OBJECTIVES:The Advances in Targeted Therapies annual meeting brings together experts within the field of rheumatology and immunology to highlight and discuss the latest scientific developments and needs in the field. The objective is to highlight unmet scientific needs in the field of rheumatology. METHODS:The 24th annual Advances in Targeted Therapies meeting convened with more than 100 international clinicians and scientific researchers in rheumatology, immunology, and other specialities relating to all aspects of immune-mediated inflammatory diseases. During the meeting, we held 5 rheumatologic disease-specific discussion sections consisting of experts in each field. These groups included rheumatoid arthritis (RA), psoriatic arthritis (PsA), axial spondyloarthritis (axSpA), osteoarthritis (OA), and systemic lupus erythematosus (SLE). In each group, experts were asked to identify the top 2 to 3 most important overarching and disease-specific scientific unmet needs to be addressed in the next 5 years. RESULTS:The overarching themes across disciplines included the need for precision medicine, improved classification of disease states, and the further identification of targets and associated therapies, including the potential role of chimeric antigen receptor (CAR) T cell therapies. Within RA, the group highlighted the lack of precision medicine and the need for better biomarkers. Further, the lack of targeted therapies against fibroblasts in RA was discussed, with the potential impact of targeting fibroblasts early in the disease as an unmet need. For PsA, there is a continued need for a better definition of disease endotypes and for the categorisation of those with complex and difficult-to-treat (D2T) diseases. The development of bispecific molecules and combination therapeutic approaches remain a high priority. For axSpA, the disease-modifying characteristics of nonsteroid anti-inflammatory drugs need further evaluation, as does the treatment of residual pain and fatigue frequently in the disease. In OA, new therapeutic targets remain an unmet need, and the discussion group prioritised potential experimental strategies that could lead to innovative therapeutic targets. Elucidating the specific signalling and target cells responsible for, or inhibiting, repair will be essential for developing targeted therapies. SLE experts emphasised the need to identify the most predictive biological contributions to disease progression in patients with early clinical precursors of SLE. The role of CAR T cell therapy must be further investigated, along with ancillary biologic studies (eg, immune system profiling) that provide critical insights into disease pathogenesis. Further, there is a need to determine the relationship of patient-relevant symptoms to the pathophysiology of SLE and identify new therapeutic targets for these symptoms. CONCLUSIONS:There remain many unmet needs on the road to precision medicine with regard to identifying disease endotypes and biomarkers for disease progression or therapeutic response. For most diseases discussed, a strong unmet need remains with regard to identifying new targets and therapies for those with refractory or D2T disease. The ability to prevent or cure rheumatic disease remains the ultimate unmet need in rheumatology.

Glycosylation of antibodies is essential for shaping immune responses, as it contributes significantly to antibody function and diversity. While immunoglobulin G (IgG) Fc glycosylation is well-characterized, variable domain glycosylation (VDG) introduces an additional and less understood layer of complexity. Notably, VDG is associated with rheumatoid arthritis, where disease-specific IgG autoantibodies abundantly express this modification. Moreover, its presence on these antibodies correlates with disease progression in at-risk individuals and therapeutic outcomes. Emerging evidence links increased VDG levels to other autoimmune diseases and B-cell malignancies, highlighting its potential as both a marker and modulator in disease onset and progression. Importantly, VDG on IgG is now recognized to influence antigen binding, enhance antibody stability, and modulate interactions with the human neonatal Fc receptor. In addition, glycans in the antigen-binding domains of autoreactive B-cell receptors (BCRs) can significantly impact B cell activation. In follicular lymphoma and other B-cell malignancies, the presence of N-glycosylation sites in the immunoglobulin variable domains leads to the introduction of oligomannose glycans, which are postulated to bind to mannose-specific lectins. This interaction might promote antigen-independent activation of BCRs, thereby supporting malignant B cell survival and proliferation. Here, we explore the regulatory pathways of VDG and its functional roles across both physiological and pathological conditions, underscoring its prevalence and significance in various autoimmune diseases and B-cell malignancies. Ultimately, advancing our understanding of the regulatory factors influencing VDG and its functional implications could be highly rewarding for identifying potential therapeutic targets and strategies to prevent and treat autoimmune diseases and B-cell malignancies.

