions, several themes were evident. Detectable peripheral airway abnormality in MBW occurred in a substantial proportion prior to HSCT. MBW indices post-HSCT were more frequently abnormal than spirometry when reporting group data and among those with extrapulmonary cGVHD and pulmonary cGVHD. Changes in MBW indices over time may be more indicative of pulmonary complications than absolute values at any given time point. Oscillometry indices were often normal at baseline, but more frequently abnormal in those who developed pulmonary cGVHD. Pooling currently available individual participant data across these studies may improve our ability to formally compare their respective sensitivity and specificity at specific time points and assess the trajectory of MBW and oscillometry indices over time.

A Nasal Inflammatory Cytokine Signature Is Associated with Early Graft-versus-Host Disease of the Lung after Allogeneic Hematopoietic Cell Transplantation: Proof of Concept

Respiratory inflammation in bronchiolitis obliterans syndrome (BOS) after hematopoietic cell transplantation (HCT) is poorly understood. Clinical criteria for early-stage BOS (stage 0p) often capture HCT recipients without BOS. Measuring respiratory tract inflammation may help identify BOS, particularly early BOS. We conducted a prospective observational study in HCT recipients with new-onset BOS (n = 14), BOS stage 0p (n = 10), and recipients without lung impairment with (n = 3) or without (n = 8) chronic graft-versus-host disease and measured nasal inflammation using nasosorption at enrollment and then every 3 mo for 1 y. We divided BOS stage 0p into impairment that did not return to baseline values (preBOS, n = 6), or transient impairment (n = 4). We tested eluted nasal mucosal lining fluid from nasosorption matrices for inflammatory chemokines and cytokines using multiplex magnetic bead immunoassays. We analyzed between-group differences using the Kruskal-Wallis method, adjusting for multiple comparisons. We found increased nasal inflammation in preBOS and therefore directly compared patients with preBOS to those with transient impairment, as this would be of greatest diagnostic relevance. After adjusting for multiple corrections, we found significant increases in growth factors (FGF2, TGF-α, GM-CSF, VEGF), macrophage activation (CCL4, TNF-α, IL-6), neutrophil activation (CXCL2, IL-8), T cell activation (CD40 ligand, IL-2, IL-12p70, IL-15), type 2 inflammation (eotaxin, IL-4, IL-13), type 17 inflammation (IL-17A), dendritic maturation (FLT3 ligand, IL-7), and counterregulatory molecules (PD-L1, IL-1 receptor antagonist, IL-10) in preBOS patients compared to transient impairment. These differences waned over time. In conclusion, a transient multifaceted nasal inflammatory response is associated with preBOS. Our findings require validation in larger longitudinal cohorts.

Bronchiolitis obliterans syndrome after lung or haematopoietic stem cell transplantation: current management and future directions

Bronchiolitis obliterans syndrome (BOS) may develop after either lung or haematopoietic stem cell transplantation (HSCT), with similarities in histopathological features and clinical manifestations. However, there are differences in the contributory factors and clinical trajectories between the two conditions. BOS after HSCT occurs due to systemic graft-versus-host-disease (GVHD), whereas BOS after lung transplantation is limited to the lung allograft. BOS diagnosis after HSCT is more challenging, as the lung function decline may occur due to extrapulmonary GVHD, causing sclerosis or inflammation in the fascia or muscles of the respiratory girdle. Treatment is generally empirical with no established effective therapies. This review provides rare insights and commonalities of both conditions, that are not well elaborated elsewhere in contemporary literature, and highlights the importance of cross disciplinary learning from experts in other transplant modalities. Treatment algorithms for each condition are presented, based on the published literature and consensus clinical opinion. Immunosuppression should be optimised, and other conditions or contributory factors treated where possible. When initial treatment fails, the ultimate therapeutic option is lung transplantation (or re-transplantation in the case of BOS after lung transplantation) in carefully selected candidates. Novel therapies under investigation include aerosolised liposomal cyclosporine, Janus kinase inhibitors, antifibrotic therapies, and (in patients with BOS after lung transplantation) B-cell–directed therapies. Effective novel treatments that have a tangible impact on survival and thereby avoid the need for lung transplantation or re-transplantation are urgently required.

