A Comparison of EMA and FDA Decisions for New Drug Marketing Applications 2014-2016: Concordance, Discordance, and Why.

The Food and Drug Administration (FDA) and the European Medicines Agency (EMA) have robust scientific and technical collaborations. As a window to the impact of these activities we compared the agencies' decisions on drug marketing applications. Decisions were compared for 107 new drug applications with a regulatory outcome at both agencies in the period 2014-2016. Further analysis addressed individual applications for which the agencies had differing outcomes in terms of marketing approval, type of approval, and approved indication, including reasons underlying differences. The EMA and the FDA had high concordance (91-98%) in decisions on marketing approvals. Divergence in approval decisions, type of approval, and approved indication were primarily due to differences in agencies' conclusions about efficacy based on review of the same data or differing clinical data submitted to support the application. This high rate of concordance suggests that engagement and collaboration on regulatory science has a positive impact.

Toward Accelerated Authorization and Access to New Medicines for Juvenile Idiopathic Arthritis.

A meeting was organized to bring together multiple stakeholders involved in the testing and authorization of new medications for juvenile idiopathic arthritis (JIA) to discuss current issues surrounding clinical trials and access to new medications for children and adolescents with JIA. The Childhood Arthritis and Rheumatology Research Alliance invited representatives of regulatory agencies (Food and Drug Administration and European Medicines Agency), and major pharmaceutical companies with JIA-approved products or products in development, patient and parent representatives, representatives of an advocacy organization (Arthritis Foundation), and pediatric rheumatology clinicians/investigators to a 1-day meeting in April 2018. The participants engaged in discussion regarding issues in clinical trials. As the pharmacologic options to treat inflammatory arthritis rapidly expand, registration trial designs to test medications in JIA patients must adapt. Many methodologies successfully used in the recent past are no longer feasible. The pool of patients meeting entry criteria who are willing to participate is shrinking while the number of medications to be tested is growing. Suggested solutions included proposing innovative clinical trial methods to regulatory agencies, as well as open discussions among stakeholders. Ensuring that new medications are authorized in a timely manner to meet the needs of JIA patients worldwide is critical. Approaches should include open dialog between regulatory agencies, pharmaceutical companies, and other stakeholders to develop and implement novel study designs, including patient and clinician perspectives to define meaningful trial outcomes, and changing existing study plans.

Establishing an Updated Core Domain Set for Studies in Juvenile Idiopathic Arthritis: A Report from the OMERACT 2018 JIA Workshop.

OBJECTIVE: The current Juvenile Idiopathic Arthritis (JIA) Core Set used in randomized controlled trials (RCT) and longitudinal observational studies (LOS) was developed without the input of patients/parents. At the Outcome Measures in Rheumatology (OMERACT) 2016, a special interest group voted to reconsider the core set, incorporating broader input. We describe subsequent work culminating in an OMERACT 2018 plenary and consensus voting. METHODS: Candidate domains were identified through literature review, qualitative surveys, and online discussion boards (ODB) held with patients with JIA and parents in Australia, Italy, and the United States. A Delphi process with parents, patients, healthcare providers, researchers, and regulators served to edit the domain list and prioritize candidate domains. After the presentation of results, OMERACT workshop participants voted, with consensus set at > 70%. RESULTS: Participants in ODB were 53 patients with JIA (ages 15-24 yrs) and 55 parents. Three rounds of Delphi considering 27 domains were completed by 190 (response rate 85%), 201 (84%), and 182 (77%) people, respectively, from 50 countries. There was discordance noted between domains prioritized by patients/parents compared to others. OMERACT conference voting approved domains for JIA RCT and LOS with 83% endorsement. Mandatory domains are pain, joint inflammatory signs, activity limitation/physical function, patient's perception of disease activity (overall well-being), and adverse events. Mandatory in specific circumstances: inflammation/other features relevant to specific JIA categories. CONCLUSION: Following the OMERACT methodology, we developed an updated JIA Core Domain Set. Next steps are to identify and systematically evaluate best outcome measures for these domains.

Identifying Provisional Generic Contextual Factor Domains for Clinical Trials in Rheumatology: Results from an OMERACT Initiative.

