Janus kinase 1/2 inhibition with baricitinib in the treatment of juvenile dermatomyositis

Type I interferon biomarker in idiopathic inflammatory myopathies: associations of Siglec-1 with disease activity and treatment response

OBJECTIVES

Novel biomarkers are needed to guide therapy in idiopathic inflammatory myopathies (IIM). Expression of Siglec-1, a type I interferon biomarker, was examined in adult patients with IIM in relation to disease activity and treatment response.

METHODS

We analyzed PBMC samples from 19 newly diagnosed adult IIM patients who participated in a phase-2 pilot study on efficacy of intravenous immunoglobulin (IVIG) monotherapy, and from 9 healthy controls. Siglec-1 expression on monocytes was measured by flow cytometry before and after treatment, and was evaluated in relation to IIM subtype, physician global activity (PhGA) scores, manual muscle strength (MMT) and the total improvement score (TIS).

RESULTS

Diagnoses included dermatomyositis (DM; n = 9), immune-mediated necrotizing myopathy (IMNM; n = 5), non-specific/overlap myositis (NSM/OM; n = 4) and antisynthetase syndrome (ASyS; n = 1). All patients showed increased Siglec-1 expression at baseline. Relative median fluorescence intensity of Siglec-1 was highest in patients with DM. After 9 weeks, follow-up samples were available for 15 patients of whom 10 patients showed a decline in Siglec-1 expression. In DM, Siglec-1 correlated with disease activity (MMT; rs = -0.603, P = 0.013 and PhGA; rs = 0.783, P < 0.001) and with the TIS (rs = -0.786, P = 0.036).

CONCLUSION

Siglec-1 was increased in treatment-naive IIM patients and showed a decline after IVIG monotherapy. In DM, Siglec-1 expression correlated with relevant clinical measures. This underlines the dynamic role of type I IFN in IIM and the biomarker potential of Siglec-1, in particular in DM. These findings should be further validated in larger cohorts with longer follow-up.

Juvenile Dermatomyositis: Updates in Pathogenesis and Biomarkers, Current Treatment, and Emerging Targeted Therapies

Juvenile dermatomyositis is a rare systemic inflammatory autoimmune disease involving muscle, skin, and vessels. Most patients do not fully respond to initial therapy, instead having a chronic refractory or polycyclic disease course. Pathogenesis is not completely understood, but immune cell dysregulation, particularly of B cells, mitochondrial dysfunction, changes in neutrophils and neutrophil extracellular traps (NETs), and increased type I and type II interferon (IFN) signaling have been described. There are limited randomized controlled trials of drugs in juvenile dermatomyositis (JDM), and treatment is largely based on lower-quality data such as case series, retrospective studies, and open-label prospective studies. These data have been compiled into expert recommendations or consensus treatment plans, which help guide therapy. While initial therapy is more standard with most including corticosteroids (high-dose oral and/or pulse intravenous methylprednisolone) and methotrexate, for refractory patients, guidelines are more varied with multiple options or combinations, including biologic therapies. There is a clear need for more efficacious and personalized therapy in JDM. Emerging treatment options worthy of further study in JDM include targeting IFN-signaling (JAK, IFNAR1, IFN beta), B-cells (CD20, CD19, BAFF, TACI, CD38, BCMA) including Chimeric Antigen Receptor (CAR)-T cell therapy, mitochondrial dysfunction, and NETs.

Elicitation of expert prior opinion to design the BARJDM trial in juvenile dermatomyositis

OBJECTIVES

To elicit and quantify expert opinion concerning the relative merits of two treatments for a rare inflammatory disease: JDM. The formal expression of expert opinion reported in this article will be used in a Bayesian analysis of a forthcoming randomized controlled trial known as BARJDM (baricitinib for JDM).

METHODS

A Bayesian prior elicitation meeting was convened, following a previously described methodological template. Opinion was sought on the probability that a patient in the BARJDM trial would achieve clinically inactive disease, off glucocorticoids (GC) within a 12-month period with either MTX (standard of care); or baricitinib (a Janus kinase inhibitor, JAKi), with GC schedules identical in both arms of the trial. Experts' views were discussed and refined following presentation and further discussion of summated published data regarding efficacy of MTX or JAKi for JDM.

RESULTS

Ten UK paediatric rheumatology consultants (including one adolescent paediatric rheumatologist) participated in the elicitation meeting. All had expertise in JDM, leading active National Health Service clinics for this disease. Consensus expert prior opinion was that the most likely probability of clinically inactive disease off GC within 12 months was 0.55 on baricitinib and 0.23 on MTX, with a greater degree of uncertainty for baricitinib.

CONCLUSION

Experts currently think that baricitinib is superior to MTX for the treatment of JDM, although there is uncertainty around this. BARJDM will therefore integrate randomized trial data with this expert prior opinion to derive a posterior distribution for the relative efficacy of baricitinib compared with MTX.

Genetic changes from type I interferons and JAK inhibitors: clues to drivers of juvenile dermatomyositis

OBJECTIVE

To better understand the pathogenesis of juvenile dermatomyositis (JDM), we examined the effect of the cytokines type I interferons (IFN I) and JAK inhibitor drugs (JAKi) on gene expression in bioengineered pediatric skeletal muscle.

METHODS

Myoblasts from three healthy pediatric donors were used to create three-dimensional skeletal muscle units termed myobundles. Myobundles were treated with IFN I, either IFNα or IFNβ. A subset of IFNβ-exposed myobundles was treated with JAKi tofacitinib or baricitinib. RNA sequencing analysis was performed on all myobundles.

RESULTS

Seventy-six myobundles were analysed. Principal component analysis showed donor-specific clusters of gene expression across IFNα and IFNβ-exposed myobundles in a dose-dependent manner. Both cytokines upregulated interferon response and proinflammatory genes; however, IFNβ led to more significant upregulation. Key downregulated pathways involved oxidative phosphorylation, fatty acid metabolism and myogenesis genes. Addition of tofacitinib or baricitinib moderated the gene expression induced by IFNβ, with partial reversal of upregulated inflammatory and downregulated myogenesis pathways. Baricitinib altered genetic profiles more than tofacitinib.

CONCLUSION

IFNβ leads to more pro-inflammatory gene upregulation than IFNα, correlating to greater decrease in contractile protein gene expression and reduced contractile force. JAK inhibitors, baricitinib more so than tofacitinib, partially reverse IFN I-induced genetic changes. Increased IFN I exposure in healthy bioengineered skeletal muscle leads to IFN-inducible gene expression, inflammatory pathway enrichment, and myogenesis gene downregulation, consistent with what is observed in JDM.

Advances in Juvenile Dermatomyositis: Pathophysiology, Diagnosis, Treatment and Interstitial Lung Diseases-A Narrative Review

Juvenile idiopathic inflammatory myopathy (JIIM) is a rare systemic autoimmune disease characterized by skeletal muscle weakness with or without a skin rash. Juvenile dermatomyositis (JDM) is the most common subtype of JIIM, accounting for 80% of JIIM. Recent studies identified several myositis-specific autoantibodies (MSAs) and myositis-associated autoantibodies (MAAs). Each MSA or MAA is associated with distinct clinical features and outcomes, although there are several differences in the prevalence of MSA/MAA and autoantibody-phenotype relationships between age and ethnic groups. Histopathological studies have revealed critical roles of type I interferons and vasculopathy in the development of JDM. Serological classification mostly corresponds to clinicopathological classification. Novel therapeutic agents, such as biologics and Janus kinase inhibitors (JAKi), have been developed; however, to date, there is a lack of high-level evidence. As advances in treatment have reduced the mortality rate of JIIM, recent studies have focused on medium- and long-term outcomes. However, rapidly progressive interstitial lung disease (RP-ILD) remains a major cause of death in anti-melanoma differentiation gene 5 autoantibody-positive JDM. Early diagnosis and intervention using a multi-drug regimen is critical for the treatment of RP-ILD. Rituximab and JAKi may reduce mortality in patients with JDM-associated RP-ILD refractory to conventional therapy.