The economic burden of NIPC and BOS following allogeneic HSCT in patients with commercial insurance in the United States

Noninfectious pulmonary complications (NIPC) after allogeneic hematopoietic stem cell transplantation (alloHSCT), including bronchiolitis obliterans syndrome (BOS), cause significant morbidity and mortality, but their impact on health care resource utilization (HRU) and costs is unknown. This longitudinal retrospective study quantified the economic burden of NIPC and BOS in alloHSCT patients using commercial claims data from the IQVIA PharMetrics Plus database. Study patients were aged 0 to 64 years and underwent alloHSCT between 1 January 2006 and 30 September 2018, and were observable 12 months before and up to 5 years after index alloHSCT. NIPC patients were identified using International Classification of Disease (ICD) diagnosis codes. Outcomes were mean per patient HRU (inpatient admissions, outpatient office, hospital visits, and prescription medications) and costs paid by insurers in each post-transplant year. Among 2162 alloHSCT patients, 254 developed NIPCs, and 155 were propensity score (PS)-matched to non-NIPC patients. The year following transplantation, NIPC patients had significantly higher inpatient admission rates (3.8 ± 3.2 vs non-NIPC: 2.6 ± 2.4; P < .001) and higher total costs ($567 870 vs $412 400; P = .07), reflecting higher costs for inpatient admissions ($452 475 vs $300 202; P = .06). Among those observable for more years, costs remained higher for NIPC patients, reflecting significantly higher inpatient admission rates in the first 3 years following transplant. Subanalysis of patients with diagnoses likely reflective of BOS were consistent with these findings. AlloHSCT patients who developed NIPC had higher health care resource utilization and incurred higher costs compared with alloHSCT patients who did not develop NIPC following transplant.

Airway disease in hematologic malignancies

INTRODUCTION

Hematologic malignancies are cancers of the blood, bone marrow and lymph nodes and represent a heterogenous group of diseases that affect people of all ages. Treatment generally involves chemotherapeutic or targeted agents that aim to kill malignant cells. In some cases, hematopoietic stem cell transplantation (HCT) is required to replenish the killed blood and stem cells. Both disease and therapies are associated with pulmonary complications. As survivors live longer with the disease and are treated with novel agents that may result in secondary immunodeficiency, airway diseases and respiratory infections will increasingly be encountered. To prevent airways diseases from adding to the morbidity of survivors or leading to long-term mortality, improved understanding of the pathogenesis and treatment of viral bronchiolitis, BOS, and bronchiectasis is necessary.

AREAS COVERED

This review focuses on viral bronchitis, BOS and bronchiectasis in people with hematological malignancy. Literature was reviewed from Pubmed for the areas covered.

EXPERT OPINION

Airway disease impacts significantly on hematologic malignancies. Viral bronchiolitis, BOS and bronchiectasis are common respiratory manifestations in hematological malignancy. Strategies to identify patients early in their disease course may improve the efficacy of treatment and halt progression of lung function decline and improve quality of life.

Home-Based Spirometry Telemonitoring After Allogeneic Hematopoietic Cell Transplantation: Mixed Methods Evaluation of Acceptability and Usability

BACKGROUND

Home-based spirometry (HS) allows for the early detection of lung complications in recipients of an allogeneic hematopoietic cell transplant (AHCT). Although the usability and acceptability of HS are critical for adherence, patient-reported outcomes of HS use remain poorly understood in this setting.

OBJECTIVE

The aim of this study is to design a longitudinal, mixed methods study to understand the usability and acceptability of HS among recipients of AHCT.

METHODS

Study participants performed HS using a Bluetooth-capable spirometer that transmitted spirometry data to the study team in real time. In addition, participants completed usability questionnaires and in-depth interviews and reported their experiences with HS. Analysis of interview data was guided by the constructs of performance expectancy, effort expectancy, and social influence from the Unified Theory of Acceptance and Use of Technology model.

RESULTS

Recipients of AHCT found HS to be highly acceptable despite modest technological barriers. On average, participants believed that the HS was helpful in managing symptoms related to AHCT (scores ranging from 2.22 to 2.68 on a scale of 0-4) and for early detection of health-related problems (score range: 2.88-3.12). Participants viewed HS favorably and were generally supportive of continued use. No significant barriers to implementation were identified from the patient's perspective. Age and gender were not associated with the patient perception of HS.

CONCLUSIONS

Study participants found HS acceptable and easy to use. Some modifiable technical barriers to performing HS were identified; however, wider implementation of pulmonary screening is feasible from the patient's perspective.