Rheumatoid arthritis (RA) is an autoimmune disease characterized by the presence of autoantibodies against modified proteins, known as anti-modified protein autoantibodies (AMPAs). While the relationship between different AMPA isotypes and various risk factors remains poorly understood, investigating this association is important for a deeper understanding of RA pathophysiology. Smoking, has its primary effects in the lungs, and it remains unclear whether smoking is preferentially linked to specific AMPA isotypes, such as IgA, which could suggest a mucosal origin. Therefore, we set out to investigate the association between smoking, genetic risk factors for RA, and the presence of specific AMPA isotypes, particular IgA. In 618 RA patients, anti-citrullinated protein antibodies (ACPA-) and anti-acetylated protein antibodies (AAPA-) IgA, -IgG and -IgM and RF-IgA and -IgM were measured by ELISA. Associations with genetic risk factors, smoking and autoantibodies were assessed with logistic regression analysis. For replication, a comprehensive meta-analysis incorporating 3309 RA patients was performed. Smoking was primarily associated with IgA AMPA, with associations that prevailed after correcting for the concurrent presence of AMPA IgG (ACPA-IgA OR 1.89 [1.14–3.12], AAPA-IgA 2.30 [1.35–3.94]). To further substantiate these results, we performed a meta-analysis of 3309 RA patients and observed that smoking was again predominantly associated with the combined presence of ACPA-IgA in addition to ACPA-IgG (OR 2.05 [1.69–2.49], p < 0.001) versus the single presence of ACPA-IgG (OR 1.18 [0.97–1.44], p = 0.11). A gene-environment interaction between the most important genetic risk factor for RA (the HLA shared epitope alleles) and smoking was only seen in patients that were both ACPA-IgG and ACPA-IgA positive, but not in patients who were only positive for ACPA-IgG. These data provide a pivotal refinement of existing knowledge regarding risk factor associations for RA and lend novel support to the hypothesis that smoking may exert its effect on RA by the induction of local (auto)immune responses at mucosal sites.

Objectives To evaluate the clinical applicability of autoantibodies (AAbs) measured by ELISA against the angiotensin II type 1 receptor (AT1R) and endothelin-1 type A receptor (ETAR) in systemic sclerosis (SSc) patients.Methods Serum samples from n=279 SSc patients from the Leiden Systemic Sclerosis cohort, n=42 patients with primary Raynaud’s phenomenon, n=24 patients with rheumatoid arthritis and n=20 healthy controls were tested for anti-AT1R- and anti-ETAR AAbs. Levels were compared between groups with Mann-Whitney U tests or Kruskal-Wallis tests. Risk ratios and Kaplan-Meier analyses were used to determine associations between AAbs and disease manifestations or all-cause mortality. Analyses were repeated in an independent cohort with n=310 SSc patients from the Radboud University Medical Center.Results AAbs against AT1R and ETAR could be detected by ELISA in the sera of all groups tested. Levels were slightly higher in the SSc group compared with the pooled non-SSc group (p=0.043). No associations could be found between anti-AT1R AAbs or anti-ETAR AAbs and disease manifestations or all-cause mortality. In the Radboud cohort, patients with diffuse cutaneous SSc (p=0.001) and interstitial lung disease (p=0.007) had higher median anti-ETAR AAb levels. Patients who died during follow-up had lower levels of anti-AT1R- (p=0.005) and anti-ETAR AAbs (p=0.020).Conclusions We confirm positive ELISAs for anti-AT1R AAbs and anti-ETAR AAbs in the sera of several patient groups and healthy controls. Previously described associations with disease manifestations and all-cause mortality could not be confirmed in our cohorts. Based on the current study, the determination of these AAbs is of limited predictive value in clinical practice.

