Disease flares with baricitinib dose reductions and development of flare criteria in patients with CANDLE/PRAAS.

OBJECTIVES: Patients with chronic atypical neutrophilic dermatosis with lipodystrophy and elevated temperature/proteasome-associated autoinflammatory syndrome (CANDLE/PRAAS) respond to the janus kinase inhibitor 1/2 inhibition with baricitinib at exposures higher than in rheumatoid arthritis. Baricitinib dose reductions to minimise exposure triggered disease flares which we used to develop 'flare criteria'. METHODS: Of 10 patients with CANDLE/PRAAS treated with baricitinib in an open-label expanded-access programme, baricitinib doses were reduced 14 times in 9 patients between April 2014 and December 2019. Retrospective data analysis of daily diary scores and laboratory markers collected before and after the dose reductions were used to develop 'clinical' and 'subclinical' flare criteria. Disease flare rates were compared among patients with <25% and >25% dose reductions and during study visits when patients received recommended 'optimized' baricitinib doses (high-dose visits) versus lower than recommended baricitinib doses (low-dose visits) using two-sided χ2 tests. RESULTS: In the 9/10 patients with CANDLE with dose reduction, 7/14 (50%) times the dose was reduced resulted in a disease flare. All four dose reductions of >25% triggered a disease flare (p <0.05). Assessment of clinical and laboratory changes during disease flares allowed the development of disease flare criteria that were assessed during visits when patients received high or low doses of baricitinib. Disease flare criteria were reached during 43.14% of low-dose visits compared with 12.75% of high-dose visits (p <0.0001). Addition of an interferon score as an additional flare criterion increased the sensitivity to detect disease flares. CONCLUSION: We observed disease flares and rebound inflammation with baricitinib dose reductions and proposed flare criteria that can assist in monitoring disease activity and in designing clinical studies in CANDLE/PRAAS.

What drives the decision to optimise biological treatment in children and youngsters with juvenile idiopathic arthritis? A discrete-choice experiment.

OBJECTIVE: To analyse factors involved in the decision to optimise biologics in juvenile idiopathic arthritis. METHODS: A "discrete-choice" methodology was used. In a nominal group meeting, factors which may influence physicians' decisions to optimise biological dose were identified, together with decision nodes. 1000Minds® was used to create multiple fictitious clinical scenarios based on the factors identified, and to deploy surveys that were sent to a panel of experts. These experts decided for each item which of two clinical scenarios prompted them to optimise the dose of biologic. A conjoint analysis was carried out, and the partial-value functions and the weights of relative importance calculated. RESULTS: In the nominal group, three decision nodes were identified: (1) time to decide; (2) to maintain/reduce or prolong interval; (3) what drug to reduce. The factors elicited were different for each node and included patient and drug attributes. The presence of macrophage activation syndrome (MAS), systemic involvement, or subclinical inflammation made the decision easier (highest weights). The presence of joints of difficult control and year of debut influenced the decision in some but not all, and in different directions. Immunogenicity, adherence, and concomitant treatments were also aspects taken into account. CONCLUSIONS: The decision to optimise the dose of biological therapy in children and youngster can be divided into several nodes, and the factors, both patient and therapy-related, leading to the decision can be detailed. These decisions taken by experts may be transported to practice, study designs, and guidelines.

Use of the Auto-inflammatory Disease Activity Index to monitor disease activity in patients with colchicine-resistant Familial Mediterranean Fever, Mevalonate Kinase Deficiency, and TRAPS treated with canakinumab.

OBJECTIVES: To evaluate the feasibility of the autoinflammatory disease activity index (AIDAI) as a tool to assess disease activity in patients with hereditary recurrent fever syndromes (HRFs) treated with canakinumab. METHODS: Patients with active colchicine-resistant familial Mediterranean fever (crFMF), mevalonate kinase deficiency (MKD), or tumor necrosis factor receptor-associated periodic syndrome (TRAPS) were enrolled in the phase III CLUSTER study and asked to complete the AIDAI questionnaire daily. All patients included in the analysis were treated with canakinumab, but regimens and periods of treatment varied per study protocol. The AIDAI for each patient was calculated weekly over the first 40 weeks of study, based on the diaries completed over 30 days. Disease-specific cut-off AIDAI values for inactive disease were calculated in a ROC analysis by comparing AIDAI scores with the occurrence of clinically inactive disease, based on the physician global assessments of disease activity and the occurrence of flares. RESULTS: Sixty patients with crFMF, 70 with MKD, and 43 with TRAPS were included in the analysis. Median AIDAI scores were high during the first 4 weeks for the three disease cohorts, and decreased afterwards, with some differences between disease cohorts. AIDAI values of 12.0, 9.6 and 15.5 were obtained as the most optimal thresholds to discriminate patients with inactive disease, with sensitivity and specificity values mostly over 75%. CONCLUSIONS: The AIDAI allows to discriminate between patients with active and inactive HRFs, and can be used in clinical practice to monitor the disease course of patients and the effect of medications.