National Institutes of Health Consensus Development Project on Criteria for Clinical Trials in Chronic Graft-versus-Host Disease: IV. The 2020 Highly morbid forms report

Chronic graft-versus-host disease (GVHD) can be associated with significant morbidity, in part because of nonreversible fibrosis, which impacts physical functioning (eye, skin, lung manifestations) and mortality (lung, gastrointestinal manifestations). Progress in preventing severe morbidity and mortality associated with chronic GVHD is limited by a complex and incompletely understood disease biology and a lack of prognostic biomarkers. Likewise, treatment advances for highly morbid manifestations remain hindered by the absence of effective organ-specific approaches targeting "irreversible" fibrotic sequelae and difficulties in conducting clinical trials in a heterogeneous disease with small patient numbers. The purpose of this document is to identify current gaps, to outline a roadmap of research goals for highly morbid forms of chronic GVHD including advanced skin sclerosis, fasciitis, lung, ocular and gastrointestinal involvement, and to propose strategies for effective trial design. The working group made the following recommendations: (1) Phenotype chronic GVHD clinically and biologically in future cohorts, to describe the incidence, prognostic factors, mechanisms of organ damage, and clinical evolution of highly morbid conditions including long-term effects in children; (2) Conduct longitudinal multicenter studies with common definitions and research sample collections; (3) Develop new approaches for early identification and treatment of highly morbid forms of chronic GVHD, especially biologically targeted treatments, with a special focus on fibrotic changes; and (4) Establish primary endpoints for clinical trials addressing each highly morbid manifestation in relationship to the time point of intervention (early versus late). Alternative endpoints, such as lack of progression and improvement in physical functioning or quality of life, may be suitable for clinical trials in patients with highly morbid manifestations. Finally, new approaches for objective response assessment and exploration of novel trial designs for small populations are required.

Lung hyperinflation quantitated by chest CT in children with bronchiolitis obliterans syndrome following allogeneic hematopoietic cell transplantation

OBJECTIVES

Bronchiolitis obliterans syndrome (BOS) diagnosis in children following allogeneic hematopoietic stem cell transplantation (post-HSCT) is based on detection of airway obstruction on spirometry and air-trapping, small airway thickening or bronchiectasis on chest CT. We assessed the relationship between spirometry indices and low-attenuation lung volume at total lung capacity (TLC) on CT.

METHODS

Data of children post-HSCT with and without BOS were analyzed. An age-specific, low-attenuation threshold (LAT) was defined as average of (mean-1SD) lung parenchyma attenuation of 5 control subjects without lung disease matched to each age subgroup of post-HSCT patients. % CT lung volume at TLC with attenuation values <LAT was calculated. Association between % lung volume with low attenuation and FEV₁/FVC was assessed.

RESULTS

Twenty-nine children post-HSCT were referred to exclude BOS and 12 of them had spirometry and an analyzable chest CT. We studied: (i) 6 children post-HSCT/BOS (median age: 8.5 years [IQR 7, 15]; median FEV₁/FVC z-score: -2.60 [IQR -2.93, -2.14]); (ii) 6 children post-HSCT/no BOS (age: 13.5 years [9.8, 16.3]; FEV₁/FVC z-score: 0.44 [-0.30, 2.10]); and (iii) 40 controls without lung disease (age:11 years [8.3, 15.8]). Patients post-HSCT/BOS had significantly higher % lung volume with low attenuation than patients post-HSCT/no BOS: median % volume 16.4% (7.1%, 37.2%) vs. 0.61% (0.34%, 2.79%), respectively; P = .004. An exponential model described the association between % CT lung volume below LAT and FEV₁/FVC z-score (r² = 0.76; P < .001).

CONCLUSION

In children post-HSCT with BOS, low-attenuation lung volume on chest CT is associated with airway obstruction severity as expressed by FEV₁/FVC z-score.

