Prediction of therapeutic response before and during i.v. cyclophosphamide pulse therapy for interstitial lung disease in systemic sclerosis: A longitudinal observational study

Efficacy and safety of oral versus intravenous cyclophosphamide in treatment of connective tissue disease-related interstitial lung disease

OBJECTIVE

Interstitial lung disease (ILD) resulting from connective tissue disease (CTD) greatly undermines people's health. Cyclophosphamide (CYC) is a widely used agent in treating CTD-ILD. We compared the efficacy and safety of oral and intravenous CYC in CTD-ILD treatment.

METHODS

The retrospectively enrolled CTD-ILD patients were divided into the oral and intravenous CYC groups. The chest high-resolution computed tomography examination, forced vital capacity (FVC), lung carbon monoxide diffusion capacity (Dlco) determinations, and 6 min walk test (6MWT) were performed pre-treatment and at the 3rd, 6th, and 12th months posttreatment. Radiographic ILD severity was assessed using the Warrick score. Krebs Von den Lungen-6, surfactant protein A (SP-A), SP-D, and erythrocyte sedimentation rate (ESR) before and at the 12th month post-treatment were determined. CYC cumulative dose and occurrence of adverse reactions during treatment were recorded.

RESULTS

CYC cumulative dose in the intravenous CYC group was reduced. Compared with oral CYC treatment, intravenous CYC caused decreased Warrick score and increased FVC and 6MWT at the 6th month, and elevated DLco at the 3rd and 6th months posttreatment. SP-A, SP-D and ESR levels in both groups were reduced 12 months posttreatment, with a more evident decrease in the intravenous CYC group. Intravenous CYC had lower total adverse reaction incidence.

CONCLUSION

Compared with oral CYC, intravenous CYC decreases Warrick score and increases FVC and 6MWT at 6 months posttreatment, and reduces SP-A, SP-D, and ESR levels after 12 months of treatment, which shows low CYC cumulative dose and adverse reaction incidence in treating CTD-ILD.

Association of serum Ly6/PLAUR domain-containing protein 1 levels with skin sclerosis in systemic sclerosis

Systemic sclerosis (SSc) is a connective tissue disease characterized by aberrant immune activation, vascular injury, and fibrosis of the skin and internal organs. Ly6/PLAUR domain-containing protein 1 (LYPD1) was reported to be secreted and to have various physiological functions such as anti-angiogenic effects. Here we investigated serum LYPD1 levels in SSc patients and the association of serum LYPD1 levels with clinical features of SSc. Serum samples were obtained from 75 SSc patients and 22 healthy individuals as controls. We measured serum LYPD1 levels using enzyme-linked immunosorbent assay kits. Then, the relationship between serum LYPD1 levels and clinical features of SSc was analyzed. Serum LYPD1 levels in diffuse cutaneous SSc (dcSSc) patients were significantly higher than those in the limited cutaneous SSc (lcSSc) patients (median [25-75th percentiles], 1693.43 [1086.61-1917.57] vs. 904.55 [714.356-1285.56] pg/mL), while there were no significant differences in the serum LYPD1 levels between lcSSc and healthy controls (904.55 [714.356-1285.56] vs. 750.71 pg/mL [544.00-912.14]). Further analysis revealed that serum LYPD1 levels in patients correlated with skin thickness scores and serum interleukin (IL)-6 levels, which were known to reflect the extent of skin thickening in SSc. Moreover, serum LYPD1 levels showed a decrease with improvement in skin thickness after treatment, along with a decrease in serum IL-6 levels. These results indicate that LYPD1 might be a potential marker for monitoring skin sclerosis and evaluating the efficacy of skin fibrosis treatment in SSc patients.