OBJECTIVES:We aimed to describe the incidence of RA-ILD in various countries worldwide, and to explore its association with RA disease activity. METHODS:In 5 countries, data on RA-ILD (clinical diagnosis based on chest X-ray or CT) were collected RA patients of two observational databases (METEOR, EAC). We investigated a possible association between disease activity over time and RA-ILD. RESULTS:16,663 patients with RA with variable disease duration were evaluated. At the first visit recorded in the database, 1/1077 (0.09 %) patients from The Netherlands, 63/11,787 (0.53 %) from India, 8/629 (1.27 %) from South Africa, 6/424 (1.42 %) from Mexico and 17/2728 (0.62 %) from Colombia had an RA-ILD diagnosis. The incidence rate of RA-ILD in patients with newly diagnosed RA was 3.8 (95 % CI 1.6 to 9.1) per 1000 patient years in The Netherlands, 1.6 (95 % CI 1.0 to 2.5) in India and 6.6 (95 % CI 2.5-17.5) in South Africa. The OR for RA-ILD development, per point increase in DAS28 over time was 1.19 (95 % CI 0.34 to 4.22). Disease activity after the RA-ILD diagnosis or a matched timepoint was statistically significantly higher in patients with RA-ILD than in controls (β 0.56 (95 % CI 0.18 to 0.93). There were no clear differences in DMARD use between the two groups. CONCLUSION:Despite slight differences in RA-ILD prevalence and incidence between countries, the incidence of RA-ILD in daily practice is low in our RA population from different continents. Patients with RA-ILD had a higher disease activity than patients without RA-ILD, and were more often ACPA positive and/or (former) smokers.

Despite treatment advances, some rheumatoid arthritis (RA) patients fail to achieve remission with biological/targeted synthetic DMARDs. We prospectively evaluated 200 patients to determine if interferon profiles and autoantibodies predict treatment outcomes. A significant positive correlation between rheumatoid factor and IFN-γ levels was observed. Patients with high IFN-γ/low IFN-α2 profiles achieved significantly higher remission rates and demonstrated elevated B cell-stimulating cytokines with distinct immunological clustering patterns. This group showed superior responses to IL-6 inhibitors. Anti-carbamylated protein IgM antibodies differed significantly between groups. Interferon profiling offers a practical screening approach for personalized therapy selection in RA.

Rheumatoid arthritis (RA) is characterized by synovial hyperplasia and cartilage/bone destruction. RA affects the synovial joints, the synovial lining, and the permeability of the synovium. As the latter is of central relevance for the distribution of systemically delivered therapeutics into synovial fluid (SF), we here assessed the protein composition of paired plasma and SF of patients diagnosed with RA at three distinct levels of depth using mass spectrometric approaches: the "total" proteome, the "total" immunoglobulin G1 (IgG1) antibody repertoire, and the RA-specific anticitrullinated protein IgG1 autoantibody repertoire. The SF proteome was found to be dominated in numbers and concentration by plasma proteins, although we additionally detected several cartilage- and neutrophil-derived proteins of lower abundance. Strikingly, the plasma proteins were not only qualitatively reflected in SF but also quantitatively, independent of their size and/or other biochemical features. Also, the synovial "total" IgG1 and autoreactive anticitrullinated protein antibody IgG1 repertoire highly resembled the IgG1 repertoires detected in plasma within the same patient. Our comprehensive multilayer data thus reveals that the proteome, including the dominant, most abundant (auto)antibody clones, present in SF of RA patients is a direct reflection of the proteome present in blood, spiked by the local (immune) processes within the RA joint. We thus conclude that proteins directly pass from blood into SF of these joints without substantial bias. These findings thereby not only exemplify the use of in-depth multilayer proteome analyses to revisit basic concepts underlying RA pathology and to monitor the local (immune) processes destructive to cartilage but also provide evidence indicating that (protein-based) therapeutics may equally enter SF of swollen joints and that pharmacokinetic analyses of such therapeutics in blood are directly relevant to the synovial compartment.

OBJECTIVES:To assess disease outcomes after 20 and 12 years of patients with RA or undifferentiated arthritis (UA), treated-to-target in the BeSt and IMPROVED trials. METHODS:In BeSt (inclusion 2000-02, duration 10 years), 508 patients with early RA were randomized to: 1. sequential monotherapy, 2. step-up combination therapy, 3. initial csDMARD combination therapy, 4. initial bDMARD/csDMARD combination therapy. The treatment target was low disease activity (DAS ≤ 2.4).In IMPROVED (inclusion 2007-10, duration 5 years), 610 patients with early RA/UA started MTX with prednisone bridging. The treatment target was remission (DAS < 1.6). Patients not in early remission were randomized to 1. csDMARD combination therapy or 2. bDMARD/csDMARD combination therapy.Between 2019 and 22, these patients were invited for long-term follow-up. RESULTS:One-hundred-fifty-three ex-Best and 282 ex-IMPROVED patients participated in the follow-up study after a median of 12 and 20 years since the study started.In ex-BeSt and ex-IMPROVED patients, the rate of low disease activity was 91%, and 68% were in DAS remission. Median SHS was 14.0 in ex-BeSt (IQR 6.0-32.5; progression since end BeSt 6.0, IQR 2.0-12.5) and 8 in ex-IMPROVED participants (IQR 3-16; progression since end IMPROVED 4, IQR 2-9). Mean HAQ was 0.8 ± 0.6 in ex-BeSt (change since end BeSt: 0.3 ± 0.5) and 0.6 ± 0.6 in ex-IMPROVED participants (change since end IMPROVED: 0.06 ± 0.5). CONCLUSION:At 12/20 years after treatment started, the majority of RA and UA patients who had been treated to target low DAS or DAS remission were in DAS remission and had limited functional disability. Radiographic damage progression was mild although not completely suppressed.

