Progressive fibrosing interstitial lung disease: treatable traits and therapeutic strategies

Use of 6-minute walk distance to predict lung transplant-free survival in fibrosing non-IPF interstitial lung diseases

BACKGROUND AND OBJECTIVE

The identification of progression in patients with fibrosing non-idiopathic pulmonary fibrosis (IPF) interstitial lung diseases (ILDs) represents an ongoing clinical challenge. Lung function decline alone may have significant limitations in the detection of clinically significant progression. We hypothesized that longitudinal changes of 6-min walk distance (6MWD) from baseline, simultaneously considered with measures of lung function, may independently predict survival and identifying clinically significant progression of disease.

METHODS

Forced vital capacity (FVC), diffusing lung capacity (DLCO) and 6MWD were considered both at baseline and at 1 year in a discovery cohort (n = 105) and in a validation cohort (n = 138) from different centres. The primary endpoint was lung transplant (LTx)-free survival.

RESULTS

Average follow-up was 3 years in both cohorts. Combined incidence of deaths and LTx was 29% and 21%, respectively. No collinearity and no strong correlations were observed among FVC, DLCO and 6MWD longitudinal changes. While age, gender and BMI were not significant, 6MWD decline ≥24 m predicted LTx-free-survival significantly and independently from FVC and DLCO declines, with high sensitivity and specificity, in both the discovery and the validation cohorts. Although FVC and DLCO declines remained significant predictors of LTx-free survival, 6MWD decline was more accurate than the proposed ATS/ERS/JRS/ALAT functional criteria. Results were confirmed after stratifying patients by baseline FVC.

CONCLUSION

Longitudinal declines of 6MWD are associated with poor survival in fibrosing ILDs across a wide range of baseline severity, with high accuracy. 6MWD longitudinal decline is largely independent from lung function decline and may be integrated into the routine assessment of progression.

Cluster features in fibrosing interstitial lung disease and associations with prognosis

BACKGROUND

Clustering is helpful in identifying subtypes in complex fibrosing interstitial lung disease (F-ILD) and associating them with prognosis at an early stage of the disease to improve treatment management. We aimed to identify associations between clinical characteristics and outcomes in patients with F-ILD.

METHODS

Retrospectively, 575 out of 926 patients with F-ILD were eligible for analysis. Four clusters were identified based on baseline data using cluster analysis. The clinical characteristics and outcomes were compared among the groups.

RESULTS

Cluster 1 was characterized by a high prevalence of comorbidities and hypoxemia at rest, with the worst lung function at baseline; Cluster 2 by young female patients with less or no smoking history; Cluster 3 by male patients with highest smoking history, the most noticeable signs of velcro crackles and clubbing of fingers, and the severe lung involvement on chest image; Cluster 4 by male patients with a high percentage of occupational or environmental exposure. Clusters 1 (median overall survival [OS] = 7.0 years) and 3 (OS = 5.9 years) had shorter OS than Clusters 2 (OS = not reached, Cluster 1: p < 0.001, Cluster 3: p < 0.001) and 4 (OS = not reached, Cluster 1: p = 0.004, Cluster 3: p < 0.001). Clusters 1 and 3 had a higher cumulative incidence of acute exacerbation than Clusters 2 (Cluster 1: p < 0.001, Cluster 3: p = 0.014) and 4 (Cluster 1: p < 0.001, Cluster 3: p = 0.006). Stratification by using clusters also independently predicted acute exacerbation (p < 0.001) and overall survival (p < 0.001).

CONCLUSIONS

The high degree of disease heterogeneity of F-ILD can be underscored by four clusters based on clinical characteristics, which may be helpful in predicting the risk of fibrosis progression, acute exacerbation and overall survival.

Prognostic Significance of Obstructive Sleep Apnea in a Population of Subjects with Interstitial Lung Diseases

INTRODUCTION

Obstructive sleep apnea (OSA) is often observed in subjects with interstitial lung disease (ILD). It may have a negative impact on the course of ILD, but its prognostic significance in relation to other known indicators of poor outcome is unclear.

