Anti-citrullinated peptide antibodies and their value for predicting responses to biologic agents: a review

Body mass index stratification enables cytokine-based prediction of ACPA status and Power-Doppler disease activity in rheumatoid arthritis

OBJECTIVE

Rheumatoid arthritis can be classified according to ACPA and RF status. ACPA status may be associated with other pathophysiological differences, e.g., the cytokines driving inflammation. Obesity influences the course of RA, likely involving leptin; the exact mechanisms are not completely understood. This study investigates BMI influence on RA cytokine profiles and the possibility of predicting ACPA status and disease activity measured by Power-Doppler sonography (PDS).

METHODS

Patients were examined using a multi-biomarker disease assay and PDS examination of wrists and MCP and PIP joints and stratified according to ACPA status and BMI, using prediction precision to determine BMI cutoff. Analysis was performed using elastic net regularization of logistic and multiple regression. We then attempted to predict ACPA status/PDS activity based on a bootstrap approach.

RESULTS

A total of 120 measurements from 95 patients were performed. ACPA status prediction peaked at BMI 26 kg/m2, with AUC 0.82. PDS activity prediction had a mean average error of < 1.6 PDS points for all groups. In obese patients, cytokine profiles appear to align in ACPA-positive and -negative patients, with leptin playing a greater role in predicting PDS activity, but with some remaining differences.

CONCLUSION

When stratified according to BMI, cytokine patterns can predict ACPA status and PDS activity in RA with a high degree of precision. This indicates that studies into the pathophysiology of RA should take BMI into account, to differentiate between disease- and obesity-associated phenomena. The underlying pathological processes of ACPA-negative and -positive RA appear different. Multi-cytokine evaluations may provide a deeper understanding of disease processes. Key Points • A multi-cytokine approach combined with ultrasonography and modern mathematical methods can contribute to a deeper understanding of the relationship between systemic and joint inflammation. • BMI influences cytokine profiles in rheumatoid arthritis and appears to "override" disease-specific processes. • Using cytokines only, and adjusting for BMI, it is possible to predict the ACPA status and joint inflammation with considerable precision.

Impact of age and cardiovascular risk factors on the incidence of adverse events in patients with rheumatoid arthritis treated with Janus Kinase inhibitors: data from a real-life multicentric cohort

Inhibiting Janus Kinases (JAK) is a crucial therapeutic strategy in rheumatoid arthritis (RA). However, the use of JAK inhibitors has recently raised serious safety concerns. The study aims to evaluate the safety profile of JAKi in patients with RA and identify potential risk factors (RFs) for adverse events (AEs). Data of RA patients treated with JAKi in three Italian centers from January 2017 to December 2022 were retrospectively analyzed. 182 subjects (F:117, 64.3%) underwent 193 treatment courses. 78.6% had at least one RF, including age ≥ 65 years, obesity, smoking habit, hypertension, dyslipidemia, hyperuricemia, diabetes, previous VTE or cancer, and severe mobility impairment. We identified 70 AEs (28/100 patients/year), among which 15 were serious (6/100 patients/year). A high disease activity was associated with AEs occurrence (p = 0.03 for CDAI at T0 and T6; p = 0.04 for SDAI at T0 and T6; p = 0.01 and p = 0.04 for DAS28ESR at T6 and T12, respectively). No significant differences in AEs occurrence were observed after stratification by JAKi molecules (p = 0.44), age groups (p = 0.08) nor presence of RFs (p > 0.05 for all of them). Neither the presence of any RFs, nor the cumulative number of RFs shown by the patient, nor age ≥ 65 did predict AEs occurrence. Although limited by the small sample size and the limited number of cardiovascular events, our data do not support the correlation between cardiovascular RFs-including age-and a higher incidence of AEs during JAKi therapy. The role of uncontrolled disease activity in AEs occurrence should by emphasized.

Sex and age do not modify the association between glucocorticoids and bone mineral density in patients with rheumatoid arthritis: a cross-sectional study

BACKGROUND

It is unclear whether sex or age modify the association of glucocorticoid (GC) use with reduced bone mineral density (BMD) in patients with rheumatoid arthritis (RA).

METHODS

We studied cross-sectional data of RA patients with current or previous GC treatment in a single center cohort study (Rh-GIOP cohort). Our primary outcome was the minimum T-score (measured by DXA) of either lumbar spine, total femur, or femoral neck. Current GC dose was the main exposure; cumulative GC dose and cumulative duration of GC use were also assessed. Following a predefined statistical analysis plan, linear regression analyses with adjustment for confounders assessed whether the association of GC use with BMD was modified by sex (men versus women) or age (≥ 65 versus < 65 years).

RESULTS

Four hundred eighty-three patients with RA (mean age 64 ± 12 years, 80% women) were included. 33% were not currently taking GCs, 32% were treated with a dose of 5 mg/d prednisone equivalent and 11% with more than 7.5 mg/d. 23% of patients had osteoporosis by DXA (minimum T-score ≤ -2.5). The slope, i.e., the association between changes in minimum T-scores with 1 mg/d change in current GC dose, was similar in men and women (-0.07 and -0.04, respectively; difference -0.03 [-0.11 to 0.04]; p for interaction = 0.41). Slopes were also similar for elderly and non-elderly patients (-0.03 and -0.04, respectively; difference -0.01 [-0.06 to 0.05]; p for interaction = 0.77). Using cumulative dose and duration of use as exposures did not lead to substantial changes of these results.

CONCLUSIONS

In our sample, the association of GC use with reduced BMD in RA was not modified by sex or age.

Sustained Remission and Outcomes with Abatacept plus Methotrexate Following Stepwise Dose De-escalation in Patients with Early Rheumatoid Arthritis

INTRODUCTION

One target of rheumatoid arthritis (RA) treatment is to achieve early sustained remission; over the long term, patients in sustained remission have less structural joint damage and physical disability. We evaluated Simplified Disease Activity Index (SDAI) remission with abatacept + methotrexate versus abatacept placebo + methotrexate and impact of de-escalation (DE) in anti-citrullinated protein antibody (ACPA)-positive patients with early RA.

METHODS

The phase IIIb, randomized, AVERT-2 two-stage study (NCT02504268) evaluated weekly abatacept + methotrexate versus abatacept placebo + methotrexate.

PRIMARY ENDPOINT

SDAI remission (≤ 3.3) at week 24. Pre-planned exploratory endpoint: maintenance of remission in patients with sustained remission (weeks 40 and 52) who, from week 56 for 48 weeks (DE period), (1) continued combination abatacept + methotrexate, (2) tapered abatacept to every other week (EOW) + methotrexate for 24 weeks with subsequent abatacept withdrawal (abatacept placebo + methotrexate), or (3) withdrew methotrexate (abatacept monotherapy).

