Biological and Clinical Changes in a Pediatric Series Treated with Off-Label JAK Inhibitors

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.

Type I interferon pathway in pediatric systemic lupus erythematosus

BACKGROUND

The role of type I interferon (IFN-I) signaling in systemic lupus erythematosus (SLE) has been well established. However, unanswered questions remain regarding the applicability of these findings to pediatric-onset SLE. The aim of this review is to provide an overview of the novel discoveries on IFN-I signaling in pediatric-onset SLE.

DATA SOURCES

A literature search was conducted in the PubMed database using the following keywords: "pediatric systemic lupus erythematosus" and "type I interferon".

RESULTS

IFN-I signaling is increased in pediatric SLE, largely due to the presence of plasmacytoid dendritic cells and pathways such as cyclic GMP-AMP synthase-stimulator of interferon genes-TANK-binding kinase 1 and Toll-like receptor (TLR)4/TLR9. Neutrophil extracellular traps and oxidative DNA damage further stimulate IFN-I production. Genetic variants in IFN-I-related genes, such as IFN-regulatory factor 5 and tyrosine kinase 2, are linked to SLE susceptibility in pediatric patients. In addition, type I interferonopathies, characterized by sustained IFN-I activation, can mimic SLE symptoms and are thus important to distinguish. Studies on interferonopathies also contribute to exploring the pathogenesis of SLE. Measuring IFN-I activation is crucial for SLE diagnosis and stratification. Both IFN-stimulated gene expression and serum IFN-α2 levels are common indicators. Flow cytometry markers such as CD169 and galectin-9 are promising alternatives. Anti-IFN therapies, such as sifalimumab and anifrolumab, show promise in adult patients with SLE, but their efficacy in pediatric patients requires further investigation. Janus kinase inhibitors are another treatment option for severe pediatric SLE patients.

CONCLUSIONS

This review presents an overview of the IFN-I pathway in pediatric SLE. Understanding the intricate relationship between IFN-I and pediatric SLE may help to identify potential diagnostic markers and targeted therapies, paving the way for improved patient care and outcomes.

Novel heterozygous TREX1 mutation in a juvenile systemic lupus erythematosus patient with severe cutaneous involvement treated successfully with Jak-inhibitors: a case report

Juvenile systemic lupus erythematosus (jSLE) is a complex inflammatory autoimmune disorder. In the last decades, genetic factors and activation pathways have been increasingly studied to understand their potential pathogenetic role better. Genetic and transcriptional abnormalities directly involved in the type I interferon (IFN) signaling cascade have been identified through family-based and genome-wide association studies. IFNs trigger signaling pathways that initiate gene transcription of IFN-stimulated genes through the activation of JAK1, TYK2, STAT1, and STAT2. Thus, the use of therapies that target the IFN pathway would represent a formidable advance in SLE. It is well known that JAK inhibitors have real potential for the treatment of rheumatic diseases, but their efficacy in the treatment of SLE remains to be elucidated. We report the case of a 13-year-old girl affected by jSLE, carrying a novel heterozygous missense variant on Three prime Repair EXonuclease 1 (TREX1), successfully treated with baricitinib on top of mofetil mycophenolate. The TREX1 gene plays an important role in DNA damage repair, and its mutations have been associated with an overproduction of type 1 interferon. This report underlines the role of translational research in identifying potential pathogenetic pathways in rare diseases to optimize treatment.

Lupus Nephritis in Children: Novel Perspectives

Childhood-onset systemic lupus erythematosus is an inflammatory and autoimmune condition characterized by heterogeneous multisystem involvement and a chronic course with unpredictable flares. Kidney involvement, commonly called lupus nephritis, mainly presents with immune complex-mediated glomerulonephritis and is more frequent and severe in adults. Despite a considerable improvement in long-term renal prognosis, children and adolescents with lupus nephritis still experience significant morbidity and mortality. Moreover, current literature often lacks pediatric-specific data, leading clinicians to rely exclusively on adult therapeutic approaches. This review aims to describe pediatric lupus nephritis and provide an overview of the novel perspectives on the pathogenetic mechanisms, histopathological classification, therapeutic approach, novel biomarkers, and follow-up targets in children and adolescents with lupus nephritis.