OBJECTIVE: The Contextual Factors Working Group aims to provide guidance on addressing contextual factors in rheumatology trials within OMERACT. METHODS: During the Special Interest Group session at OMERACT 2018, preliminary results were presented from a case scenario survey and semistructured interviews, including contextual factors mentioned in these. A group-based exercise sought to identify and rank important generic contextual factors. RESULTS: A total of 79 candidate factors were listed. Across the 3 groups, gender/sex, comorbidities, and the healthcare system were ranked as most important. CONCLUSION: The identified important contextual factor domains may be considered a provisional list pending further research.

Extrapolation in the development of paediatric medicines: examples from approvals for biological treatments for paediatric chronic immune-mediated inflammatory diseases.

The European Union (EU) Paediatric Regulation requires that all new medicinal products applying for a marketing authorisation (MA) in the EU provide a paediatric investigation plan (PIP) covering a clinical and non-clinical trial programme relating to the use in the paediatric population, unless a waiver applies. Conducting trials in children is challenging on many levels, including ethical and practical issues, which may affect the availability of the clinical evidence. In scientifically justified cases, extrapolation of data from other populations can be an option to gather evidence supporting the benefit-risk assessment of the medicinal product for paediatric use. The European Medicines Agency (EMA) is working on providing a framework for extrapolation that is scientifically valid, reliable and adequate to support MA of medicines for children. It is expected that the extrapolation framework together with therapeutic area guidelines and individual case studies will support future PIPs. Extrapolation has already been employed in several paediatric development programmes including biological treatment for immune-mediated diseases. This article reviews extrapolation strategies from MA applications for products for the treatment of juvenile idiopathic arthritis, paediatric psoriasis and paediatric inflammatory bowel disease. It also provides a summary of extrapolation advice expressed in relevant EMA guidelines and initiatives supporting the use of alternative approaches in paediatric medicine development.

Pediatric Crohn Disease Clinical Outcome Assessments and Biomarkers: Current State and Path Forward for Global Collaboration.

OBJECTIVE: There is a pressing need for drug development in pediatric Crohn disease (CD). Our aim was to provide strategic approaches toward harmonization of current thinking about clinical outcome assessments (COAs) and biomarkers to facilitate drug development in pediatric CD. METHODS: Scientists from the United States Food and Drug Administration, European Medicines Agency, Health Canada, and the Pharmaceuticals and Medical Devices Agency of Japan had monthly teleconferences from January 2014 through May 2015. A literature review was conducted to assess the measurement properties of all existing COA tools and to evaluate the current landscape of biomarkers used in pediatric CD. Based on the findings of literature review, we reached the consensus on the strategic approaches for evaluating outcomes in pediatric CD trials. RESULTS: The pediatric Crohn's Disease Activity Index, Crohn's Disease Activity Index, and Harvey-Bradshaw's index were used in pediatric CD clinical studies. But they lack adequate measurement properties (validity, reliability, and ability to detect change of the treatment) that are required to support approval of products intended to treat pediatric CD. Biomarkers (ie, fecal lactoferrin, osteoprotegerin, and calprotectin) have shown some promise for their potential as noninvasive surrogate endpoints in CD. CONCLUSIONS: Lack of well-defined and reliable COAs presents a hurdle for global drug development in pediatric CD. It is essential to develop well-defined and reliable COAs that can measure meaningful clinical benefit for patients in terms of how they feel, function, and survive. Development of noninvasive biomarkers as reliable surrogate endpoints needs to be further explored.

Steps toward harmonization for clinical development of medicines in pediatric ulcerative colitis-a global scientific discussion, part 1: efficacy endpoints and disease outcome assessments.

OBJECTIVES: There is a pressing need for drug development in pediatric ulcerative colitis (UC). Lack of scientific consensus on efficacy endpoints and disease outcome assessments presents a hurdle for global drug development in pediatric UC. Scientists from 4 regulatory agencies convened an International Inflammatory Bowel Disease Working Group (i-IBD Working Group) to harmonize present thinking about various aspects of drug development in pediatric UC globally. METHODS: The i-IBD Working Group was convened in 2012 by scientists from the US Food and Drug Administration, European Medicines Agency, Health Canada, and the Pharmaceuticals and Medical Devices Agency of Japan. The members of this group considered reasons for differences in their acceptance of efficacy endpoints and disease activity indices used in pediatric UC, reviewed the available literature, and developed consensus opinions regarding approaches for evaluating outcomes in pediatric UC trials. RESULTS: There is lack of harmonization in using efficacy endpoint and outcome assessments including disease activity indices to assess clinical benefit in pediatric UC trials. Many disease activity indices have been developed, but their biometric properties, such as responsiveness, reliability, and validity, have not been properly validated. Biomarkers, such as fecal calprotectin and lactoferrin, are being investigated for their potential as noninvasive surrogate endpoints in UC. CONCLUSIONS: Consensus on the efficacy endpoints, disease activity indices, and outcome assessments is needed for globalization of pediatric UC trials. The i-IBD Working Group offers several perspectives to facilitate harmonization across regions. The development of noninvasive biomarkers as reliable surrogate endpoints needs to be explored further.