OBJECTIVE:The presence of antinuclear antibodies (ANAs) is characteristic for systemic lupus erythematosus (SLE). Antibody dynamics over time are thought to reflect the cellular source of ANAs and their therapeutic targetability. Anti-double-stranded DNA (anti-dsDNA) is the most prevalent and well-studied of all ANAs, and fluctuations in anti-dsDNA serum levels are associated with disease activity. Antibody dynamics of other ANAs, such as antibodies targeting RNA-binding proteins (RBPs), are often considered more stable compared to anti-dsDNA. However, anti-RBPs may be heterogeneous in nature, and their fluctuation has not been extensively analyzed. Therefore, we aimed to study the dynamics of the different ANAs and their susceptibility to B cell-targeting treatments in patients with SLE. METHODS:Seroconversion of specific ANAs was analyzed using electronic health records from patients with SLE. Titers of specific ANAs and anti-varicella zoster virus (VZV) were determined in serum samples from a longitudinal cohort of patients with SLE and serum from patients with SLE treated with rituximab and belimumab. RESULTS:Anti-Smith (anti-Sm) and anti-RNP, similar to anti-dsDNA titers, seroconverted more frequently compared to anti-SS-A/SS-B. Furthermore, anti-Sm/RNP and anti-dsDNA titers, but not anti-SS-A/SS-B titers, fluctuated significantly compared to stable anti-VZV controls. Likewise, reductions in anti-dsDNA and anti-Sm/RNP titers after B cell-depleting treatment were comparable in magnitude. However, only anti-dsDNA titer reductions associated with clinical outcomes. CONCLUSION:Together, these results show that anti-Sm/RNP and anti-dsDNA, in contrast to anti-SS-A/SS-B, frequently fluctuate and their levels can decrease following B cell-targeted treatments. Thus, distinct ANAs have variable kinetics, potentially reflecting their derivation from different B cell differentiation pathways.

Systemic Lupus Erythematosus (SLE) is an autoimmune disease characterized by an array of autoantibodies, in particular anti-nuclear antibodies (ANA). The disease is also hallmarked by an expansion of plasmablasts (PB) and hypergammaglobulinemia. The mechanisms underlying this hyperactivity and its relation to autoantibody production is not clear. We aimed to characterize B cell hyperactivity in SLE to identify its underlying mechanisms.Using deep phenotyping with spectral flow cytometry and scRNAseq, we demonstrate that a high frequency of PB relative to memory B cells marks a subgroup of SLE patients, particularly those with higher disease activity and positive for Sm/RNP autoantibodies. We identified the origin of this phenotype in a prominent IFN signature in PB and increased activation in the switched CD27+ memory B cell compartment. PB from this group of SLE patients displayed high levels of CD45RB and somatic hypermutation frequencies similar to memory B cells. Repertoire analysis revealed a highly polyclonal expansion of PB and skewing towards IgG1. B cell hyperactivity correlated with hypergammaglobulinemia, especially increased IgG serum levels.In summary, we show for the first time a direct relationship between IFN and PB expansion in a subgroup of SLE patients. Increased activation and differentiation of class-switched B cells driven by IFN may directly underlie PB expansion and hypergammaglobulinemia. These results provide insight into the pathways leading to B cell hyperactivity and autoantibody production which may guide the tailoring of B cell- and IFN-targeted therapies.