METHODS

After a detailed work-up, including overnight unattended type III polygraphy, all subjects newly diagnosed with ILDs referred to our clinics were followed-up for at least 1.5 years or until death or progression of disease [> 10% decline in forced vital capacity (FVC) below baseline]. We analyzed relationships between some prespecified variables of interest, including sleeping results, to establish parameters predictive of progressive course.

RESULTS

Our population consisted of 46 subjects (mean age 59.6 years; males 61%); 23.9% and 41% had idiopathic pulmonary fibrosis and ILD associated with systemic diseases, respectively. Mean baseline forced vital capacity and diffusion capacity of carbon monoxide were 83% and 57% of predicted, respectively. Mean (± SE) Apnea-Hypopnea Index (AHI) was 17 (± 3) events/h. AHI in the ranges 5-14.9, 15-29.9, and ≥ 30 was recorded in 14 (31%), 6 (13%), and 9 (20%) subjects, respectively. Mean distance covered in the 6-MWG walk test (6MWT) was 302 (± 19) m and 26 subjects (57%) showed exertional oxyhemoglobin desaturation. The median follow-up was about 18 months. Multivariate logistic regression analysis showed that exertional desaturation (HR 8.2; 1.8-36.5 95% CI; p = 0.006) and AHI ≥ 30, namely the threshold of severe OSA (HR 7.5; 1.8-30.6; p = 0.005), were the only independent variables related to progressive disease course.

CONCLUSION

We conclude that exertional desaturation and elevated AHI had independent negative prognostic significance in our ILD population.

ILD-GAP Combined with the Charlson Comorbidity Index Score (ILD-GAPC) as a Prognostic Prediction Model in Patients with Interstitial Lung Disease

Background

The ILD-GAP scoring system has been widely used to predict the prognosis of patients with interstitial lung disease (ILD). The ability of the ILD-GAP scoring system combined with the Charlson Comorbidity Index score (CCIS) (ILD-GAPC) to predict ILD prognosis was investigated.

Methods

In ILD patients, including idiopathic pulmonary fibrosis (IPF), idiopathic nonspecific interstitial pneumonia (iNSIP), collagen vascular disease-related interstitial pneumonia (CVD-IP), chronic hypersensitivity pneumonitis (CHP), and unclassifiable ILD (UC-ILD), treated between April 2013 and April 2017, the relationships between baseline clinical parameters, including age, sex, CCIS, ILD diagnosis, pulmonary function test results, and disease outcomes, were retrospectively assessed, and the ability to predict prognosis was compared between the ILD-GAP and ILD-GAPC models, respectively.

Results

A total of 185 patients (mean age, 71.9 years), all of whom underwent pulmonary function testing, including percentage predicted diffusion capacity for carbon monoxide, were assessed. ILD diagnosis consisted of IPF in 57 cases, iNSIP and CVD-IP in 117 cases, CHP in 6 cases, and UC-ILD in 5 cases. The ILD-GAPC provided a greater area under the receiver operating characteristic curve (0.758) for predicting 3-year ILD-related events than the ILD-GAP (0.721). In addition, log-rank tests showed that the Kaplan-Meier curves differed significantly among low, middle, and high ILD-GAPC scores (P < 0.001), unlike ILD-GAP scores (P = 0.083).

Conclusions

The ILD-GAPC model could provide more accurate information for predicting prognosis in patients with ILD than the ILD-GAP model.

Real-world impact of antifibrotics on prognosis in patients with progressive fibrosing interstitial lung disease

OBJECTIVE

No studies have demonstrated the real-world efficacy of antifibrotics for progressive fibrosing interstitial lung disease (PF-ILD). Therefore, we evaluated the efficacy of antifibrotics in patients with PF-ILD.

METHODS

We retrospectively reviewed the medical records of patients with ILD from January 2012 to July 2021. Patients were diagnosed with PF-ILD if they had ≥10% fibrosis on high-resolution CT (HRCT) and a relative forced vital capacity (FVC) decline of either ≥10% or >5% to <10% with clinical deterioration or progression of fibrosis on HRCT during overlapping windows of 2 years and with a %FVC of ≥45%. We compared FVC changes and overall survival (OS) between patients with and without antifibrotics. FVC changes were analysed using generalised estimating equations. We used inverse probability weighting (IPW) and statistical matching to adjust for covariates.

