Differential Binding of Sarilumab and Tocilizumab to IL-6Rα and Effects of Receptor Occupancy on Clinical Parameters.

We evaluated interleukin-6 (IL-6) receptor-α subunit (IL-6Rα) signaling inhibition with sarilumab and tocilizumab, the association between IL-6Rα receptor occupancy (RO) and C-reactive protein (CRP), and the potential clinical relevance of any differences. For this, we measured IL-6Rα binding and signaling inhibition with sarilumab and tocilizumab in vitro, simulated soluble IL-6Rα RO over time for approved sarilumab subcutaneous (SC) and tocilizumab intravenous (IV) and SC doses, and assessed associations between calculated RO and CRP reduction, 28-joint Disease Activity Score based on CRP, and 20%/50%/70% improvement in American College of Rheumatology responses from clinical data. Sarilumab binds IL-6Rα in vitro with 15- to 22-fold higher affinity than tocilizumab, and inhibits IL-6-mediated classical and trans signaling via membrane-bound and soluble IL-6Rα. Sarilumab 200 and 150 mg SC every 2 weeks achieved >90% RO after first and second doses, respectively, maintained throughout the treatment period. At steady-state trough, RO was greater with sarilumab 200 mg (98%) and 150 mg SC every 2 weeks (94%), and tocilizumab 162 mg SC weekly (>99%) and 8 mg/kg IV every 4 weeks (99%), vs tocilizumab 162 mg SC every 2 weeks (84%) and 4 mg/kg IV every 4 weeks (60%). Higher RO was associated with greater CRP reduction and 28-joint Disease Activity Score based on CRP reduction, and more sarilumab patients achieving 20%/50%/70% improvement in American College of Rheumatology responses. The greatest reduction in CRP levels was observed with sarilumab (both doses) and tocilizumab 8 mg/kg IV every 4 weeks (reductions proportionally smaller with 4 mg/kg IV every 4 weeks). Higher IL-6Rα binding affinity translated into higher RO with sarilumab vs tocilizumab 4 mg/kg every 4 weeks or 162 mg every 2 weeks; tocilizumab required the higher dose or increased frequency to maintain the same degree of RO and CRP reduction. Higher RO was associated with clinical parameter improvements.

Comparative effectiveness of first-line tumour necrosis factor inhibitor versus non-tumour necrosis factor inhibitor biologics and targeted synthetic agents in patients with rheumatoid arthritis: results from a large US registry study.

OBJECTIVES: This study evaluated the comparative effectiveness of a tumour necrosis factor inhibitor (TNFi) versus a non-TNFi (biological disease-modifying antirheumatic drugs (bDMARDs) and targeted synthetic DMARDs (tsDMARDs)) as the first-line treatment following conventional synthetic DMARDs, as well as potential modifiers of response, observed in US clinical practice. METHODS: Data were from a large US healthcare registry (Consortium of Rheumatology Researchers of North America Rheumatoid Arthritis Registry). The analysis included patients (aged ≥18 years) with a documented diagnosis of rheumatoid arthritis (RA), a valid baseline Clinical Disease Activity Index (CDAI) score of >2.8 and no prior bDMARD or tsDMARD use. Outcomes were captured at 1-year postinitiation of a TNFi (adalimumab, etanercept, certolizumab pegol, golimumab or infliximab) or a non-TNFi (abatacept, tocilizumab, rituximab, anakinra or tofacitinib) and included CDAI, 28-Joint Modified Disease Activity Score, patient-reported outcomes (including the Health Assessment Questionnaire Disability Index, EuroQol-5 Dimension score, sleep, anxiety, morning stiffness and fatigue) and rates of anaemia. Groups were propensity score-matched at baseline to account for potential confounding. RESULTS: There were no statistically significant differences observed between the TNFi and non-TNFi treatment groups for outcomes assessed, except the incidence rate ratio for anaemia, which slightly favoured the TNFi group (19.04 per 100 person-years) versus the non-TNFi group (24.01 per 100 person-years, p=0.03). No potential effect modifiers were found to be statistically significant. CONCLUSIONS: The findings of no significant differences in outcomes between first-line TNF versus first-line non-TNF groups support RA guidelines, which recommend individualised care based on clinical judgement and consideration of patient preferences.

Data-Driven Patient Clustering and Differential Clinical Outcomes in the Brigham and Women's Rheumatoid Arthritis Sequential Study Registry.