Objective Combination therapy with rituximab and belimumab is a novel treatment strategy for severe SLE and lupus nephritis. Phase II studies have shown promising results, although long-term data are currently lacking. To address this, we analysed outcomes of patients with severe treatment-refractory SLE who previously participated in the phase II Synbiose Study, with a particular focus on immunological parameters.Methods Eight patients continued belimumab treatment beyond the 2-year duration of the original trial. We conducted a descriptive study to evaluate the course of treatment and immunological parameters over an extended follow-up. Our analyses include blood cell counts, immunoglobulins, autoantibodies, complement markers and clinical disease activity parameters. Additionally, we examined long-term effects on the B cell compartment employing high-sensitivity flow cytometry.Results Over a median follow-up period of 6.8 years, six out of eight previously treatment-refractory patients maintained long-term clinical remission, while two experienced a major flare. Among those in remission, two patients achieved immunosuppression-free remission, and four continued belimumab. Long-term effects on humoral (auto-)immunity were a persistent decrease in IgM levels, while IgG normalised. Most patients maintained low autoantibody titres, and complement markers remained normal. On the cellular level, belimumab treatment after rituximab prevented B cell repopulation. Notably, patients exhibited a stable reduction of double-negative (DN) B cells, irrespective of continuing or stopping belimumab.Conclusions Long-lasting remission was observed in patients with SLE following combination treatment with rituximab and belimumab. We observed no significant hypogammaglobulinaemia and, notably, persistent reduction of DN B cells.

Introduction:While rheumatoid arthritis (RA)-associated cervical spine deformity seems to be less prevalent following the introduction of the medication regimen to suppress inflammation in RA in an early stage, identifying patients at risk for atlantoaxial subluxation (AAS) or subaxial subluxation (SAS) remains challenging. Research question:The aim of the current study is to evaluate the association of the frequency of flares in systemic disease activity (DAS) and RA-associated cervical spine deformity. Materials and methods:This is a sub-analysis of the BeSt Study, where patients were treated to target DAS≤2.4. Lateral X-rays at 5- and 10-years follow-up were assessed for AAS and SAS. Results:Of 272 RA patients with radiographs of cervical spine that were included, 108 (40 %) had cervical deformity (AAS and/or SAS >2 mm). Although the number of patients with 3 or more flares was low, the majority of these patients did not demonstrate cervical spine deformity. After adjustment for the potential confounders age, gender, ACPA-status and RF-status, the presence of 3 or more flares was associated with a non-significant OR of 0.338 (95 % CI: 0.095-1.207) for the presence of RA-associated cervical spine deformity after 10 years. Discussion and conclusion:A trend towards less RA-associated cervical deformity in patients with more flares was discerned, though no statistically significant differences could be established. It is hypothesized that the occurrence of a flare leads to an increase in medication, which may in turn protect the cervical spine from developing deformities. Future studies should more in detail explore the effect of medication on cervical deformity.

Objective Over the past decades, the incidence of surgery for rheumatoid arthritis (RA)-associated cervical spine deformity decreased. Infliximab has been observed as a protective treatment for joint damage in hands and feet; yet, the protective association between infliximab and the cervical spine has been uncertain.Methods Duration of infliximab use during 10 years of follow-up was evaluated in patients with new-onset RA (case control study using data from the BeSt Trial). Missing values on the exposure were imputed using last observation carried forward. Lateral X-rays at 5-year and 10-year follow-ups were assessed for atlantoaxial subluxation (AAS) and subaxial subluxation (SAS). Multiple logistic regression models adjusted for age, gender, baseline Disease Activity Score (DAS44), ACPA-positivity and rheumatoid factor-positivity were used to estimate ORs and their 95% CIs. Mediation analysis was performed to evaluate whether a potential association was mediated via mean DAS44.Results Cervical deformity (AAS and/or SAS>2 mm) was observed in 108 (40%) of 272 patients. There was an 11% reduction in odds for cervical spine deformity (OR: 0.89, 95% CI: 0.81 to 0.98; p=0.02) for every 1-year increase in duration of infliximab use. Mediation analysis could not reveal an influence of DAS44 on the association between infliximab use and cervical spine outcomes.Conclusions There was evidence of a beneficial association between longer duration of use of infliximab and cervical spine deformity after 10 years follow-up. Thus, it is important to balance the favourable effects of infliximab use for the joints and possibly the cervical spine with the potential adverse events of this medication when used continuously.Trial registration number Netherlands Trial Register Number: NTR262.