Lung Function Predicts Outcome in Children With Obstructive Lung Disease After Hematopoietic Stem Cell Transplantation

Obstructive lung disease (OLD) that develops after hematopoietic stem cell transplantation (HSCT) has a significant impact on morbidity and mortality. We investigated the role of pulmonary function tests (PFTs) in the prediction of prognosis of OLD in children who have undergone HSCT. We retrospectively reviewed 538 patients who underwent allogenic HSCT in the Department of Pediatrics, Seoul St. Mary's Hospital, South Korea, from April 2009 to July 2017. OLD was identified on PFTs or chest computed tomography scans obtained from 3 months after HSCT onwards. OLD developed after HSCT in 46 patients (28 male individuals, median age: 11.2 y). The group that developed OLD with an unfavorable prognosis (n=23) had a lower forced vital capacity (FVC) (% of predicted, 78.53±24.00 vs. 97.71±16.96, P=0.01), forced expiratory volume in 1 second (FEV1) (% of predicted, 52.54±31.77 vs. 84.44±18.59, P=0.00), FEV1/FVC (%, 59.28±18.68 vs. 79.94±9.77, P=0.00), and forced expiratory flow at 25% to 75% of forced vital capacity (FEF25-75) (% of predicted, 30.95±39.92 vs. 57.82±25.71, P=0.00) at diagnosis than the group that developed OLD with a favorable prognosis (n=23). The group that developed OLD with an unfavorable prognosis had significant reductions in FVC, FEV1, FEV1/FVC, and FEF25-75 at 2 years after diagnosis. Children who develop OLD with an unfavorable prognosis after HSCT already have poor lung function at the time of diagnosis. Additional treatment should be considered in patients who develop OLD after HSCT according to their PFTs at diagnosis.

Machine Learning Algorithms to Differentiate Among Pulmonary Complications After Hematopoietic Cell Transplant

BACKGROUND

Pulmonary complications, including infections, are highly prevalent in patients after hematopoietic cell transplantation with chronic graft-vs-host disease. These comorbid diseases can make the diagnosis of early lung graft-vs-host disease (bronchiolitis obliterans syndrome) challenging. A quantitative method to differentiate among these pulmonary diseases can address diagnostic challenges and facilitate earlier and more targeted therapy.

STUDY DESIGN AND METHODS

We conducted a single-center study of 66 patients with CT chest scans analyzed with a quantitative imaging tool known as parametric response mapping. Parametric response mapping results were correlated with pulmonary function tests and clinical characteristics. Five parametric response mapping metrics were applied to K-means clustering and support vector machine models to distinguish among posttransplantation lung complications solely from quantitative output.

RESULTS

Compared with parametric response mapping, spirometry showed a moderate correlation with radiographic air trapping, and total lung capacity and residual volume showed a strong correlation with radiographic lung volumes. K-means clustering analysis distinguished four unique clusters. Clusters 2 and 3 represented obstructive physiology (encompassing 81% of patients with bronchiolitis obliterans syndrome) in increasing severity (percentage air trapping 15.6% and 43.0%, respectively). Cluster 1 was dominated by normal lung, and cluster 4 was characterized by patients with parenchymal opacities. A support vector machine algorithm differentiated bronchiolitis obliterans syndrome with a specificity of 88%, sensitivity of 83%, accuracy of 86%, and an area under the receiver operating characteristic curve of 0.85.

INTERPRETATION

Our machine learning models offer a quantitative approach for the identification of bronchiolitis obliterans syndrome vs other lung diseases, including late pulmonary complications after hematopoietic cell transplantation.

Managing pulmonary complications in allogeneic hematopoietic stem cell transplantation

Introduction: Progress in allogeneic hematopoietic stem cell transplantation (HSCT) procedures has been associated with improved survival in HSCT recipients. However, they have also brought to light organ-specific complications, especially pulmonary complications. In this setting, pulmonary complications are consistently associated with poor outcomes, and improved management of these complications is required. Areas covered: We review the multiple infectious and noninfectious lung complications that occur both early and late after allogeneic HSCT. This includes the description of these complications, risk factors, diagnostic approach and outcome. A literature search was performed using PubMed-indexed journals. Expert commentary: Multiple lung complications after allogeneic HSCT can be diagnosed concomitantly and require a multidisciplinary approach. A specific clinical evaluation including a precise analysis of a lung CT scan is necessary. Management of these lung complications, especially the noninfectious ones, is impaired by the lack of prospective, randomized control trials, suggesting preventive strategies should be developed.

Lung histopathology of non-infectious pulmonary complications after allogeneic haematopoietic stem cell transplantation

AIMS

Non-infectious pulmonary complications (NIPCs) occur frequently following allogeneic haematopoietic stem cell transplantation (HSCT). As there is no consensus on the description of the related pulmonary pathological lesions, pathologist reports and clinical conclusions are largely inconsistent in routine practice. The aim of our study was to provide an accurate overview of post-allogeneic HSCT NIPCs from a large number of lung biopsies.

