Erosion Regression in Patients with RA After Upadacitinib-A Pilot Study Using High Resolution Peripheral Quantitative Computed Tomography

Abstract

Background: Janus kinases inhibitor (JAKi) is a potent drug in treating patients with rheumatoid arthritis (RA). However, the effect of JAKi on finite structural changes remained uncertain. This study aims to investigate the effect of JAKi on erosion repair evaluated by high-resolution peripheral quantitative computer tomography (HR-pQCT) in patients with active RA. Methods: This was a prospective, non-randomized pilot study. We enrolled 20 adult patients with active RA with [Formula: see text]1 bone erosion on HR-pQCT. They were given upadacitinib 15mg once daily for 24 weeks. HR-pQCT of the metacarpophalangeal joint was performed at baseline and 24-week. The serum bone biomarkers level was evaluated before and after treatment. Twenty age-and-sex matched RA patients from another study treated with conventional synthetic disease modifying anti-rheumatic drugs (csDMARDs) were included as active controls. Results: Nineteen patients in the upadacitinib group completed the study procedures. After 24 weeks, despite similar improvement in disease activity, a reversed trend in the mean erosion volume change on HR-pQCT was observed comparing the upadacitinib and active control group (upadacitinib group: -0.23± 3.26mm3vs control group: 1.32± 6.05mm3, p=0.131). A greater proportion of erosions in the upadacitinib group demonstrated regression (27% vs 12%, p=0.085). Using general estimating equation (GEE), the use of upadacitinib was significantly associated with erosion regression (OR: 3.61, 95% CI: 1.00-13.00, p=0.049) after adjusting for the difference in disease duration. The serum levels of bone resorption markers reduced after upadacitinib treatment. No new safety signal was noted. Conclusion: Despite a similar improvement in RA disease activity after upadacitinib compared to csDMARDs, a differential regression of erosion on HR-pQCT was observed in patients received upadacitinib. The potential role of JAK1 inhibition in erosion repair should be investigated.