Current evidence for janus kinase inhibitors in adult and juvenile dermatomyositis and key comparisons

INTRODUCTION

Adult dermatomyositis (DM) and juvenile dermatomyositis (JDM) are rare autoimmune diseases with characteristic skin rashes, weakness, and other systemic features. Upregulated interferon signaling has been consistently described in both adult and juvenile DM which makes janus kinase inhibitors (jakinibs) an attractive therapeutic agent that has a targeted mechanism of action.

AREAS COVERED

Herein is a review of the growing literature of jakinib use in adult and juvenile DM, including reports on specific disease features and safety of jakinibs in this population and a comparison between adult and juvenile DM. We performed a literature review using PubMed including all English-language publications before 1 February 2024 and abstracts from key recent rheumatology conferences.

EXPERT OPINION

Jakinibs are an exciting and promising treatment in both adult and juvenile DM. Current Phase 2 and 3 randomized placebo-controlled trials of jakinibs in both adult and JDM will provide significant insights into the efficacy of this class of medication as a potentially more mechanistically targeted treatment of both skin and muscle disease. In fact, these results will likely inform the treatment paradigm of dermatomyositis in that it may even be considered as first or second line. The next five years in the therapeutic landscape of both juvenile and adult DM is an exciting time for both patients and medical providers.

JAK inhibitors in refractory juvenile rheumatic diseases: Efficacy, tolerance and type-I interferon profiling, a single center retrospective study

OBJECTIVES

- Janus Kinase inhibitors (JAKi) are a new class of drugs available for pediatric rheumatic diseases. This study aimed to describe the safety and effectiveness of JAKi in these diseases, with a focus on longitudinal interferon-stimulated genes (ISG) assessment.

METHODS

- We present a single-center retrospective study of children with refractory pediatric rheumatic diseases including connective tissue diseases, monogenic type I interferonopathies or juvenile idiopathic arthritis, receiving JAKi. According to physicians' assessment, treatment effectiveness was classified at 12 months as a complete response in the total absence of disease activity, partial response in case of significant (>50%) but incomplete improvement or no response in the case of non-response or improvement of less than 50% of the clinical and biological parameters. ISG were monitored longitudinally using Nanostring technology.

RESULTS

- 22 children were retrospectively included in this study, treated either by baricitinib or ruxolitinib. Complete response was achieved at 12 months in 9/22 (41%) patients. 6/22 (27%) patients were non-responders and treatment had been discontinued in five of them. Within the interferon (IFN)-related diseases group, ISG-score was significantly reduced 12 months after JAKi onset (p = 0.0068). At 12 months, daily glucocorticoid doses had been reduced with a median dose of 0.16 mg/kg/day (IQR 0.11; 0.33) (p = 0.0425). 7/22 (32%) patients had experienced side effects, infections being the most common. Increase of the body mass index was also recorded in children in the first 6 months of treatment.

CONCLUSION

- JAKi represent a promising treatment of immune-mediated pediatric diseases, enabling to decrease type-I IFN transcriptomic signature in responding patients, especially in the context of juvenile dermatomyositis. JAKi represent steroid-sparing drugs but they induce metabolic changes linked to weight gain, posing a concern in the treatment of young patients and teenagers. More data are required to define the efficacy and safety of JAKi in the management of refractory pediatric rheumatic diseases.

Treatment with Janus kinase inhibitors in juvenile dermatomyositis: A review of the literature

BACKGROUND/OBJECTIVES

Janus kinase (JAK) inhibitors have been increasingly used in the treatment of juvenile dermatomyositis (JDM). This review aims to comprehensively analyze previous studies concerning the utilization of JAK inhibitors in JDM patients.

METHODS

We conducted a thorough review of MEDLINE and Scopus databases, spanning from their inception to September 1st, 2023, to identify articles involving JDM patients treated with JAK inhibitors.

RESULTS

Our literature search yielded 26 articles that encompassed 195 patients with JDM who received JAK inhibitors. The median (min-max) age of the patients was 4.9 (1-17) years (F/M:1.2). The most frequently used JAK inhibitor was tofacitinib (57.4 %), and improvement was achieved in 89.7 % of patients treated with tofacitinib. The improvement rate for ruxolitinib, which was the second most frequently used JAK inhibitor (27.2 %), was 69.2 %. For baricitinib (15.4 %), the improvement rate was 92.7 %. The most prevalent indication for JAK inhibitor use was resistant/recurrent skin involvement (34.7 %) followed by resistant/recurrent muscle involvement (28.6 %). Adverse events were reported in 72.1 % of the patients; an increase in infections (especially upper respiratory tract infections) was the most common side effect.

CONCLUSION

Our findings suggest that JAK inhibitors may be a good therapeutic option, particularly in the management of refractory JDM cases with an acceptable safety profile. However, further controlled studies are essential to establish a higher level of evidence for the optimal use of JAK inhibitors in JDM treatment.

Updates on efficacy and safety janus kinase inhibitors in juvenile dermatomyositis

INTRODUCTION

Juvenile dermatomyositis (JDM) is a rare autoimmune disease most commonly with proximal weakness due to inflammation and characteristic skin rashes. Most patients have a chronic or polycyclic disease course on standard therapy so better treatments are needed. An interferon signature is well-established in key tissues of JDM. Janus kinase inhibitors (jakinibs), which can decrease IFN signaling, are therefore appealing as a targeted therapy.

AREAS COVERED

Herein is a review of the growing literature on JDM patients in jakinibs, including specifics of their jakinib exposure, summary of efficacy, disease features, and characteristics of patients treated, and safety parameters.

EXPERT OPINION

The vast majority of refractory JDM patients respond to jakinib therapy, though they have varied features, doses, and previous/concurrent medications, and data is largely retrospective. Jakinibs are an exciting and promising treatment in JDM. Evaluation with larger prospective controlled studies is needed to answer remaining questions about jakinibs in JDM regarding dosing, which JDM patients to treat with jakinibs, potential biomarkers to use, and how best to monitor safety risks in JDM.