OBJECTIVE:To determine whether higher serum exposure during subcutaneous (SC) abatacept (ABA) treatment was associated with an increased infection risk in adult patients with early rheumatoid arthritis (RA). METHODS:Data from Assessing Very Early Rheumatoid Arthritis Treatment-2 (AVERT2; ClinicalTrials.gov: NCT02504268), a randomized, placebo-controlled study in anticitrullinated protein antibody-positive patients with early RA, were analyzed. A post hoc population pharmacokinetic (PPK) analysis was performed. The association between steady-state ABA concentration exposures (ie, steady-state time-averaged serum concentration, steady-state trough serum concentration, steady-state maximum serum concentration) and first infection was evaluated using Kaplan-Meier plots of probability vs time receiving treatment and Cox proportional hazards models. RESULTS:The PK model of SC ABA was defined as a linear 2-compartment model with first-order absorption and elimination, and higher body weight was the only covariate with a clinically relevant effect in the final PPK model. Infections occurred in 330/693 patients treated with ABA + methotrexate (MTX; 47.6%; 11/693 [1.6%] with serious infections) and 134/301 of those treated with ABA placebo + MTX (44.5%; 4/301 [1.3%] with serious infections). Exposure-response analysis demonstrated no exposure relationship for an increased risk of first infection for patients with concomitant use of MTX and glucocorticoids (GCs) during the induction period, baseline GC use, or higher-than-median body weight (> 70 kg) at baseline. CONCLUSION:This exposure-response analysis of AVERT-2 showed no increase in the risk of first infection, regardless of ABA exposure level, in patients with RA treated with SC ABA. Similarly, no effect on the risk of first infection was found for concomitant MTX and GC use in patients with RA treated with SC ABA + MTX.

Rheumatoid arthritis (RA) is a heterogeneous disease with variable symptoms, prognosis, and treatment response, necessitating refined patient classification. We applied multimodal deep learning and clustering to identify distinct RA phenotypes using baseline clinical data from 1,387 patients in the Leiden Rheumatology clinic. Four Joint Involvement Patterns (JIP) emerged: foot-predominant arthritis, seropositive oligoarticular disease, seronegative hand arthritis, and polyarthritis. Findings were validated in clinical trial data (n = 307) and an independent secondary care cohort (n = 515). Clusters showed high stability and significant differences in remission rates (P = 0.007) and methotrexate failure (P < 0.001). JIP-hand patients had superior outcomes (particularly in ACPA-positive patients) versus JIP-foot (HR:0.37, P < 0.001) and JIP-poly (HR:0.33, P = 0.005), independent of baseline disease activity and clinical markers. Synovial histology analysis (n = 194) revealed distinct inflammatory patterns across clusters, hinting at different underlying biological mechanisms. These validated RA phenotypes based on joint involvement patterns may enable targeted research into disease mechanisms and personalized treatment strategies.

RA patients are often prescribed glucocorticoids, although it is known that their long-term use increases the risk of osteoporosis and fractures. The association between glucocorticoid use and RA-associated cervical spine deformity is yet to be determined. Duration and dose of glucocorticoid use were evaluated in patients with new onset RA (BeSt Trial). Missing values on the exposure were imputed using the last observation carried forward. Lateral X-rays at 5- and 10-year follow-ups were assessed for atlantoaxial subluxation (AAS) and subaxial subluxation (SAS). To estimate the association between glucocorticoids and cervical spine deformity, multiple logistic regression models adjusted for age, gender, baseline Disease Activity Score (DAS), ACPA positivity, and RF positivity were used to estimate odds ratios (ORs) and their 95