Targeting Progression in Pulmonary Fibrosis: An Overview of Underlying Mechanisms, Molecular Biomarkers, and Therapeutic Intervention

Interstitial lung diseases comprise a heterogenous range of diffuse lung disorders, potentially resulting in pulmonary fibrosis. While idiopathic pulmonary fibrosis has been recognized as the paradigm of a progressive fibrosing interstitial lung disease, other conditions with a progressive fibrosing phenotype characterized by a significant deterioration of the lung function may lead to a burden of significant symptoms, a reduced quality of life, and increased mortality, despite treatment. There is now evidence indicating that some common underlying biological mechanisms can be shared among different chronic fibrosing disorders; therefore, different biomarkers for disease-activity monitoring and prognostic assessment are under evaluation. Thus, understanding the common pathways that induce the progression of pulmonary fibrosis, comprehending the diversity of these diseases, and identifying new molecular markers and potential therapeutic targets remain highly crucial assignments. The purpose of this review is to examine the main pathological mechanisms regulating the progression of fibrosis in interstitial lung diseases and to provide an overview of potential biomarker and therapeutic options for patients with progressive pulmonary fibrosis.

The pentraxin family in autoimmune disease

The pentraxins represent a family of multifunctional proteins composed of long and short pentamers. The latter includes serum amyloid P component (SAP) and C-reactive protein (CRP) whereas the former includes neuronal PTX1 and PTX2 (NPTX1 and NPTX2, respectively), PTX3 and PTX4. These serve as a bridge between adaptive immunity and innate immunity and a link between inflammation and immunity. Similarities and differences between long and short pentamers are examined and their roles in autoimmune disease are discussed. Increased CRP and PTX3 could indicate the activity of rheumatoid arthritis, systemic lupus erythematosus or other autoimmune diseases. Mechanistically, CRP and PTX3 may predict target organ injury, regulate bone metabolic immunity and maintain homeostasis as well as participate in vascular endothelial remodeling. Interestingly, PTX3 is pleiotropic, being involved in inflammation and tissue repair. Given the therapeutic potential of PTX3 and CRP, targeting these factors to exert a beneficial effect is the focus of research efforts. Unfortunately, studies on NPTX1, NPTX2, PTX4 and SAP are scarce and more research is clearly needed to elaborate their potential roles in autoimmune disease.

Serum cold-inducible RNA-binding protein levels as a potential biomarker for systemic sclerosis-associated interstitial lung disease

Systemic sclerosis (SSc) is a complex autoimmune disease characterized by fibrotic, inflammatory, and vascular dysfunction. Danger-associated molecular patterns (DAMPs)-mediated inflammasome activation has been reported to be involved in the pathogenesis of SSc. Cold-inducible RNA-binding protein (CIRP) is newly identified as a DAMP. Here we examined the clinical significance of serum levels of CIRP in 60 patients with SSc and 20 healthy control patients (HCs) using an enzyme-linked immunosorbent assay. Serum CIRP levels in diffuse cutaneous SSc (dcSSc) patients were significantly increased compared with limited cutaneous SSc (lcSSc) patients or HCs. When examining the relationship with SSc-specific parameters, serum CIRP levels with the presence of interstitial lung disease (ILD) were higher than those without ILD. In detail, serum CIRP levels correlated negatively with the percent predicted diffusing capacity for carbon monoxide and positively with levels of Krebs von den Lungen-6. In addition, elevated serum CIRP levels declined along with decreased SSc-ILD activity in patients who received immunosuppressive therapy. These results suggest that CIRP may play a role in the development of ILD in SSc. Moreover, CIRP could serve as a useful serological marker of SSc-ILD in terms of disease activity and therapeutic effects.

Exogenous Apelin-13 Administration Ameliorates Cyclophosphamide- Induced Oxidative Stress, Inflammation, and Apoptosis in Rat Lungs

BACKGROUND

Apelin-13 is an endogenous adipocytokine known for its antioxidant, antiinflammatory, and antiapoptotic properties.

OBJECTIVE

We aimed to investigate the possible protective effects of exogenous Apelin-13 administration on oxidative stress, inflammation, and apoptosis induced by the cytotoxic agent cyclophosphamide (CP) in the lungs.