Biologic drugs in the treatment of juvenile dermatomyositis: a literature review

There is no clear consensus in the literature regarding the choice of biologic therapies and efficacy in juvenile dermatomyositis (JDM). In this review, we aimed to examine previous studies regarding biologic drug use in JDM patients. We screened MEDLINE and Scopus for articles involving JDM patients treated with biologic drugs. We identified 74 articles describing 495 JDM patients treated with biologic drugs (538 biologic treatments) during our literature search. The median (min-max) age of these patients was 9.8 (1-17) years (F/M:1.8). The most frequently used biologic drugs were rituximab (RTX, 50%) and tumor necrosis factor (TNF) inhibitors (34.8%). In a few cases, abatacept (4.3%), anti-interleukin-1 agents (0.9%), tocilizumab (0.9%), bortezomib (0.4%), ustekinumab (0.2%), eculizumab (0.2%), and golimumab (0.2%) were used. RTX was most frequently preferred in patients with severe skin involvement (46.3%). Improvement with RTX was obtained in 60.1% of RTX treatments. Infliximab was most frequently preferred in calcinosis (43.3%), while adalimumab in skin involvement (50%) and etanercept in resistant/recurrent diseases (80%). Improvement was achieved in 44.4% of anti-TNF treatments. Adverse events were observed in 46.8% (58/124) of all treatments. Our results suggest that biologic agents may be a promising alternative for the treatment of particularly resistant JDM cases. Controlled studies are required to provide higher level of evidence for the timing of biologic use in JDM treatment. Key Points • There is no consensus on the choice and efficacy of biologic therapies in JDM. • RTX and TNF inhibitors are the most commonly used biologic drugs. • Biologics were especially preferred in severe skin involvement, calcinosis, and resistant diseases.

Long-Term Safety Profile and Off-Label Use of JAK Inhibitors in Dermatological Disorders

JAK inhibitors target specific inflammatory cytokines involved in various inflammatory diseases. Four molecules have been approved for dermatological use: upadacitinib, baricitinib, abrocitinib and topical ruxolitinib. Off-label prescriptions for other dermatological conditions have been reported. We conducted a narrative review of the literature to assess the long-term safety profile of currently approved JAK inhibitors in dermatology, and their off-label use in skin disorders. We performed literature searches with PubMed and Google Scholar from January 2000 to January 2023, using the keywords "Janus kinase inhibitors", "JAK inhibitors","off-label", "dermatology", "safety", "adverse events", "ruxolitinib", "upadacitinib","abrocitinib" and "baricitinib". Our search yielded a total of 37 dermatological disorders with studies supporting the use of these JAK inhibitors. Preliminary studies indicate that JAK inhibitors generally have a favorable safety profile and can be considered as an option in many dermatological disorders.

Long-Term Safety Profile and Off-Label Use of JAK Inhibitors in Dermatological Disorders

JAK inhibitors target specific inflammatory cytokines involved in various inflammatory diseases. Four molecules have been approved for dermatological use: upadacitinib, baricitinib, abrocitinib and topical ruxolitinib. Off-label prescriptions for other dermatological conditions have been reported. We conducted a narrative review of the literature to assess the long-term safety profile of currently approved JAK inhibitors in dermatology, and their off-label use in skin disorders. We performed literature searches with Pubmed and Google Scholar from January 2000 to January 2023, using the keywords "Janus kinase inhibitors", "JAK inhibitors", "off-label", "dermatology", "safety", "adverse events", "ruxolitinib", "upadacitinib", "abrocitinib" and "baricitinib". Our search yielded a total of 37 dermatological disorders with studies supporting the use of these JAK inhibitors. Preliminary studies indicate that JAK inhibitors generally have a favorable safety profile and can be considered as an option in many dermatological disorders.

Rapid and sustained response to JAK inhibition in a child with severe MDA5 + juvenile dermatomyositis

BACKGROUND

Juvenile dermatomyositis (jDM) is the most common idiopathic inflammatory myopathy of childhood. Amyopathic or hypomyopathic courses have been described.

CASE PRESENTATION

We present the case of a 4-year-old patient with MDA5 antibody positive jDM and interstitial lung disease. In our patient, typical symptoms of jDM with classical skin lesions, arthritis, proximal muscle weakness, and ulcerative calcifications were observed. Due to the severity of the disease and the pulmonary changes, therapy with the Janus kinase (JAK) inhibitor ruxolitinib was added to the therapy with corticosteroids, intravenous immunoglobulins (IVIG) and hydroxychloroquine leading to a fast and sustained remission.

CONCLUSION

While there is growing evidence that JAK inhibition is a promising therapeutic option in jDM our case report shows that this approach may also be effective in MDA5-positive jDM with high risk features.

Juvenile idiopathic inflammatory myositis: an update on pathophysiology and clinical care

The childhood-onset or juvenile idiopathic inflammatory myopathies (JIIMs) are a heterogenous group of rare and serious autoimmune diseases of children and young people that predominantly affect the muscles and skin but can also involve other organs, including the lungs, gut, joints, heart and central nervous system. Different myositis-specific autoantibodies have been identified that are associated with different muscle biopsy features, as well as with different clinical characteristics, prognoses and treatment responses. Thus, myositis-specific autoantibodies can be used to subset JIIMs into sub-phenotypes; some of these sub-phenotypes parallel disease seen in adults, whereas others are distinct from adult-onset idiopathic inflammatory myopathies. Although treatments and management have much improved over the past decade, evidence is still lacking for many of the current treatments and few validated prognostic biomarkers are available with which to predict response to treatment, comorbidities (such as calcinosis) or outcome. Emerging data on the pathogenesis of the JIIMs are leading to proposals for new trials and tools for monitoring disease.

JAK inhibitors and autoimmune rheumatic diseases

The four Janus kinase (JAK) proteins and the seven Signal Transducers of Activated Transcription (STAT) mediate intracellular signal transduction downstream of cytokine receptors, which are involved in the pathology of allergic, autoimmune, and inflammatory diseases. The development of targeted small-molecule treatments with diverse selective inhibitory profiles, such as JAK inhibitors (JAKi), has supported an important change in the treatment of multiple disorders. Indeed, JAKi inhibit intracellular signalling controlled by numerous cytokines implicated in the disease process of rheumatoid arthritis and several other inflammatory and immune diseases. Therefore, JAKi have the capacity to target multiple pathways of those diseases. Other autoimmune diseases treated with JAKi include systemic sclerosis, systemic lupus erythematosus, dermatomyositis, primary Sjogren's syndrome, and vasculitis. In all of these cases, innate immunity stimulation activates adaptive immunity, resulting in the production of autoreactive T cells as well as the stimulation and differentiation of B cells. Mechanism-based treatments that target JAK-STAT pathways have the possibility of improving outcomes by reducing the consumption of glucocorticoids and/or non-specific immunosuppressive drugs in the management of systemic immune-mediated inflammatory diseases.

Successful baricitinib treatment of refractory anti-synthetase syndrome associated with interstitial lung disease

A 47-year-old Japanese man was admitted with dyspnoea on exertion (DOE), skin rash and myalgia. Clinical findings of Gottron's sign and mechanic's hands were observed, with increased serum levels of Krebs von den Lungen-6, surfactant protein-D, creatine kinase, and anti-EJ on laboratory tests. In both lungs, chest computed tomography revealed diffuse reticular opacities and lower lobe predominance. The patient was diagnosed with anti-synthetase syndrome (ASS) and associated interstitial lung disease. Despite repeated administration of high-dose intravenous corticosteroids, cyclophosphamide and immunoglobulin, his skin rash, myalgia, and DOE followed a relapsing and remitting course. He was then given rituximab therapy. This was initially successful, but disease activity increased approximately 12 months after starting rituximab therapy. Finally, in addition to prednisolone and cyclosporine A, we administered baricitinib. There has been no relapse of the disease in the 12 months since he began baricitinib treatment.