RESULTS

Of the 574 patients, 167 were diagnosed with PF-ILD (idiopathic pulmonary fibrosis (IPF), n=64; non-IPF, n=103). Antifibrotics improved the FVC decline in both IPF (p=0.002) and non-IPF (p=0.05) (IPW: IPF, p=0.015; non-IPF, p=0.031). Among patients with IPF, OS was longer in the antifibrotic group (log-rank p=0.001). However, among patients with non-IPF, OS was not longer in the antifibrotic group (p=0.3263) (IPW and statistical matching: IPF, p=0.0534 and p=0.0018; non-IPF, p=0.5663 and p=0.5618).

CONCLUSION

This is the first real-world study to show that antifibrotics improve the FVC decline in PF-ILD. However, among patients with non-IPF, we found no significant difference in mortality between those with and without antifibrotics. Future studies must clarify whether antifibrotics improve the prognosis of non-IPF.

Pulmonary sarcoidosis complicated by rheumatoid arthritis in a patient presenting with progressive fibrosing interstitial lung disease and treated with nintedanib: a case report and literature review

Sarcoidosis is a multisystem disease with an unknown etiology and is characterized by the formation of noncaseating granulomas in the affected organs. We present the case of a 69-year-old male Japanese patient with bilateral hilar lymphadenopathy on chest radiographs for more than 10 years, left without further investigation. The patient reported no clinical symptoms. Chest computed tomography revealed ground-glass opacities and reticular shadows in both lungs, along with bilateral hilar and mediastinal lymphadenopathy. Lymphocytosis was observed in bronchoalveolar lavage fluid. Pathological examination of transbronchial lung biopsy revealed noncaseating, epithelioid granulomas congruous with sarcoidosis, together with other findings. There were no abnormalities on electrocardiogram, echocardiogram, and ophthalmic examination.For progressive dyspnea on exertion, systemic corticosteroid therapy with oral prednisolone (25 mg/day) was initiated in 2017 and gradually tapered. Despite this intervention, the decline in forced vital capacity (FVC) was accelerated. Three years later, the patient noticed swelling in his right wrist. Further investigation revealed elevated anti-cyclic citrullinated peptide antibodies and absence of noncaseating epithelioid granuloma on surgical biopsy, leading to the diagnosis of rheumatoid arthritis (RA). Thereafter, the anti-fibrotic agent nintedanib was initiated, because interstitial lung disease (ILD) was considered to have converted into a progressive fibrosing phenotype (PF-ILD) with overlapping RA-associated lung involvement. With treatment, the progression of decline in FVC was slowed, although home oxygen therapy was introduced.

Syndrome of Combined Pulmonary Fibrosis and Emphysema: An Official ATS/ERS/JRS/ALAT Research Statement

Background: The presence of emphysema is relatively common in patients with fibrotic interstitial lung disease. This has been designated combined pulmonary fibrosis and emphysema (CPFE). The lack of consensus over definitions and diagnostic criteria has limited CPFE research. Goals: The objectives of this task force were to review the terminology, definition, characteristics, pathophysiology, and research priorities of CPFE and to explore whether CPFE is a syndrome. Methods: This research statement was developed by a committee including 19 pulmonologists, 5 radiologists, 3 pathologists, 2 methodologists, and 2 patient representatives. The final document was supported by a focused systematic review that identified and summarized all recent publications related to CPFE. Results: This task force identified that patients with CPFE are predominantly male, with a history of smoking, severe dyspnea, relatively preserved airflow rates and lung volumes on spirometry, severely impaired DlCO, exertional hypoxemia, frequent pulmonary hypertension, and a dismal prognosis. The committee proposes to identify CPFE as a syndrome, given the clustering of pulmonary fibrosis and emphysema, shared pathogenetic pathways, unique considerations related to disease progression, increased risk of complications (pulmonary hypertension, lung cancer, and/or mortality), and implications for clinical trial design. There are varying features of interstitial lung disease and emphysema in CPFE. The committee offers a research definition and classification criteria and proposes that studies on CPFE include a comprehensive description of radiologic and, when available, pathological patterns, including some recently described patterns such as smoking-related interstitial fibrosis. Conclusions: This statement delineates the syndrome of CPFE and highlights research priorities.