METHODS

Twenty-four male Wistar albino rats were divided into four groups: Control (saline), CP (200 mg/kg), Apelin-13 (10 μg/kg/day), and CP+Apelin-13. CP was administered as a single dose on the fifth day, and apelin-13 was administered intraperitoneally for five days. Total oxidant status (TOS), total antioxidant status (TAS), and lipid peroxidation were determined with spectrophotometry, TNFα and IL1β were determined with ELISA, APJ, Sirt1, NF-κB, and p53 mRNA expressions were determined with qRT-PCR, cytochrome (Cyt) C and caspase-3 protein expressions were studied with western blotting in lung tissues. The oxidative stress index (OSI) was also calculated. Furthermore, serum surfactant protein-D (SP-D) and Krebs von den Lungen-6 (KL-6) levels were measured with ELISA.

RESULTS

Compared to the control group, TOS, OSI, lipid peroxidation, TNFα, IL1β, cyt C, caspase-3, APJ, NF-κB, and p53 were higher, and Sirt1 was lower in the lung tissue of rats in the CP group. Serum KL-6 and SP-D levels were higher in the CP group. Co-administration of CP with Apelin-13 completely reversed the changes induced by CP administration.

CONCLUSION

Exogenous Apelin-13 treatment protected lung tissue against injury by inhibiting cyclophosphamide-induced oxidative stress, inflammation, and apoptosis. This protective effect of apelin-13 was accompanied by upregulation of the Sirt1 and downregulation of NF-κB/p53 in the lungs.

Assessment of disease outcome measures in systemic sclerosis

The assessment of disease activity in systemic sclerosis (SSc) is challenging owing to its heterogeneous manifestations across multiple organ systems, the variable rate of disease progression and regression, and the relative paucity of patients in early-phase therapeutic trials. Despite some recent successes, most clinical trials have failed to show efficacy, underscoring the need for improved outcome measures linked directly to disease pathogenesis, particularly applicable for biomarker studies focused on skin disease. Current outcome measures in SSc-associated interstitial lung disease and SSc skin disease are largely adequate, although advancing imaging technology and the incorporation of skin mRNA biomarkers might provide opportunities for earlier detection of the therapeutic effect. Biomarkers can further inform pathogenesis, enabling early phase trials to act as reverse translational studies through the incorporation of routine high-throughput sequencing.

C-reactive protein and ground-glass opacity as predictors for intractable interstitial lung disease in patients with systemic sclerosis under cyclophosphamide treatment regardless of concomitant glucocorticoids

OBJECTIVES

Cyclophosphamide (CYC) has been proposed as a standard induction regimen for interstitial lung disease (ILD) associated with systemic sclerosis (SSc). However, there remain patients with SSc-ILD who are intractable to the therapy. This study aimed to identify factors associated with inadequate response to CYC and investigate how to treat SSc-ILD, especially in the need for glucocorticoids (GCs) combined with CYC.

METHODS

This retrospective study included consecutive patients diagnosed with SSc-ILD and treated with CYC between 2009 and 2020. Logistic regression models were used to determine the prognostic factors indicating significant progression of ILD (SP-ILD). The clinical findings of patients treated with vs. without GCs were compared.

RESULTS

Nineteen patients were registered, with a median age of 61.0 years. Fifteen were females, and five were classified into SP-ILD. Baseline high C-reactive protein (CRP) levels and non-widespread or localized ground-glass opacities (GGOs) predicted SP-ILD in multivariable analyses, and the cut-off level of CRP was 0.41 mg/dL. In clinical courses, SSc-ILD with high inflammation temporarily responded to CYC, regardless of the combined use of GCs; however, the therapeutic effects deteriorated soon after stopping CYC.

CONCLUSION

High CRP levels with non-widespread GGO predicted progressive ILD in patients with SSc treated with CYC.