Are infections in children with juvenile idiopathic arthritis more frequent than in healthy children? A prospective multicenter observational study.

Background: Children with juvenile idiopathic arthritis (JIA) might be at a higher risk of infection. Our objectives are to describe and compare infection rates in patients with JIA vs. healthy patients. Methods: A prospective, multicenter observational study was performed in Spain from January 2017 to June 2019. Patients with JIA from 7 participating hospitals and children without JIA (siblings of patients with JIA, and non-JIA children from primary health centers) were followed up with quarterly questionnaires to record infection episodes. Tuberculosis, herpes zoster, and infections requiring hospital admission were considered severe infections. Rates of infection (episodes/patient/year) were compared using a generalized estimating equations model. Results: A total of 371 children (181 with and 190 without JIA) were included. The median age was 8.8 years (IQR 5.5-11.3); 75% of the patients with JIA received immunosuppressive treatment (24% methotrexate, 22% biologic, 26% both). A total of 667 infections were recorded; 15 (2.2%) were considered severe. The infection rate was 1.31 (95%CI 1.1-1.5) in JIA and 1.12 (95%CI 0.9-1.3) in non-JIA participants (p = 0.19). Age <4 years increased the infection rate by 2.5 times (2.72 vs. 1.12, p < 0.001) in both groups. The most frequent infection sites were upper respiratory (62.6% vs. 74.5%) and gastrointestinal (18.8% vs. 11.4%). There were no differences in severe infections (2.5% vs. 2%, p = 0.65) between the groups. In children with JIA, younger age and higher disease activity (JADAS71) were associated with a higher infection rate. Conclusion: We found no differences in the infection rate or infection severity between patients with and without JIA. Most infections were mild. An age younger than 4 years increased the infection risk in both groups. Higher disease activity was associated with a higher infection rate.

Oral Versus Intravenous Antibiotics for Pediatric Osteoarticular Infection: When and to Whom?

BACKGROUND: Osteoarticular infections (OAIs) are typically treated initially with intravenous antibiotics. The objective of this study was to evaluate whether an exclusive oral treatment in selected children may be appropriate. METHODS: The Spanish Network of Osteoarticular Infections is a nationwide multicenter registry comprising 37 hospitals in Spain. The registry prospectively includes clinical characteristics and outcome of children with OAI. One of the hospitals from RioPed offers oral treatment to children meeting certain criteria. Patients were classified into 2 groups. Group 1: management with initial intravenous antibiotic therapy. Group 2: patients exclusively treated with oral antibiotics. A comparison between the 2 groups was performed. RESULTS: We compared 893 children who initially received intravenous antibiotics (group 1) with 64 children who received exclusively oral therapy (group 2). Patients from group 2 were younger (33.9 vs. 20.3 months; P = 0.001), had a lower percentage of Staphylococcus aureus (23.3% vs. 3.1%; P < 0.001), a higher proportion of Kingella kingae (12.1% vs. 28.1%; P = 0.001), higher erythrocyte sedimentation rate/C-reactive protein (CRP) ratio (1.4 interquartile range 0.6-3.6 vs. 3.3 interquartile range 1.7-5.7; P < 0.001) and showed lower rate of fever (63% vs. 48.8%; P = 0.024) than in group 1. Complications were not found in group 2. CONCLUSIONS: An exclusively oral administration could be a safe option in selected patients with OAI. Low-risk criteria are proposed: good general condition, no underlying disease, 6 months to 3 years old, appropriate oral tolerance, C-reactive protein <80 mg/L, erythrocyte sedimentation rate/C-reactive protein ratio ≥0.67, no skin injury, no recent surgery, no cervical spondylodiscitis and no local complications at onset.

Clinical course and seroprevalence of COVID-19 in children with rheumatic diseases-cross-sectional study from a reference centre in Spain.