Steps toward harmonization for clinical development of medicines in pediatric ulcerative colitis-a global scientific discussion, part 2: data extrapolation, trial design, and pharmacokinetics.

OBJECTIVES: To facilitate global drug development, the International Pediatric Inflammatory Bowel Disease Working Group (i-IBD Working Group) discussed data extrapolation, trial design, and pharmacokinetic (PK) considerations for drugs intended to treat pediatric ulcerative colitis (UC), and considered possible approaches toward harmonized drug development. METHODS: Representatives from the US Food and Drug Administration, European Medicines Agency, Health Canada, and the Pharmaceuticals and Medical Devices Agency of Japan convened monthly to explore existing regulatory approaches, reviewed the results of a literature search, and provided perspectives on pediatric UC drug development based on the available medical literature. RESULTS: Although pediatric UC, when compared with UC in adults, has a similar disease progression and response to intervention, the similarity of the exposure-response relation has not been adequately established. Consequently, clinical endpoints should be selected to optimally assess efficacy in children. The inclusion of a placebo control in pediatric trials to assure assay sensitivity may be appropriate under limited circumstances. In clinical studies, although the drug under investigation could provide possible direct benefit, placebo treatment should present no more than a minor increase over minimal risk to children with UC. CONCLUSIONS: Partial extrapolation of efficacy from informative adult studies may be appropriate. Placebo-controlled efficacy trials are scientifically and ethically appropriate for pediatric UC given appropriate patient selection and the use of early escape. Clinical studies in pediatric UC may include initial dose-finding studies and exposure-response modeling followed by an efficacy and safety study to further explore the exposure-response relation.

Using registries to identify adverse events in rheumatic diseases.

The proven effectiveness of biologics and other immunomodulatory products in inflammatory rheumatic diseases has resulted in their widespread use as well as reports of potential short- and long-term complications such as infection and malignancy. These complications are especially worrisome in children who often have serial exposures to multiple immunomodulatory products. Post-marketing surveillance of immunomodulatory products in juvenile idiopathic arthritis (JIA) and pediatric systemic lupus erythematosus is currently based on product-specific registries and passive surveillance, which may not accurately reflect the safety risks for children owing to low numbers, poor long-term retention, and inadequate comparators. In collaboration with the US Food and Drug Administration (FDA), patient and family advocacy groups, biopharmaceutical industry representatives and other stakeholders, the Childhood Arthritis and Rheumatology Research Alliance (CARRA) and the Duke Clinical Research Institute (DCRI) have developed a novel pharmacosurveillance model (CARRA Consolidated Safety Registry [CoRe]) based on a multicenter longitudinal pediatric rheumatic diseases registry with over 8000 participants. The existing CARRA infrastructure provides access to much larger numbers of subjects than is feasible in single-product registries. Enrollment regardless of medication exposure allows more accurate detection and evaluation of safety signals. Flexibility built into the model allows the addition of specific data elements and safety outcomes, and designation of appropriate disease comparator groups relevant to each product, fulfilling post-marketing requirements and commitments. The proposed model can be applied to other pediatric and adult diseases, potentially transforming the paradigm of pharmacosurveillance in response to the growing public mandate for rigorous post-marketing safety monitoring.

Impact of the European paediatric legislation in paediatric rheumatology: past, present and future.