Use of Janus kinase inhibitors in dermatomyositis: a systematic literature review

Dermatomyositis (DM) is an idiopathic inflammatory myopathy that commonly manifests with proximal muscle weakness and is associated with extramuscular pathology, including characteristic skin lesions such as Gottron's papules and heliotrope rash, as well as lung, gastrointestinal, joint, and cardiac involvement. Systemic corticosteroids are a cornerstone of therapy, and more recently intravenous immunoglobulin (IVIG; OCTAGAM®) has been approved by the US Food and Drug Administration for the treatment of adults with DM. Both steroids and IVIG represent nonspecific anti-inflammatory therapy, and more targeted approaches are lacking. Transcriptomics has identified upregulation of interferon (IFN)-regulated genes as key features of both adult DM and juvenile DM (JDM). Accordingly, blocking IFN signalling through inhibition of the Janus kinase (JAK) pathway represents a potential treatment option for DM. Placebo-controlled trial data assessing the use of JAK inhibitors for the treatment of DM are limited; as such, a systematic literature review was undertaken to assess the evidence of JAK inhibitors in the treatment of patients with DM. Terms related to DM and JAK inhibitors were searched using PubMed, Embase, Web of Science, Scopus, and Dimensions to identify peer-reviewed publications reporting patients with DM who were treated with a JAK inhibitor. Baseline demographics, clinical characteristics, and treatment outcome data were extracted. A total of 48 publications reporting 145 unique patients (adult DM, n=84; JDM, n=61) were identified. Among cases of adult DM, 61 of 84 (73%) had refractory skin disease at baseline, and all (61 of 61) reported improvement in cutaneous symptoms. Of patients with adult DM, 16 of 84 (19%) had refractory muscle disease at baseline, and all (16 of 16) reported improvement in muscle symptoms. In patients with adult DM complicated by interstitial lung disease (ILD; n=33), 31 (94%) patients improved with JAK inhibitor treatment. Among cases of JDM with refractory skin disease at baseline (60 of 61), most patients (57 of 60; 95%) showed improvements in skin symptoms after JAK inhibitor treatment. Of patients with JDM with refractory muscle disease at baseline (36 of 61), most (30 of 36; 83%) reported improvement in muscle symptoms. Four patients with JDM and ILD experienced improvement in lung disease activity following treatment with a JAK inhibitor. Among both DM and JDM cases, all patients (17 with DM and 16 with JDM) who had elevated serum IFN and/or IFN-stimulated gene expression at baseline showed reduction in IFN or IFN gene expression. Although the conclusions that can be drawn from this analysis are limited because of the differences in assessments used across publications, overall treatment of patients with DM or JDM with a JAK inhibitor was associated with significant improvement of a wide range of DM manifestations, including skin lesions, muscle weakness, and ILD. Our systematic literature review suggests that JAK inhibitors may be a viable treatment option for DM/JDM, and randomised controlled trials are necessary to confirm these findings.

A multi-center, open-label, randomized study to explore efficacy and safety of baricitinib in active primary Sjogren's syndrome patients

BACKGROUND

Primary Sjogren's syndrome (pSS) is a systemic autoimmune disease involving multiple organ systems. The Janus kinase/signal transduction and activator of transcription (JAK/STAT) signaling pathway is a key pathway involving the pathogenesis of pSS. Baricitinib, a selective JAK1 and JAK2 inhibitor, has been approved for treatment of active rheumatoid arthritis and reported in treatment of some other autoimmune diseases including systemic lupus erythematosus. We have found that baricitinib might be effective and safe in pSS in a pilot study. However, there is no published clinical evidence of baricitinib in pSS. Hence, we conducted this randomized study to further explore the efficacy and safety of baricitinib in pSS.

METHODS

This is a multi-center, prospective, open-label, randomized study to compare the efficacy of baricitinib + hydroxychloroquine (HCQ) with HCQ alone in pSS patients. We plan to involve 87 active pSS patients with European League Against Rheumatism pSS disease activity index (ESSDAI) ≥ 5 from eight different tertiary centers in China. Patients will be randomized (2:1) to receive baricitinib 4 mg per day + HCQ 400 mg per day or HCQ 400 mg per day alone. We will switch HCQ to baricitinib + HCQ if the patient in the latter group has no ESSDAI response at week 12. The final evaluation will be at week 24. The primary endpoint is the percentage of ESSDAI response, or minimal clinically important improvement (MCII), which was defined as an improvement of ESSDAI at least three points at week 12. The secondary endpoints include EULAR pSS patient-reported index (ESSPRI) response, change of Physician's Global Assessment (PGA) score, serological activity parameters, salivary gland function test, and focus score on labial salivary gland biopsy.

DISCUSSION

This is the first randomized controlled study to evaluate the clinical efficacy and safety of baricitinib in pSS. We hope that the result of this study can provide more reliable evidence of the efficacy and safety of baricitinib in pSS.

TRIAL REGISTRATION

ClinicalTrials.gov NCT05016297. Registered on 19 Aug 2021.

The role of bDMARDs in idiopathic inflammatory myopathies: A systematic literature review

Idiopathic inflammatory myopathies (IIM) are a group of different conditions typically affecting striate muscle, lung, joints, skin and gastrointestinal tract. Treatment typically relies on glucocorticoids and synthetic immunosuppressants, but the occurrence of refractory, difficult to treat, manifestations, may require more aggressive treatment, borrowed from other autoimmune diseases, including biologic disease modifying drugs (bDMARDs). In this regard, we conducted a systemic literature review in order to depict the current evidence about the use of bDMARDs in IIM. A total of 78 papers, published during the last 21 years, were retrieved. The majority of patients was treated with TNF-α inhibitors, whose effectiveness was assessed particularly in recalcitrant striate muscle, skin and joints involvement. Rituximab, whose evidence is supported by a large number of real-life studies and trials, seems to be an excellent option in case of ILD and anti-synthetase syndrome, while Tocilizumab, despite not meeting primary and secondary endpoints in a recently published clinical trial, proved its effectiveness in rapidly progressing ILD. Similarly, Abatacept, studied in a phase IIb clinical trial with conflicting evidence, was reported to be effective in some case reports of refractory dermatomyositis. Less data exist for anti-IL1 and anti-IL23 agents, which were employed particularly for inclusion body myositis and severe skin disease, respectively. This study provides an organ-focused assessment of bDMARDs in IIM, which display encouraging results in the treatment of refractory subsets of disease.

Calcinosis in juvenile dermatomyositis: Updates on pathogenesis and treatment

Calcinosis, or the deposition of insoluble calcium salts in the skin, subcutaneous tissue, fascia, tendons, and muscles, is a feared complication of juvenile dermatomyositis. Calcinosis is estimated to affect up to 40% of patients with juvenile dermatomyositis and contributes to significant disease morbidity. Calcinosis can be challenging to treat, and the most effective treatment remains unknown because of a lack of comparative studies. We aim to review the literature published in the last 5 years to summarize updates on the pathogenesis and treatment of calcinosis in juvenile dermatomyositis and describe future areas for research.

Update on dermatomyositis

PURPOSE OF REVIEW

This review summarizes and comments on current knowledge in dermatomyositis.