SARS-CoV-2 infections in children are frequently asymptomatic or mild and can go unnoticed. This study aimed to describe the seroprevalence and clinical course of SARS-CoV-2 in a cohort of children with rheumatic diseases in a real-life setting and assess possible risk factors. A cross-sectional study was performed in a paediatric rheumatology unit (September 2020 to February 2021). At inclusion, a specific questionnaire was completed and SARS-CoV-2 serology was performed. Demographics, treatment and disease activity of patients with and without laboratory-confirmed SARS-CoV-2 infection were compared. A total of 105 children were included. SARS-CoV-2 infection was demonstrated in 27 patients (25.7%). The mean age was 11.8 years, and most patients were females (72.4%). The most frequent underlying condition was juvenile idiopathic arthritis (70.3%; 19/27). Patients received immunosuppressive treatment in 78% of cases (21/27). Overall, 44.4% (12/27) of infected patients were asymptomatic. A total of 66.7% (18/27) of patients did not require medical assistance. Three patients required hospital admission because of COVID-19. Children with confirmed SARS-CoV-2 infection were less frequently in remission (52% vs 72%; p 0.014). Moderate disease activity and treatment with oral corticosteroids were associated with higher risk for SARS-CoV-2 (OR 5.05; CI 95%: 1.56-16.3 and OR 4.2; CI 95%: 1.26-13.9, respectively). In a cohort of Spanish paediatric patients with rheumatic diseases, clinical course of COVID-19 was mild, with more than one third of asymptomatic cases. Higher disease activity and oral corticosteroids appear to be risk factors for SARS-CoV-2 infection. Key Points • We aimed to investigate the seroprevalence of SARS-CoV-2 infection in a cohort of Spanish paediatric patients with RD, testing both symptomatic and asymptomatic patients. We also compared treatment and disease activity of patients with and without laboratory-confirmed SARS-CoV-2 infection. • In our cohort of 105 paediatric patients with rheumatic diseases, the clinical course of COVID-19 was mild and 44% of cases were asymptomatic. Three cases required hospital admission with no complications. Seroprevalence was 20%. • No association was found between disease activity or treatment with corticosteroids and symptomatic or asymptomatic infection. Higher disease activity and treatment with oral corticosteroids appeared to be risk factors for laboratory-confirmed SARS-CoV-2 infection.

Severe Thrombocytopenia as the Main Manifestation of Childhood-Onset Systemic Lupus Erythematosus.

Thrombocytopenia is a common hematologic abnormality of childhood-onset systemic lupus erythematosus (cSLE). Although in most cases thrombocytopenia is mild, severe thrombocytopenia with bleeding complications might occur, and is further correlated with disease activity and a worse prognosis. We report two female patients with severe thrombocytopenia as the initial manifestation of cSLE, which were successfully treated by intensive immunosuppression including several high-dose methylprednisolone pulses and IV cyclophosphamide. Both patients were initially diagnosed with idiopathic thrombopenic purpura (ITP) refractory to conventional treatment and complicated with haemorrhagic manifestations. For this matter, patients with ITP should be assessed for the presence of ANA, anti-dsDNA antibodies, and complement levels, since they are at high risk to develop cSLE.

Canakinumab improves patient-reported outcomes in children and adults with autoinflammatory recurrent fever syndromes: results from the CLUSTER trial.

OBJECTIVES: To evaluate the effect of canakinumab on health-related quality of life (HRQoL), work/school and social life of patients with autoinflammatory recurrent fever syndromes, including colchicine-resistant familial Mediterranean fever, mevalonate kinase deficiency, and tumour necrosis factor receptor-associated periodic syndrome, in the CLUSTER trial. METHODS: HRQoL of patients who received canakinumab 150 mg or 300 mg every four weeks in the CLUSTER trial (n=173) was assessed at baseline and Weeks 17 and 41. For children we used the Child Health Questionnaire - Parent Form 50 (CHQ-PF50), including psychosocial (PsS) and physical (PhS) component summary scores. For adults, the Short-Form-12 (SF-12) Health Survey was used, including physical (PFS) and mental (PCS) component summary scores. The Sheehan Disability Scale (SDS) was used to determine the impact of treatment on work/school, social and family life. RESULTS: The results obtained were remarkably consistent in both paediatric and adult patients across the three disease cohorts. At baseline, median scores for physical components were relatively low (26-29 for PhS and 34-38 for PFS); they improved to values similar to those expected in the general population by Week 17, and this improvement was sustained at Week 41, when median PhS scores were 47-50 and PFS 44-54. Psychosocial and mental scores also improved from baseline to Week 17 and 41, with scores comparable to the general population. Notable improvements were also observed in the SDS scale. CONCLUSIONS: Patients with three inherited autoinflammatory syndromes experienced sustained improvements on their HRQoL, work/school, and social life on treatment with canakinumab.