JAK Inhibition in Juvenile Idiopathic Arthritis (JIA): Better Understanding of a Promising Therapy for Refractory Cases

Juvenile idiopathic arthritis (JIA) is a heterogeneous group of diseases with probably differential underlying physiopathology. Despite the revolutionary era of biologics, some patients remain difficult to treat because of disease severity, drug adverse events, drug allergy or association with severe comorbidities, i.e., uveitis, interstitial lung disease and macrophagic activation syndrome. Janus Kinase (JAK) inhibitors are small molecules that target JAK/Signal Transducers and Activators of Transcription (STAT) pathways, which could then prevent the activity of several proinflammatory cytokines. They may provide a useful alternative in these cases of JIA or in patients actually affected by Mendelian disorders mimicking JIA, such as type I interferonopathies with joint involvement, and might be the bridge for haematopoietic stem cell transplantation in these disabling conditions. As these treatments may have side effects that should not be ignored, ongoing and further controlled studies are still needed to provide data underlying long-term safety considerations in children and delineate subsets of JIA patients that will benefit from these promising treatments.

Expected impact of immunomodulatory agents during pregnancy: A newborn's perspective

The neonatal immune ontogeny begins during pregnancy to ensure that the neonate is well-suited for perinatal life. It prioritizes Th2/M2 and regulatory responses over Th/M1 activity to avoid excessive inflammatory responses and to ensure immune tolerance and homeostasis. Newborns also present increased Th17/Th22 responses providing effective anti-fungal immunity and mucosal protection. Intrauterine exposure to immune modulatory drugs with the placental transfer may influence the natural course of the fetal immune development. The vertical transfer of both biological therapy and small molecules begins during the first trimester through neonatal Fc receptor or placental diffusion, respectively, reaching its maximum transfer potential during the third trimester of pregnancy. Most of the biological therapy have a prolonged half-life in newborn's blood, being detectable in infants up to 12 months after birth (usually 6-9 months). The use of immunomodulators during pregnancy is gaining global interest. Current evidence mainly reports birth-related outcomes without exhaustive analysis of the on-target side effect on the perinatal immune system ontogeny, the infection risk, or the immune dysregulation. The present review will focus on: (1) the main characteristics of the perinatal immune system to understand its specific features and vulnerabilities to immune modulation; (2) the mechanisms of placental transfer of immunomodulators; and (3) the immune changes reported to date in newborns exposed to immunomodulators with emphasis on the current concerns and gaps in knowledge.

A toddler with an unusually severe polyarticular arthritis and a lung involvement: a case report

Background

COPA syndrome is a rare hereditary inflammatory disease caused by mutations in the gene encoding the coatomer protein subunit alpha, causing excessive production of type I interferon.

This case is a reminder for the general paediatrician, highlighting the relevance of the association between arthritis and lung involvement in toddlers.

Case presentation

We report the case of a 2-year-old girl with intermittent limping and joint pain. Her family history was relevant for a Still disease with lung involvement in the mother. Physical examination showed moderate wrist swelling. Laboratory findings on admission showed an increase in inflammatory markers, positive rheumatoid factor, antibodies antinuclear antibody (ANA) and cyclic citrullinated peptide (anti-CCP). Wrists’ ultrasound documented synovial thickening, and chest X-rays showed an unexpected severe interstitial pneumopathy. Genetic testing confirmed the diagnosis of a heterozygous mutation of the COPA gene in c.841C > T (p.R281W). Janus kinase treatment was started (baricitinib, 4 mg daily per os) with a remarkable improvement in limping and joint pain after two weeks.

Conclusions

In cases of recurrent arthritis with family history and multiple involvement organs, a genetic disorder should be suspected and genetic testing should be performed. Furthermore, this case suggests that therapy with jak inhibitors may be effective and safe in interferonopathies.

Effectiveness and Safety of JAK Inhibitors in Autoinflammatory Diseases: A Systematic Review

Introduction

Autoinflammatory diseases (AID) are rare diseases presenting with episodes of sterile inflammation. These involve multiple organs and can cause both acute organ damage and serious long-term effects, like amyloidosis. Disease-specific anti-inflammatory therapeutic strategies are established for some AID. However, their clinical course frequently includes relapsing, uncontrolled conditions. Therefore, new therapeutic approaches are needed. Janus Kinase inhibitors (JAKi) block key cytokines of AID pathogenesis and can be a potential option.

Methods

A systematic review of the literature in accordance with the PRISMA guidelines was conducted. Three databases (MEDLINE, Embase and Cochrane Central Register of Controlled Trials) were searched for publications regarding the use of JAKi for AID. Data from the included publications was extracted and a narrative synthesis was performed. Criteria for defining treatment response were defined and applied.

