Objective To develop EULAR points-to-consider for therapeutic drug monitoring (TDM) of biopharmaceuticals in inflammatory rheumatic and musculoskeletal diseases (RMDs). Methods The points-to-consider were developed in accordance with EULAR standardised operation procedures by a multidisciplinary task force from eight European countries, based on a systematic literature review and expert consensus. Level of evidence and strength of the points-to-consider were determined, and mean levels of agreement among the task force were calculated using a 10-point rating scale. Results Six overarching principles and 13 points-to-consider were formulated. The level of agreement among the task force for the overarching principles and points-to-consider ranged from 8.4 to 9.9.The overarching principles define TDM and its subtypes, and reinforce the underlying pharmacokinetic/pharmacodynamic principles, which are relevant to all biopharmaceutical classes. The points-to-consider highlight the clinical utility of the measurement and interpretation of biopharmaceutical blood concentrations and antidrug antibodies in specific clinical scenarios, including factors that influence these parameters. In general, proactive use of TDM is not recommended but reactive TDM could be considered in certain clinical situations. An important factor limiting wider adoption of TDM is the lack of both high quality trials addressing effectiveness and safety of TDM and robust economic evaluation in patients with RMDs. Future research should focus on providing this evidence, as well as on further understanding of pharmacokinetic and pharmacodynamic characteristics of biopharmaceuticals. Conclusion These points-to-consider are evidence-based and consensus-based statements for the use of TDM of biopharmaceuticals in inflammatory RMDs, addressing the clinical utility of TDM.

Objectives Anti-drug antibodies (ADA) are responsible for decreased adalimumab efficacy in axial spondyloarthritis (SpA). We aimed to evaluate the ability of methotrexate (MTX) to decrease adalimumab immunisation. Methods A total of 110 patients eligible to receive adalimumab 40 mg subcutaneously (s.c.) every other week were randomised (1:1 ratio) to receive, 2 weeks before adalimumab (W-2) and weekly, MTX 10 mg s.c. (MTX+) or not (MTX−). ADA detection and adalimumab serum concentration were assessed at weeks 4 (W4), 8 (W8), 12 (W12) and 26 (W26) after starting adalimumab (W0). The primary outcome was the proportion of patients with ADA at W26. Four years after the study completion, we retrospectively analysed adalimumab maintenance in relation with MTX co-treatment duration. Results We analysed data for 107 patients (MTX+; n=52; MTX-; n=55). ADA were detected at W26 in 39/107 (36.4%) patients: 13/52 (25%) in the MTX+ group and 26/55 (47.3%) in the MTX− group (p=0.03). Adalimumab concentration was significantly higher in the MTX+ than MTX− group at W4, W8, W12 and W26. The two groups did not differ in adverse events or efficacy. In the follow-up study, MTX co-treatment >W26 versus no MTX or ≤W26 was significantly associated with adalimumab long-term maintenance (p=0.04). Conclusion MTX reduces the immunogenicity and ameliorate the pharmacokinetics of adalimumab in axial SpA. A prolonged co-treatment of MTX>W26 seems to increase adalimumab long-term maintenance.

Objectives Alterations in tryptophan (Trp) metabolism have been reported in inflammatory diseases, including rheumatoid arthritis (RA). However, understanding whether these alterations participate in RA development and can be considered putative therapeutic targets remains undetermined. In this study, we combined quantitative Trp metabolomics in the serum from patients with RA and corrective administration of a recombinant enzyme in experimental arthritis to address this question. Methods Targeted quantitative Trp metabolomics was performed on the serum from 574 previously untreated patients with RA from the ESPOIR (Etude et Suivi des POlyarthrites Indifférenciées Récentes) cohort and 98 healthy subjects. A validation cohort involved 69 established patients with RA. Dosages were also done on the serum of collagen-induced arthritis (CIA) and collagen antibody-induced arthritis (CAIA) mice and controls. A proof-of-concept study evaluating the therapeutic potency of targeting the kynurenine pathway was performed in the CAIA model. Results Differential analysis revealed dramatic changes in Trp metabolite levels in patients with RA compared with healthy controls. Decreased levels of kynurenic (KYNA) and xanthurenic (XANA) acids and indole derivatives, as well as an increased level of quinolinic acid (QUIN), were found in the serum of patients with RA. They correlated positively with disease severity (assessed by both circulating biomarkers and disease activity scores) and negatively with quality-of-life scores. Similar profiles of kynurenine pathway metabolites were observed in the CAIA and CIA models. From a mechanistic perspective, we demonstrated that QUIN favours human fibroblast-like synoviocyte proliferation and affected their cellular metabolism, through inducing both mitochondrial respiration and glycolysis. Finally, systemic administration of the recombinant enzyme aminoadipate aminotransferase, responsible for the generation of XANA and KYNA, was protective in the CAIA model. Conclusions Altogether, our preclinical and clinical data indicate that alterations in the Trp metabolism play an active role in the pathogenesis of RA and could be considered as a new therapeutic avenue.

Significant peripheral blood CD4+ T-cell depletion has been observed after a first cycle of rituximab, a monoclonal antibody directed against the CD20 antigen, which is currently used in rheumatoid arthritis. Of note, an absence of CD4+ T-cell decrease has been observed in non-responders. Herein, we describe CD4+ T-cell changes over repeated cycles of rituximab and their relationship with clinical outcomes. Patients with rheumatoid arthritis who started rituximab between July 2007 and July 2013 were analyzed up to November 2014. Lymphocyte phenotyping and clinical assessments were performed before, and 3 and 6 months after each cycle. Lymphocytes counts and disease activity were compared at each time point, using nonparametric tests. Patients received up to seven cycles of treatment during the study period. Mean CD4+ T-cell counts were above the upper limit of the reference range before each rituximab infusion and repeatedly reached the reference range at 6 months (and/or 3 months) post infusion. CD4+ T cells decreased concurrently with disease activity score. CD4+ T-cell counts could be a relevant biomarker of response to rituximab in rheumatoid arthritis and could be considered in making decisions about the timing of retreatment.

Objective To identify patient characteristics associated with responsiveness to tumour necrosis factor inhibitors (TNFi) in rheumatoid arthritis (RA). Materials and methods Individual patient data from 29 randomised controlled trials (RCTs) evaluating the efficacy of a TNFi versus placebo or conventional therapy were obtained. Response to treatment was assessed in subgroups according to the following baseline characteristics: smoking status, physical activity, sex, age, body mass index, autoantibody profile, disease duration, high initial disease activity defined by Disease Activity Score on 28 joints (DAS28)(C reactive protein (CRP)) >5.1. The primary outcome was the between-treatment group difference in DAS28(CRP) change from baseline to 6 months. The secondary endpoints were the between-treatment group difference in final DAS28(CRP) measured until 6 months and EULAR response criteria until 6 months. Data from each RCT were then pooled by the Mantel-Haenszel method using a random effects model. A linear metaregression was also carried out on two data-sharing platforms separately to support the results. Results Individual data of 11 617 patients from 29 RCTs were analysed. Until 6 months, a significantly higher EULAR non-response rate was observed in obese patients (OR 0.52 vs 0.36 for non-obese, p=0.01). A multivariable regression model performed on 7457 patients indicated that patients treated by TNFi had a final DAS28(CRP) decreased by 0.02 for each year of disease duration (p5.1 (p<0.001). Conclusions In RA, patients who are more responsive to TNFi are those who are non-obese, have a long disease duration and have a high initial disease activity.