Conducting clinical trials in paediatric rheumatology has been difficult mainly because of the lack of funding for academic studies and the lack of interest by pharmaceutical companies in the small and non-rewarding paediatric market. The situation changed dramatically a few years ago with the introduction of the Best Pharmaceuticals for Children Act in the USA and of specific legislation for the development of paediatric medicines (Paediatric Regulation) in the European Union (EU). The EU Paediatric Regulation had a positive impact in paediatric rheumatology-in particular, on the development of new treatments for children with juvenile idiopathic arthritis (JIA). Some problems remain, however, such as greater harmonisation of the regulatory aspects of medicines, how to handle me-too agents, how to conduct adequate pharmacokinetic studies and develop age-appropriate formulations, ethical problems in study review and implementation, and a change in the current JIA classification. The introduction of specific legislation, coupled with the existence of large international networks such as the Pediatric Rheumatology Collaborative Study Group (PRCSG at http://www.prcsg.org), covering North America, and the Paediatric Rheumatology International Trials Organisation (PRINTO at http://www.printo.it), covering more than 50 countries, has led to great advances in paediatric rheumatology. Future changes might increase the possibility of conducting trials with similar approaches in other paediatric rheumatological conditions and provide evidence-based treatments for children affected by rheumatic diseases.

Phagocyte-specific S100 proteins and high-sensitivity C reactive protein as biomarkers for a risk-adapted treatment to maintain remission in juvenile idiopathic arthritis: a comparative study.

OBJECTIVES: Juvenile idiopathic arthritis (JIA) is a chronic inflammatory joint disease affecting children. Even if remission is successfully induced, about half of the patients experience a relapse after stopping anti-inflammatory therapy. The present study investigated whether patients with JIA at risk of relapse can be identified by biomarkers even if clinical signs of disease activity are absent. METHODS: Patients fulfilling the criteria of inactive disease on medication were included at the time when all medication was withdrawn. The phagocyte activation markers S100A12 and myeloid-related proteins 8/14 (MRP8/14) were compared as well as the acute phase reactant high-sensitivity C reactive protein (hsCRP) as predictive biomarkers for the risk of a flare within a time frame of 6 months. RESULTS: 35 of 188 enrolled patients experienced a flare within 6 months. Clinical or standard laboratory parameters could not differentiate between patients at risk of relapse and those not at risk. S100A12 and MRP8/14 levels were significantly higher in patients who subsequently developed flares than in patients with stable remission. The best single biomarker for the prediction of flare was S100A12 (HR 2.81). The predictive performance may be improved if a combination with hsCRP is used. CONCLUSIONS: Subclinical disease activity may result in unstable remission (ie, a status of clinical but not immunological remission). Biomarkers such as S100A12 and MRP8/14 inform about the activation status of innate immunity at the molecular level and thereby identify patients with unstable remission and an increased risk of relapse.

An international registry on autoinflammatory diseases: the Eurofever experience.

OBJECTIVE: To report on the demographic data from the first 18 months of enrollment to an international registry on autoinflammatory diseases in the context of the Eurofever project. METHODS: A web-based registry collecting baseline and clinical information on autoinflammatory diseases and related conditions is available in the member area of the PRINTO web-site. Anonymised data were collected with standardised forms. RESULTS: 1880 (M:F=916:964) individuals from 67 centers in 31 countries have been entered in the Eurofever registry. Most of the patients (1388; 74%), reside in western Europe, 294 (16%) in the eastern and southern Mediterranean region (Turkey, Israel, North Africa), 106 (6%) in eastern Europe, 54 in Asia, 27 in South America and 11 in Australia. In total 1049 patients with a clinical diagnosis of a monogenic autoinflammatory diseases have been enrolled; genetic analysis was performed in 993 patients (95%): 703 patients have genetically confirmed disease and 197 patients are heterozygous carriers of mutations in genes that are mutated in patients with recessively inherited autoinflammatory diseases. The median diagnosis delay was 7.3 years (range 0.3-76), with a clear reduction in patients born after the identification of the first gene associated with autoinflammatory diseases in 1997. CONCLUSIONS: A shared online registry for patients with autoinflammatory diseases is available and enrollment is ongoing. Currently, there are data available for analysis on clinical presentation, disease course, and response to treatment, and to perform large scale comparative studies between different conditions.

Development and initial validation of composite parent- and child-centered disease assessment indices for juvenile idiopathic arthritis.