OBJECTIVE: To use unbiased, data-driven, principal component (PC) and cluster analysis to identify patient phenotypes of rheumatoid arthritis (RA) that might exhibit distinct trajectories of disease progression, response to treatment, and risk for adverse events. METHODS: Patient demographic, socioeconomic, health, and disease characteristics recorded at entry into a large, single-center, prospective observational registry cohort, the Brigham and Women's Rheumatoid Arthritis Sequential Study (BRASS), were harmonized using PC analysis to reduce dimensionality and collinearity. The number of PCs was established by eigenvalue >1, cumulative variance, and interpretability. The resulting PCs were used to cluster patients using a K-means approach. Longitudinal clinical outcomes were compared between the clusters over 2 years. RESULTS: Analysis of 142 variables from 1,443 patients identified 41 PCs that accounted for 77% of the cumulative variance in the data set. Cluster analysis distinguished 5 patient clusters: 1) less RA disease activity/multimorbidity, shorter RA duration, lower incidence of comorbidities; 2) less RA disease activity/multimorbidity, longer RA duration, more infections, psychiatric comorbidities, health care utilization; 3) moderate RA disease activity/multimorbidity, more neurologic comorbidity; 4) more RA disease activity/multimorbidity, shorter RA duration, more metabolic comorbidity, higher body mass index; 5) more RA disease activity/multimorbidity, longer RA duration, more hepatic, orthopedic comorbidity and RA-related surgeries. The clusters exhibited differences in clinical outcomes over 2 years of follow-up. CONCLUSION: Data-driven analysis of the BRASS registry identified 5 distinct phenotypes of RA. These results illustrate the potential of data-driven patient profiling as a tool to support personalized medicine in RA. Validation in an independent data set is ongoing.

Subcutaneous Sarilumab in Patients With Rheumatoid Arthritis who Previously Received Subcutaneous Sarilumab or Intravenous Tocilizumab: An Open-Label Extension of a Randomized Clinical Trial.

OBJECTIVE: This post hoc analysis evaluated the safety and efficacy of open-label sarilumab in patients with rheumatoid arthritis (RA) who completed the phase III double-blind ASCERTAIN study (NCT01768572) and switched from intravenous (IV) tocilizumab to subcutaneous (SC) sarilumab, or who continued SC sarilumab in the open-label extension (OLE) study EXTEND (NCT01146652). METHODS: Patients who completed ASCERTAIN were eligible to enroll in EXTEND to receive sarilumab 200 mg SC every 2 weeks (Q2W). Safety and efficacy were reported through 96 weeks in the OLE in patients who switched from tocilizumab IV to sarilumab 200 mg SC Q2W, who switched from sarilumab 150 mg SC Q2W to sarilumab 200 mg SC Q2W, or who continued sarilumab 200 mg SC Q2W. RESULTS: Of 175 patients who completed ASCERTAIN, 168 (96%) enrolled in EXTEND, and 38 of these patients (23%) discontinued the OLE. Cumulative sarilumab exposure during follow-up was 273.7 patient-years. No new safety signals were identified, infections occurred at a rate of 59.9/100 patient-years, and there were no cases of grade 4 neutropenia. Efficacy-as assessed by Disease Activity Score (28 joints) based on C-reactive protein, Clinical Disease Activity Index, and Health Assessment Questionnaire-Disability Index scores-was sustained over 96 weeks of follow-up when switching to, or continuing, sarilumab 200 mg SC Q2W. CONCLUSION: Switching from IV to SC interleukin-6 receptor inhibitor therapy produced no new safety concerns, and clinical efficacy was sustained over 96 weeks of follow-up. These findings alleviate potential concerns over switching route of administration with interleukin-6 receptor inhibitor therapy for RA.

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.

Population Pharmacodynamic Model of Neutrophil Margination and Tolerance to Describe Effect of Sarilumab on Absolute Neutrophil Count in Patients with Rheumatoid Arthritis.