METHODS AND RESULTS

We reviewed 61 lung biopsies in patients with an NIPC, including 51 surgical lung biopsies, four post-mortem biopsies and six lung explants. We found both bronchiolar (n = 59) and alveolar/interstitial pathologies (n = 27). We describe two types of bronchiolar lesions: bronchiolectasies (n = 37) and fibrous and cellular lesions with luminal narrowing (n = 43). We found a wide spectrum of airway/interstitial pathologies that were labelled using the terminology of the 2013 American Thoracic Society and European Respiratory Society (ATS/ERS) classification of idiopathic interstitial pneumonias (IIPs), including the following: organising pneumonia (OP, n = 8), non-specific interstitial pneumonia (NSIP, n = 9), diffuse alveolar damage (DAD, n = 6), lymphoid interstitial pneumonia (LIP, n = 1) and pleuroparenchymal fibroelastosis (PPFE, n = 2), as well as one instance of associated PPFE and NSIP.

CONCLUSIONS

Interstitial pathology was associated with bronchiolar lesions in 41% of the cases reviewed (n = 25). Lung airway and interstitial inflammation was still present in lung explants from patients who underwent lung transplantation for post-allogeneic HSCT end-stage respiratory insufficiency. Herein, we describe a wide spectrum of pathological lung lesions encountered in post-allogeneic HSCT NIPCs.

High-Resolution CT Findings of Obstructive and Restrictive Phenotypes of Chronic Lung Allograft Dysfunction: More Than Just Bronchiolitis Obliterans Syndrome

OBJECTIVE

The purpose of this article is to review the high-resolution CT characteristics of individual obstructive and restrictive chronic lung allograft dysfunction (CLAD) phenotypes to aid in making accurate diagnoses and guiding treatment.

CONCLUSION

Long-term survival and function after lung transplant are considerably worse compared with after other organ transplants. CLAD is implicated as a major limiting factor for long-term graft viability. Historically thought to be a single entity, bronchiolitis obliterans syndrome, CLAD is actually a heterogeneous group of disorders with distinct subtypes.

Noninfectious lung complications after allogeneic haematopoietic stem cell transplantation

Epidemiological data on late-onset noninfectious pulmonary complications (LONIPCs) following allogeneic haematopoietic stem cell transplantation (HSCT) are derived exclusively from retrospective studies and are conflicting. We aimed to evaluate prospectively the incidence, risk factors and outcomes for LONIPCs.All consecutive patients scheduled to receive allogeneic HSCT between 2006 and 2008 at a university teaching hospital in France were screened for inclusion in the study. Eligible patients were those surviving at day 100. Among 243 screened patients, 198 patients were included in the analysis. The median (interquartile range) follow-up was 72.3 (15.2-88.5) months. 55 LONIPCs were diagnosed in 43 patients. Bronchiolitis obliterans syndrome (n=22) and interstitial lung disease (n=12) were the most common LONIPCs. At 36 months after inclusion, the estimated cumulative incidence of LONIPCs was 19.8% (95% CI 14.2-25.3%). The estimated median survival after the diagnosis of LONIPCs was 78.5 months (95% CI 20.0-not reached). Based on a multivariate Cox model, a history of chest irradiation anytime prior to HSCT, a history of pneumonia within 100 days post-HSCT and a low mean forced expiratory flow at 25-75% of forced vital capacity at day 100 were associated with the development of LONIPCs.Our data provide clues to identify patients at high risk of developing LONIPCs. These patients should be targeted for close monitoring to provide earlier LONIPC treatment or prophylactic treatment.

Bronchiolitis Obliterans Syndrome and Other Late Pulmonary Complications After Allogeneic Hematopoietic Stem Cell Transplantation

As more individuals survive their hematologic malignancies after allogeneic hematopoietic stem cell transplantation (HSCT), there is growing appreciation of the late organ complications of this curative procedure for malignant and nonmalignant hematologic disorders. Late noninfectious pulmonary complications encompass all aspects of the bronchopulmonary anatomy. There have been recent advances in the diagnostic recognition and management of bronchiolitis obliterans syndrome, which is recognized as a pulmonary manifestation of chronic graft-versus-host disease. Organizing pneumonia and other interstitial lung diseases are increasingly recognized. This article provides an update on these entities as well as pleural and pulmonary vascular disease after allogeneic HSCT.