To assess radiographic progression in certolizumab pegol (CZP)+methotrexate (MTX) vs placebo (PBO)+MTX-treated patients (pts) with rheumatoid arthritis (RA), stratified by rheumatoid factor (RF) level, in the C-EARLY ( NCT01519791 ) and C-OPERA ( NCT01451203 ) phase 3 randomized trials. A pooled analysis of pts with early (≤1 year active disease) moderate-to-severe RA with poor prognostic factors in the C-EARLY and C-OPERA trials is presented (full analysis set). At Week (Wk)24, PBO-treated non-responders could switch to CZP for the remaining 28 wks (early escapers). Pts were stratified by baseline (BL) RF level (low: <200 IU/mL; high: ≥200 IU/mL), per published strata.[1,2] Change from BL in modified total Sharp score (mTSS) and proportions of pts experiencing minimum clinically important difference (worsening) of mTSS (>5) at Wk24 and Wk52 are reported. 813 CZP-treated (low RF: N=571; high RF: N=242) and 367 PBO-treated (low RF: N=242; high RF: N=125) pts with BL RF measurements were included; 56 PBO-treated pts were early escapers. BL characteristics were similar between CZP- and PBO-treated pts within each RF stratification. However, pts with high RF had more severe disease at BL than those with low RF, with higher mean C-reactive protein, anti-citrullinated protein antibodies, mTSS, and erosion scores. By Wk52, mean mTSS increased from BL in PBO-treated pts with both high RF (change from BL [CfB]: 2.36±6.20) and low RF (CfB: 1.37±3.43) but was comparable in CZP-treated pts (high RF, CfB: 0.28±2.63; low RF, CfB: 0.14±3.11). The proportion of pts with meaningfully worsening radiographic progression was higher in PBO-treated pts with high RF compared to low RF at both Wk24 (6.48% vs 2.84%) and Wk52 (17.59% vs 10.43%) (Figure). By contrast, a smaller proportion of CZP-treated pts experienced meaningful worsening and this was similar between pts with high and low RF (Wk24: 0.00% vs 1.05%; Wk52: 5.29% vs 3.14%, respectively). Figure. Individual pt CfB in mTSS at Wk24 and Wk52, stratified by baseline RF level (low [<200 IU/mL] vs high [≥200 IU/mL]) Pts with high BL RF levels had more severe RA and BL radiographic damage than those with low RF. Worsening radiographic damage was observed in PBO-treated pts, with slightly greater progression in high RF pts than low RF. In contrast, irrespective of BL RF levels, CZP-treated pts demonstrated consistently lower radiographic progression, suggesting RF does not adversely influence radiographic response to CZP. Previously submitted to: ACR 2024. [1.] Vastesaeger N. Rheumatology (Oxford) 2009;48:1114-21; [2.] Smolen J. Arthritis Rheumatol 2023;75(suppl 9).