Results

We report data from 38 publications with a total of 101 patients describing the effects of JAKi in AID. Data on Type I Interferonopathies, Adult-Onset Still's Disease (AOSD), Systemic Juvenile Idiopathic Arthritis (sJIA), Familial Mediterranean Fever (FMF), and Behçet's Syndrome (BS) was identified. From a total of 52 patients with type I interferonopathies, in seven patients (7/52, 13.5%) a complete response was achieved, most (35/52, 67.3%) showed a partial response and a minority (10/52, 19.2%) showed no treatment response. For AOSD, a complete or a partial response was achieved by eleven (11/26, 42.3%) patients each. Two sJIA patients achieved complete response (2/4, 50%) and in two cases (2/4, 50%) a partial response was reported. Half of FMF patients showed a complete response and the other half had a partial one (3/6, 50.0%). Amongst BS patients most achieved a partial response (8/13, 61.5%). Five patients showed no response to therapy (5/13, 38.5%). Overall, the most frequent AEs were upper respiratory tract infections (17), pneumonia (10), BK virus viremia (10) and viruria (4), herpes zoster infection (5), viral gastroenteritis (2) and other infections (4).

Conclusion

The results from this systematic review show that JAKi can be beneficial in certain AID. The risk of AEs, especially viral infections, should be considered. To accurately assess the risk benefit ratio of JAKi for AID, clinical trials should be conducted.

Druggable monogenic immune defects hidden in diverse medical specialties: Focus on overlap syndromes

In the last two decades two new paradigms changed our way of perceiving primary immunodeficiencies: An increasing number of immune defects are more associated with inflammatory or autoimmune features rather than with infections. Some primary immune defects are due to hyperactive pathways that can be targeted by specific inhibitors, providing innovative precision treatments that can change the natural history of diseases. In this article we review some of these “druggable” inborn errors of immunity and describe how they can be suspected and diagnosed in diverse pediatric and adult medicine specialties. Since the availability of precision treatments can dramatically impact the course of these diseases, preventing the development of organ damage, it is crucial to widen the awareness of these conditions and to provide practical hints for a prompt detection and cure.

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.

Off-label medication use in rare pediatric diseases in the United States

Many pediatric patients with rare diseases use drugs off-label due to limited data in pediatric patients. Off-label treatment remains an important public health issue for neonates, infants, children, and adolescents, especially for pediatric patients with rare diseases. For patients with rare diseases, the majority of medications have no or limited information in labelling for pediatric use. Children present unique considerations in clinical trials due to ethical and clinical concerns, which have limited and even discouraged testing of drugs in the pediatric population. Numerous legislative measures have been enacted to address barriers in pediatric drug testing. This research reviewed off-label medication use in rare pediatric diseases, evaluated recent medication uses in pediatric clinical practice, discussed key regulations for rare pediatric diseases, and summarized recent drug approvals for rare pediatric diseases. This study demonstrates the ongoing medical need for newly approved medications to treat pediatric rare diseases and revealed the positive impact of regulations from the Orphan Drug Act of 1983 to the Research to Accelerate Cures and Equity (RACE) for Children Act on drug development and off-label medication practice in rare pediatric disease management. This article provides informative historical background and current considerations of off-label use of medications in neonates, infants, children, and adolescents with rare diseases.

The Pathogenesis, Molecular Mechanisms, and Therapeutic Potential of the Interferon Pathway in Systemic Lupus Erythematosus and Other Autoimmune Diseases

Therapeutic success in treating patients with systemic lupus erythematosus (SLE) is limited by the multivariate disease etiology, multi-organ presentation, systemic involvement, and complex immunopathogenesis. Agents targeting B-cell differentiation and survival are not efficacious for all patients, indicating a need to target other inflammatory mediators. One such target is the type I interferon pathway. Type I interferons upregulate interferon gene signatures and mediate critical antiviral responses. Dysregulated type I interferon signaling is detectable in many patients with SLE and other autoimmune diseases, and the extent of this dysregulation is associated with disease severity, making type I interferons therapeutically tangible targets. The recent approval of the type I interferon-blocking antibody, anifrolumab, by the US Food and Drug Administration for the treatment of patients with SLE demonstrates the value of targeting this pathway. Nevertheless, the interferon pathway has pleiotropic biology, with multiple cellular targets and signaling components that are incompletely understood. Deconvoluting the complexity of the type I interferon pathway and its intersection with lupus disease pathology will be valuable for further development of targeted SLE therapeutics. This review summarizes the immune mediators of the interferon pathway, its association with disease pathogenesis, and therapeutic modalities targeting the dysregulated interferon pathway.