Pharmacological treatments for SSc-ILD: Systematic review and critical appraisal of the evidence

Many therapies have been investigated for systemic sclerosis-associated interstitial lung disease (SSc-ILD), including immunosuppressive therapies, antifibrotic agents, immunomodulators and monoclonal antibodies. There is a high unmet medical need to better understand the current evidence for treatment efficacy and safety. This systematic review aims to present the existing literature on different drug treatments investigated for SSc-ILD and to critically assess the level of evidence for these drugs. A systematic review was performed in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. A structured literature search was performed for clinical trials and observational studies on the treatment of SSc-ILD with pharmaceutical interventions from 1 January 1990 to 15 December 2020. The quality of each reference was assessed using the Grades of Recommendation, Assessment, Development, and Evaluation (GRADE) criteria. A total of 77 references were reviewed and 13 different treatments were identified. We found high-quality evidence for the use of cyclophosphamide, nintedanib, mycophenolate and tocilizumab. Therefore, we would posit that the clinical community has four valid options for treatment of SSc-ILD. Further research is mandatory to provide more evidence for the optimal treatment strategy in SSc-ILD, including the optimal time to initiate treatment, selection of patients for treatment and upfront combination therapy.

Predictive Significance of Serum Interferon-Inducible Protein Score for Response to Treatment in Systemic Sclerosis-Related Interstitial Lung Disease

OBJECTIVE

Response to immunosuppression is highly variable in systemic sclerosis (SSc)-related interstitial lung disease (ILD). This study was undertaken to determine whether a composite serum interferon (IFN)-inducible protein score exhibits predictive significance for the response to immunosuppression in SSc-ILD.

METHODS

Serum samples collected in the Scleroderma Lung Study II, a randomized controlled trial of mycophenolate mofetil (MMF) versus cyclophosphamide (CYC), were examined. Results were validated in an independent observational cohort receiving active treatment. A composite score of 6 IFN-inducible proteins IFNγ-inducible 10-kd protein, monokine induced by IFNγ, monocyte chemotactic protein 2, β2 -microglobulin, tumor necrosis factor receptor type II, and macrophage inflammatory protein 3β) was calculated, and its predictive significance for longitudinal forced vital capacity percent predicted measurements was evaluated.

RESULTS

Higher baseline IFN-inducible protein score predicted better response over 3 to 12 months in the MMF arm (point estimate = 0.41, P = 0.001) and CYC arm (point estimate = 0.91, P = 0.009). In contrast, higher baseline C-reactive protein (CRP) levels were predictive of a worse ILD course in both treatment arms. The predictive significance of the IFN-inducible protein score and CRP levels remained after adjustment for baseline demographic and clinical predictors. During the second year of treatment, in which patients in the CYC arm were switched to placebo, a higher IFN-inducible protein score at 12 months showed a trend toward predicting a worse ILD course (point estimate = -0.61, P = 0.068), while it remained predictive of better response to active immunosuppression in the MMF arm (point estimate = 0.28, P = 0.029). The predictive significance of baseline IFN-inducible protein score was replicated in the independent cohort (rs = 0.43, P = 0.028).

CONCLUSION

A higher IFN-inducible protein score in SSc-ILD is predictive of better response to immunosuppression and could potentially be used to identify patients who may derive the most benefit from MMF or CYC.

Biomarkers in Progressive Fibrosing Interstitial Lung Disease: Optimizing Diagnosis, Prognosis, and Treatment Response

Interstitial lung disease (ILD) comprises a heterogenous group of diffuse lung disorders that commonly result in irreversible pulmonary fibrosis. While idiopathic pulmonary fibrosis (IPF) is the prototypical progressive fibrosing ILD (PF-ILD), a high proportion of patients with other ILD subtypes develop a PF-ILD phenotype. Evidence exists for shared pathobiology leading to progressive fibrosis, suggesting that biomarkers of disease activity may prove informative across the wide spectrum of ILDs. Biomarker investigation to date has identified a number of molecular markers that predict relevant ILD endpoints, including disease presence, prognosis, and/or treatment response. In this review, we provide an overview of potentially informative biomarkers in patients with ILD, including those suggestive of a PF-ILD phenotype. We highlight the recent genomic, transcriptomic, and proteomic investigations that identified these biomarkers and discuss the body compartments in which they are found, including the peripheral blood, airway, and lung parenchyma. Finally, we identify critical gaps in knowledge within the field of ILD biomarker research and propose steps to advance the field toward biomarker implementation.