OBJECTIVE: To develop and validate a parent-centered and a child-centered composite disease assessment index for juvenile idiopathic arthritis (JIA): the Juvenile Arthritis Parent Assessment Index (JAPAI) and the Juvenile Arthritis Child Assessment Index (JACAI), respectively. METHODS: The JAPAI and the JACAI include 4 measures: parent/child rating of overall well-being, pain, physical function, and health-related quality of life (HRQOL). Validation analyses were conducted on nearly 5,000 patients and included assessment of construct validity, discriminant validity, responsiveness to change, and reliability. Besides the 4-item version, a 3-item version of both indices, which did not include HRQOL, was tested. RESULTS: The JAPAI and the JACAI demonstrated good construct validity, yielding high correlations with the Juvenile Arthritis Disease Activity Score and moderate correlations with physician global rating and joint counts. Correlations obtained for the JAPAI and the JACAI and for the 4-item and the 3-item versions were comparable. Factorial analysis by principal component analysis showed that both indices are monodimensional. Both the JAPAI and JACAI discriminated well between different disease states and courses and between different levels of American College of Rheumatology Pediatric criteria in a clinical trial, and revealed fair responsiveness to clinical change. Internal consistency was satisfactory, with a Cronbach's alpha of >0.80 in all but 1 of the patient samples tested. CONCLUSION: The JAPAI and the JACAI were found to be valid instruments for assessment of disease status in JIA and suitable surrogates of physicians' evaluations. Both indices are potentially applicable in clinical practice, observational studies, and therapeutic trials.

The Pediatric Rheumatology International Trials Organization/American College of Rheumatology provisional criteria for the evaluation of response to therapy in juvenile systemic lupus erythematosus: prospective validation of the definition of improvement.

OBJECTIVE: To use the Pediatric Rheumatology International Trials Organization (PRINTO) core set of outcome measures to develop a validated definition of improvement for the evaluation of response to therapy in juvenile systemic lupus erythematosus (SLE). METHODS: Thirty-seven experienced pediatric rheumatologists from 27 countries, each of whom had specific experience in the assessment of juvenile SLE patients, achieved consensus on 128 patient profiles as being clinically improved or not improved. Using the physicians' consensus ratings as the gold standard measure, the chi-square, sensitivity, specificity, false-positive and false-negative rates, area under the receiver operating characteristic curve, and kappa level of agreement for 597 candidate definitions of improvement were calculated. Only definitions with a kappa value greater than 0.7 were retained. The top definitions were selected based on the product of the content validity score multiplied by its kappa statistic. RESULTS: The definition of improvement with the highest final score was at least 50% improvement from baseline in any 2 of the 5 core set measures, with no more than 1 of the remaining worsening by more than 30%. CONCLUSION: PRINTO proposes a valid and reproducible definition of improvement that reflects well the consensus rating of experienced clinicians and that incorporates clinically meaningful change in core set measures in a composite end point for the evaluation of global response to therapy in patients with juvenile SLE. The definition is now proposed for use in juvenile SLE clinical trials and may help physicians to decide whether a child with SLE responded adequately to therapy.

Localized scleroderma in childhood is not just a skin disease.

OBJECTIVE: Juvenile localized scleroderma is usually considered a disease that is confined to the skin and subcutaneous tissue. We studied the prevalence and clinical features of extracutaneous manifestations in a large cohort of children with juvenile localized scleroderma. METHODS: Data from a multinational study on juvenile scleroderma was used for this in-depth study. Clinical features of patients with extracutaneous manifestations were compared with those of patients who had exclusively skin involvement. RESULTS: Seven hundred fifty patients entered the study. One hundred sixty-eight patients (22.4%) presented with a total of 193 extracutaneous manifestations, as follows: articular (47.2%), neurologic (17.1%), vascular (9.3%), ocular (8.3%), gastrointestinal (6.2%), respiratory (2.6%), cardiac (1%), and renal (1%). Other autoimmune conditions were present in 7.3% of patients. Neurologic involvement consisted of epilepsy, central nervous system vasculitis, peripheral neuropathy, vascular malformations, headache, and neuroimaging abnormalities. Ocular manifestations were episcleritis, uveitis, xerophthalmia, glaucoma, and papilledema. In more than one-fourth of these children, articular, neurologic, and ocular involvements were unrelated to the site of skin lesions. Raynaud's phenomenon was reported in 16 patients. Respiratory involvement consisted essentially of restrictive lung disease. Gastrointestinal involvement was reported in 12 patients and consisted exclusively of gastroesophageal reflux. Thirty patients (4%) had multiple extracutaneous features, but systemic sclerosis (SSc) developed in only 1 patient. In patients with extracutaneous involvement, the prevalence of antinuclear antibodies and rheumatoid factor was significantly higher than that among patients with only skin involvement. However, Scl-70 and anticentromere, markers of SSc, were not significantly increased. CONCLUSION: Extracutaneous manifestations of juvenile localized scleroderma developed in almost one-fourth of the children in this study. These extracutaneous manifestations often were unrelated to the site of the skin lesions and sometimes were associated with multiple organ involvement. The risk of developing SSc was very low. This subgroup of patients with juvenile localized scleroderma should be evaluated extensively, treated more aggressively, and monitored carefully.