Emerging Place of JAK Inhibitors in the Treatment of Inborn Errors of Immunity

Among inborn errors of immunity (IEIs), some conditions are characterized by inflammation and autoimmunity at the front line and are particularly challenging to treat. Monogenic diseases associated with gain-of-function mutations in genes critical for cytokine signaling through the JAK-STAT pathway belong to this group. These conditions represent good candidates for treatment with JAK inhibitors. Type I interferonopathies, a group of recently identified monogenic auto-inflammatory diseases characterized by excessive secretion of type I IFN, are also good candidates with growing experiences reported in the literature. However, many questions remain regarding the choice of the drug, the dose (in particular in children), the efficacy on the various manifestations, the monitoring of the treatment, and the management of potent side effects in particular in patients with infectious susceptibility. This review will summarize the current experiences reported and will highlight the unmet needs.

An Update on the Management of Childhood-Onset Systemic Lupus Erythematosus

Childhood-onset systemic lupus erythematosus (cSLE) is a prototype of a multisystemic, inflammatory, heterogeneous autoimmune condition. This disease is characterized by simultaneous or sequential organ and system involvement, with unpredictable flare and high levels of morbidity and mortality. Racial/ethnic background, socioeconomic status, cost of medications, difficulty accessing health care, and poor adherence seem to impact lupus outcomes and treatment response. In this article, the management of cSLE patients is updated. Regarding pathogenesis, a number of potential targets for drugs have been studied. However, most treatments in pediatric patients are off-label drugs with recommendations based on inadequately powered studies, therapeutic consensus guidelines, or case series. Management practices for cSLE patients include evaluations of disease activity and cumulative damage scores, routine non-live vaccinations, physical activity, and addressing mental health issues. Antimalarials and glucocorticoids are still the most common drugs used to treat cSLE, and hydroxychloroquine is recommended for nearly all cSLE patients. Disease-modifying antirheumatic drugs (DMARDs) should be standardized for each patient, based on disease flare and cSLE severity. Mycophenolate mofetil or intravenous cyclophosphamide is suggested as induction therapy for lupus nephritis classes III and IV. Calcineurin inhibitors (cyclosporine, tacrolimus, voclosporin) appear to be another good option for cSLE patients with lupus nephritis. Regarding B-cell-targeting biologic agents, rituximab may be used for refractory lupus nephritis patients in combination with another DMARD, and belimumab was recently approved by the US Food and Drug Administration for cSLE treatment in children aged > 5 years. New therapies targeting CD20, such as atacicept and telitacicept, seem to be promising drugs for SLE patients. Anti-interferon therapies (sifalimumab and anifrolumab) have shown beneficial results in phase II randomized control trials in adult SLE patients, as have some Janus kinase inhibitors, and these could be alternative treatments for pediatric patients with severe interferon-mediated inflammatory disease in the future. In addition, strict control of proteinuria and blood pressure is required in cSLE, especially with angiotensin-converting enzyme inhibitor and angiotensin receptor blocker use.

Vasculitis, Autoimmunity, and Cytokines: How the Immune System Can Harm the Brain

More and more findings suggest that neurological disorders could have an immunopathological cause. Thus, immune-targeted therapies are increasingly proposed in neurology (even if often controversial), as anakinra, inhibiting IL-1 for febrile inflammatory illnesses, and JAK inhibitors for anti-interferons treatment. Precision medicine in neurology could be fostered by a better understanding of the disease machinery, to develop a rational use of immuno-modulators in clinical trials. In this review, we focus on monogenic disorders with neurological hyper-inflammation/autoimmunity as simplified "models" to correlate immune pathology and targeted treatments. The study of monogenic models yields great advantages for the elucidation of the pathogenic mechanisms that can be reproduced in cellular/animal models, overcoming the limitations of biological samples to study. Moreover, monogenic disorders provide a unique tool to study the mechanisms of neuroinflammatory and autoimmune brain damage, in all their manifestations. The insight of clinical, pathological, and therapeutic aspects of the considered monogenic models can impact knowledge about brain inflammation and can provide useful hints to better understand and cure some neurologic multifactorial disorders.