Clinical outcomes in patients switched from adalimumab to baricitinib due to non-response and/or study design: phase III data in patients with rheumatoid arthritis.

OBJECTIVE: To evaluate clinical outcomes in patients who changed treatment from adalimumab to baricitinib, an oral Janus kinase (JAK)1/JAK2 inhibitor, during a phase III programme. METHODS: In phase III RA-BEAM, patients were randomised 3:3:2 to placebo, baricitinib 4 mg once daily, or adalimumab 40 mg biweekly. At week 16 or subsequent visits, non-responders were rescued to open-label baricitinib 4 mg. At week 52, patients could enter a long-term extension (LTE) and continue on baricitinib or switch from adalimumab to baricitinib 4 mg with no adalimumab washout period. Percentage of patients achieving low disease activity and remission were assessed, along with physical function, patient's assessment of pain, and safety. RESULTS: Thirty-five (7%) baricitinib-treated and 40 (12%) adalimumab-treated patients were rescued to baricitinib in RA-BEAM; 78% (381/487) of baricitinib-treated and 72% (238/330) of adalimumab-treated patients who were not rescued in RA-BEAM, entered the LTE and continued/were switched to baricitinib. In both baricitinib-rescued and adalimumab-rescued patients, there were significant improvements in all measures up to 12 weeks after rescue compared with the time of rescue. Patients who switched from adalimumab to baricitinib showed improvements in disease control through 12 weeks in the LTE. Exposure-adjusted incidence rates for treatment-emergent adverse events (TEAEs) and infections, including serious events, were similar for patients who switched from adalimumab to baricitinib and those who continued on baricitinib. CONCLUSIONS: Switching from adalimumab to baricitinib (without adalimumab washout) was associated with improvements in disease control, physical function and pain during the initial 12 weeks postswitch, without an increase in TEAEs, serious adverse events or infections. TRIAL REGISTRATION NUMBERS: NCT01710358, NCT01885078.

Efficacy and safety of tabalumab, an anti-B-cell-activating factor monoclonal antibody, in patients with rheumatoid arthritis who had an inadequate response to methotrexate therapy: results from a phase III multicentre, randomised, double-blind study.

OBJECTIVES: Randomised, double-blind, placebo-controlled study to evaluate efficacy and safety of tabalumab in patients with rheumatoid arthritis (RA) with inadequate responses to methotrexate (MTX-IR). METHODS: 1041 patients with moderate-severe RA despite ongoing MTX enrolled in a 52-week study evaluating subcutaneous tabalumab 120 mg every four weeks (120/Q4W) or 90 mg every two weeks (90/Q2W) versus placebo. Primary endpoints were American College of Rheumatology 20% (ACR20) response rate and Health Assessment Questionnaire-Disability Index change from baseline at 24 weeks and modified Total Sharp Score (mTSS) change at 52 weeks. RESULTS: There were no significant differences in ACR20 responses at week 24 or mTSS change from baseline at week 52 among treatment groups. Declines were seen in CD20+ B cells and immunoglobulin levels in tabalumab groups, but not placebo: B cells (-15.0%, -18.8%, 5.3%, in the 120/Q4W, 90/Q2W, and placebo groups, respectively); IgM (-16.3%, -19.4%, -0.1%), IgA (-11.4%, -4.7%, 1.2%) and IgG (-8.6%, -7.8%, 0.1%). Discontinuations due to adverse events were similar between groups. Numerically more serious infections were reported in tabalumab groups (1.7%, 0.6%, 0.3%); numerically more injection-site reactions were reported in the 90/Q2W group (2.3%, 4.3%, 2.3%). CONCLUSIONS: Neither clinical efficacy nor significant safety signals were observed with tabalumab despite evidence of biological activity. This study was terminated early due to insufficient efficacy. TRIAL REGISTRATION NUMBER: NCT01198002.

Real-world burden of systemic lupus erythematosus in the USA: a comparative cohort study from the Medical Expenditure Panel Survey (MEPS) 2016-2018.