Evidence suggests that effects of interleukin-6 pathway inhibitors sarilumab, tocilizumab, and sirukumab on absolute neutrophil count (ANC) are due to margination of circulating neutrophils into rapidly mobilizable noncirculating pools. We developed a population pharmacodynamic model using compartments for neutrophil margination and ANC-specific tolerance to describe rapid, transient ANC changes in blood following administration of subcutaneous sarilumab and intravenous/subcutaneous tocilizumab based on data from 322 patients with rheumatoid arthritis in two single-dose (NCT02097524 and NCT02404558) and one multiple-dose (NCT01768572) trials. The model incorporated a tolerance compartment to account for ANC nadir and beginning of recovery before maximal drug concentration after subcutaneous dosing, and absence of a nadir plateau when the ANC response is saturated after subcutaneous or intravenous dosing. The model effectively describes the ANC changes and supports neutrophil margination and tolerance as an explanation for the absence of increased infection risk associated with low ANC due to interleukin-6 pathway inhibitor treatment.

Long-term safety of sarilumab in rheumatoid arthritis: an integrated analysis with up to 7 years' follow-up.

OBJECTIVE: Sarilumab is a human monoclonal antibody that blocks IL-6 from binding to membrane-bound and soluble IL-6 receptor-α. We assessed the long-term safety of sarilumab in patients from eight clinical trials and their open-label extensions. METHODS: Data were pooled from patients with rheumatoid arthritis who received at least one dose of sarilumab in combination with conventional synthetic disease-modifying antirheumatic drugs (csDMARDs; combination group) or as monotherapy (monotherapy group). Treatment-emergent adverse events (AEs) and AEs and laboratory values of special interest were assessed. RESULTS: 2887 patients received sarilumab in combination with csDMARDs and 471 patients received sarilumab monotherapy, with mean exposure of 2.8 years and 1.7 years, maximum exposure 7.3 and 3.5 years, and cumulative AE observation period of 8188 and 812 patient-years, respectively. Incidence rates per 100 patient-years in the combination and monotherapy groups, respectively, were 9.4 and 6.7 for serious AEs, 3.7 and 1.0 for serious infections, 0.6 and 0.5 for herpes zoster (no cases were disseminated), 0.1 and 0 for gastrointestinal perforations, 0.5 and 0.2 for major adverse cardiovascular events, and 0.7 and 0.6 for malignancy. Absolute neutrophil counts <1000 cells/mm3 were recorded in 13% and 15% of patients, respectively. Neutropenia was not associated with increased risk of infection or serious infection. Analysis by 6-month interval showed no signal for increased rate of any AE over time. CONCLUSION: The long-term safety profile of sarilumab, either in combination with csDMARDs or as monotherapy, remained stable and consistent with the anticipated profile of a molecule that inhibits IL6 signalling.

Safety and efficacy of switching from adalimumab to sarilumab in patients with rheumatoid arthritis in the ongoing MONARCH open-label extension.

Objective: Evaluate open-label sarilumab monotherapy in patients with rheumatoid arthritis switching from adalimumab monotherapy in MONARCH (NCT02332590); assess long-term safety and efficacy in patients continuing sarilumab during open-label extension (OLE). Methods: During the 48-week OLE, patients received sarilumab 200 mg subcutaneously once every 2 weeks. Safety (March 2017 cut-off) and efficacy, including patient-reported outcomes, were evaluated. Results: In the double-blind phase, patients receiving sarilumab or adalimumab monotherapy showed meaningful improvements in disease activity; sarilumab was superior to adalimumab for improving signs, symptoms and physical function. Overall, 320/369 patients completing the 24-week double-blind phase entered OLE (155 switched from adalimumab; 165 continued sarilumab). Sarilumab safety profile was consistent with previous reports. Treatment-emergent adverse events were similar between groups; no unexpected safety signals emerged in the first 10 weeks postswitch. Among switch patients, improvement in disease activity was evident at OLE week 12: 47.1%/34.8% had changes ≥1.2 in Disease Activity Score (28 joints) (DAS28)-erythrocyte sedimentation rate/DAS28-C-reactive protein. In switch patients achieving low disease activity (LDA: Clinical Disease Activity Index (CDAI) ≤10; Simplified Disease Activity Index (SDAI) ≤11) by OLE week 24, 70.7%/69.5% sustained CDAI/SDAI LDA at both OLE weeks 36 and 48. Proportions of switch patients achieving CDAI ≤2.8 and SDAI ≤3.3 by OLE week 24 increased through OLE week 48. Improvements postswitch approached continuation-group values, including scores ≥normative values. Conclusions: During this OLE, there were no unexpected safety issues in patients switching from adalimumab to sarilumab monotherapy, and disease activity improved in many patients. Patients continuing sarilumab reported safety consistent with prolonged use and had sustained benefit.