Effect of Azithromycin on Airflow Decline-Free Survival After Allogeneic Hematopoietic Stem Cell Transplant: The ALLOZITHRO Randomized Clinical Trial

IMPORTANCE

Bronchiolitis obliterans syndrome has been associated with increased morbidity and mortality after allogeneic hematopoietic stem cell transplant (HSCT). Previous studies have suggested that azithromycin may reduce the incidence of post-lung transplant bronchiolitis obliterans syndrome.

OBJECTIVE

To evaluate if the early administration of azithromycin can improve airflow decline-free survival after allogeneic HSCT.

DESIGN, SETTING, AND PARTICIPANTS

The ALLOZITHRO parallel-group trial conducted in 19 French academic transplant centers and involving participants who were at least 16 years old, had undergone allogeneic HSCT for a hematological malignancy, and had available pretransplant pulmonary function test results. Enrollment was from February 2014 to August 2015 with follow-up through April 26, 2017.

INTERVENTIONS

Patients were randomly assigned to receive 3 times a week either 250 mg of azithromycin (n = 243) or placebo (n = 237) for 2 years, starting at the time of the conditioning regimen.

MAIN OUTCOMES AND MEASURES

The primary efficacy end point was airflow decline-free survival at 2 years after randomization. Main secondary end points were overall survival and bronchiolitis obliterans syndrome at 2 years.

RESULTS

Thirteen months after enrollment, the independent data and safety monitoring board detected an unanticipated imbalance across blinded groups in the number of hematological relapses, and the treatment was stopped December 26, 2016. Among 480 randomized participants, 465 (97%) were included in the modified intention-to-treat analysis (mean age, 52 [SD, 14] years; 75 women [35%]). At the time of data cutoff, 104 patients (22%; 54 azithromycin vs 50 placebo) had experienced an airflow decline; 138 patients (30%) died (78 azithromycin vs 60 placebo). Two-year airflow decline-free survival was 32.8% (95% CI, 25.9%-41.7%) with azithromycin and 41.3% (95% CI, 34.1%-50.1%) with placebo (unadjusted hazard ratio [HR], 1.3; 95% CI, 1.02-1.70; P = .03). Of the 22 patients (5%) who experienced bronchiolitis obliterans syndrome, 15 (6%) were in the azithromycin group and 7 (3%) in the placebo group (P = .08). The azithromycin group had increased mortality, with a 2-year survival of 56.6% (95% CI, 50.2%-63.7%) vs 70.1% (95% CI, 64.2%-76.5%) in the placebo group (unadjusted HR, 1.5; 95% CI, 1.1-2.0; P = .02). In a post hoc analysis, the 2-year cumulative incidence of hematological relapse was 33.5% (95% CI, 27.3%-39.7%) with azithromycin vs 22.3% (95% CI, 16.4%-28.2%) with placebo (unadjusted cause-specific HR, 1.7; 95% CI, 1.2-2.4; P = .002).

CONCLUSIONS AND RELEVANCE

Among patients undergoing allogeneic HSCT for hematological malignancy, early administration of azithromycin resulted in worse airflow decline-free survival than did placebo; these findings are limited by early trial termination. The potential for harm related to relapse requires further investigation.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT01959100.

Pulmonary Clinicopathological Correlation after Allogeneic Hematopoietic Stem Cell Transplantation: An Autopsy Series

Pulmonary complications are a significant cause of morbidity, mortality, and resource utilization after hematopoietic stem cell transplantation (HSCT). The objective of this study was to compare antemortem clinical suspicion of pulmonary complications and postmortem findings in a modern HSCT cohort. All patients who underwent allogeneic HSCT at our institution (n = 1854) between January 1, 2000 and June 30, 2010 were reviewed and patients who died of any cause greater than 1 year after HSCT and had an unrestricted autopsy available for analysis were included. Presence of pulmonary graft-versus-host disease (GVHD) was assessed by a pathologist blinded to the autopsy report, as previously described by Yousem (1995). A total of 35 (1.9%) patients had autopsies available for review. Airway disease, vascular disease, and interstitial disease were all clinically under-recognized compared with the pathological findings on autopsy. Varying degrees of pathological changes were detected, including 10 (28.6%) patients having bronchiolitis obliterans (BO) and 12 (34.3%) patients having pulmonary veno-occlusive disease (PVOD). Pulmonary manifestations of chronic GVHD, particularly BO and PVOD, were clinically under-recognized in our cohort. Our results suggest that PVOD, which has traditionally been considered a rare complication, may be clinically and histologically under-recognized.