Prevalence of thrombotic complications in children with SARS-CoV-2.

Knowledge of thrombosis in children with SARS-CoV-2 is scarce. In this multicentre national cohort of children with SARS-CoV-2 involving 49 hospitals, 4 patients out of 537 infected children developed a thrombotic complication (prevalence of 0.7% (95% CI: 0.2% to 1.9%) out of the global cohort and 1.1% (95% CI: 0.3% to 2.8%) out of the hospitalised patients). We describe their characteristics and review other published paediatric cases. Three out of the four patients were adolescent girls, and only two cases had significant thrombotic risk factors. In this paediatric cohort, D-dimer value was not specific enough to predict thrombotic complications. Adolescence and previous thrombotic risk factors may be considered when initiating anticoagulant prophylaxis on children with SARS-CoV-2 disease (COVID-19).

Fatal outcome of anti-MDA5 juvenile dermatomyositis in a paediatric COVID-19 patient: a case report.

Anti-melanoma differentiation-associated gene 5 juvenile dermatomyositis (anti-MDA5 JDM) is associated with high risk of developing rapidly progressive interstitial lung disease (RP-ILD). Here we report an 11-year-old girl with anti-MDA5 JDM and RP-ILD which led to a fatal outcome, further aggravated by SARS-CoV-2 infection. She was referred to our hospital after being diagnosed with anti-MDA5 JDM and respiratory failure due to RP-ILD. On admission, fibrobronchoscopy with bronchoalveolar lavage (BAL) revealed Pneumocystis jirovecii infection so treatment with intravenous trimethoprim-sulfamethoxazole was initiated. Due to RP-ILD worsening, immunosuppressive therapy was intensified using methylprednisolone pulses, cyclophosphamide, tofacitinib and intravenous immunoglobulin without response. She developed severe hypoxemic respiratory failure, pneumomediastinum and pneumothorax, further complicated with severe RP-ILD and cervical subcutaneous emphysema. Three real-time RT-PCR for SARS-CoV-2 were made with a negative result. In addition, she was complicated with a secondary hemophagocytic lymphohistiocytosis and a fourth real-time PCR for SARS-CoV-2 performed in BAS sample was positive. Despite aggressive treatment of RP-ILD due to anti-MDA5 JDM, there was no improvement of respiratory failure in the following days and patient developed refractory septic shock and died. Anti-MDA5 JDM patients with RP-ILD have a poor prognosis with a high mortality rate. For this reason, intensive immunosuppressive therapy is essential including the use of promising drugs such as tofacitinib. COVID-19 in children with underlying health conditions like anti-MDA5 JDM may still be at risk for disease and severe complications.

Colchicine treatment in children with periodic fever, aphthous stomatitis, pharyngitis, and cervical adenitis (PFAPA) syndrome: A multicenter study in Spain.

OBJECTIVE: To evaluate the efficacy of colchicine therapy in pediatric patients with PFAPA syndrome who present with an incomplete response to the standard treatment or with frequent episodes (an interval of less than 14 days between two disease flares). METHODS: A multicenter cohort study of children diagnosed with PFAPA syndrome and treated with colchicine was performed in three separate hospitals located in Spain. The patients clinical and laboratory data were reviewed by accessing their medical records. Response to colchicine was evaluated after 12 months of treatment for frequency, duration, and intensity of PFAPA episodes. RESULTS: A total of 13 children were included in our study, 43% of whom were boys. Median age of the colchicine therapy initiation was 6 years (interquartile range (IQR)=3-9.5). Following a 12-month period of colchicine therapy (median dosage of 0.02 mg/kg/day; IQR=0.02-0.03), a significant decrease in the median number of flares (median 8; IQR=7-14 vs 3; IQR=2-4; p=0.005) and the duration of disease episodes (median 4 days; IQR=3.25-5.125 vs 1 day; IQR=1-2; p=0.003) was observed. Furthermore, the highest degree of fever during disease flares was reduced from median 40ºC (IQR=39.5-40) to 38.5ºC (IQR=37.7-38.9) (p=0.002). CONCLUSION: Colchicine therapy decreased the frequency and intensity of PFAPA. The use of colchicine could be an effective treatment in pediatric patients with PFAPA syndrome who present with frequent or severe relapses.