OBJECTIVE: SLE is a chronic, multiorgan, autoimmune disease; however, current prevalence estimates are dated and often from non-generalisable patient populations, and quality of life and patient-reported outcomes in the real-world SLE population are not well-published. The present study used the Medical Expenditure Panel Survey (MEPS), a generalisable US data source encompassing a representative sample of regions/payers, to estimate SLE prevalence and characterise disease burden compared with non-SLE respondents. METHODS: Retrospective population-based survey data weighted to the full US population from MEPS for the calendar years 2016-2018, pooled over the full study period, was used. The primary inclusion criteria included adults with self-reported SLE and either a record of SLE-related medication and/or rheumatologist visit in the calendar year. A matched-control cohort was created and the general non-SLE MEPS population was matched to MEPS SLE respondents by gender, age, region and MEPS reporting year using a 1:5 ratio. RESULTS: From 2016 to 2018, 96 996 adults reported annual data in MEPS, of whom 154 respondents met the primary SLE definition, equivalent to 490 385 weighted number of adults with SLE. The prevalence of SLE was 195 (95% CI 149 to 242) per 100000, with greater prevalence observed in the US South, African-American/black and publicly insured people and females. SLE respondents reported limitations in physical function at 3 times greater rate (45% vs 15%; p<0.0001), higher rates of pain-limiting work (67% vs 39%; p<0.001) and feeling depressed 'nearly every day' (7% vs 2%; p<0.001) compared with non-SLE respondents. All-cause healthcare and prescription expenses were significantly higher in SLE respondents (US$17 270 vs US$8350 (p<0.0001) and US$4512 vs US$1952 (p<0.001), respectively, in 2018 US dollars). CONCLUSION: Wide variation of SLE prevalence exists among patients of different regional, demographic and payer groups; SLE is associated with adverse quality of life, productivity and economic outcomes compared with non-SLE respondents.

Low rates of radiographic progression of structural joint damage over 2 years of baricitinib treatment in patients with rheumatoid arthritis.

Objectives: To evaluate radiographic progression of structural joint damage over 2 years in patients with rheumatoid arthritis from baricitinib clinical trials who were disease-modifying antirheumatic drug (DMARD)-naïve or had an inadequate response to conventional synthetic DMARDs (csDMARD-IR). Methods: Patients had completed one of three phase III studies and entered a long-term extension (LTE) study, continuing on the same baricitinib dose as at originating study completion. At 52 weeks, DMARD-naïve patients receiving methotrexate (MTX) or combination therapy (baricitinib 4 mg+MTX) were switched to baricitinib 4 mg monotherapy (±MTX per investigator opinion); MTX-IR patients receiving adalimumab were switched to baricitinib 4 mg on background MTX. At 24 weeks, csDMARD-IR patients receiving placebo were switched to baricitinib 4 mg on background csDMARD. Radiographs at baseline, year 1 and year 2 were scored using the van der Heijde modified Total Sharp Score. Linear extrapolation was used for missing data. Results: Of 2573 randomised patients, 2125 (82.6%) entered the LTE, of whom 1893 (89.1%) entered this analysis. At year 2, progression was significantly lower with initial baricitinib (monotherapy or combination therapy) versus initial MTX in DMARD-naïve patients (proportion with non-progression defined by ≤smallest detectable change (SDC): 87.3% baricitinib 4 mg+MTX; 70.6% MTX; p≤ 0.001). In MTX-IR patients, progression with initial baricitinib was significantly lower than with initial placebo and similar to initial adalimumab (≤SDC: 82.7% baricitinib 4 mg; 83.5% adalimumab; 70.6% placebo; p≤0.001). In csDMARD-IR patients, significant benefit was seen with baricitinib 4 mg (≤SDC: 87.2% vs 73.2% placebo; p≤0.01). Conclusions: Treatment with once-daily baricitinib resulted in low rates of radiographic progression for up to 2 years.

Comparison of baricitinib, upadacitinib, and tofacitinib mediated regulation of cytokine signaling in human leukocyte subpopulations.