Major Pulmonary Complications After Hematopoietic Stem Cell Transplant

Both autologous and allogeneic hematopoietic stem cell transplants are important therapeutic options for several benign and malignant disorders. Pulmonary complications, although they have become less frequent, remain a significant cause of morbidity and mortality after hematopoietic stem cell transplant. These complications range from bacterial, fungal, and viral pulmonary infections to noninfectious conditions such as diffuse alveolar hemorrhage and idiopathic pneumonia syndrome. Bronchiolitis obliterans syndrome is the primary chronic pulmonary complication, and treatment of this condition remains challenging. This report highlights the advances in the diagnosis and management of the major pulmonary complications after hematopoietic stem cell transplant. It also underscores the need for prospective and multicenter research to have a better understanding of the mechanisms behind these complications and to obtain more effective diagnostic tool and therapeutic options.

[Small airway diseases and immune deficiency]

INTRODUCTION

Innate or acquired immune deficiency may show respiratory manifestations, often characterized by small airway involvement. The purpose of this article is to provide an overview of small airway disease across the major causes of immune deficiency.

BACKGROUND

In patients with common variable immune deficiency, recurrent lower airway infections may lead to bronchiolitis and bronchiectasis. Follicular and/or granulomatous bronchiolitis of unknown origin may also occur. Bronchiolitis obliterans is the leading cause of death after the first year in patients with lung transplantation. Bronchiolitis obliterans also occurs in patients with allogeneic haematopoietic stem cell transplantation, especially in the context of systemic graft-versus-host disease.

VIEWPOINT AND CONCLUSION

Small airway diseases have different clinical expression and pathophysiology across various causes of immune deficiency. A better understanding of small airways disease pathogenesis in these settings may lead to the development of novel targeted therapies.

A call to arms: a critical need for interventions to limit pulmonary toxicity in the stem cell transplantation patient population

Noninfectious pulmonary toxicity after allogeneic hematopoietic stem cell transplantation (allo-HSCT) causes significant morbidity and mortality. Main presentations are idiopathic pneumonia syndrome (IPS) in the acute setting and bronchiolitis obliterans syndrome (BOS) and cryptogenic organizing pneumonia (COP) at later time point. While COP responds well to corticosteroids, IPS and BOS often are treatment refractory. IPS, in most cases, is rapidly fatal, whereas BOS progresses over time, resulting in chronic respiratory failure, impaired quality of life, and eventually, death. Standard second-line treatments are currently lacking, and current approaches, such as augmented T cell-directed immunosuppression, B cell depletion, TNF blockade, extracorporeal photopheresis, and tyroskine kinase inhibitor therapy, are unsatisfactory with responses in only a subset of patients. Better understanding of underlying pathophysiology hopefully results in the identification of future targets for preventive and therapeutic strategies along with an emphasis on currently underutilized rehabilitative and supportive measures.

Long-Lasting Impact of Neonatal Exposure to Total Body Gamma Radiation on Secondary Lymphoid Organ Structure and Function