Potential Biomarkers in Systemic Sclerosis: A Literature Review and Update

Systemic sclerosis (SSc) is a chronic autoimmune disease characterized by dysregulation of the immune system, vascular damage, and fibrosis of the skin and internal organs. Patients with SSc show a heterogeneous phenotype and a range of clinical courses. Therefore, biomarkers that are helpful for precise diagnosis, prediction of clinical course, and evaluation of the therapeutic responsiveness of disease are required in clinical practice. SSc-specific autoantibodies are currently used for diagnosis and prediction of clinical features, as other biomarkers have not yet been fully vetted. Krebs von den Lungen-6 (KL-6), surfactant protein-D (SP-D), and CCL18 have been considered as serum biomarkers of SSc-related interstitial lung disease. Moreover, levels of circulating brain natriuretic peptide (BNP) and N-terminal pro-brain natriuretic peptide (NT-proBNP) can provide diagnostic information and indicate the severity of pulmonary arterial hypertension. Assessment of several serum/plasma cytokines, chemokines, growth factors, adhesion molecules, and other molecules may also reflect the activity or progression of fibrosis and vascular involvement in affected organs. Recently, microRNAs have also been implicated as possible circulating indicators of SSc. In this review, we focus on several potential SSc biomarkers and discuss their clinical utility.

Association between immunosuppressive therapy and course of mild interstitial lung disease in systemic sclerosis

OBJECTIVE

Interstitial lung disease (ILD) is a leading cause of mortality in SSc. Little is known about the benefits of immunosuppressive drugs in mild ILD. Our aim was to determine whether use of CYC or MMF was associated with an improved ILD course in patients with normal or mildly impaired lung function.

METHODS

A retrospective cohort of SSc subjects with ILD, disease duration below seven years and no exposure to CYC or MMF prior to the baseline visit was constructed from the Canadian Scleroderma Research Group registry. Subjects were categorized as having mild ILD if baseline forced vital capacity (FVC % predicted) was >85%. The primary exposure was any use of CYC or MMF at the baseline visit. FVC at one year was compared between exposed and unexposed subjects, using multivariate linear regression.

RESULTS

Out of 294 eligible SSc-ILD subjects, 116 met criteria for mild ILD. In this subgroup, mean (s.d.) disease duration was 3.7 (2.0) years. Thirteen (11.2%) subjects were exposed to CYC or MMF at baseline. The one-year FVC was higher in exposed subjects compared with unexposed subjects, by a difference of 8.49% (95% CI: 0.01-16.98%). None of the exposed subjects experienced clinically meaningful progression over two years, whereas 24.6% of unexposed subjects did.

CONCLUSION

In this real-world setting, CYC/MMF exposure at baseline was associated with higher FVC values and a lower risk of progression among subjects with mild ILD. These data suggest a window of opportunity to preserve lung function in SSc-ILD.

Rapid decrease of serum surfactant protein-D levels predicts the reactivity of rituximab therapy in systemic sclerosis-associated interstitial lung disease

Systemic sclerosis (SSc) is an autoimmune disorder characterized by vascular damage and excessive fibrosis. SSc-associated interstitial lung disease (ILD) is a leading cause of death in SSc. Several studies have shown the efficacy of rituximab (RTX) in SSc-ILD, but no study has examined the relation between RTX reactivity and change of serum marker levels. In this study we examined the relation between change of serum surfactant protein-D (SP-D) levels and change of percentage forced vital capacity (FVC) in 11 SSc-ILD patients with anti-topoisomerase I antibody treated by RTX. Serum SP-D levels were significantly decreased compared with baseline at 2 weeks after first RTX infusion in good responders (P = 0.04), while not in poor responders (P = 0.77). Moreover, ΔSP-D at 2 weeks negatively correlated with Δ%FVC at 24 weeks (P = 0.001). In conclusion, we suggested that the rapid decrease of SP-D levels may be a predictive marker of RTX effect against SSc-ILD.