Biological therapy in refractory chronic nonbacterial osteomyelitis: A case series of 19 patients.

INTRODUCTION: Chronic non-bacterial osteomyelitis (CNO) represents an autoinflammatory bone disorder. Currently there are no standardized diagnostic or treatment guidelines. The objective of the study is to describe our experience with biological therapy in children with the disease. METHODS: Retrospective chart review of patients with CNO treated with biological therapy followed at two tertiary hospitals from January 2007 to April 2020. Biologicals were started in most patients due to persistent disease activity after receiving standard therapy with at least 2 drugs (NSAIDs and corticosteroids and/or pamidronate). RESULTS: Twenty-five patients were diagnosed with CNO. Out of those, 19 patients (15 females) failed conventional therapy. The mean age at diagnosis was 8.8±2.9 years and the mean diagnostic delay was 6.9±8.3 months. All patients presented with bone pain and 6/19 also had fever. The most frequently affected bones were femur (9 patients), followed by clavicle, tibia and vertebrae (6, 6 and 5 patients respectively). Nine children had skin lesions. C-reactive protein was elevated in 13/19 patients (mean 20.2mg/L±11.7) and ESR in 16/19 (mean 48mm/h±29). All patients received nonsteroidal anti-inflammatory drugs, 15/19 pamidronate, 10/19 corticosteroids and 19 anti-TNF-therapy. At the last follow-up visit, 10/19 patients were still on biological therapy (8 adalimumab, 2 infliximab) and 18 out of 19 remained asymptomatic. In regards to adverse effects, one patient receiving infliximab developed S. aureus osteomyelitis and another cutaneous leishmaniosis. CONCLUSIONS: This research emphasizes that anti-TNF-therapy represents an effective and safe alternative for patients with CNO refractory to conventional treatments.

Biallelic loss-of-function LACC1/FAMIN Mutations Presenting as Rheumatoid Factor-Negative Polyarticular Juvenile Idiopathic Arthritis.

Juvenile idiopathic arthritis (JIA) is a complex rheumatic disease with both autoimmune and autoinflammatory components. Recently, familial cases of systemic-onset JIA have been attributed to mutations in LACC1/FAMIN. We describe three affected siblings from a Moroccan consanguineous family with an early-onset chronic, symmetric and erosive arthritis previously diagnosed as rheumatoid factor (RF)-negative polyarticular JIA. Autozygosity mapping identified four homozygous regions shared by all patients, located in chromosomes 3, 6 (n:2) and 13, containing over 330 genes. Subsequent whole exome sequencing identified two potential candidate variants within these regions (in FARS2 and LACC1/FAMIN). Genotyping of a cohort of healthy Moroccan individuals (n: 352) and bioinformatics analyses finally supported the frameshift c.128_129delGT mutation in the LACC1/FAMIN gene, leading to a truncated protein (p.Cys43Tyrfs*6), as the most probable causative gene defect. Additional targeted sequencing studies performed in patients with systemic-onset JIA (n:23) and RF-negative polyarticular JIA (n: 44) revealed no pathogenic LACC1/FAMIN mutations. Our findings support the homozygous genotype in the LACC1/FAMIN gene as the defect underlying the family here described with a recessively inherited severe inflammatory joint disease. Our evidences provide further support to the involvement of LACC1/FAMIN deficiency in different types of JIA in addition to the initially described systemic-onset JIA.

JAK1/2 inhibition with baricitinib in the treatment of autoinflammatory interferonopathies.

