Jeffrey D. Greenberg

Genetics of rheumatoid arthritis contributes to biology and drug discovery

A major challenge in human genetics is to devise a systematic strategy to integrate disease-associated variants with diverse genomic and biological data sets to provide insight into disease pathogenesis and guide drug discovery for complex traits such as rheumatoid arthritis (RA). Here we performed a genome-wide association study meta-analysis in a total of >100,000 subjects of European and Asian ancestries (29,880 RA cases and 73,758 controls), by evaluating ∼10 million single-nucleotide polymorphisms. We discovered 42 novel RA risk loci at a genome-wide level of significance, bringing the total to 101 (refs 2, 3, 4). We devised an in silico pipeline using established bioinformatics methods based on functional annotation, cis-acting expression quantitative trait loci and pathway analyses—as well as novel methods based on genetic overlap with human primary immunodeficiency, haematological cancer somatic mutations and knockout mouse phenotypes—to identify 98 biological candidate genes at these 101 risk loci. We demonstrate that these genes are the targets of approved therapies for RA, and further suggest that drugs approved for other indications may be repurposed for the treatment of RA. Together, this comprehensive genetic study sheds light on fundamental genes, pathways and cell types that contribute to RA pathogenesis, and provides empirical evidence that the genetics of RA can provide important information for drug discovery.

Tumour necrosis factor antagonist use and associated risk reduction of cardiovascular events among patients with rheumatoid arthritis

Objective To examine the association of cardiovascular events with tumour necrosis factor (TNF) α antagonist use compared with non-biological disease-modifying antirheumatic drug (DMARD) utilisation in patients with rheumatoid arthritis (RA). Methods The study population included 10 156 patients enrolled in the Consortium of Rheumatology Researchers of North America RA registry. Three study cohorts were defined based on three mutually exclusive drug use categories, including TNF antagonists, methotrexate and other non-biological DMARDs. HR were calculated adjusting for cardiovascular risk factors, RA disease characteristics and prednisone use. The primary study outcome was a composite of non-fatal myocardial infarction (MI), transient ischaemic attack (TIA) or stroke and cardiovascular-related death. Results There were 88 cardiovascular events, including 26 MI, 45 TIA/strokes and 17 cardiovascular-related deaths. After adjusting for age, gender, cardiovascular risk factors and RA disease characteristics, patients using a TNF antagonist experienced a reduced risk of the primary composite cardiovascular endpoint (HR 0.39, 95% CI 0.19 to 0.82) compared with users of non-biological DMARDs. Methotrexate was not associated with a reduced risk (HR 0.94, 95% CI 0.49 to 1.80). Prednisone use was associated with a dose-dependent increased risk (p=0.04). The risk reduction associated with TNF antagonists was also observed for non-fatal cardiovascular events (HR 0.35, 95% CI 0.16 to 0.74). Conclusion TNF antagonist use was associated with a reduced risk of cardiovascular events in patients with RA.

Explaining the cardiovascular risk associated with rheumatoid arthritis: traditional risk factors versus markers of rheumatoid arthritis severity

Background Cardiovascular (CV) disease has a major impact on patients with rheumatoid arthritis (RA), however, the relative contributions of traditional CV risk factors and markers of RA severity are unclear. The authors examined the relative importance of traditional CV risk factors and RA markers in predicting CV events. Methods A prospective longitudinal cohort study was conducted in the setting of the CORRONA registry in the USA. Baseline data from subjects with RA enrolled in the CORRONA registry were examined to determine predictors of CV outcomes, including myocardial infarction, stroke or transient ischemic attack. Possible predictors were of two types: traditional CV risk factors and markers of RA severity. The discriminatory value of these variables was assessed by calculating the area under the receiver operating characteristic curve (c-statistic) in logistic regression. The authors then assessed the incidence rate for CV events among subjects with an increasing number of traditional CV risk factors and/or RA severity markers. Results The cohort consisted of 10 156 patients with RA followed for a median of 22 months. The authors observed 76 primary CV events during follow-up for a composite event rate of 3.98 (95% CI 3.08 to 4.88) per 1000 patient-years. The c-statistic improved from 0.57 for models with only CV risk factors to 0.67 for models with CV risk factors plus age and gender. The c-statistic improved further to 0.71 when markers of RA severity were also added. The incidence rate for CV events was 0 (95% CI 0 to 5.98) for persons without any CV risk factors or markers of RA severity, while in the group with two or more CV risk factors and three or more markers of RA severity the incidence was 7.47 (95% CI 4.21 to 10.73) per 1000 person-years. Conclusions Traditional CV risk factors and markers of RA severity both contribute to models predicting CV events. Increasing numbers of both types of factors are associated with greater risk.