Biomarkers in systemic sclerosis

PURPOSE OF REVIEW

To discuss recent advances in identification of biomarkers in systemic sclerosis for disease severity, prognosis, and treatment response.

RECENT FINDINGS

Recent reports describe novel circulating markers of disease severity, autoantibody associations with specific manifestations including cancer, and skin gene expression-based predictors of modified Rodnan skin score progression and treatment response. Moreover, there is converging evidence that C-reactive protein and pneumoproteins such as Krebs von den Lungen-6 and chemokine ligand 18 could serve as prognostic biomarkers in systemic sclerosis-associated interstitial lung disease.

SUMMARY

Several novel biomarkers show promise in improving the assessment of systemic sclerosis (SSc) disease severity, prognosis, and treatment response. Their potential utility in prospective selection of patients for clinical trials and in individual patient management require additional research.

Biomarkers in systemic sclerosis-associated interstitial lung disease: review of the literature

SSc is a rare disease of unknown origin associated with multiple organ involvement. One of the major complications that drives the mortality of SSc patients is interstitial lung disease. The course of SSc-interstitial lung disease progression has a wide spectrum. Since the treatment is based on aggressive immunosuppression it should not be given to stable or non-progressing disease. The correct identification of disease with high risk of progression remains a challenge for early therapeutic intervention, and biomarkers remain urgently needed. In fact, eight categories of biomarkers have been identified and classified according to the different biological pathways involved. The purpose of this article is to describe the main biomarkers thought to be of interest with clinical value in the diagnosis and prognosis of SSc-interstitial lung disease.

Change in Serum Biomarker CA 15-3 as an Early Predictor of Response to Treatment and Survival in Hypersensitivity Pneumonitis

BACKGROUND

Hypersensitivity pneumonitis (HP) is an interstitial lung disease with a heterogeneous course of disease and treatment response. Cancer antigen 15-3 (CA 15-3), part of mucin 1, is believed to reflect epithelial cell injury and lung permeability and could be a potential biomarker for treatment response in HP.

OBJECTIVE

To assess the value of CA 15-3 as a predictive biomarker in non-fibrotic and fibrotic HP during immunosuppressive therapy.

DESIGN

Serum levels of CA 15-3 and pulmonary function tests (PFTs) were retrospectively retrieved from 48 HP patients treated with prednisone or cyclophosphamide at initiation of therapy (baseline), after 3 and 6 months. Pearson's correlation coefficient was computed to assess correlations between change in serum levels and PFT. Survival was evaluated using Kaplan-Meier curves.

RESULTS

After 6 months of immunosuppressive therapy CA 15-3 levels decreased significantly compared to baseline (p = 0.001). Change in CA 15-3 after 6 months correlated with FVC change (r =  - 0.469; p = 0.001). Correlations with FVC change were observed in prednisone-treated HP (r =  - 0.514; p = 0.005) and fibrotic HP (r =  - 0.417; p = 0.007). Three-month CA 15-3 change correlated with 6-month FVC change (r =  - 0.599; p < 0.001). CA 15-3 declines of at least 7.9% after 6 months were associated with increased survival compared to minor CA 15-3 changes (HR 0.34; p = 0.020).

CONCLUSION

Serum CA 15-3 correlates with PFT during 6 months of immunosuppressive therapy in HP. Interestingly, early CA 15-3 changes could predict future PFT. Furthermore, a decrease in CA 15-3 is related to longer survival. Therefore, serum CA 15-3 is a promising biomarker for implementation in HP care.

Inflammatory stays inflammatory: a subgroup of systemic sclerosis characterized by high morbidity and inflammatory resistance to cyclophosphamide

Background/purpose

Elevated levels of C-reactive protein (CRP) in systemic sclerosis (SSc) have been linked to early inflammatory stages of the disease. This study has been designed to investigate CRP levels longitudinally in a cohort of SSc patients and to correlate these findings with comorbidities and disease characteristics.