Towards Treatable Traits for Pulmonary Fibrosis

Interstitial lung diseases (ILD) are a heterogeneous group of disorders, of which many have the potential to lead to progressive pulmonary fibrosis. A distinction is usually made between primarily inflammatory ILD and primarily fibrotic ILD. As recent studies show that anti-fibrotic drugs can be beneficial in patients with primarily inflammatory ILD that is characterized by progressive pulmonary fibrosis, treatment decisions have become more complicated. In this perspective, we propose that the ‘treatable trait’ concept, which is based on the recognition of relevant exposures, various treatable phenotypes (disease manifestations) or endotypes (shared molecular mechanisms) within a group of diseases, can be applied to progressive pulmonary fibrosis. These targets for medical intervention can be identified through validated biomarkers and are not necessarily related to specific diagnostic labels. Proposed treatable traits are: cigarette smoking, occupational, allergen or drug exposures, excessive (profibrotic) auto- or alloimmunity, progressive pulmonary fibrosis, pulmonary hypertension, obstructive sleep apnea, tuberculosis, exercise intolerance, exertional hypoxia, and anxiety and depression. There are also several potential traits that have not been associated with relevant outcomes or for which no effective treatment is available at present: air pollution, mechanical stress, viral infections, bacterial burden in the lungs, surfactant-related pulmonary fibrosis, telomere-related pulmonary fibrosis, the rs35705950 MUC5B promoter polymorphism, acute exacerbations, gastro-esophageal reflux, dyspnea, and nocturnal hypoxia. The ‘treatable traits’ concept can be applied in new clinical trials for patients with progressive pulmonary fibrosis and could be used for developing new treatment strategies.

Prognostic Predictive Characteristics in Patients With Fibrosing Interstitial Lung Disease: A Retrospective Cohort Study

Background: Limited data are available regarding the entire spectrum of interstitial lung disease with a progressive fibrosing feature. We investigated the prevalence and prognostic predictive characteristics in patients with PF-ILD.

Methods: This retrospective cohort study included patients with fibrosing ILD who were investigated between 1 January 2015 and 30 April 2021. We recorded clinical features and outcomes to identify the possible risk factors for fibrosing progression as well as mortality.

Results: Of the 579 patients with fibrosing ILD, 227 (39.21%) met the criteria for progression. Clubbing of fingers [odds ratio (OR) 1.52, 95% confidence interval (CI) 1.03 to 2.24, p = 0.035] and a high-resolution computed tomography (HRCT)-documented usual interstitial pneumonia (UIP)-like fibrotic pattern (OR 1.95, 95% CI 1.33 to 2.86, p = 0.001) were risk factors for fibrosis progression. The mortality was worse in patients with PF with hypoxemia [hazard ratio (HR) 2.08, 95% CI 1.31 to 3.32, p = 0.002], in those with baseline diffusion capacity of the lung for carbon monoxide (DLCO) % predicted &lt;50% (HR 2.25, 95% CI 1.45 to 3.50, p &lt; 0.001), or in those with UIP-like fibrotic pattern (HR 1.68, 95% CI 1.04 to 2.71, p &lt; 0.001).

Conclusion: Clubbing of fingers and an HRCT-documented UIP-like fibrotic pattern were more likely to be associated with progressive fibrosing with varied prevalence based on the specific diagnosis. Among patients with progressive fibrosing, those with hypoxemia, lower baseline DLCO% predicted, or UIP-like fibrotic pattern showed poor mortality.

Sensitization of the UPR by loss of PPP1R15A promotes fibrosis and senescence in IPF

The unfolded protein response (UPR) is a direct consequence of cellular endoplasmic reticulum (ER) stress and a key disease driving mechanism in IPF. The resolution of the UPR is directed by PPP1R15A (GADD34) and leads to the restoration of normal ribosomal activity. While the role of PPP1R15A has been explored in lung epithelial cells, the role of this UPR resolving factor has yet to be explored in lung mesenchymal cells. The objective of the current study was to determine the expression and role of PPP1R15A in IPF fibroblasts and in a bleomycin-induced lung fibrosis model. A survey of IPF lung tissue revealed that PPP1R15A expression was markedly reduced. Targeting PPP1R15A in primary fibroblasts modulated TGF-β-induced fibroblast to myofibroblast differentiation and exacerbated pulmonary fibrosis in bleomycin-challenged mice. Interestingly, the loss of PPP1R15A appeared to promote lung fibroblast senescence. Taken together, our findings demonstrate the major role of PPP1R15A in the regulation of lung mesenchymal cells, and regulation of PPP1R15A may represent a novel therapeutic strategy in IPF.