RESULTS

Primary study endpoint was not met: 21.3% (48/225) of patients in the combination and 16.0% (24/150) in the abatacept placebo + methotrexate arm achieved SDAI remission at week 24 (p = 0.2359). There were numerical differences favoring combination therapy in clinical assessments, patient-reported outcomes (PROs) and week 52 radiographic non-progression. After week 56, 147 patients in sustained remission with abatacept + methotrexate were randomized (combination, n = 50; DE/withdrawal, n = 50; abatacept monotherapy, n = 47) and entered DE. At DE week 48, SDAI remission (74%) and PRO improvements were mostly maintained with continued combination therapy; lower remission rates were observed with abatacept placebo + methotrexate (48.0%) and with abatacept monotherapy (57.4%). Before withdrawal, de-escalating to abatacept EOW + methotrexate preserved remission.

CONCLUSIONS

The stringent primary endpoint was not met. However, in patients achieving sustained SDAI remission, numerically more maintained remission with continued abatacept + methotrexate versus abatacept monotherapy or withdrawal.

TRIAL REGISTRATION

ClinicalTrials.gov identifier, NCT02504268. Video abstract (MP4 62241 KB).

Identification of anti-citrullinated osteopontin antibodies and increased inflammatory response by enhancement of osteopontin binding to fibroblast-like synoviocytes in rheumatoid arthritis

BACKGROUND

Anti-citrullinated protein/peptide antibodies (ACPAs) are present in patients at onset and have important pathogenic roles during the course of rheumatoid arthritis (RA). The characteristics of several molecules recognized by ACPA have been studied in RA, but the positivity rate of autoantibodies against each antigen is not high, and the pathogenic mechanism of each antibody is not fully understood. We investigated the role of anti-citrullinated osteopontin (anti-cit-OPN) antibodies in RA pathogenesis.

METHODS

Enzyme-linked immunosorbent assays on RA patients' sera were used to detect autoantibodies against OPN. Fibroblast-like synoviocytes (FLS) isolated from RA patients were used to test the binding activity and inflammatory response of OPN mediated by anti-cit-OPN antibodies, and their effect was tested using an inflammatory arthritis mouse model immunized with cit-OPN. Anti-cit-OPN antibody positivity and clinical characteristics were investigated in the patients as well.

RESULTS

Using sera from 224 RA patients, anti-cit-OPN antibodies were positive in approximately 44% of RA patients, while approximately 78% of patients were positive for the cyclic citrullinated peptide (CCP2) assay. IgG from patients with anti-cit-OPN antibody increased the binding activity of OPN to FLSs, which further increased matrix metalloproteinase and interleukin-6 production in TNF-stimulated FLSs. Mice immunized with cit-OPN antibodies experienced severe arthritis. Anti-cit-OPN antibodies in RA patients decreased the drug survival rate of tumor necrosis factor (TNF) inhibitors, while it did not decrease that of CTLA4-Ig.

CONCLUSIONS

Anti-cit-OPN antibodies were detected in patients with RA. IgG from patients with anti-cit-OPN antibodies aggravated RA, and anti-cit-OPN antibody was a marker of reduced the survival rate of TNF inhibitors in RA patients.

Positive Effects of Biologics on Osteoporosis in Rheumatoid Arthritis

Osteoporosis is a systemic skeletal disorder that causes vulnerability of bones to fracture owing to reduction in bone density and deterioration of the bone tissue microstructure. The prevalence of osteoporosis is higher in patients with autoimmune inflammatory rheumatic diseases, including rheumatoid arthritis (RA), than in those of the general population. In this autoimmune inflammatory rheumatic disease, in addition to known risk factors for osteoporosis, various factors such as chronic inflammation, autoantibodies, metabolic disorders, drugs, and decreased physical activity contribute to additional risk. In RA, disease-related inflammation plays an important role in local or systemic bone loss, and active treatment for inflammation can help prevent osteoporosis. In addition to conventional synthetic disease-modifying anti-rheumatic drugs that have been traditionally used for treatment of RA, biologic DMARDs and targeted synthetic DMARDs have been widely used. These agents can be employed more selectively and precisely based on disease pathogenesis. It has been reported that these drugs can inhibit bone loss by not only reducing inflammation in RA, but also by inhibiting bone resorption and promoting bone formation. In this review, the pathogenesis and research results of the increase in osteoporosis in RA are reviewed, and the effects of biological agents on osteoporosis are discussed.

Anti-Citrullinated Protein Antibody Titers Are Independently Modulated by Both Disease Activity and Conventional or Biologic Anti-Rheumatic Drugs

This study aimed to analyze the factors that influence anti-citrullinated protein antibody (ACPA) titers in a seropositive early arthritis (EA) population under non-protocolized treatment with disease-modifying anti-rheumatic drugs (DMARDs). A total of 130 ACPA-positive patients from the PEARL (Princesa Early Arthritis Longitudinal) study were studied along a 5-year follow-up. Sociodemographic, clinical, and therapeutic variables, along with serum samples, were collected at five visits by protocol. Anti-cyclic citrullinated peptide 2 (CCP2) ACPA titers were measured by ELISA. The effect of different variables on anti-CCP2 titers was estimated using longitudinal multivariate analysis models, nested by visit and patient. Data from 471 visits in 130 patients were analyzed. A significant decrease in anti-CCP2 titers was observed at all time-points, compared to baseline, following the decline of disease activity. In the multivariate analysis, active or ever smoking was significantly associated with the highest anti-CCP2 titers while reduction in disease activity was associated with titer decline. After adjusting for these variables, both conventional synthetic (cs) and biologic (b) DMARDs accounted for the decline in anti-CCP2 titers as independent factors. Conclusion: In patients with EA, an early and sustained reduction in ACPA titers can be detected associated with the decline in disease activity, irrespective of the treatment used.