The acute period after total body irradiation (TBI) is associated with an increased risk of infection, principally resulting from the loss of hematopoietic stem cells, as well as disruption of mucosal epithelial barriers. Although there is a return to baseline infection control coinciding with the apparent progressive recovery of hematopoietic cell populations, late susceptibility to infection in radiation-sensitive organs such as lung and kidney is known to occur. Indeed, pulmonary infections are particularly prevalent in hematopoietic cell transplant (HCT) survivors, in both adult and pediatric patient populations. Preclinical studies investigating late outcomes from localized thoracic irradiation have indicated that the mechanisms underlying pulmonary delayed effects are multifactorial, including exacerbated and persistent production of pro-inflammatory molecules and abnormal cross-talk among parenchymal and infiltrating immune and inflammatory cell populations. However, in the context of low-dose TBI, it is not clear whether the observed exacerbated response to infection remains contingent on these same mechanisms. It is possible instead, that after systemic radiation-induced injury, the susceptibility to infection may be independently related to defects in alternative organs that are revealed only through the challenge itself; indeed, we have hypothesized that this defect may be due to radiation-induced chronic effects in the structure and function of secondary lymphoid organs (SLO). In this study, we investigated the molecular and cellular alterations in SLO (i.e., spleen, mediastinal, inguinal and mesenteric lymph nodes) after TBI, and the time points when there appears to be immune competence. Furthermore, due to the high incidence of pulmonary infections in the late post-transplantation period of bone marrow transplant survivors, particularly in children, we focused on outcomes in mice irradiated as neonates, which served as a model for a pediatric population, and used the induction of adaptive immunity against influenza virus as a functional end point. We demonstrated that, in adult animals irradiated as neonates, high endothelial venule (HEV) expansion, generation of follicular helper T cells (TFH) and formation of splenic germinal centers (GC) were rapidly and, more importantly, persistently impaired in SLO, suggesting that the early-life exposure to sublethal radiation had long-lasting effects on the induction of humoral immunity. Although the neonatal TBI did not affect the overall outcome from influenza infection in the adults at the earlier time points assessed, we believe that they nonetheless contribute significantly to the increased mortality observed at subsequent late time points. Furthermore, we speculate that the detrimental and persistent impact on the induction of CD4 T- and B-cell responses in the mediastinal lymph nodes will decrease the animals' ability to respond to other aerial pathogens. Since many of these pathogens are normally cleared by antibodies, our findings provide an explanation for the susceptibility of survivors of childhood HCT to life-threatening respiratory tract infections. These findings have implications regarding the need for increased monitoring in pediatric hematopoietic cell transplant patients, since they indicate that there are ongoing and cumulative defects in SLO, which, importantly, develop during the immediate and early postirradiation period when patients may appear immunologically competent. The identification of changes in immune-related signals may offer bioindicators of progressive dysfunction, and of potential mechanisms that could be targeted so as to reduce the risk of infection from extracellular pathogens. Furthermore, these results support the potential susceptibility of the pediatric population to infection after sublethal irradiation in the context of a nuclear or radiological event.

NIH Consensus development project on criteria for clinical trials in chronic graft-versus-host disease: II. The 2014 Pathology Working Group Report

The 2005 National Institute of Health (NIH) Consensus Conference outlined histopathological diagnostic criteria for the major organ systems affected by both acute and chronic graft-versus-host disease (GVHD). The 2014 Consensus Conference led to this updated document with new information from histopathological studies of GVHD in the gut, liver, skin, and oral mucosa and an expanded discussion of GVHD in the lungs and kidneys. The recommendations for final histological diagnostic categories have been simplified from 4 categories to 3: no GVHD, possible GVHD, and likely GVHD, based on better reproducibility achieved by combining the previous categories of "consistent with GVHD" and "definite GVHD" into the single category of "likely GVHD." Issues remain in the histopathological characterization of GVHD, particularly with respect to the threshold of histological changes required for diagnostic certainty. Guidance is provided for the incorporation of biopsy information into prospective clinical studies of GVHD, particularly with respect to biomarker validation.

Biopsy-verified bronchiolitis obliterans and other noninfectious lung pathologies after allogeneic hematopoietic stem cell transplantation

Bronchiolitis obliterans (BO) is a serious complication of allogeneic hematopoietic stem cell transplantation (HSCT). Lung biopsy is the gold standard for diagnosis. This study describes the course of BO and assesses the congruity between biopsy-verified BO and a modified version of the National Institutes of Health's consensus criteria for BO syndrome (BOS) based exclusively on noninvasive measures. We included 44 patients transplanted between 2000 and 2010 who underwent lung biopsy for suspected BO. Of those, 23 were diagnosed with BO and 21 presented other noninfectious pulmonary pathologies, such as cryptogenic organizing pneumonia, diffuse alveolar damage, interstitial pneumonia, and nonspecific interstitial fibrosis. Compared with patients with other noninfectious pulmonary pathologies, BO patients had significantly lower values of forced expiratory volume in 1 second (FEV1), FEV1/forced vital capacity, and maximal mid-expiratory flow throughout follow-up, but there was no difference in the change in pulmonary function from the time of lung biopsy. The BO diagnosis was not associated with poorer overall survival. Fifty-two percent of patients with biopsy-verified BO and 24% of patients with other noninfectious pulmonary pathology fulfilled the BOS criteria. Pathological BO diagnosis was not superior to BOS criteria in predicting decrease in pulmonary function beyond the time of biopsy. A lung biopsy may provide a characterization of pathological patterns that can extend our knowledge on the pathophysiology of HSCT-related lung diseases.