The justification for the progressive fibrotic phenotype

PURPOSE OF REVIEW

Describe the concept and recent data for the concept of progressive fibrotic interstitial lung disease (ILD).

RECENT FINDINGS

Making an accurate diagnosis is critical to help determine appropriate therapy and predict prognosis. This is certainly true in the field of ILD where a diagnosis of idiopathic pulmonary fibrosis (IPF) leads a clinician to consider initiation of antifibrotic therapy, and avoidance of immunosuppression due to possible harm, at the time of diagnosis due to the high probability of disease progression. In other types of ILD immunosuppression may be helpful such as those associated with a connective tissue disease or in combination with antigen avoidance in hypersensitivity pneumonia. It is also recognized that despite initial approaches to therapy some non-IPF ILDs will develop progressive fibrosis leading to increased symptoms, decreased quality of life and early mortality. Once fibrosis is present, the biologic pathways responsible for progression can be redundant and respond in a similar fashion to antifibrotic therapy independent of the underlying disease.

SUMMARY

There are clinical and biological rationale for the justification of a progressive fibrotic phenotype that complements the therapeutic decisions and prognosis provided by initial diagnosis.

Selective deletion of connective tissue growth factor attenuates experimentally-induced pulmonary fibrosis and pulmonary arterial hypertension

Connective tissue growth factor (CTGF, CCN2) is a matricellular protein which plays key roles in normal mammalian development and in tissue homeostasis and repair. In pathological conditions, dysregulated CCN2 has been associated with cancer, cardiovascular disease, and tissue fibrosis. In this study, genetic manipulation of the CCN2 gene was employed to investigate the role of CCN2 expression in vitro and in experimentally-induced models of pulmonary fibrosis and pulmonary arterial hypertension (PAH). Knocking down CCN2 using siRNA reduced expression of pro-fibrotic markers (fibronectin p < 0.01, collagen type I p < 0.05, α-SMA p < 0.0001, TIMP-1 p < 0.05 and IL-6 p < 0.05) in TGF-β-treated lung fibroblasts derived from systemic sclerosis patients. In vivo studies were performed in mice using a conditional gene deletion strategy targeting CCN2 in a fibroblast-specific and time-dependent manner in two models of lung disease. CCN2 deletion significantly reduced pulmonary interstitial scarring and fibrosis following bleomycin-instillation, as assessed by fibrotic scores (wildtype bleomycin 3.733 ± 0.2667 vs CCN2 knockout (KO) bleomycin 4.917 ± 0.3436, p < 0.05) and micro-CT. In the well-established chronic hypoxia/Sugen model of pulmonary hypertension, CCN2 gene deletion resulted in a significant decrease in pulmonary vessel remodelling, less right ventricular hypertrophy and a reduction in the haemodynamic measurements characteristic of PAH (RVSP and RV/LV + S were significantly reduced (p < 0.05) in CCN2 KO compared to WT mice in hypoxic/SU5416 conditions). These results support a prominent role for CCN2 in pulmonary fibrosis and in vessel remodelling associated with PAH. Therefore, therapeutics aimed at blocking CCN2 function are likely to benefit several forms of severe lung disease.

When things go wrong: exploring possible mechanisms driving the progressive fibrosis phenotype in interstitial lung diseases