Indigenous Nigeria medicinal herbal remedies: A potential source for therapeutic against rheumatoid arthritis

Rheumatoid arthritis (RA) is a debilitating disease associated with locomotion impairment, and conventional therapeutic drugs are not optimal for managing RA. There is an avalanche of medications used for the management of RA. Still, studies have shown that they are associated with severe side effects, including hepatotoxicity, retinopathy, and cardiotoxicity disorders of the central nervous system (CNS), skin, blood, and infections. Complementary and alternative medicine (CAM) is currently gaining attention as a novel panacea for managing debilitating diseases, such as RA. Nigerian folk herbal remedies are replete with a plethora of curative medicine, albeit unvalidated scientifically but with seemingly miraculous provenance. Studies of the identification of bioactive compounds present in these botanicals using advanced spectral analytical techniques have enhanced our understanding of the role of Nigerian herbal remedies in the treatment and management of RA. Interestingly, experimental studies abound that the bioactive compounds present in the extracts of plant botanicals protected animals from the development of RA in different experimental models and reduced the toxicity associated with conventional therapeutics. Validated mechanisms of RA amelioration in human and animal models include suppression of the expression of NF-κB, IL-1β, TNF-α, IL-6, IL-8, IL-17, IL-23, chemokines, TGF-β, RANKL, RANK, iNOS, arginase, COX-2, VEGFA, VEGFR, NFATC1, and TRAP in the synoviocytes. Decreased ROS, NO, MDA, carbonyl groups, and PGE₂ in the synovial fluid increased the expression of PPARα/γ; antioxidant and anti-inflammatory molecules also improve RA etiology. In this mini-review, we discuss the global burden of RA, the novel role of plant-based botanicals as potential therapeutics against signaling pathways in RA. Also addressed is the possible repurposing/reprofiling of plant botanicals to increase their therapeutic index among RA patients that patronize traditional healers in Nigeria with a global projection.

The Impact of Seropositivity on Systemic Bone Loss in Rheumatoid Arthritis-A 3-Year Interim Analysis of a Longitudinal Observational Cohort Study

Objective

To explore the impact of seropositivity on systemic bone loss in rheumatoid arthritis (RA).

Methods

We conducted an interim analysis of the RA registry. Patients were examined with dual-energy X-ray absorptiometry at baseline and again 3 years later. Participants were grouped into seropositive (SPRA) and seronegative (SNRA) based on the presence or absence of rheumatoid factor (RF) and/or anti-cyclic citrullinated peptide antibodies (ACPA). After matching (1:2) for age and sex, SNRA and SPRA patients were divided into groups A and B. Each matched group (A or B) was further subdivided according to the number of antibodies present (0, group I; 1, group II; 2, group III). Multiple ordinary least squares regression was used with the dependent variables to develop a model to predict bone mineral density (BMD) change.

Results

A total of 477 participants who completed a 3-year observation period were included. After matching, 312 participants were enrolled (group A, 104; group B, 208). Three years later, group B had significant BMD reduction in the femoral neck (FN) (p < 0.001), total hip (TH) (p = 0.001), and first through fourth lumbar vertebrae (L1–4) (p = 0.006), while group A had bone loss only at FN (p = 0.002). Groups I, II, and III included 104, 52, and 156 participants, respectively. Compared to baseline, BMD decreased significantly at FN (p = 0.002) in group I, FN (p < 0.001) in group II, and FN (p < 0.001), TH (p = 0.002), and L1–4 (p = 0.016) in group III. In terms of regression-adjusted percent change in BMD, more significantly negative changes were found at all measured sites in group B (p < 0.001, all) and at TH and L1–4 within groups I-III (p for trend < 0.001 and < 0.001, respectively). Regardless of antibodies, anti-osteoporotic therapy can preserve bone density in RA patients.

Conclusion

After 3 years, SPRA patients lost more bone density than SNRA patients. More attention should be paid to SPRA patients, especially those with double-positive antibodies, including a vigorous evaluation of BMD and fracture risk. Anti-osteoporotic therapy can prevent BMD loss irrespective of autoantibodies.

Difficult-to-treat rheumatoid arthritis in real clinical practice. Preliminary results

Aim. To compare the features of the course of the disease and the therapy in rheumatoid arthritis (RA) patients who meet the criteria of difficult-to-treat RA (D2T). Materials and methods. The study included 505 RA patients (ACR/EULAR 2010). Rheumatologist experts discussed all patients, since the treatment of RA ware perceived as problematic and/or insufficient. All patients had at least one of the following signs: the activity of the disease is no lower than moderate; the inability to reduce the dose of glucocorticoids to low; rapid radiological progression; RA symptoms causing a decrease in quality of life. The D2T group included 35 patients with true inefficiency or intolerance of two or more of bDMARDs/tsDMARDs of different mechanism of action. The control group (K) included patients with RA who already had experience of taking at least one class of bDMARDs/tsDMARDs (n=291). Results. On average, every 15 patients (7%) with RA met the EULAR criteria for D2T. The median age of patients in the D2T group was 45 years, which is less than in K (Me 54 [43; 62] years; p=0.046). The duration of RA in both groups was comparable. The severity of articular destruction in D2T was higher than in K (stage IV in 40% and 23%, respectively). Positivity for the RF and ACPA in D2T was less common than in K (60% and 85.9%; 60% and 76.6%, respectively). The presence of systemic manifestations of RA was more typical for K than for D2T (28.6% and 63%, p=0.0001). In the group of D2T patients, the number of previously taken DMARDs was higher than in K (p=0.002). Methotrexate was more often prescribed as the first DMARDs in both groups (in 62.9 and 65.7%, respectively). Initiation of bDMARDs/tsDMARDs therapy in D2T was more often performed by TNF-a inhibitors (OR 2.8; p=0.003) and co-stimulation blocker abatacept (OR 4.6; p=0.004), and in control by B-cell inhibitor rituximab (OR 6.9; p0.0001). Conclusion. The results of this study suggest that in Russia, as well as abroad, the principle of RA treatment treat to target has not yet become widespread, and the development of adequate therapy takes too much time.

Longitudinal analysis of blood DNA methylation identifies mechanisms of response to tumor necrosis factor inhibitor therapy in rheumatoid arthritis

Background

Rheumatoid arthritis (RA) is a chronic, immune-mediated inflammatory disease of the joints that has been associated with variation in the peripheral blood methylome. In this study, we aim to identify epigenetic variation that is associated with the response to tumor necrosis factor inhibitor (TNFi) therapy.

Methods

Peripheral blood genome-wide DNA methylation profiles were analyzed in a discovery cohort of 62 RA patients at baseline and at week 12 of TNFi therapy. DNA methylation of individual CpG sites and enrichment of biological pathways were evaluated for their association with drug response. Using a novel cell deconvolution approach, altered DNA methylation associated with TNFi response was also tested in the six main immune cell types in blood. Validation of the results was performed in an independent longitudinal cohort of 60 RA patients.