RECENT FINDINGS

The 2018 European Neuromuscular Centre classification of dermatomyositis has been challenging by the discovery of clinicopathological features associated with dermatomyositis-specific antibody (DMSA) that were not incorporated in the original criteria. These features include but may not be limited to the presence of perifascicular necrosis in anti-Mi-2 dermatomyositis; presence of diffuse nonperifascicular sarcoplasmic myxovirus resistance protein A expression in anti-MDA5 dermatomyositis; and dermatomyositis sine dermatitis in anti-NXP-2 dermatomyositis. Variations and subclassifications within the same DMSA subtypes are observed: anti-MDA5 dermatomyositis is clinically subcategorized into good, intermediate, and poor prognostic subgroups; concurrent anti-CCAR1 and anti-TIF1-γ positivity identify anti-TIF1-γ-positive patient with a lower risk for cancer-associated myositis. Owing to distinct IFN1-signaling pathway activation in dermatomyositis, JAK-STAT inhibitor - the pathway-targeted therapy, have been studied with promising results in refractory dermatomyositis and some new-onset dermatomyositis. In addition, the potential serum biomarkers for IFN1 pathway activation are being investigated for their performance in monitoring the disease activity and the efficacy of the treatment.

SUMMARY

DMSA, evidence of prominent IFN1 pathway activation, and risk/severity-associated biomarkers would likely play major roles in future dermatomyositis classification, disease monitoring, and treatment decision.

Advancements in the Treatment of Cutaneous Lupus Erythematosus and Dermatomyositis: A Review of the Literature

Background

Cutaneous lupus erythematosus (CLE) and dermatomyositis (DM) are autoimmune diseases that present with a wide variety of cutaneous manifestations. In both cases, first-line therapy includes topical corticosteroids. Patients may present with more widespread disease requiring systemic treatments, including corticosteroids, traditional immunosuppressants, or antimalarials. Due to their complex nature, both CLE and DM remain difficult to treat and continue to cause significant distress to patients.

Objective

To summarize the most recent literature on the safety and efficacy of novel treatment modalities for CLE and DM.

Methods

A literature search was conducted on PubMed using search terms “(dermatomyositis) AND (treatment)” and “(cutaneous lupus) AND (treatment)”. Additional search terms included specific names of biologic agents, phosphodiesterase inhibitors (apremilast), and JAK inhibitors.

Results

JAK inhibitors, PDE-4 inhibitors, and biologics have shown promise in reducing cutaneous symptoms of both CLE and DM, including reduction in SLE Disease Activity Index 2000 (SLEDAI-2K), Cutaneous Lupus Erythematosus Disease Area and Severity Index (CLASI), British Isles Lupus Assessment Group (BILAG), Cutaneous Dermatomyositis Disease Area and Severity Index (CDASI), and Disease Activity Score (DAS).

Conclusion

While there have been recent advancements in the treatment for CLE and DM, further research and clinical trials are required to better elucidate which therapy is best for individual patients.

Calcinosis in dermatomyositis: Origins and possible therapeutic avenues

Calcinosis, insoluble calcium compounds deposited in skin and other tissues, is a crippling sequela of dermatomyositis. Prolonged disease associated with ongoing inflammation, ischemia, repetitive trauma, and certain autoantibodies are associated with calcinosis. Herein, we describe potential pathogenic mechanisms including the role of mitochondrial calcification. There are no widely effective treatments for calcinosis. We review available pharmacologic therapies for calcinosis including those targeting calcium and phosphorus metabolism; immunosuppressive/anti-inflammatory therapies; and vasodilators. Mounting evidence supports the use of various formulations of sodium thiosulfate in the treatment of calcinosis. Although the early institution of aggressive immunosuppression may prevent calcinosis in juvenile dermatomyositis, only limited data support improvement once it has developed. Minocycline can be useful particularly for lesions associated with surrounding inflammation. Powerful vasodilators, such as prostacyclin analogs, may have promise in the treatment of calcinosis, but further studies are necessary. Surgical removal of lesions when amenable is our treatment of choice.

Possible future avenues for myositis therapeutics: DM, IMNM and IBM

Idiopathic inflammatory myopathies (IIMs) represent a heterogeneous group of systemic autoimmune diseases characterized by immune-mediated muscle injury. As insights into pathogenesis of IIM evolve, novel therapeutic strategies have become available to optimize outcomes. Herein, we summarize novel and emerging strategies in the management of dermatomyositis (DM), immunemediated necrotizing myopathy (IMNM), and inclusion body myositis (IBM).

Cardiovascular Abnormalities in Juvenile Dermatomyositis: A Scoping Review for the Clinical Rheumatologists

Juvenile dermatomyositis (JDM) is a common form of inflammatory myositis in children. Vasculopathy and endothelial dysfunction play significant roles in the pathogenesis of JDM. Cardiac involvement in JDM is often underestimated, and it may be a potential indicator of poor prognosis. Cardiac dysfunction in JDM can occur both in the acute and chronic stages of the disease. Amongst the acute complications, acute congestive heart failure (CHF), myocarditis, arrhythmia, and complete heart block are common. However, these remain unrecognized due to a lack of overt clinical manifestations. Increased rates of cardiovascular abnormalities have been noted with anti-SRP and anti-Jo 1 auto-antibody positivity. Long-term follow-up studies in JDM have shown an increased prevalence of hypertension, atherosclerosis, coronary artery disease, and metabolic syndrome in adolescence and adulthood. Monitoring of body-mass index, blood pressure, and laboratory evaluation of fasting glucose and lipid profile may help in identifying metabolic syndrome in children with JDM. Steroid-sparing agents, daily exercise, and a healthy diet may reduce such long-term cardiac morbidities. Current use of multimodality imaging such as stress-echocardiography, contrast-enhanced echocardiography, cardiac magnetic resonance imaging, and positron emission tomography has increased the diagnostic yield of subclinical heart disease during acute and chronic stages of JDM. This review elaborates on different aspects of cardiac dysfunction in JDM. It also emphasizes the importance of cardiac screening in long-term follow-up of children with JDM.

Investigating the efficacy of baricitinib in new onset type 1 diabetes mellitus (BANDIT)—study protocol for a phase 2, randomized, placebo controlled trial

Background

Type 1 diabetes (T1D) places an extraordinary burden on individuals and their families, as well as on the healthcare system. Despite recent advances in glucose sensors and insulin pump technology, only a minority of patients meet their glucose targets and face the risk of both acute and long-term complications, some of which are life-threatening.

The JAK-STAT pathway is critical for the immune-mediated pancreatic beta cell destruction in T1D. Our pre-clinical data show that inhibitors of JAK1/JAK2 prevent diabetes and reverse newly diagnosed diabetes in the T1D non-obese diabetic mouse model. The goal of this study is to determine if the JAK1/JAK2 inhibitor baricitinib impairs type 1 diabetes autoimmunity and preserves beta cell function.

Methods

This will be as a multicentre, two-arm, double-blind, placebo-controlled randomized trial in individuals aged 10–30 years with recent-onset T1D. Eighty-three participants will be randomized in a 2:1 ratio within 100 days of diagnosis to receive either baricitinib 4mg/day or placebo for 48 weeks and then monitored for a further 48 weeks after stopping study drug. The primary outcome is the plasma C-peptide 2h area under the curve following ingestion of a mixed meal. Secondary outcomes include HbA1c, insulin dose, continuous glucose profile and adverse events. Mechanistic assessments will characterize general and diabetes-specific immune responses.