Long-term safety and efficacy of sarilumab plus methotrexate on disease activity, physical function and radiographic progression: 5 years of sarilumab plus methotrexate treatment.

Objective: In MOBILITY (NCT01061736), sarilumab significantly reduced disease activity, improved physical function and inhibited radiographic progression at week 52 versus placebo in patients with rheumatoid arthritis (RA) and an inadequate response to methotrexate. We report 5-year safety, efficacy and radiographic outcomes of sarilumab from NCT01061736 and the open-label extension (EXTEND; NCT01146652), in which patients received sarilumab 200 mg every 2 weeks (q2w) + methotrexate. Methods: Patients (n=1197) with moderately to severely active RA were initially randomised to placebo, sarilumab 150 mg or sarilumab 200 mg subcutaneously q2w plus weekly methotrexate for 52 weeks. Completers were eligible to enrol in the open-label extension and receive sarilumab 200 mg q2w + methotrexate. Results: Overall, 901 patients entered the open-label extension. The safety profile remained stable over 5-year follow-up and consistent with interleukin-6 receptor blockade. Absolute neutrophil count <1000 cells/mm3 was observed but not associated with increased infection rate. Initial treatment with sarilumab 200 mg + methotrexate was associated with reduced radiographic progression over 5 years versus sarilumab 150 mg + methotrexate or placebo + methotrexate (mean±SE change from baseline in van der Heijde-modified Total Sharp Score: 1.46±0.27, 2.35±0.28 and 3.68±0.27, respectively (p<0.001 for each sarilumab dose versus placebo)). Clinical efficacy was sustained through 5 years according to Disease Activity Score (28-joint count) using C reactive protein, Clinical Disease Activity Index (CDAI) and Health Assessment Questionnaire-Disability Index. The number of patients achieving CDAI ≤2.8 at 5 years was similar among initial randomisation groups (placebo, 76/398 (19%); sarilumab 150 mg, 68/400 (17%); sarilumab 200 mg, 84/399 (21%)). Conclusion: Clinical efficacy, including inhibition of radiographic progression, reduction in disease activity and improvement in physical function, was sustained with sarilumab + methotrexate over 5 years. Safety appeared stable over the 5-year period.

Mycobacterium tuberculosis expresses methionine sulphoxide reductases A and B that protect from killing by nitrite and hypochlorite.

Methionine sulphoxide reductases (Msr) reduce methionine sulphoxide to methionine and protect bacteria against reactive oxygen intermediates (ROI) and reactive nitrogen intermediates (RNI). Many organisms express both MsrA, active against methionine-(S)-sulphoxide, and MsrB, active against methionine-(R)-sulphoxide. Mycobacterium tuberculosis (Mtb) expresses MsrA, which protects DeltamsrA-Escherichia coli from ROI and RNI. However, the function of MsrA in Mtb has not been defined, and it is unknown whether Mtb expresses MsrB. We identified MsrB as the protein encoded by Rv2674 in Mtb and confirmed the distinct stereospecificities of recombinant Mtb MsrA and MsrB. We generated strains of Mtb deficient in MsrA, MsrB or both and complemented the mutants. Lysates of singly deficient strains displayed half as much Msr activity as wild type against N-acetyl methionine sulphoxide. However, in contrast to other bacteria, single mutants were no more vulnerable than wild type to killing by ROI/RNI. Only Mtb lacking both MsrA and MsrB was more readily killed by nitrite or hypochlorite. Thus, MsrA and MsrB contribute to the enzymatic defences of Mtb against ROI and RNI.

Peptide methionine sulfoxide reductase: structure, mechanism of action, and biological function.

Reactive oxygen and nitrogen intermediates can cause damage to many cellular components and have been implicated in a number of diseases. Cells have developed a variety of mechanisms to destroy these reactive molecules or repair the damage once it occurs. In proteins one of the amino acids most easily oxidized is methionine, which is converted to methionine sulfoxide. An enzyme, peptide methionine sulfoxide reductase (MsrA), catalyzes the reduction of methionine sulfoxide in proteins back to methionine. There is growing evidence that MsrA plays an important role in protecting cells against oxidative damage. This paper reviews the biochemical properties and biological role of MsrA.