Findings

Treatment with TNFi was associated with significant longitudinal peripheral blood methylation changes in biological pathways related to RA (FDR<0.05). 139 biological functions were modified by therapy, with methylation levels changing systematically towards a signature similar to that of healthy controls. Differences in the methylation profile of T cell activation and differentiation, GTPase-mediated signaling, and actin filament organization pathways were associated with the clinical response to therapy. Cell type deconvolution analysis identified CpG sites in CD4+T, NK, neutrophils and monocytes that were significantly associated with the response to TNFi.

Interpretation

Our results show that treatment with TNFi restores homeostatic blood methylation in RA. The clinical response to TNFi is associated to methylation variation in specific biological pathways, and it involves cells from both the innate and adaptive immune systems.

Funding

The Instituto de Salud Carlos III.

The impact of seropositivity on the effectiveness of biologic anti-rheumatic agents: results from a collaboration of 16 registries

OBJECTIVES

RF and ACPA are used as diagnostic tools and their presence has been associated with clinical response to some biologic DMARDs (bDMARDs) in RA. This study compared the impact of seropositivity on drug discontinuation and effectiveness of bDMARDs in patients with RA, using head-to-head comparisons in a real-world setting.

METHODS

We conducted a pooled analysis of 16 observational RA registries. Inclusion criteria were a diagnosis of RA, initiation of treatment with rituximab (RTX), abatacept (ABA), tocilizumab (TCZ) or TNF inhibitors (TNFis) and available information on RF and/or ACPA status. Drug discontinuation was analysed using Cox regression, including drug, seropositivity, their interaction, adjusting for concomitant and past treatments and patient and disease characteristics and accounting for country and calendar year of bDMARD initiation. Effectiveness was analysed using the Clinical Disease Activity Index evolution over time.

RESULTS

Among the 27 583 eligible patients, the association of seropositivity with drug discontinuation differed across bDMARDs (P for interaction <0.001). The adjusted hazard ratios for seropositive compared with seronegative patients were 1.01 (95% CI 0.95, 1.07) for TNFis, 0.89 (0.78, 1.02)] for TCZ, 0.80 (0.72, 0.88) for ABA and 0.70 (0.59, 0.84) for RTX. Adjusted differences in remission and low disease activity rates between seropositive and seronegative patients followed the same pattern, with no difference in TNFis, a small difference in TCZ, a larger difference in ABA and the largest difference in RTX (Lundex remission difference +5.9%, low disease activity difference +11.6%).

CONCLUSION

Seropositivity was associated with increased effectiveness of non-TNFi bDMARDs, especially RTX and ABA, but not TNFis.

Interactions between rheumatoid arthritis antibodies are associated with the response to anti-tumor necrosis factor therapy

BACKGROUND

Blocking of the Tumor Necrosis Factor (TNF) activity is a successful therapeutic approach for 50-60% of rheumatoid arthritis (RA) patients. However, there are yet no biomarkers to stratify patients for anti-TNF therapy. Rheumatoid factor (RF) and anti-cyclic-citrullinated antibodies (anti-CCP) have been evaluated as biomarkers of response but the results have shown limited consistency. Anti-carbamylated protein (anti-CarP) and anti-peptidylarginine deiminase type 4 (anti-PAD4) antibodies have been much less studied. Despite being linked to common immune processes, the interaction between these markers has not been evaluated yet. Our aim was to analyze the interaction between these four antibodies in relation to the response to anti-TNF therapy.

METHODS

For this objective, a prospective cohort of n = 80 RA patients starting anti-TNF therapy was recruited. Serum determinations at baseline were performed for RF, anti-CCP, anti-CarP and anti-PAD4 antibodies using enzyme-linked immunosorbent assays (ELISA). The clinical response to anti-TNF therapy was determined at week 12 using the change in DAS28 score. Association was performed using multivariate linear regression adjusting for baseline DAS28, sex and age.

RESULTS

The interaction between pairs of antibodies was tested by the addition of an interaction term. We found two highly significant antibody interactions associated with treatment response: anti-CarP with anti-PAD4 (p = 0.0062), and anti-CCP with RF (p = 0.00068). The latter antibody interaction was replicated in an independent retrospective cohort of RA patients (n = 199, p = 0.04).

CONCLUSIONS

The results of this study suggest that antibody interaction effects are important factors in the response to anti-TNF therapy in RA.

Novel autoantibodies identified in ACPA-negative rheumatoid arthritis

OBJECTIVES

Lack of effective biomarkers in anti-citrullinated protein antibody (ACPA)-negative rheumatoid arthritis (RA) impedes early diagnosis and treatment. This study aimed to identify novel autoantibodies in RA and verify their diagnostic values in ACPA-negative RA based on protein microarray technology.

METHODS

A total of 1011 sera from 559 RA (276 ACPA-positive and 283 ACPA-negative), 239 disease controls (DCs) and 213 healthy controls (HCs) were collected and sampled on two sequential microarrays and ELISA and western blot (WB) detection, for novel autoantibodies discovery, validation and verification, respectively. The high-density protein microarray printed with a broad spectrum of recombinant human proteins was first employed to screen candidate autoantibodies, then focused microarrays composed of candidate autoantigens were used for validation, followed by ELISA and WB to verify the presence of the most promising candidates in ACPA-negative RA.

RESULTS

Nine novel autoantibodies were identified by two sequential microarrays with positivity 17.93%-27.59% and specificities >90% in ACPA-negative RA. Among these, anti-PTX3 and anti-DUSP11 autoantibodies presented with the highest sensitivity and were consistently verified by ELISA and WB. Pooling samples of all cohorts, the positivities of anti-PTX3 and anti-DUSP11 in ACPA-negative RA were 27.56% and 31.80%, respectively, similar to those in ACPA-positive RA, and significantly higher than in HCs (4.69% and 2.35%) and DCs (10.04% and 8.49%) (p<0.0001). Combination of anti-PTX3 with anti-DUSP11 significantly increased the diagnostic sensitivity (38.00%) with specificity of 88.72%, regardless of ACPA status.

CONCLUSION

Anti-PTX3 and anti-DUSP11 autoantibodies are newly identified biomarkers for diagnosis of ACPA-negative RA.