Association of methotrexate and tumour necrosis factor antagonists with risk of infectious outcomes including opportunistic infections in the CORRONA registry

Objective: To examine the association of methotrexate (MTX) and tumour necrosis factor (TNF) antagonists with the risk of infectious outcomes including opportunistic infections in patients with rheumatoid arthritis (RA). Methods: Patients with RA enrolled in the Consortium of Rheumatology Researchers of North America (CORRONA) registry prescribed MTX, TNF antagonists or other disease-modifying antirheumatic drugs (DMARDs) were included. The primary outcomes were incident overall and opportunistic infections. Incident rate ratios were calculated using generalised estimating equation Poisson regression models adjusted for demographics, comorbidities and RA disease activity measures. Results: A total of 7971 patients with RA were followed. The adjusted rate of infections per 100 person-years was increased among users of MTX (30.9, 95% CI 29.2 to 32.7), TNF antagonists (40.1, 95% CI 37.0 to 43.4) and a combination of MTX and TNF antagonists (37.1, 95% CI 34.9 to 39.3) compared with users of other non-biological DMARDs (24.5, 95% CI 21.8 to 27.5). The adjusted incidence rate ratio (IRR) was increased in patients treated with MTX (IRR 1.30, 95% CI 1.12 to 1.50) and TNF antagonists (IRR 1.52, 95% CI 1.30 to 1.78) compared with those treated with other DMARDs. TNF antagonist use was associated with an increased risk of opportunistic infections (IRR 1.67, 95% CI 0.95 to 2.94). Prednisone use was associated with an increased risk of opportunistic infections (IRR 1.63, 95% CI 1.20 to 2.21) and an increased risk of overall infection at doses >10 mg daily (IRR 1.30, 95% CI 1.11 to 1.53). Conclusions: MTX, TNF antagonists and prednisone at doses >10 mg daily were associated with increased risks of overall infections. Low-dose prednisone and TNF antagonists (but not MTX) increased the risk of opportunistic infections.

Elevated liver enzyme tests among patients with rheumatoid arthritis or psoriatic arthritis treated with methotrexate and/or leflunomide

Introduction: Potential hepatotoxicity associated with disease-modifying antirheumatic drugs (DMARDs) requires laboratory monitoring. In patients with rheumatoid arthritis (RA) or psoriatic arthritis (PsA), the incidence of elevated alanine aminotransferase/aspartate aminotransferase (ALT/AST) enzymes associated with methotrexate (MTX), leflunomide (LEF) and MTX+LEF versus other DMARDs was examined. Methods: Patients with RA and PsA enrolled in the Consortium of Rheumatology Researchers of North America (CORRONA) initiating DMARDs were identified. Abnormalities were identified when either was 1- or 2-fold times above the upper limits of normal (ULN). Odds ratios (OR) between MTX/LEF dose and elevated ALT/AST enzymes were estimated using generalised estimating equations. Interaction terms for use of MTX+LEF quantified the incremental risk of the combination compared with each individually. Results: Elevated ALT/AST levels (>1× ULN) occurred in 22%, 17%, 31% and 14% of patients with RA receiving MTX, LEF, MTX+LEF or neither, respectively; elevations were 2.76-fold (95% CI 1.84 to 4.15) more likely in patients with PsA. Elevations >2× ULN occurred in 1–2% of patients on MTX or LEF monotherapy compared with 5% with the combination. After multivariable adjustment and compared with either monotherapy, the combination of MTX and LEF was associated with a greater risk according to MTX dose used as part of the combination: MTX 10–17.5 mg/week, OR 2.91 (95% CI 1.23 to 6.90); MTX ⩾20 mg/week, OR 3.98 (95% CI 1.72 to 9.24). Conclusions: Abnormal ALT/AST levels developed in 14–35% of patients with RA or PsA initiating DMARD therapy. The risks were incrementally greater in those with PsA and in those receiving MTX (⩾10 mg/day) + LEF. These findings should help inform monitoring for potential hepatotoxicity in these patient populations.

