Potential alleviation of bone mineral density loss with Janus kinase inhibitors in rheumatoid arthritis

Objective Rheumatoid arthritis (RA) is characterized by localized bone loss, general osteoporosis and increased fracture risks. Tumour necrosis factor inhibitors (TNFi), non-tumour necrosis factor inhibitors (non-TNFi) biologic, Janus kinase inhibitors (JAKi) had shown the suppression effects to osteoclast activation and improvement of bone mineral density (BMD). Anti-cyclic citrullinated peptide antibody (ACPA) is associated with osteoclast activation and the resultant bone loss. However, few studies have compared BMD changes among patients with RA treated with targeted therapies that have different mechanisms of action. Methods This retrospective study recruited patients with RA who had undergone BMD testing twice. Changes in the BMD were compared using the generalized estimating equation (GEE) in treatment groups that received conventional synthetic disease-modifying anti-rheumatic drugs (csDMARDs), TNFi, non-TNFi biologics, and JAKi. Results In total, 362 patients with RA were enrolled (csDMARDs, n = 153, TNFi, n = 71, non-TNFi biologics, n = 108, JAKi, n = 30). We observed greater changes in femoral BMD (left, 0.06, 95% CI 0.01–0.12, p = 0.016; right, 0.09, 95% CI 0.04–0.15, p = 0.001 by GEE) following JAKi treatment as compared with other treatments. Compared to the ACPA-negative group, patients with ACPA positivity exhibited greater improvement in the femoral BMD (left, 0.09, 95% CI 0.02–0.15, p = 0.008; right, 0.11, 95% CI 0.05–0.18, p = 0.001). Conclusion Compared to other targeted therapies, JAKi might exert a more potent effect to prevent BMD loss, specifically in ACPA-positive patients with RA, and could be a potential therapeutic option to mitigate generalized bone loss. Key Points •JAKi therapy inhibits systemic bone loss in patients with RA. •ACPA-positive RA patients exhibited a greater BMD improvement than ACPA-negative RA patients. •JAKi might more potently prevent BMD decline than conventional synthetic or biological DMARDs.