Biomarkers to Personalize the Treatment of Rheumatoid Arthritis: Focus on Autoantibodies and Pharmacogenetics

Rheumatoid arthritis (RA) is a chronic inflammatory disease that is very complex and heterogeneous. If not adequately treated, RA patients are likely to manifest excess of morbidity and disability with an important impact on the quality of life. Pharmacological treatment is based on the administration of the disease-modifying antirheumatic drugs (DMARDs), subdivided into conventional synthetic (csDMARDs), targeted synthetic (tsDMARDs), and biological (bDMARDs). bDMARDs are now frequently administered in patients, both as alternative treatment and together with csDMARDs. Unfortunately, there is a therapeutic response variability both to old and new drugs. Therefore, to identify pre-therapeutic and on-treatment predictors of response is a priority. This review aims to summarize recent advances in understanding the causes of the variability in treatment response in RA, with particular attention to predictive potential of autoantibodies and DMARD pharmacogenetics. In recent years, several biomarkers have been proposed to personalize the therapy. Unfortunately, a magic bullet does not exist, as many factors concur to disease susceptibility and treatment outcomes, acting around the patient’s congenital background. Models integrating demographic, clinical, biochemical, and genetic data are needed to enhance the predictive capacity of specific factors singularly considered to optimize RA treatment in light of multidisciplinary patient management.

Fluctuation in anti-cyclic citrullinated protein antibody level predicts relapse from remission in rheumatoid arthritis: KURAMA cohort

Background

The positivity of anti-citrullinated protein/peptide antibodies (ACPAs) is a clinically useful diagnostic and prognostic marker in rheumatoid arthritis (RA). However, the significance of ACPA titer and its fluctuation remain unclear. This study aimed to assess the role of ACPA titer and its fluctuation on disease activity and the prognosis of RA.

Methods

Data obtained from the Kyoto University Rheumatoid Arthritis Management Alliance (KURAMA) cohort was analyzed. Patients whose ACPA was measured at least twice between 2011 and 2019 and whose ACPA was positive at least once were included in this study. The association between the clinical variable and ACPA titer or its change was investigated.

Results

ACPA titer was measured in a total of 3286 patients, 1806 of whom were ACPA-positive at least once. Among them, the ACPA titer level was measured more than once in 1355 patients. Very weak correlation was observed between the ACPA titer level and disease activity. Additionally, there was no trend in the fluctuation of ACPA titer level in each patient; ACPA titer level fluctuated in some patients, but not in others. Patients with high variable levels of ACPA titer were more likely to relapse from remission. In the analysis of two consecutive ACPA measurements, the titer changes predicted the relapse from remission within a year of the second measurement.

Conclusions

The ACPA titer level fluctuated in some patients. Very weak correlation was observed between the ACPA titer level and disease activity. Fluctuation in ACPA titer level predicted relapse from remission in patients with RA.

Supplementary information

The online version contains supplementary material available at 10.1186/s13075-020-02366-x.

Efficacy and safety of sarilumab in combination with csDMARDs or as monotherapy in subpopulations of patients with moderately to severely active rheumatoid arthritis in three phase III randomized, controlled studies

Background

The interleukin-6 receptor inhibitor sarilumab demonstrated efficacy in combination with conventional synthetic disease-modifying antirheumatic drugs (csDMARDs) or as monotherapy in patients with moderately to severely active rheumatoid arthritis (RA) with an inadequate response (IR) or intolerant (INT) to methotrexate (MTX) or tumour necrosis factor (TNF)-α inhibitors. This analysis investigated the efficacy and safety of sarilumab in patient subgroups.

Methods

Data were included from phase III studies: two placebo-controlled studies of subcutaneous sarilumab 150/200 mg every 2 weeks (q2w) either + MTX in MTX-IR patients (52 weeks) or + csDMARDs in TNF-IR/INT patients (24 weeks), and a monotherapy study of sarilumab 200 mg q2w vs. adalimumab 40 mg q2w in MTX-IR/INT patients (24 weeks). Prespecified and post hoc subgroups included patient demographics, disease characteristics, and prior treatments. Prespecified and post hoc endpoints included clinical, radiographic, and physical function measures, and p values are considered nominal. Safety was assessed during double-blind treatment.

Results

The superiority of sarilumab (either as monotherapy vs. adalimumab or in combination with csDMARDs vs. placebo + csDMARDs) across clinical endpoints was generally consistent across subgroups defined by patient demographics, disease characteristics, and prior treatments, demonstrating the benefit of sarilumab treatment for a wide range of patient types. Interaction p values of < 0.05 were consistently observed across studies only for baseline anti-cyclic citrullinated peptide antibody (ACPA) status for American College of Rheumatology 20% response, but not American College of Rheumatology 50% or 70% response. Adverse events and worsening laboratory parameters occurred more frequently in sarilumab-treated vs. placebo-treated patients and were more frequent in the small number of patients ≥ 65 years (n = 289) vs. patients < 65 years (n = 1819). Serious infections occurred in six patients aged ≥ 65 years receiving sarilumab, although the incidence of serious infections was generally higher in patients aged ≥ 65 years regardless of treatment.

Conclusions

Apart from ACPA status, there were no consistent signals indicating differential effects of sarilumab in any of the subpopulations assessed. Sarilumab demonstrated consistent efficacy and safety across a wide range of patients with RA.

Trial registration

ClinicalTrials.gov NCT01061736, registered on February 03, 2010; ClinicalTrials.gov NCT01709578, registered on October 18, 2012; ClinicalTrials.gov NCT02332590, registered on January 07, 2015

Two-year abatacept retention rate in clinical practice in the French ACTION cohort

OBJECTIVES

Abatacept retention rates were evaluated in the French cohort in the prospective ACTION study (2010-2013), which included patients with moderate-to-severe rheumatoid arthritis managed in everyday clinical practice and started on intravenous abatacept therapy.

METHODS

Two-year abatacept retention rates were evaluated in 455 patients classified according to treatment line, body mass index (BMI), and status for rheumatoid factor (RF) and anti-citrullinated peptide antibody (ACPA).

RESULTS

After 2 years, the overall abatacept retention rate was 44%. The retention rate was non-significantly higher in the patients with vs. without a history of unresponsiveness to at least one biologic (48.1% vs. 41.8%, respectively). No significant retention rate differences were found across BMI categories (444 patients; <25, 45.5%; ≥25 to <30, 48.9%; and ≥30, 36.6%). Neither were any significant differences demonstrated according to RF and ACPA status (RF+ and ACPA+, 45.7%; RF+ or ACPA+, 43.8%; and FR- and ACPA-, 39.1%).

CONCLUSION

The 44% 2-year retention rate in the French ACTION cohort supports the usefulness of abatacept therapy. In this study, retention was not associated with treatment line, BMI, or antibody status.

[Rheumatoid arthritis: achievements and unresolved issues]

Success in a treatment of rheumatoid arthritis (RA), associated with a development of new medications and improving treatment strategies, allows to achieve remission in many patients. Despite this a lot of theoretical and clinical issues remain, including a definition of the term "remission", its characteristics and types as well as approaches to optimal tactics of "symptomatic" and "pathogenetic" drug therapy at different stages of the disease. Use of a such tactics will allow to induce quickly a state of remission and maintain it for a long term. Further research is needed which should be directed to investigation of a heterogeneity of RA pathogenetic mechanisms and to elaboration of approaches to its early diagnosis as well as to improving methods for monitoring a disease activity, biomarkers of efficacy and resistance to therapy, and finally, to developing of a differentiated therapy, including a search for new "therapeutic" targets.