Interstitial lung diseases (ILDs) comprise a large and heterogeneous group of disorders of known and unknown aetiology characterised by diffuse damage of the lung parenchyma. In recent years it has become evident that patients with different types of ILD are at risk of developing progressive pulmonary fibrosis, known as progressive fibrosing ILD (PF-ILD). This is a phenotype that behaves similar to idiopathic pulmonary fibrosis, the archetypical example of progressive fibrosis. PF-ILD is not a distinct clinical entity but describes a group of ILDs with similar clinical behaviour. This phenotype may occur in diseases displaying distinct aetiologies and different biopathology during their initiation and development. Importantly, these entities may have the potential for improvement or stabilisation prior to entering the progressive fibrosing phase. The crucial questions are: 1) why does a subset of patients develop a progressive and irreversible fibrotic phenotype even with appropriate treatment? and 2) what are the possible pathogenic mechanisms driving progression? Here, we provide a framework highlighting putative mechanisms underlying progression, including genetic susceptibility, ageing, epigenetics, structural fibrotic distortion, aberrant composition and stiffness of the extracellular matrix, and the emergence of distinct pro-fibrotic cell subsets. Understanding the cellular and molecular mechanisms behind PF-ILD will provide the basis for identifying risk factors and appropriate therapeutic strategies.

Use of nintedanib in interstitial lung disease other than idiopathic pulmonary fibrosis: much caution is warranted

Interstitial lung disease (ILD) other than idiopathic pulmonary fibrosis (IPF) is currently treated with immunosuppressive therapy, with a dynamic algorithm based on continued clinical surveillance. Published results on mycophenolate mofetil, cyclophosphamide and azathioprine showed either stabilization or improvement of lung function with these therapies. However, despite treatment optimization, progression of disease in ILD other than IPF is often observed, and a role for antifibrotic drug nintedanib has been hypothesized. The present article first reviews relevant aspects when considering anti-fibrotic therapy in progressing ILD other than IPF, including accuracy of the diagnosis, optimization of disease-modifying, immunosuppressive therapy and optimal timing. Next, a critical appraisal of published results on nintedanib in ILD other than IPF considers the design of the studies, inclusion criteria, used definition of "progression" of disease, frequency and severity of side effects observed and cost of the therapy. There currently is a strong and legitimate interest in additional therapies that can help controlling progressing ILD other than IPF. When the studies on the use of nintedanib are carefully considered, however, caution should be exercised before prematurely endorsing and applying this therapy. The conduction of studies that will clarify and justify its potential role as switch vs. add-on therapy and, at the same time, a more rigorous definition of disease progression are both strongly encouraged.

Causes of acute respiratory hospitalizations predict survival in fibrosing interstitial lung diseases

Acute exacerbation of ILD (AE-ILD) is a common reason for hospitalization; it is also associated with significant mortality. Less is known about the prognostic significance of other events causing acute, non-elective hospitalizations in ILD patients. ILD patients hospitalized due to acute respiratory worsening were collected from medical records. Reasons for respiratory deterioration were classified into AE-ILDs and other causes. Clinical features and survival data of idiopathic pulmonary fibrosis (IPF) and other types of ILDs were evaluated and compared. In all, 237 patients (138 with IPF and 99 with other ILD) fulfilled the inclusion criteria. Of the non-IPF ILD types, the most prevalent subgroups were connective tissue disease-associated ILD (n = 33) and asbestosis (n = 22). The most common cause for hospitalization was AE-ILD explaining 41% of hospitalizations. Lower respiratory tract infection (22%), subacute progression of ILD (12%) and cardiovascular causes (7.2%) were other common reasons for hospital treatment. Patients with a lower respiratory tract infection had a more favorable prognosis compared with patients with AE-ILD. AE-ILDs were less fatal than cardiovascular or concurrent non-ILD-related causes for hospitalizations in non-IPF patients. High Gender-Age-Physiology (GAP) index was a marker for shortened survival and earlier AE-ILDs in all patients. IPF patients had a significantly shorter overall and post-hospitalization survival time compared with other ILDs. Most respiratory hospitalizations in ILD patients were related to causes other than AE-ILD, which highlights the importance of accurate differential diagnosis in order to target the appropriate treatment for each ILD patient.

Nintedanib and intensive immunosuppressive therapy to treat rapidly progressive interstitial lung disease presenting anti-ARS antibodies

We describe a case of fulminant onset, rapidly progressive-interstitial lung disease (RP-ILD) with anti-ARS antibodies (anti-PL-7). The patient was successfully treated with nintedanib in addition to intensive immunosuppressive therapies, including intravenous cyclophosphamide. Nintedanib has just been approved for treatment of progressive fibrosing ILD, but to date, no reports of RP-ILD treated with nintedanib have been published. This case report may advance discussions regarding the use and timing of nintedanib in treating RP-ILD.