Discussion

This study will determine if baricitinib slows the progressive, immune-mediated loss of beta cell function that occurs after clinical presentation of T1D. Preservation of beta cell function would be expected to improve glucose control and prevent diabetes complications, and justify additional trials of baricitinib combined with other therapies and of its use in at-risk populations to prevent T1D.

Trial registration

ANZCTR ACTRN12620000239965. Registered on 26 February 2020. ClinicalTrials.gov NCT04774224. Registered on 01 March 2021

Janus kinase inhibitors in immunoinflammatory diseases: 10 years of clinical practice in rheumatology

Despite great advances in the diagnosis and treatment of Immune-mediated inflammatory diseases (IMIDs), which have led to a significant improvement in the prognosis in many patients, the central medical problems of this pathology – restoring the quality of life and reducing mortality to the population level – are far from being resolved. This served as a powerful stimulus for the study of new approaches to the pharmacotherapy of IMIDs, one of which is associated with the discovery of targets for small-molecule therapeutics that inhibit intracellular “signaling” molecules JAKs (Janus kinases). The current achievements, trends and recommendations regarding the use of JAK inhibitors in the treatment of IMIDs and also in the hyper-response phase of COVID-19 are reviewed.

Evaluating the use of JAK inhibitors in inflammatory connective tissue diseases in pediatric patients: an update

INTRODUCTION

Connective tissue diseases (CTDs) are a category of conditions that affect tissues that support and provide structure to the body. These diseases include rheumatoid arthritis, systemic lupus erythematosus, dermatomyositis, and sclerosing diseases. CTDs can be caused by dysregulation of inflammatory pathways, specifically an upregulation of interferons and JAK/STAT pathway activation.

AREAS COVERED

While CTDs have historically been treated with broadly immunosuppressant medications such as corticosteroids and disease-modifying antirheumatic drugs (DMARDS), newer and more targeted immunomodulating medications called Janus kinase inhibitors (JAKi), have emerged as potential treatments.

EXPERT OPINION

While most studies regarding JAKi for CTDs have focused on adult populations, pediatric patients with CTDs may also benefit from JAKi therapy. Moreover, the JAK/STAT inhibitor tofacitinib has been approved by the FDA for the treatment of active polyarticular course juvenile idiopathic arthritis. In this review, we have summarized what has been published on the use of JAKi for various pediatric CTDs.

Emerging Therapeutics in the Management of Connective Tissue Disease. Part II. Dermatomyositis and Scleroderma

The management of connective tissue diseases is dramatically evolving with the advent of biologics and novel oral systemic therapeutics. Despite involvement in the care of these complex patients, there is a knowledge gap in the field of dermatology regarding these emerging agents. The second article in this continuing medical education series discusses new and emerging therapeutics for dermatomyositis and scleroderma that target cells, intracellular signaling pathways, and cytokines.

Short-term effectiveness of baricitinib in children with refractory and/or severe juvenile dermatomyositis

OBJECTIVE

To determine the short-term effectiveness safety of baricitinib in children with refractory and/or severe juvenile dermatomyositis (rsJDM) in a real-world setting.

METHODS

This was a single-center retrospective study, including 20 children with rsJDM. They were all treated using baricitinib combined with steroids and other immunosuppressive agents. The childhood myositis assessment scale (CMAS) and PRINTO remission criteria were used to evaluate the disease severity and treatment outcome at 0, 4, 12, and 24 weeks after initiation of baricitinib.

RESULTS

The skin rash improved in 95% of patients (19/20) at week 24, with a significant decrease of skin-DAS at weeks 12 (6.0 vs. 2.0, p < 0.05] and week 24 [6.0 vs. 1.0, p < 0.05) by median statistics. The CMAS score increased significantly at week 12 (41.0 [29.0, 44.0] vs. 46.0 [42.0, 52.0], p < 0.05) and week 24 (41.0 [29.0, 44.0] vs. 50.0 [45.0, 52.0], p < 0.05), as did the manual muscle testing (MMT)-8 score at week 24 (73.0 [610, 76.0] vs. 79.0 [77.0, 80.0], p < 0.05). At 24 weeks, the complete response (CR) and partial response (PR) were achieved in 75% (15/20) and 15% (3/20), respectively. The dose of corticosteroids (CS) decreased by 37% from the baseline (0.53 [0.42, 1.00] mg/kg) to week 12 (0.33 [0.18, 0.40] mg/kg) (p < 0.05), and by 49% at week 24 (p < 0.05). No serious side effects were observed.

CONCLUSION

Baricitinib combined with traditional immunosuppressants treatment was efficacious in rsJDM. Add-on therapy of baricitinib was helpful for tapering CS dose. No serious side effects were observed in this study.

Janus kinase inhibition in induction treatment of anti-MDA5 juvenile dermatomyositis-associated rapidly progressive interstitial lung disease

Tofacitinib has an important role in pediatric rapidly progressive interstitial lung disease (ILD) associated with juvenile dermatomyositis (JDM), an otherwise potentially fatal condition. It may be useful in induction of remission and can be used safely to maintain remission. Serum ferritin and interleukin-18 are useful markers for tracking activity and response of JDM-associated ILD.

The JAK/STAT signaling pathway: from bench to clinic

The Janus kinase/signal transducer and activator of transcription (JAK/STAT) signaling pathway was discovered more than a quarter-century ago. As a fulcrum of many vital cellular processes, the JAK/STAT pathway constitutes a rapid membrane-to-nucleus signaling module and induces the expression of various critical mediators of cancer and inflammation. Growing evidence suggests that dysregulation of the JAK/STAT pathway is associated with various cancers and autoimmune diseases. In this review, we discuss the current knowledge about the composition, activation, and regulation of the JAK/STAT pathway. Moreover, we highlight the role of the JAK/STAT pathway and its inhibitors in various diseases.

The JAK/STAT signaling pathway: from bench to clinic

The Janus kinase/signal transducer and activator of transcription (JAK/STAT) signaling pathway was discovered more than a quarter-century ago. As a fulcrum of many vital cellular processes, the JAK/STAT pathway constitutes a rapid membrane-to-nucleus signaling module and induces the expression of various critical mediators of cancer and inflammation. Growing evidence suggests that dysregulation of the JAK/STAT pathway is associated with various cancers and autoimmune diseases. In this review, we discuss the current knowledge about the composition, activation, and regulation of the JAK/STAT pathway. Moreover, we highlight the role of the JAK/STAT pathway and its inhibitors in various diseases.

Inflammatory myopathies in childhood

Myositis in childhood can occur under different conditions and with various aetiologies, juvenile dermatomyositis (jDM) being by far the most frequent entity. The exact diagnostic workup and precise assessment of muscular as well as extramuscular involvement of organs in these systemic autoimmune diseases are relevant for specific and adjunct treatment of complications. Many new insights have become available with respect to the pathophysiological concepts as well as modern diagnostic measures and therapeutic approaches. Autoantibody detection in the serum of children with myositis is one of the major novelties that has become widely used and that is indeed helpful for diagnostic and prognostic measures. The pathophysiological relevance of type I interferons in jDM has been studied intensively in the past years. jDM is now seen as an acquired interferonopathy and first therapeutic consequences have been drawn from this pathogenic finding with the use of Janus-kinase inhibitors for severe and not otherwise treatable children.