Methods

In this retrospective study, patients with SSc treated at the outpatient clinic of the Department of Rheumatology and Clinical Immunology, University Medical Center Freiburg, were analyzed. Only patients with at least three consecutive visits and at least 1 year follow-up were included in this study. CRP serum levels were measured at every visit and categorized as positive if CRP concentrations were ≥ 5 mg/l. Subjects with elevated CRP levels at more than 80% of visits were defined as inflammatory SSc. The longitudinal CRP profiles were correlated with disease characteristics and comorbidities.

Results

A total of 1815 consecutive visits of 131 SSc patients were analyzed. Over the observed time span (7.6 (1.0–19.5) years), 18.3% (n = 24) of patients had continuously elevated CRP levels (inflammatory SSc), whereas in 29% (n = 38), CRP levels were always in the normal range. There was no association between disease duration and CRP levels at first visit. Inflammatory SSc was associated with male gender (p = 0.022), anti-Scl-70 antibodies (p = 0.009), diffuse cutaneous SSc (p = 0.036), pulmonary fibrosis (p < 0.001), rheumatoid arthritis (p = 0.007), and cardiac arrhythmia (p = 0.048). Moreover, patients with inflammatory SSc revealed higher modified Rodnan skin scores (p < 0.001); lower forced vital capacity (FVC) (p < 0.001), total lung capacity (p = 0.001), and diffusing capacity (p = 0.008); and faster decline of FVC per year (p = 0.007). Even treatment with cyclophosphamide (CYC) did not decrease CRP levels (p = 0.754).

Conclusion

Inflammatory SSc is characterized by a more severe phenotype, high morbidity, and a large proportion of male patients. Even treatment with CYC does not alter CRP levels in this subpopulation with a high unmet medical need.

Progression of Interstitial Lung Disease in Systemic Sclerosis: The Importance of Pneumoproteins Krebs von den Lungen 6 and CCL18

OBJECTIVE

To investigate the relationship between Krebs von den Lungen 6 (KL-6) and CCL18 levels and the severity and progression of systemic sclerosis (SSc)-related interstitial lung disease (ILD).

METHODS

Patients enrolled in the Scleroderma Lung Study II (cyclophosphamide [CYC] versus mycophenolate mofetil [MMF]) were included. Baseline and 12-month plasma samples were analyzed by enzyme-linked immunosorbent assay to assess CCL18 and KL-6 levels. The forced vital capacity (FVC) and the diffusing capacity for carbon monoxide (DLco) were measured every 3 months. Joint models were created to investigate the relationship between baseline CCL18 and KL-6 levels and the course of the FVC and DLco over 1 year according to treatment arm.

RESULTS

Baseline KL-6 and CCL18 levels each correlated with the extent of radiographic fibrosis. Levels of both CCL18 and KL-6 declined significantly at 1 year. In both treatment arms (n = 71 for CYC, n = 62 for MMF), a higher baseline KL-6 level predicted progression of ILD based on the course of FVC (P = 0.024 for CYC; P = 0.005 for MMF) and DLco (P < 0.001 for CYC; P = 0.004 for MMF) over 1 year. A higher baseline CCL18 level predicted progression of ILD based on the course of the FVC (P < 0.001 for CYC; P = 0.007 for MMF) and DLco (P = 0.001 for CYC; P < 0.001 for MMF) over 1 year, as well as mortality (P = 0.0008 for CYC arm only).

CONCLUSION

In a rigorously conducted clinical trial for SSc-related ILD, KL-6 and CCL18 levels correlated with ILD severity and declined with immunosuppression. Patients with higher baseline KL-6 and CCL18 levels were more likely to experience disease progression despite treatment. KL-6 and CCL18 levels could be used to identify patients with a progressive ILD phenotype who may benefit from a more aggressive initial treatment approach.