A randomized trial of parenteral methotrexate comparing an intermediate dose with a higher dose in children with juvenile idiopathic arthritis who failed to respond to standard doses of methotrexate.

OBJECTIVE: To compare the safety and efficacy of parenteral methotrexate (MTX) at an intermediate dosage (15 mg/m(2)/week) versus a higher dosage (30 mg/m(2)/week) in patients with polyarticular-course juvenile idiopathic arthritis (JIA) who failed to improve while receiving standard dosages of MTX (8-12.5 mg/m(2)/week). METHODS: In the screening phase, 595 patients who were newly started on a standard dose of MTX were followed up for 6 months. Subsequently, the nonresponders, defined according to the American College of Rheumatology (ACR) pediatric 30% improvement criteria (pediatric 30), were randomized to receive an intermediate dose or higher dose of parenteral MTX for an additional 6 months. Improvement in the screening and randomization phase was defined by the ACR pediatric 30 response, as well as by the 50% and 70% response levels (ACR pediatric 50 and ACR pediatric 70, respectively). RESULTS: In the screening phase, after receiving standard doses of MTX, 430 patients (72%) improved according to the ACR pediatric 30, while 360 (61%) met the ACR pediatric 50 and 225 (38%) met the ACR pediatric 70; among these patients, 69 (12%) also met the definition of complete disease control. Of the 133 nonresponders, 80 were randomized to receive an intermediate dose or higher dose of MTX. In the randomization phase, the ACR pediatric 30 response rate was 25 of 40 children (62.5%) in the intermediate-dose group versus 23 of 40 children (57.5%) in the higher-dose group. An ACR pediatric 50 response rate was attained by 23 patients (57.5%) receiving an intermediate dose versus 22 (55%) in the higher-dose group. An ACR pediatric 70 response rate was seen in 18 children (45%) receiving an intermediate dose versus 19 (47.5%) receiving a higher dose. Five children (12.5%) in the intermediate-dose group versus 4 (10%) receiving the higher dose of MTX also met the definition of complete disease control. None of the intergroup differences in response rate were significant. There were no significant differences in the frequency of adverse events or laboratory abnormalities between the 2 randomized groups. CONCLUSION: This study shows that the plateau of efficacy of MTX in JIA is reached with parenteral administration of 15 mg/m(2)/week and that a further increase in dosage is not associated with any additional therapeutic benefit. MTX should be administered for up to 9-12 months to appreciate its full therapeutic effect.

Serum level of KL-6 as a marker of interstitial lung disease in patients with juvenile systemic sclerosis.

OBJECTIVE: Serum KL-6 has been found to be elevated in diseases characterized by diffuse interstitial lung involvement. The purpose of this study was to evaluate serum KL-6 as a marker of interstitial lung disease (ILD) in patients with juvenile systemic sclerosis (JSS). METHODS: Serum concentrations of KL-6 were measured with an immunoassay in 39 serum samples from 12 children with diffuse cutaneous form of JSS (6 patients with and 6 patients without ILD) and from 20 healthy controls comparable for age. In patients sampled serially, the relationship of KL-6 concentrations with the severity of ILD and its response to treatment were evaluated. RESULTS: Serum concentrations of KL-6 were significantly higher in patients with ILD (1687 +/- 979 IU/ml) than in patients without (345 +/- 95 IU/ml, p < 0.01) and healthy controls (311 +/- 114 IU/ml, p < 0.001). Serum KL-6 concentrations of patients without ILD were not statistically different from those of healthy controls. We found a significant correlation of serum KL-6 concentrations with vital capacity and with diffusing capacity for carbon monoxide (DLCO). Analysis of individual patients showed that serum concentrations of KL-6 were correlated with ILD severity and its response to treatment. CONCLUSION: Measurement of serum KL-6 concentration is a useful noninvasive marker of pulmonary fibrosis in children with JSS. Its advantages over conventional methods of ILD assessment, such as pulmonary function test and high-resolution computerized tomography, are that it is easy to quantify and to measure repeatedly and it does not need children's cooperation.