Updates on Juvenile Dermatomyositis from the Last Decade: Classification to Outcomes

Juvenile dermatomyositis (JDM) is a heterogeneous disease with new classification criteria and updates in myositis-specific autoantibody and myositis-associated antibody groups. There are many validated assessment tools for assessing disease activity in JDM. Future studies will optimize these tools and improve feasibility in clinical and research contexts. Genetic and environmental risk factors, mechanisms of muscle pathology, role of interferon, vascular markers, and changes in immune cells provide insights to JDM pathogenesis. Outcomes have improved, but chronic disease, damage, and mortality highlight the need for better outcome predictors and treatments. Increased collaboration of stakeholders may help overcome research barriers and improve JDM treatment.

JAK inhibitors: a potential treatment for JDM in the context of the role of interferon-driven pathology

Juvenile Idiopathic Inflammatory Myopathies (IIM) are a group of rare diseases that are heterogeneous in terms of pathology that can include proximal muscle weakness, associated skin changes and systemic involvement. Despite options for treatment, many patients continue to suffer resistant disease and lasting side-effects. Advances in the understanding of the immunopathology and genetics underlying IIM may specify new therapeutic targets, particularly where conventional treatment has not achieved a clinical response. An upregulated type I interferon signature is strongly associated with disease and could be a prime target for developing more specific therapeutics. There are multiple components of the IFN pathway that could be targeted for blockade therapy.Downstream of the cytokine receptor complexes are the Janus kinase-signal transducers and activators of transcription (JAK-STAT) pathway, which consists of JAK1-3, TYK2, and STAT1-6. Therapeutic inhibitors have been developed to target components of this pathway. Promising results have been observed in case studies reporting the use of the JAK inhibitors, Baricitinib, Tofacitinib and Ruxolitinib in the treatment of refractory Juvenile Dermatomyositis (JDM). There is still the question of safety and efficacy for the use of JAK inhibitors in JDM that need to be addressed by clinical trials. Here we review the future for the use of JAK inhibitors as a treatment for JDM.

Updates on interferon in juvenile dermatomyositis: pathogenesis and therapy

PURPOSE OF REVIEW

This review provides updates regarding the role of interferon (IFN) in juvenile dermatomyositis (JDM), including comparison to interferonopathies and therapeutic implications.

RECENT FINDINGS

Transcriptomic and protein-based studies in different tissues and peripheral IFN-α assessment have demonstrated the importance of the dysregulated IFN pathway in JDM. Additional studies have validated IFN-regulated gene and protein expression correlation with disease activity in blood and muscle, with potential to predict flares. Type I and II IFN both are dysregulated in peripheral blood and muscle, with more type I IFN in skin. Muscle studies connects hypoxia to IFN production and IFN to vascular dysfunction and muscle atrophy. JDM overlaps with interferonopathy phenotype and IFN signature. There are multiple case reports and case series noting decreased IFN markers and clinical improvement in refractory JDM with Janus kinase (JAK) inhibitors.

SUMMARY

Studies confirm IFN, particularly type I and II IFN, is an important part of JDM pathogenesis by the level of dysregulation and correlation with disease activity, as well as IFN recapitulating key JDM muscle pathology. Smaller studies indicate there may be differences by myositis-specific autoantibody group, but validation is needed. JAK inhibitors are a promising therapy as they can inhibit IFN signaling, but further study is needed regarding which patients will benefit, dosing, and safety monitoring.

JAK Inhibitors: Prospects in Connective Tissue Diseases

The dysregulation of the JAK-STAT pathway is associated with various immune disorders. Four JAK inhibitors have been approved for rheumatoid arthritis (RA), and numerous JAK inhibitors are currently being tested in phase II and III trials for the treatment of various autoimmune inflammatory diseases. In this narrative review, we elucidate the involvement of the JAK-STAT signaling pathway in the pathogenesis of connective tissue diseases (CTDs). We also discuss the efficacy of the first- and second-generation JAK inhibitors (tofacitinib, baricitinib, ruxolitinib, peficitinib, filgotinib, upadacitinib, solcitinib, itacitinib, decernotinib, R333, and pf-06651600) for CTDs including RA, systemic lupus erythematosus, dermatomyositis, systemic sclerosis, Sjögren's syndrome, and vasculitis, based on laboratory and clinical research findings. JAK inhibitors have great potential for the treatment of various CTDs by reducing multiple cytokine production and suppressing inflammation, with the advantages of rapid onset in an oral formulation and decreased corticosteroid dependence and the associated adverse events, especially in refractory cases. We also highlight the safety of novel JAK inhibitors, which can cause opportunistic infections, especially viral infections. Being a very recent therapeutic option, information regarding the safety of JAK inhibitors during pregnancy and for pediatric use is limited. However, it is recommended that JAK inhibitors should be avoided in pregnant and breastfeeding women. More clinical data, especially on highly selective inhibitors, are required to judge the efficacy and safety of JAK inhibition in CTDs.

The Vasculopathy of Juvenile Dermatomyositis: Endothelial Injury, Hypercoagulability, and Increased Arterial Stiffness

OBJECTIVE

Vasculopathy is considered central to the pathogenesis of juvenile dermatomyositis (DM) and is associated with severe extramuscular manifestations. We undertook this study to investigate the hypothesis that the vasculopathy of juvenile DM can be noninvasively tracked by examining biomarkers of endothelial injury, subclinical inflammation, hypercoagulability, and vascular arterial stiffness.

METHODS

The study population was a UK cohort of children with juvenile DM. Circulating endothelial cells (CECs) and microparticles (MPs) were identified using immunomagnetic bead extraction and flow cytometry, respectively. Plasma thrombin generation was determined using a fluorogenic assay. Cytokine and chemokine levels were measured by electrochemiluminescence. Arterial stiffness was assessed using pulse wave velocity (PWV). Results were expressed as the median and interquartile range (IQR), and statistical significance was assessed using nonparametric analyses.

RESULTS

Ninety patients with juvenile DM and 79 healthy control subjects were included. The median age of the patients was 10.21 years (IQR 6.68-13.40), and the median disease duration was 1.63 years (IQR 0.28-4.66). CEC counts were higher in all patients with juvenile DM compared to controls (median 96 cells/ml [IQR (40-192] and 12 cells/ml [IQR 8-24], respectively; P < 0.0001). Circulating MP numbers were also significantly higher in patients with active juvenile DM compared to controls (median 204.7 × 103 /ml [IQR 87.9-412.6] and 44.3 × 103 /ml [IQR 15.0-249.1], respectively; P < 0.0001). MPs were predominantly of platelet and endothelial origin. Enhanced plasma thrombin generation was demonstrated in patients with active juvenile DM compared to those with inactive disease (P = 0.0003) and controls (P < 0.0001). Carotid-radial PWV adjusted for age was increased in patients with juvenile DM compared to controls (P = 0.003).

CONCLUSION

We observed increased endothelial injury and increased levels of proinflammatory cytokines in patients with active juvenile DM. MP profiles reflected distinct disease activity status in juvenile DM and are markers of vascular pathology, platelet activation, and thrombotic propensity. Ongoing long-term vascular injury may result in increased arterial stiffness in patients with juvenile DM.

