Objective Fenebrutinib (GDC‐0853) is a noncovalent, oral, and highly selective inhibitor of Bruton’s tyrosine kinase (BTK). The efficacy, safety, and pharmacodynamics of fenebrutinib in systemic lupus erythematosus (SLE) were assessed in this phase II, multicenter, randomized, placebo‐controlled study. Methods Patients who had moderately to severely active SLE while receiving background standard therapy were randomized to receive placebo, fenebrutinib 150 mg once daily, or fenebrutinib 200 mg twice daily. Glucocorticoid taper was recommended from weeks 0 to 12 and from weeks 24 to 36. The primary end point was the SLE Responder Index 4 (SRI‐4) response at week 48. Results Patients (n = 260) were enrolled from 44 sites in 12 countries, with the majority from Latin America, the US, and Western Europe. The SRI‐4 response rates at week 48 were 51% for fenebrutinib 150 mg once daily (P = 0.37 versus placebo), 52% for fenebrutinib 200 mg twice daily (P = 0.34 versus placebo), and 44% for placebo. British Isles Lupus Assessment Group–based Combined Lupus Assessment response rates at week 48 were 53% for fenebrutinib 150 mg once daily (P = 0.086 versus placebo), 42% for fenebrutinib 200 mg twice daily (P = 0.879 versus placebo), and 41% for placebo. Safety results were similar across all arms, although serious adverse events were more frequent with fenebrutinib 200 mg twice daily. By week 48, patients treated with fenebrutinib had reduced levels of a BTK‐dependent plasmablast RNA signature, anti–double‐stranded DNA autoantibodies, total IgG, and IgM, as well as increased complement C4 levels, all relative to placebo. Conclusion While fenebrutinib had an acceptable safety profile, the primary end point, SRI‐4 response, was not met despite evidence of strong pathway inhibition.

Background:The prevalence of human leukocyte antigen B27 (HLA-B27) is variable around the world. Our objectives were to estimate the frequency of HLA-B27 in an Argentinian cohort of axial spondyloarthritis (axSpA), to evaluate the differences between HLA-B27-positive and HLA-B27negative patients, and to analyze its performance as a diagnostic biomarker.Methods: Observational study including patients older than 18 years, with axSpA diagnosis assessed in a fast track program (Reuma-Check SpA). All patients underwent the following: blood tests, HLA-B27, sacroiliac images, and enthesitis ultrasound. Sociodemographic data and SpA symptoms were also collected. The clinical assessor was blinded to complementary studies. For the sensitivity and specificity analysis, patients with chronic low back pain without axSpA who performed the same circuit in the same period were used as control, paired 1:1 (sex and age).Results: One hundred fifty patients were included, 75 axSpA and 75 controls. The frequency of HLA-B27 was 43% (95% confidence interval [CI], 30-53). The differences between HLA-B27-positive and HLA-B27negative patients were observed in age of low back pain onset (36 vs 46 years), BASFI (Bath Ankylosing Spondylitis Functional Index) (4 vs 5), and extra-articular SpA features such as uveitis and inflammatory bowel disease (29% vs 50%). When this frequency was compared (low back pain control group), the difference was 43% versus 9% (odds ratio, 7.7; 95% CI, 2.8-24), and HLA-B27 had a sensitivity of 43%, specificity of 91%, positive predictive value of 85%, negative predictive value of 58%, and likelihood ratio of 4.9 (95% CI, 3-8). Conclusions:The frequency of HLA-B27 in axSpA was 43%; positive patients had an earlier age of onset (36), a higher BASFI, and more SpA features. For the diagnosis of SpA, HLA-B27 had a good specificity but low sensitivity.

Background: Non-radiographic axial spondyloarthritis (nr-axSpA) data from South America are scarce, especially regarding image features. ObjectiveTo estimate the frequency of nr-axSpA and ankylosing spondylitis (AS) in a cohort of Argentinian patients with chronic low back pain (LBP) and to analyze the difference between both, with focus on magnetic resonance imaging (MRI) lesions, at diagnosis. Methods:Patients with LBP and a diagnosis of axSpA who participated in a reumacheck program were included. All patients with a suspicion of SpA were evaluated using blood analytics, HLA-B27, and images (MRI). Sociodemographic data, SpA features, diagnostic dela,y and clinimetrics were assessed by an operator who was blinded to the patient's test results. On MRI, the presence of SpA lesions was assessed and a concordance exercise was carried out between rheumatologists and radiologist.Result: Of 198 LBP patients, 97 had axSpA, 54% of whom were nr-axSpA. A positive MRI was found in 50%. No difference in terms of disease activity, functional impact, laboratory or treatments between nr-axSpA and AS were found. Higher frequencies of male sex and chronic lesions on sacroiliac MRI were found in AS patients. In the logistic regression, an independent association with AS diagnosis was found: male (odds ratio [OR] 4.8), MRI fat replacement (OR 4.6), MRI sclerosis (OR 7.6), and diagnostic delay of more than 2 years (OR 10). The concordance between rheumatologists and radiologists was considered good to very good (κ 0.7-0.8). Conclusion:The frequency of nr-axSpA was 54%. We found a higher frequency of being male, more SpA features, and a longer diagnostic delay in patients with AS.Patients with AS had more structural lesions, with a good concordance between rheumatologist and radiologist.

Aim:To determine the efficacy and safety of certolizumab pegol for the treatment of rheumatoid arthritis in a real-world setting.Materials & methods:Patients with moderate-to-severe rheumatoid arthritis who initiated therapy with certolizumab were followed for 12 weeks. Response was assessed with Disease Activity Score of 28 joints, European Ligue Against Rheumatism criteria and Simplified Disease Activity Index. Predictors of response were analyzed with binary logistic regression models.Results:Statistically significant decreases in tender and swollen joint counts, laboratory parameters and use of corticosteroids and disease-modifying antirheumatic drugs were found. Disease activity also significantly diminished. Higher Disease Activity Score of 28 joints at baseline was the main predictor of response. No severe adverse events were reported.Conclusion:Certolizumab was effective and well tolerated, particularly in the subpopulation with higher inflammatory burden at baseline.