Background: Studying which biological pathways are involved in reaching remission in auto-immune diseases could highlight possible targetable mechanisms. Rheumatoid arthritis (RA) is the ideal model disease to study this hypothesis due to well-defined and widely-used measures of disease activity. Objectives: To increase understanding of the mechanisms and biological pathways underlying autoimmune disease remission through GWAS directed functional studies. Methods: The RTCure network collected genetic data of 5,622 deeply phenotyped treatment naive RA patients with longitudinal disease activity data. Data were uniformly QC’ed and imputed using the Haplotype Reference Consortium reference panel. We carried out a GWAS per dataset with DAS28-CRP below 2.6 at 6 months as our outcome, including top 10 principal components, age and sex as covariates. We combined the results using a fixed-effect meta-analysis. SNPs were mapped to genes using Open Targets Genetics. We assessed gene expression using single cell RNAseq of synovial biopsies (AMP-I [1], PEAC [2], Zurich and Queensland) and eQTL data of circulating CD4+ T-cells from untreated RA patients (NEAC) [3]. To investigate the role of Ca2+ induced endoplasmic reticulum (ER) stress on FKBP7, Rheumatoid Arthritis fibroblast-like synoviocytes (RA-FLS) HPRT-knockout cells were stimulated with 400nM thapsigargin (Tg) for 24 hours and cell lysate was collected for RNA analysis. Relative mRNA expression of FKBP7 and stress-related genes CHOP, Grp78 and sXBP1 was calculated against the housekeeper β-actin. Results: Our top hit (P < 5 x 10-8), rs16866400 (Figure 1A-B), has the strongest e-, p- and sQTL association with FK506 binding protein 7 (FKBP7), whose relevance to auto-immunity is understudied. The association was not driven by CCP status, HLA or DMARD usage. The FKBP7 protein is an ER resident chaperone regulating the folding of proteins. Both public and proprietary data show that FKBP7 is differentially overexpressed in a key RA tissue, fibroblast-like synoviocytes (FLS), rather than in circulating B- and T-cells(Figure 1C-E). FKBP7 expression in blood associated both with baseline and change in DAS28-CRP. (Figure 1F) Our studies show that in response to Tg induced Ca2+ ER stress, but not other stressors such as tunicamycin or pro-inflammatory cytokines, FKBP7 was upregulated in RA FLS (Figure 2). FKBP7 has been found to regulate the NOD2 pathway[4]. As this is strongly associated with inflammatory immune responses in Crohn’s Disease (CD), we checked published Crohn’s progression GWAS data for colonic FKPB7 eQTLs.[5] 22% of the colonic FKBP7 eQTLs (GTEx) included in the CD GWAS were significantly (P < 0.05) associated with CD severity. Conclusion: We found the ER resident molecular chaperone encoding gene FKBP7 to link to both RA remission and CD severity. Our functional studies demonstrate a role for the chaperone in the regulation of Ca2+ ER stress and highlights FKBP7 as an interesting gene for further research related to the induction of remission. Elucidating the underlying mechanisms will both increase our understanding of auto-immune pathophysiology as well as facilitate the discovery of novel treatment targets. REFERENCES: [1] Zhang et al, 2019, Nat Imm.[2] Lewis et al, 2019, Cell Rep.[3] Thalayasingam et al, 2018, A&R.[4] Warner et al, 2013, Sci. Signal.[5] Lee, J. C., Biasci, D., et al., 2017, Nat Genet. Acknowledgements: We would like to acknowledge support by SPIDeRR Horizon EU (grant 101080711), RTCure, the IMI2 JU (grant 777357), ZonMW (grant 90719069), MRC/Versus Arthritis MATURA Consortium, Versus Arthritis Inflammatory Arthritis Centre Versus Arthritis, NIHR Newcastle Biomedical Research Centre, NIHR Leeds BioMedical Research Centre, UK Medical Research Council (TACERA) and Pfizer. Disclosure of Interests: Marc P. Maurits: None declared, Amy Cameron: None declared, Scott Jelinsky No conflict of interest applies to this abstract, Stephan Blüml: None declared, Lydia Abasolo: None declared, Johan Askling: None declared, Anne Barton: None declared, Stefan Böhringer: None declared, Andrew Cope: None declared, Saurav De No conflict of interest applies to this abstract, Paul Emery: None declared, Stephen Eyre: None declared, Vasanthi Priyadarshini Gaddi: None declared, Isidoro González-Álvaro: None declared, Carl S Goodyear: None declared, Xinli Hu No conflict of interest applies to this abstract, Tom Huizinga: None declared, Martina Johannesson: None declared, Samantha Jurado-Zapata: None declared, Lars Klareskog: None declared, Dennis Lendrem: None declared, Paul Martin: None declared, Iain B. Mc Innes: None declared, Raphael Micheroli: None declared, Ann Morgan: None declared, Fraser Morton: None declared, Najib Naamane: None declared, Yasuo Nagafuchi: None declared, Gisela Orozco: None declared, Leonid Padyukov: None declared, Caron Paterson: None declared, Costantino Pitzalis: None declared, Darren Plant: None declared, Duncan Porter: None declared, Louise Reynard: None declared, Luis Rodriguez Rodriguez: None declared, Daniela Sieghart: None declared, Paul Studenic: None declared, John Taylor: None declared, Rene E.M. Toes: None declared, Erik B. van den Akker: None declared, Annette H.M. van der Helm – van Mil: None declared, Lotta Vaskimo: None declared, Suzanne Verstappen: None declared, Helga Westerlind: None declared, John Isaacs: None declared, Myles Lewis: None declared, Arthur Pratt: None declared, Caroline Ospelt: None declared, Aaron Winkler No conflict of interest applies to this abstract, Ranjeny Thomas: None declared, Rachel Knevel: None declared.Figure 1(A) Manhattan plot, dashed line at p = 5 x 10-8, (B) forest plot of rs16866400 locus, (C) FKBP7 expression in fibroblasts, monocytes, T-cells and B-cells in RA, osteoarthritis and healthy participants [1] (n = 55 RA patients), (D-E) expression across cell types in arthritis patients (n=355 RA patients and n = 26 synovial tissues of 5 arthritides respectively) and (F) association between FKBP7 levels in blood and DAS28-CRP (response). Figure 2Thapsigargin treated (24h) vs untreated RA-FLS HPRTKO. Relative mRNA expression of (a) FKBP7 and stress genes (b) CHOP, (c) Grp78 and (d) sXBP1 calculated against β-actin. n=8/group