Assessing prognosis and prediction of treatment response in early rheumatoid arthritis: systematic reviews

BACKGROUND

Rheumatoid arthritis (RA) is a chronic, debilitating disease associated with reduced quality of life and substantial costs. It is unclear which tests and assessment tools allow the best assessment of prognosis in people with early RA and whether or not variables predict the response of patients to different drug treatments.

OBJECTIVE

To systematically review evidence on the use of selected tests and assessment tools in patients with early RA (1) in the evaluation of a prognosis (review 1) and (2) as predictive markers of treatment response (review 2).

DATA SOURCES

Electronic databases (e.g. MEDLINE, EMBASE, The Cochrane Library, Web of Science Conference Proceedings; searched to September 2016), registers, key websites, hand-searching of reference lists of included studies and key systematic reviews and contact with experts.

STUDY SELECTION

Review 1 - primary studies on the development, external validation and impact of clinical prediction models for selected outcomes in adult early RA patients. Review 2 - primary studies on the interaction between selected baseline covariates and treatment (conventional and biological disease-modifying antirheumatic drugs) on salient outcomes in adult early RA patients.

RESULTS

Review 1 - 22 model development studies and one combined model development/external validation study reporting 39 clinical prediction models were included. Five external validation studies evaluating eight clinical prediction models for radiographic joint damage were also included. c-statistics from internal validation ranged from 0.63 to 0.87 for radiographic progression (different definitions, six studies) and 0.78 to 0.82 for the Health Assessment Questionnaire (HAQ). Predictive performance in external validations varied considerably. Three models [(1) Active controlled Study of Patients receiving Infliximab for the treatment of Rheumatoid arthritis of Early onset (ASPIRE) C-reactive protein (ASPIRE CRP), (2) ASPIRE erythrocyte sedimentation rate (ASPIRE ESR) and (3) Behandelings Strategie (BeSt)] were externally validated using the same outcome definition in more than one population. Results of the random-effects meta-analysis suggested substantial uncertainty in the expected predictive performance of models in a new sample of patients. Review 2 - 12 studies were identified. Covariates examined included anti-citrullinated protein/peptide anti-body (ACPA) status, smoking status, erosions, rheumatoid factor status, C-reactive protein level, erythrocyte sedimentation rate, swollen joint count (SJC), body mass index and vascularity of synovium on power Doppler ultrasound (PDUS). Outcomes examined included erosions/radiographic progression, disease activity, physical function and Disease Activity Score-28 remission. There was statistical evidence to suggest that ACPA status, SJC and PDUS status at baseline may be treatment effect modifiers, but not necessarily that they are prognostic of response for all treatments. Most of the results were subject to considerable uncertainty and were not statistically significant.

LIMITATIONS

The meta-analysis in review 1 was limited by the availability of only a small number of external validation studies. Studies rarely investigated the interaction between predictors and treatment.

SUGGESTED RESEARCH PRIORITIES

Collaborative research (including the use of individual participant data) is needed to further develop and externally validate the clinical prediction models. The clinical prediction models should be validated with respect to individual treatments. Future assessments of treatment by covariate interactions should follow good statistical practice.

CONCLUSIONS

Review 1 - uncertainty remains over the optimal prediction model(s) for use in clinical practice. Review 2 - in general, there was insufficient evidence that the effect of treatment depended on baseline characteristics.

STUDY REGISTRATION

This study is registered as PROSPERO CRD42016042402.

FUNDING

The National Institute for Health Research Health Technology Assessment programme.

Comparative Effectiveness of Abatacept Versus Tumor Necrosis Factor Inhibitors in Patients with Rheumatoid Arthritis Who Are Anti-CCP Positive in the United States Corrona Registry

Introduction

Anti-citrullinated protein antibodies (ACPAs) are highly specific serological biomarkers that are indicative of a poor prognosis in patients with rheumatoid arthritis (RA). The effectiveness of biologic disease-modifying antirheumatic drugs (bDMARDs) with different mechanisms of action may vary, based on patients’ serostatus. The aim of this study is to compare the effectiveness of abatacept versus tumor necrosis factor inhibitors (TNFis) in patients with RA who were anti-cyclic citrullinated peptide antibody positive (anti-CCP+).

Methods

Abatacept or TNFi initiators with anti-CCP+ status (≥ 20 U/ml) at or prior to treatment initiation were identified from a large observational US cohort (1 December 2005–31 August 2016). Using propensity score matching (1:1), stratified by prior TNFi use (0, 1 and ≥ 2), effectiveness at 6 months after initiation was evaluated. Primary outcome was mean change in Clinical Disease Activity Index (CDAI) score. Secondary outcomes included achievement of remission (CDAI ≤ 2.8), low disease activity/remission (CDAI ≤ 10), modified American College of Rheumatology 20/50/70 responses and mean change in modified Health Assessment Questionnaire score.

Results

After propensity score matching, the baseline characteristics between 330 pairs of abatacept and TNFi initiators (biologic naïve, n = 97; TNFi experienced, n = 233) were well balanced with absolute value standardized differences of ≤ 0.1. Both overall, and in the biologic-naïve cohort, there were no significant differences in mean change in CDAI score at 6 months. However, in the TNFi-experienced cohort, there was a significantly greater improvement in CDAI score at 6 months with abatacept versus TNFi initiators (p = 0.033). Secondary outcomes showed similar trends.

Conclusions

Improvements in clinical disease activity were seen in anti-CCP+ abatacept and TNFi initiators. TNFi-experienced anti-CCP+ patients with RA had more improvement in disease activity with abatacept versus TNFis, whereas outcomes were similar between treatments in the overall population and in biologic-naïve patients.

Trial Registration

ClinicalTrials.gov identifier: NCT01625650.

Funding

This study is sponsored by Corrona, LLC and funded by Bristol-Myers Squibb. Bristol-Myers Squibb funded the publication of this manuscript.

Electronic supplementary material

The online version of this article (10.1007/s40744-019-0149-3) contains supplementary material, which is available to authorized users.