A Comparison of Patient Characteristics and Outcomes in Selected European and U.S. Rheumatoid Arthritis Registries

PURPOSE Randomized controlled trials (RCTs) have demonstrated the efficacy of biologic agents in the treatment of rheumatic diseases. However, results from RCTs may not be generalizable to clinical practice because of their strict inclusion and exclusion criteria. Assessment of safety using RCT data also is limited by short duration of follow-up and relatively small sample sizes, which generally preclude analysis of longer term outcomes and rare adverse events. In rheumatology, various observational cohorts and registries have been created to complement information obtained from RCTs, some with the primary purpose of monitoring effectiveness and safety of biologic agents. Most registries are either drug based or disease based. These registries include patients with a variety of rheumatic diseases including RA. METHODS To provide a qualitative comparison of selected U.S. and European rheumatoid arthritis (RA) biologics registries and cohorts including ARTIS, BIOBADASER, BSRBR, BRASS, CLEAR, CORRONA, NDB, RABBIT, SCQM, and VARA. RESULTS A careful comparison of these registries, as provided in this article, can provide a basis for understanding the many similarities and differences inherent in their design, as well as societal context and content, all of which can significantly impact their results and comparisons across registers. SUMMARY The increasing use of biologic agents for treatment of rheumatic diseases has raised important questions about cost, safety, and effectiveness of these agents. The unique and variable features of patient populations and registry designs in Europe and the U.S. provide valuable and complementary data on comparative effectiveness and safety of biologic agents to what can be derived from RCTs.

High disease activity is associated with an increased risk of infection in patients with rheumatoid arthritis

Objective To determine the relationship of disease activity to infections in patients with rheumatoid arthritis (RA). Methods From the CORRONA database, the incidence of physician-reported infections in RA patients on stable disease-modifying antirheumatic drug, biological, and corticosteroid therapy for at least 6 months was ascertained. Two composite measures of disease activity were defined: clinical disease activity index (CDAI) and disease activity score 28 (DAS28). Incident rate ratios (IRR) were calculated using generalised estimating equation Poisson regression models adjusted for demographics, medications and clinical factors. Results Of 1 6242 RA patients, 6242 were on stable therapy for at least 6 months and were eligible for analysis. 2282 infections were reported in the cohort, followed over 7290 patient-years. After controlling for possible confounders, disease activity was associated with an increased rate of infections. Each 0.6 unit increase in DAS28 score corresponded to a 4% increased rate of outpatient infections (IRR 1.04, p=0.01) and a 25% increased rate of infections requiring hospitalisation (IRR 1.25, p=0.03). There was a dichotomy in the relationship between infections and CDAI scores. For CDAI <10 (mild disease activity) patients had a 12% increased rate of outpatient infections with each 5 unit increase in CDAI score (IRR 1.12, p=0.003). At CDAI scores ≥10, there was no further increase in the rate of outpatient infections associated with higher disease activity. The relationship of CDAI to hospitalised infections showed similar trends to outpatient data but did not reach statistical significance after multivariate analysis (CDAI <10: IRR 1.56, p=0.08). Conclusions In this large cohort of RA patients, higher disease activity was associated with a higher probability of developing infections.

A comparative effectiveness study of adalimumab, etanercept and infliximab in biologically naive and switched rheumatoid arthritis patients: results from the US CORRONA registry