BACKGROUND: The in vitro pharmacology of baricitinib, upadacitinib, and tofacitinib was evaluated to understand differences among these JAK inhibitors (JAKis) at the cellular level. METHODS: Peripheral blood mononuclear cells from healthy donors were incubated with different JAKis, levels of phosphorylated signal transducer and activator of transcription (pSTAT) were measured following cytokine stimulation, and half maximum inhibitory concentration (IC50) values were calculated in phenotypically gated leukocyte subpopulations. Therapeutic dose relevance of the in vitro analysis was assessed using calculated mean concentration-time profiles over 24 h obtained from JAKi-treated subjects. Time above IC50 and average daily percent inhibition of pSTAT formation were calculated for each JAKi, cytokine, and cell type. RESULTS: Distinct JAKis displayed different in vitro pharmacologic profiles. For example, tofacitinib and upadacitinib were the most potent inhibitors of the JAK1/3-dependent cytokines tested (interleukin [IL]-2, IL-4, IL-15, and IL-21) with lower IC50 values and increased time above IC50 translating to a greater overall inhibition of STAT signaling during the dosing interval. All JAKis tested inhibited JAK1/2-dependent cytokines (e.g., IL-6 and interferon [IFN]-γ), the JAK1/tyrosine kinase 2 (TYK2)-dependent cytokines IL-10 and IFN-α, the JAK2/2-dependent cytokines IL-3 and granulocyte-macrophage colony-stimulating factor (GM-CSF), and the JAK2/TYK2-dependent cytokine granulocyte colony-stimulating factor (G-CSF), but often to significantly differing degrees. CONCLUSIONS: Different JAKis modulated distinct cytokine pathways to varying degrees, and no agent potently or continuously inhibited an individual cytokine signaling pathway throughout the dosing interval. Notably, baricitinib inhibited JAK1/3 signaling to a lesser extent than upadacitinib and tofacitinib, while upadacitinib, baricitinib, and tofacitinib inhibited the signaling of JAK2/2-dependent cytokines, including GM-CSF and IL-3, as well as the signaling of the JAK2/TYK2-dependent cytokine G-CSF.

Animal models of rheumatoid arthritis and their relevance to human disease.

Rodent models of rheumatoid arthritis (RA) are useful tools to study the pathogenic process of RA. Among the most widely used models of RA are the streptococcal cell wall (SCW) arthritis model and the collagen-induced arthritis (CIA). Both innate and adaptive immune mechanisms are involved in these rodent models. While no models perfectly duplicate the condition of human RA, they are easily reproducible, well defined and have proven useful for development of new therapies for arthritis, as exemplified by cytokine blockade therapies. Besides SCW and CIA models, there are numerous others including transgenic models such as K/BxN, induced models such as adjuvant-induced and pristane models, and spontaneous models in certain mouse strains, that have been used to help understand some of the underlying mechanisms. This review provides an update and analysis of RA models in mice and rats. The array of models has provided rheumatologists and immunologists a means to understand the multifactorial disease in humans, to identify new drug targets, and to test new therapies.

Efficacy and safety of tabalumab, an anti-BAFF monoclonal antibody, in patients with moderate-to-severe rheumatoid arthritis and inadequate response to TNF inhibitors: results of a randomised, double-blind, placebo-controlled, phase 3 study.

BACKGROUND: Tabalumab is a human monoclonal antibody that neutralises B-cell activating factor. OBJECTIVES: To evaluate tabalumab efficacy and safety in patients with rheumatoid arthritis (RA). METHODS: This phase 3, randomised, double-blind, placebo-controlled study evaluated 456 patients with active RA after 24-week treatment with subcutaneous tabalumab (120 mg every 4 weeks (120/Q4W) or 90 mg every 2 weeks (90/Q2W)) versus placebo, with loading doses (240 or 180 mg) at week 0. Patients were allowed background disease-modifying antirheumatic drugs and previously discontinued ≥1 tumour necrosis factor α inhibitors for lack of efficacy/intolerance. Primary end point was American College of Rheumatology 20% (ACR20) response at 24 weeks. This study was terminated early due to futility. RESULTS: Most patients had moderate-to-high baseline disease activity. There was no significant difference in week 24 ACR20 responses between 120/Q4W, 90/Q2W, and placebo (17.6%, 24.3%, 20%) per non-responder imputation analysis. Mean percent changes in CD20+ B-cell count (-10.8%, -9.6%, +10.9%) demonstrated expected pharmacodynamic effects. Treatment-emergent adverse events (AEs) were similar (59.5%, 51.7%, 52.6%), as were AE discontinuations (2.6%, 2.7%, 2.6%), serious AEs (4.6%, 4.1%, 3.9%), serious infectious events (1.3%, 0, 0) and events of interest: infections (23.5%, 25.9%, 24%), injection site reactions (13.1%, 25.8%, 11%) and allergy/hypersensitivity (3.9%, 4.1%, 3.9%) reports. Incidence of treatment-emergent antidrug antibodies was similar to placebo (3.9%, 4.8%, 3.9%). No deaths or new/unexpected safety findings were reported. CONCLUSIONS: Tabalumab did not demonstrate clinical efficacy in patients with RA in this phase 3 study, despite evidence of biological activity. There were no notable differences in safety parameters between tabalumab treatment groups and placebo. TRIAL REGISTRATION NUMBER: NCT01202773.