Tocilizumab in the treatment of rheumatoid arthritis: an evidence-based review and patient selection

Rheumatoid arthritis (RA) is a chronic autoimmune disease characterized by articular and systemic manifestations, such as anemia, fatigue, osteoporosis, and increased risk for cardiovascular diseases. The pathogenesis of RA is driven by a complex network of proinflammatory cytokines, with a pivotal role of IL-6 and tumor necrosis factor (TNF). The management of RA has been dramatically changed during the last years by the introduction of a treat-to-target approach aiming to achieve an acceptable disease control. Nowadays, TNF inhibitors (TNFis) are the most frequently prescribed class of biologic therapies, but the significant proportion of patients experiencing the failure of a TNFi led to the development of alternative therapeutic options targeted on different pathways. Considering the increasing number of targeted therapeutic options for RA, there is a growing interest in the identification of potential predictors of clinical response to each available mechanism of action, with the aim to drive the management of the disease toward a personalized approach according to the concept of precision medicine. Tocilizumab (TCZ) is the first humanized anti-IL-6 receptor subunit alpha (anti-IL-6R) monoclonal antibody approved for the treatment of RA refractory to methotrexate or TNFis. TCZ inhibits both the cis- and trans-signaling cascades involving the Janus kinase-signal transducer and the activator of transcription pathway, playing a crucial role in modulating not only joint inflammation but also the previously mentioned extra-articular manifestations and comorbidities of RA, such as fatigue, anemia, bone loss, depression, type 2 diabetes, and increased cardiovascular risk. In this review, moving from pathogenetic insights and evidence-based clinical data from randomized controlled trials and real-life observational studies, we will discuss the drivers for the selection of patient candidates to receive TCZ, in order to clarify the current positioning of this drug in the treatment algorithm of RA.

RHEUMATOID ARTHRITIS: THE PROBLEMS OF REMISSION AND THERAPY RESISTANCE

Rheumatoid arthritis (RA) is an immunoinflammatory (autoimmune) rheumatic disease of unknown etiology, which is characterized by chronic erosive arthritis and systemic visceral organ damage that results in early disability and shorter patient survival. Despite RA treatment advances associated with the design of novel drugs and the improvement of treatment strategies to achieve remission in many patients, there are still many theoretical and clinical problems concerning both the definition of the concept of remission, its characteristics and types and approaches to the optimum policy of symptomatic and pathogenetic drug therapy at different stages of the disease, the use of which will be able to rapidly induce and maintain remission in the long-term. Further investigations are needed to study the nature of heterogeneity of pathogenetic mechanisms of RA and approaches to early diagnosis, to improve methods for monitoring disease activity and biomarkers for the efficiency of and resistance to therapy and, finally, to develop differentiation therapy, including those related to a search for new therapeutic targets.

Experience With the Use of Rituximab for the Treatment of Rheumatoid Arthritis in a Tertiary Hospital in Spain: RITAR Study

Supplemental digital content is available in the text.

There is evidence supporting that there are no relevant clinical differences between dosing rituximab 1000 mg or 2000 mg per cycle in rheumatoid arthritis (RA) patients in clinical trials, and low-dose cycles seem to have a better safety profile. Our objective was to describe the pattern of use of rituximab in real-life practice conditions.

Tocilizumab in the treatment of adult rheumatoid arthritis

Rheumatoid arthritis (RA) is the most prevalent immune-mediated chronic rheumatic disease and is associated with joint destruction and disability. Therapeutic strategies, including biological disease-modifying antirheumatic drugs (bDMARDs) have improved the prognosis and quality of life of RA patients. Tocilizumab (TCZ) is a humanized monoclonal antibody against IL-6 receptor licensed in 2009 that has demonstrated clinical efficacy in various adult RA populations. RA management guidelines and recommendations consider TCZ as one of the bDMARDS indicated after methotrexate or other conventional synthetic DMARDs and/or TNF inhibitors failure in adult RA. Of particular interest is the demonstration of its effectiveness in monotherapy in comparison with other bDMARDs. Recent observational studies have shown good results for the safety profile of TCZ with no new alert signals.

Tocilizumab potentially prevents bone loss in patients with anticitrullinated protein antibody-positive rheumatoid arthritis

Rheumatoid arthritis (RA) is associated with a high risk of osteoporosis and fracture. Interleukin (IL)-6 inhibitors may suppress osteoclast activation. Anticitrullinated protein antibody (ACPA) titers are inversely associated with bone mineral density (BMD). However, the differential effect of ACPA on bone turnover marker (BTM) and BMD changes after IL-6 inhibition remains unclear. This prospective study recruited patients with active RA with inadequate response to methotrexate or biologics. BMD was measured before and after 2-year tocilizumab (TCZ) treatment. Serum osteocalcin, N-terminal propeptide of type I collagen (P1NP), and C-terminal cross-linking telopeptide of type I collagen (CTX) levels were assessed at the baseline and after treatment. We enrolled 76 patients with RA (89.5% women, age: 57.2 ± 13.3 years) receiving TCZ. The 28-joint disease activity score was negatively correlated with BMD and T-scores of the lumbar spine and bilateral femoral neck. ACPA-positive patients had lower lumbar spine and femoral neck T-scores. After 2-year TCZ treatment, CTX levels significantly decreased (0.32 ± 0.21 vs. 0.26 ± 0.17, p = 0.038). Femoral neck BMD increased significantly (0.71 ± 0.22 vs. 0.69 ± 0.55, p = 0.008). Decreased CTX levels and improved BMD were observed only in ACPA-positive patients. After treatment, femoral neck BMD significantly increased only in patients receiving a glucocorticoid dose of ≥5 mg/day. Two-year TCZ treatment reduced bone resorption and increased femoral BMD in ACPA-positive patients. The net effects of glucocorticoids and IL-6 inhibition on BMD imply that strict inflammation control might affect bone metabolism.

[Management of rheumatoid arthritis]

Rheumatoid arthritis is the most common inflammatory rheumatic disease. Due to the destruction of joints in the course of the disease it leads to significant morbidity in affected patients. The quality of life and even life expectancy can be severely impaired. Early diagnosis and early initiation of treatment is a decisive step towards a more benign course of the disease. New classification criteria have been published in order to help in early diagnosis. Methods of imaging, such as ultrasound and magnetic resonance imaging help in the detection of synovitis, which is the major pathomorphological manifestation of arthritis and should be identified without any doubt. Treatment follows the rule of treat to target with the aim of achieving remission or if this is not realistic, at least the lowest possible level of disease activity. The first and perhaps most important step in therapy is the initiation of methotrexate or if contraindications are present, another disease-modifying antirheumatic drug (DMARD) as soon as the diagnosis is made. Initial addition of glucocorticoids is recommended, which should be reduced in dose and terminated as soon as possible. Furthermore, either the combination of different DMARDs or the start of biologic DMARDs, such as tumor necrosis factor alpha (TNF-alpha) inhibitors or second generation biologic DMARDs is possible as a treatment option. The treatment follows the rule of shared decision-making and is the standard to treat comorbidities, the use an interdisciplinary approach and to treat functional deficits by rehabilitation measures, such as physiotherapy.