Purpose To compare the effectiveness of anti-tumour necrosis factor (TNF) agents in biologically naive and ‘switched’ rheumatoid arthritis (RA) patients. Methods RA patients enrolled in the CORRONA registry newly prescribed adalimumab (n=874), etanercept (n=640), or infliximab (n=728) were stratified based on previous anti-TNF use. Clinical effectiveness at 6, 12 and 24 months was examined using the modified American College of Rheumatology response criteria (mACR20/50/70) and achievement of remission (28-joint disease activity score (DAS28) and clinical disease activity index (CDAI)) in unadjusted and adjusted analyses. The persistence of anti-TNF treatment was examined using Cox proportional hazard models. Results Among 2242 patients (1475 biologically naive, 767 switchers), mACR20, 50 and 70 responses were similar (p>0.05) for adalimumab, etanercept and infliximab at all time points, as were rates of CDAI and DAS28 remission (p>0.05). Response and remission outcomes were consistently inferior for switched versus biologically naive patients. The adjusted OR for achieving an mACR20 response was 0.54 (95% CI 0.38 to 0.76) in first-time switchers and 0.42 (95% CI 0.23 to 0.78) in second-time switchers versus biologically naive patients at 6 months. The adjusted OR for achieving DAS28 remission were 0.29 (95% CI 0.15 to 0.58) for first-time switchers and 0.26 (95% CI 0.08 to 0.84) for second-time switchers. Persistence was higher in biologically naive patients, for whom persistence was highest with infliximab. Conclusions No differences in rates of drug response or remission were observed among the three anti-TNF. Infliximab was associated with greater persistence in biologically naive patients. Response, remission and persistence outcomes were diminished for patients who switched anti-TNF.

The role of microRNA in rheumatoid arthritis and other autoimmune diseases.

MicroRNAs (miRNAs) represent a class of non-coding RNA molecules playing pivotal roles in cellular and developmental processes. miRNAs modulate the expression of multiple target genes at the post-transcriptional level and are predicted to affect up to one-third of all human protein-encoding genes. Recently, miRNA involvement in the adaptive and innate immune systems has been recognized. Rheumatoid arthritis serves an example of a chronic inflammatory disorder in which miRNAs modulate the inflammatory process in the joints, with the potential to serve as biomarkers for both the inflammatory process and the potential for therapeutic response. This review discusses the investigations that led to miRNA discovery, miRNA biogenesis and mode of action, and the diverse roles of miRNAs in modulating the immune and inflammatory responses. We conclude with a discussion of the implications of miRNA biology in rheumatoid arthritis and other autoimmune disorders.

Cardiovascular outcomes in high-risk patients with osteoarthritis treated with Ibuprofen, Naproxen, or Lumiracoxib.

Background: Evidence suggests that both selective cyclooxygenase (COX)-2 inhibitors and non-selective non-steroidal anti-inflammatory drugs (NSAIDs) increase the risk of cardiovascular events. However, evidence from prospective studies of currently available COX-2 inhibitors and non-selective NSAIDs is lacking in patients at high cardiovascular risk who are taking aspirin. Objective: To determine the cardiovascular outcomes in high risk patients with osteoarthritis treated with ibuprofen, naproxen or lumiracoxib. Methods: The Therapeutic Arthritis Research and Gastrointestinal Event Trial (TARGET) of 18 325 patients with osteoarthritis comprised two parallel substudies, comparing lumiracoxib (COX-2 inhibitor) with either ibuprofen or naproxen. A post hoc analysis by baseline cardiovascular risk, treatment assignment, and low-dose aspirin use was performed. The primary composite end point was cardiovascular mortality, non-fatal myocardial infarction, and stroke at 1 year; a secondary end point was the development of congestive heart failure (CHF). Results: In high risk patients among aspirin users, patients in the ibuprofen substudy had more primary events with ibuprofen than lumiracoxib (2.14% vs 0.25%, p = 0.038), whereas in the naproxen substudy rates were similar for naproxen and lumiracoxib (1.58% vs 1.48%, p = 0.899). High risk patients not taking aspirin had fewer primary events with naproxen than with lumiracoxib (0% vs 1.57%, p = 0.027), but not for ibuprofen versus lumiracoxib (0.92% vs 0.80%, p = 0.920). Overall, CHF developed more often with ibuprofen than lumiracoxib (1.28% vs 0.14%; p = 0.031), whereas no difference existed between naproxen and lumiracoxib. Conclusions: These data suggest that ibuprofen may confer an increased risk of thrombotic and CHF events relative to lumiracoxib among aspirin users at high cardiovascular risk. The study indicates that naproxen may be associated with lower risk relative to lumiracoxib among non-aspirin users. This study is subject to inherent limitations, and therefore should be interpreted as a hypothesis-generating study.