BACKGROUND: Monogenic IFN-mediated autoinflammatory diseases present in infancy with systemic inflammation, an IFN response gene signature, inflammatory organ damage, and high mortality. We used the JAK inhibitor baricitinib, with IFN-blocking activity in vitro, to ameliorate disease. METHODS: Between October 2011 and February 2017, 10 patients with CANDLE (chronic atypical neutrophilic dermatosis with lipodystrophy and elevated temperatures), 4 patients with SAVI (stimulator of IFN genes-associated [STING-associated] vasculopathy with onset in infancy), and 4 patients with other interferonopathies were enrolled in an expanded access program. The patients underwent dose escalation, and the benefit was assessed by reductions in daily disease symptoms and corticosteroid requirement. Quality of life, organ inflammation, changes in IFN-induced biomarkers, and safety were longitudinally assessed. RESULTS: Eighteen patients were treated for a mean duration of 3.0 years (1.5-4.9 years). The median daily symptom score decreased from 1.3 (interquartile range [IQR], 0.93-1.78) to 0.25 (IQR, 0.1-0.63) (P < 0.0001). In 14 patients receiving corticosteroids at baseline, daily prednisone doses decreased from 0.44 mg/kg/day (IQR, 0.31-1.09) to 0.11 mg/kg/day (IQR, 0.02-0.24) (P < 0.01), and 5 of 10 patients with CANDLE achieved lasting clinical remission. The patients' quality of life and height and bone mineral density Z-scores significantly improved, and their IFN biomarkers decreased. Three patients, two of whom had genetically undefined conditions, discontinued treatment because of lack of efficacy, and one CANDLE patient discontinued treatment because of BK viremia and azotemia. The most common adverse events were upper respiratory infections, gastroenteritis, and BK viruria and viremia. CONCLUSION: Upon baricitinib treatment, clinical manifestations and inflammatory and IFN biomarkers improved in patients with the monogenic interferonopathies CANDLE, SAVI, and other interferonopathies. Monitoring safety and efficacy is important in benefit-risk assessment. TRIAL REGISTRATION: ClinicalTrials.gov NCT01724580 and NCT02974595. FUNDING: This research was supported by the Intramural Research Program of the NIH, NIAID, and NIAMS. Baricitinib was provided by Eli Lilly and Company, which is the sponsor of the expanded access program for this drug.

Outpatients with acute osteoarticular infections had favourable outcomes when they received just oral antibiotics without intravenous antibiotics.

AIM: The traditional approach for acute paediatric osteoarticular infections (OAI) has comprised initial intravenous antibiotics followed by prompt oral antibiotics. We assessed how providing just oral antibiotics compared to the traditional two-step approach. METHODS: This prospective study was performed at the Hospital La Paz, Madrid, Spain, from September 2015 to September 2016. We compared 25 outpatients, with good general health and a mean age of 25 months who received just oral antibiotics, with 228 hospitalised children of a similar age who received intravenous and oral antibiotics from other hospitals in the Spanish Network of Osteoarticular Infections. RESULTS: The groups were comparable in terms of age, sex, fever, erythrocyte sedimentation rate value, C-reactive protein and diagnosis. The oral group comprised 15 with osteomyelitis, seven with septic arthritis, two with osteoarthritis and one with spondylodiscitis. This group had a lower percentage of Staphylococcus aureus (8% vs 26%, p = 0.06) and higher proportion of Kingella kingae (24% vs 9%, p = 0.017) than the intravenous group. There were complications (24%) and follow-up sequelae (6%) in the intravenous group, but none in the oral group. CONCLUSION: Outpatients with OAI who were in good general health had favourable outcomes when they received oral antibiotics without intravenous antibiotics.

Current Practices for Therapeutic Drug Monitoring of Biopharmaceuticals in Pediatrics.

Biopharmaceuticals have recently emerged as effective treatments for refractory pediatric autoimmune conditions. Several reports have shown a relationship between drug concentration, antidrug antibodies, and clinical response in these patients, strongly suggesting the potential interest, usefulness, and reliability of therapeutic drug monitoring (TDM) in children. This article reviews the current state of research in juvenile idiopathic arthritis, pediatric inflammatory bowel disease, and pediatric psoriasis from a TDM point of view. There is a remarkable lack of evidence-based data in pediatric patients, which is reflected throughout the article. Most investigations of TDM are focused on research of tumor necrosis factor alpha antagonists in inflammatory bowel disease, albeit preliminary publications are emerging from pediatric rheumatologists and dermatologists. To date, immunogenicity has been a primary concern, particularly regarding infliximab and adalimumab therapy in children, as it may lead to a loss of therapeutic response. Preliminary investigations show that adjusting the dose according to blood drug concentrations improves disease outcomes by overcoming antidrug antibodies, suggesting a crucial role for TDM. Patients who receive other drugs, such as etanercept, abatacept, or tocilizumab, could benefit from TDM because dosage can be optimized by adjusting it to the minimum effective dose.