Personalized medicine in rheumatology: the paradigm of serum autoantibodies

The sequencing of the human genome is now well recognized as the starting point of personalized medicine. Nonetheless, everyone is unique and can develop different phenotypes of the same disease, despite identical genotypes, as well illustrated by discordant monozygotic twins. To recognize these differences, one of the easiest and most familiar examples of biomarkers capable of identifying and predicting the outcome of patients is represented by serum autoantibodies. In this review, we will describe the concept of personalized medicine and discuss the predictive, prognostic and preventive role of antinuclear antibodies (ANA), anti-citrullinated peptide antibodies (ACPA), rare autoantibodies and anti-drug antibodies (ADA), to evaluate how these can help to identify different disease immune phenotypes and to choose the best option for treating and monitoring rheumatic patients in everyday practice. The importance of ANA resides in the prediction of clinical manifestations in systemic sclerosis and systemic lupus erythematosus and their association with malignancies. ACPA have a predictive role in rheumatoid arthritis, they are associated with the development of a more aggressive disease, extra-articular manifestations and premature mortality in RA patients; moreover, they are capable of predicting therapeutic response. Rare autoantibodies are associated with different disease manifestations and also with a greater incidence of cancer. The determination of ADA levels may be useful in patients where the clinical efficacy of TNF-α inhibitor has dropped, for the assessment of a right management. The resulting scenario supports serum autoantibodies as the cornerstone of personalized medicine in autoimmune diseases.

Biologic therapies and bone loss in rheumatoid arthritis

INTRODUCTION

Rheumatoid arthritis (RA) is a common systemic autoimmune disease of unknown cause, characterized by a chronic, symmetric, and progressive inflammatory polyarthritis. One of the most deleterious effects induced by the chronic inflammation of RA is bone loss. During the last 15 years, the better knowledge of the cytokine network involved in RA allowed the development of potent inhibitors of the inflammatory process classified as biological DMARDs. These new drugs are very effective in the inhibition of inflammation, but there are only few studies regarding their role in bone protection. The principal aim of this review was to show the evidence of the principal biologic therapies and bone loss in RA, focusing on their effects on bone mineral density, bone turnover markers, and fragility fractures.

METHODS

Using the PICOST methodology, two coauthors (PC, LM-S) conducted the search using the following MESH terms: rheumatoid arthritis, osteoporosis, clinical trials, TNF- antagonists, infliximab, adalimumab, etanercept, certolizumab, golimumab, IL-6 antagonists, IL-1 antagonists, abatacept, tocilizumab, rituximab, bone mineral density, bone markers, and fractures. The search was conducted electronically and manually from the following databases: Medline and Science Direct. The search period included articles from 2003 to 2015. The selection included only original adult human research written in English. Titles were retrieved and the same two authors independently selected the relevant studies for a full text. The retrieved selected studies were also reviewed completing the search for relevant articles. The first search included 904 titles from which 253 titles were selected. The agreement on the selection among researchers resulted in a Kappa statistic of 0.95 (p < 0.000). Only 248 abstracts evaluated were included in the acronym PICOST. The final selection included only 28 studies, derived from the systematic search. Additionally, a manual search in the bibliography of the selected articles was made and included into the text and into the section of "small molecules of new agents."

CONCLUSION

Treatment with biologic drugs is associated with the decrease in bone loss. Studies with anti-TNF blocking agents show preservation or increase in spine and hip BMD and also a better profile of bone markers. Most of these studies were performed with infliximab. Only three epidemiological studies analyzed the effect on fractures after anti-TNF blocking agent's treatment. IL-6 blocking agents also showed improvement in localized bone loss not seen with anti-TNF agents. There are a few studies with rituximab and abatacept. Although several studies reported favorable actions of biologic therapies on bone protection, there are still unmet needs for studies regarding their actions on the risk of bone fractures.

The immunopathogenesis of seropositive rheumatoid arthritis: from triggering to targeting

Patients with rheumatoid arthritis can be divided into two major subsets characterized by the presence versus absence of antibodies to citrullinated protein antigens (ACPAs) and of rheumatoid factor (RF). The antibody-positive subset of disease, also known as seropositive rheumatoid arthritis, constitutes approximately two-thirds of all cases of rheumatoid arthritis and generally has a more severe disease course. ACPAs and RF are often present in the blood long before any signs of joint inflammation, which suggests that the triggering of autoimmunity may occur at sites other than the joints (for example, in the lung). This Review summarizes recent progress in our understanding of this gradual disease development in seropositive patients. We also emphasize the implications of this new understanding for the development of preventive and therapeutic strategies. Similar temporal and spatial separation of immune triggering and clinical manifestations, with novel opportunities for early intervention, may also occur in other immune-mediated diseases.

Metabolomic profiling predicts outcome of rituximab therapy in rheumatoid arthritis

OBJECTIVE

To determine whether characterisation of patients' metabolic profiles, utilising nuclear magnetic resonance (NMR) and mass spectrometry (MS), could predict response to rituximab therapy. 23 patients with active, seropositive rheumatoid arthritis (RA) on concomitant methotrexate were treated with rituximab. Patients were grouped into responders and non-responders according to the American College of Rheumatology improvement criteria, at a 20% level at 6 months. A Bruker Avance 700 MHz spectrometer and a Thermo Scientific Q Exactive Hybrid Quadrupole-Orbitrap mass spectrometer were used to acquire (1)H-NMR and ultra high pressure liquid chromatography (UPLC)-MS/MS spectra, respectively, of serum samples before and after rituximab therapy. Data processing and statistical analysis were performed in MATLAB. 14 patients were characterised as responders, and 9 patients were considered non-responders. 7 polar metabolites (phenylalanine, 2-hydroxyvalerate, succinate, choline, glycine, acetoacetate and tyrosine) and 15 lipid species were different between responders and non-responders at baseline. Phosphatidylethanolamines, phosphatidyserines and phosphatidylglycerols were downregulated in responders. An opposite trend was observed in phosphatidylinositols. At 6 months, 5 polar metabolites (succinate, taurine, lactate, pyruvate and aspartate) and 37 lipids were different between groups. The relationship between serum metabolic profiles and clinical response to rituximab suggests that (1)H-NMR and UPLC-MS/MS may be promising tools for predicting response to rituximab.