Synoviolin promotes IRE1 ubiquitination and degradation in synovial fibroblasts from mice with collagen-induced arthritis.

The E3 ubiquitin ligase synoviolin (SYVN1) functions as an anti-apoptotic factor that is responsible for the outgrowth of synovial cells during the development of rheumatoid arthritis. The molecular mechanisms underlying SYVN1 regulation of cell death are largely unknown. Here, we report that elevated SYVN1 expression correlates with decreased levels of the protein inositol-requiring enzyme 1 (IRE1)-a pro-apoptotic factor in the endoplasmic reticulum (ER)-stress-induced apoptosis pathway-in synovial fibroblasts from mice with collagen-induced arthritis (CIA). SYVN1 interacts with and catalyses IRE1 ubiquitination and consequently promotes IRE1 degradation. Suppression of SYVN1 expression in synovial fibroblasts from CIA mice restores IRE1 protein expression and reverses the resistance of ER-stress-induced apoptosis of CIA synovial fibroblasts. These results show that SYVN1 causes the overgrowth of synovial cells by degrading IRE1, and therefore antagonizes ER-stress-induced cell death.

A major B cell epitope present on the apoptotic but not the intact form of the U1-70-kDa ribonucleoprotein autoantigen.

Apoptotically modified forms of autoantigens have been hypothesized to participate in lupus immunopathogenesis. This study identifies a major B cell epitope present on the apoptotic but not the intact form of the U1-70-kDa ribonucleoprotein lupus autoantigen (70k). Human autoimmune sera with strong recognition of apoptotic 70k and minimal recognition of intact 70k were identified and tested for reactivity to truncated forms of 70k by immunoblot and ELISA. Patient sera that preferentially recognized apoptotic 70k were specific for an epitope dependent on residues 180-205 of the protein. This epitope was also recognized by 19 of 28 (68%) intact anti-70k-positive autoimmune human sera with Abs also recognizing apoptotic but not the intact form 70k, but only 1 of 9 (11%) intact 70k-positive sera without such Abs (Fisher's exact, p = 0.0055). Immunization of HLA-DR4-transgenic C57BL/6 mice with a peptide containing this epitope induced anti-70k immunity in 13 of 15 mice, including Abs recognizing apoptotic but not intact forms of autoantigens in 12 of 15 mice. Anti-70k responder mice also developed spreading of immunity to epitopes on the endogenous form of 70k, and proliferative lung lesions consistent with those described in patients with anti-70k autoimmunity. Thus, a major epitope in the B cell response to U1-70 kDa localizes to the RNA binding domain of the molecule, overlaps with the most common T cell epitope in the anti-70k response, and is not present on the intact form of the 70k molecule. Immunization of mice against this epitope induces an immune response with features seen in human anti-70k autoimmune disease.

U1 RNA induces innate immunity signaling.

OBJECTIVE: The U1-70-kd RNP is a prominent target of autoimmunity in connective tissue diseases. In this study, we explored whether its endogenous ligand, U1 RNA, mediates a proimmune signal and may be immunogenic. METHODS: We assayed the proliferation of control and MyD88-knockout splenocytes in response to in vitro-synthesized U1 RNA, and measured interleukin-6 (IL-6) and IL-8 secretion induced by U1 RNA in a human cell line competent for signaling through Toll-like receptor 3 (TLR-3) and TLR-5. RESULTS: Treatment with U1 RNA or with poly(I-C), a known agonist of TLR-3, induced approximately twice as much control splenocyte proliferation as did treatment with RNase-digested U1 RNA. Proliferation in response to either poly(I-C) or U1 RNA by MyD88-knockout splenocytes was similarly attenuated. Similar to poly(I-C), U1 RNA induced significant secretion of both IL-6 and IL-8 from a TLR-3-expressing human cell line; in contrast, the TLR-5 agonist flagellin induced predominantly IL-8 secretion. Pretreatment of U1 RNA with RNase abolished IL-6 and IL-8 secretion. CONCLUSION: U1 RNA is capable of inducing manifestations consistent with TLR-3 activation. The ability of U1 RNA (which has a substantial double-stranded secondary structure) to activate TLR-3 may contribute to the immunogenicity of the U1-70-kd autoantigen. Stimulation of innate immunity by native RNA molecules with a double-stranded secondary structure may help explain the high prevalence of autoimmunity to RNA binding proteins.