Type I Interferons in the Pathogenesis and Treatment of Autoimmune Diseases

Type I interferons (IFN-Is) are a very important group of cytokines that are produced by innate immune cells but also act on adaptive immune cells. IFN-Is possess antiviral, antitumor, and anti-proliferative effects, as well are associated with the initiation and maintenance of autoimmune disorders. Studies have shown that aberrantly expressed IFN-Is and/or type I IFN-inducible gene signatures in the serum or tissues of patients with autoimmune disorders are linked to their pathogenesis, clinical manifestations, and disease activity. Type I interferonopathies with mutations in genes impacting the type I IFN signaling pathway have shown symptoms and characteristics similar to those of systemic lupus erythematosus (SLE). Furthermore, both interventions in animal models and clinical trials of therapies targeting the type I IFN signaling pathway have shown efficacy in the treatment of autoimmune diseases. Our review aims to summarize the functions and targeted therapies (as well as clinical trials) of IFN-Is in both adult and pediatric autoimmune diseases, such as SLE, pediatric SLE (pSLE), rheumatoid arthritis (RA), juvenile idiopathic arthritis (JIA), juvenile dermatomyositis (JDM), Sjögren syndrome (SjS), and systemic sclerosis (SSc), discussing the potential abnormal regulation of transcription factors and epigenetic modifications and providing a potential mechanism for pathogenesis and therapeutic strategies for future clinical use.

Juvenile Dermatomyositis: New Clues to Diagnosis and Therapy

PURPOSE OF REVIEW

To identify clues to disease activity and discuss therapy options.

RECENT FINDINGS

The diagnostic evaluation includes documenting symmetrical proximal muscle damage by exam and MRI, as well as elevated muscle enzymes-aldolase, creatine phosphokinase, LDH, and SGOT-which often normalize with a longer duration of untreated disease. Ultrasound identifies persistent, occult muscle inflammation. The myositis-specific antibodies (MSA) and myositis-associated antibodies (MAA) are associated with specific disease course variations. Anti-NXP-2 is found in younger children and is associated with calcinosis; anti-TIF-1γ+ juvenile dermatomyositis has a longer disease course. The diagnostic rash-involving the eyelids, hands, knees, face, and upper chest-is the most persistent symptom and is associated with microvascular compromise, reflected by loss of nailfold (periungual) end row capillaries. This loss is associated with decreased bioavailability of oral prednisone; the bioavailability of other orally administered medications should also be considered. At diagnosis, at least 3 days of intravenous methyl prednisolone may help control the HLA-restricted and type 1/2 interferon-driven inflammatory process. The requirement for avoidance of ultraviolet light exposure mandates vitamin D supplementation.

SUMMARY

This often chronic illness targets the cardiovascular system; mortality has decreased from 30 to 1-2% with corticosteroids. New serological biomarkers indicate occult inflammation: ↑CXCL-10 predicts a longer disease course. Some biologic therapies appear promising.

JAK inhibitors are effective in a subset of patients with juvenile dermatomyositis: a monocentric retrospective study

OBJECTIVE

To evaluate the efficacy and safety of JAK inhibitors (JAKi) in juvenile dermatomyositis (JDM).

METHODS

We conducted a single-center retrospective study of patients with JDM treated by JAKi with a follow-up of at least 6 months. Proportion of clinically inactive disease (CID) within six months of JAKi initiation was evaluated using PRINTO criteria and skin Disease Activity Score. Serum IFN-α concentration was measured by SIMOA assay.

RESULTS

Nine refractory and one new-onset patients with JDM treated with ruxolitinib (n = 7) or baricitinib (n = 3) were included. The main indications for treatment were refractory muscle involvement (n = 8) and ulcerative skin disease (n = 2). CID was achieved in 5/10 patients (2/2 anti-MDA5, 3/4 anti-NXP2, 0/3 anti-TIF1γ positive patients) within six months of JAKi introduction. All responders could withdraw plasmatic exchange, immunoadsorption and other immunosuppressive drugs. The mean daily steroid dose decreased from 1.1 mg/Kg (range 0.35-2 mg/Kg/d) to 0.1 (range, 0-0.3, p= 0.008) in patients achieving CID, and was stopped in two. Serum IFN-α concentrations were elevated in all patients at the time of treatment initiation and normalized in both responder and non-responder. A muscle biopsy repeated in one patient 26 months after the initiation of JAKi, showed a complete restoration of muscle endomysial microvascular bed. Herpes zoster and skin abscesses developed in three and two patients, respectively.

CONCLUSION

JAKis resulted in a CID in a subset of new-onset or refractory patients with JDM and may dramatically reverse severe muscle vasculopathy. Overall tolerance was good except for a high rate of herpes zoster infection.

Treatment of Calcinosis in Juvenile Dermatomyositis

PURPOSE OF REVIEW

Juvenile dermatomyositis (JDM) is a rare autoimmune disease characterised by muscle and skin involvement. Calcinosis is a debilitating complication of JDM which is difficult to treat and may cause long-term morbidity. The purpose of this review is to provide an update for the treatment of JDM-associated calcinosis based on previously published studies.

RECENT FINDINGS

Evidence-based studies are lacking for the management of calcinosis, and current treatment modalities have been largely based on case reports, case series, cohort studies, limited controlled studies and anecdotal clinical experience. The use of early aggressive therapy for resistant cases is strongly suggested to halt persistent disease activity which may help in reducing steroid use and their associated complications. Recent insights into disease pathogenesis, myositis-specific antibodies and genetic associations have led to identification of novel therapeutic targets such as Janus kinase (JAK) 1/2. Different treatment regimens with variable outcomes are in use for the treatment of refractory calcinosis; nevertheless, the level of evidence is not sufficient to propose specific guidelines. Recently, JAK 1/2 inhibitors have shown to be effective as an emerging therapeutic option highlighting that translational and clinical research is crucial to develop targeted treatment for JDM-associated calcinosis.

Anti-MDA5 juvenile idiopathic inflammatory myopathy: a specific subgroup defined by differentially enhanced interferon-α signalling

OBJECTIVES

JDM and juvenile overlap myositis represent heterogeneous subtypes of juvenile idiopathic inflammatory myopathy (JIIM). Chronic evolution can occur in up to 60% of cases, and morbidity/mortality is substantial. We aimed to describe the clinical, biological, histological and type I IFN status in JIIM associated with anti-melanoma differentiation-associated protein 5 (anti-MDA5) autoantibodies at presentation (group 1) in comparison with other JIIM (group 2).

METHODS

This was a retrospective and prospective study of patients with JIIM ascertained from three French paediatric rheumatology reference centres between 2013 and 2019. Muscle biopsies were reviewed. Type I interferon pathway activity was assessed by dosage of IFNα serum protein and the expression of IFN-stimulated genes.

RESULTS

Sixty-four patients were included, 13 in group 1 (54% JDM and 46% juvenile overlap myositis) and 51 in group 2 (76% JDM and 24% juvenile overlap myositis). Group 1 patients demonstrated more arthritis, skin ulcerations, lupus features and interstitial lung disease, and a milder muscular involvement. Serum IFNα levels were higher in group 1 than 2, and decreased after treatment or improvement in both groups. Outcome was similar in both groups. Unconventional treatment (more than two lines) was required in order to achieve remission, especially when skin ulceration was reported.

CONCLUSION

This study indicates a higher frequency of arthritis, skin ulcerations and interstitial lung disease, but milder muscular involvement, in JIIM with positive anti-MDA5 autoantibodies compared with other JIIM. Our data support an important role of systemic IFNα in disease pathology, particularly in the anti-MDA5 auto-antibody-positive subgroup. In severe and refractory forms of JIIM, IFNα may represent a therapeutic target.