The effect of tocilizumab on bone mineral density, serum levels of Dickkopf-1 and bone remodeling markers in patients with rheumatoid arthritis

Previous studies showed that the control of inflammation by biological therapies has a positive effect on bone in inflammatory diseases. The objective of this study was to assess the effects on bone mineral density (BMD) and bone remodeling of an anti-IL-6 monoclonal antibody (tocilizumab (TCZ)) in patients with rheumatoid arthritis (RA). Methods: One hundred and three patients (75% women, 52 ± 12. years) with active RA were treated with TCZ 8. mg/kg + methotrexate (MTX) every 4 weeks during 48 weeks. Hip and lumbar spine BMDs were measured at baseline and after 48 weeks by dual energy X-ray absorptiometry (DXA). Pro-collagen serum type I N-terminal propeptide (PINP), serum C-terminal cross-linked telopeptide of type I collagen (CTX-I), and serum levels of total Dickkopf-1 (Dkk-1) and sclerostin were assessed at baseline, 12 and 48 weeks. Results: BMD was available for 76 patients at baseline and at the end of the study. There was no change in lumbar spine and hip BMD over 48 weeks. Serum PINP increased from baseline by 22% (P≤ 0.001) and 19% (P≤ 0.001) at week 12 and week 48, whereas serum CTX-I remained stable. Serum DKK-1 significantly decreased from baseline by -31% (P≤ 0.001) and -25% (P= 0.025) at week 12 and 48. Similar results were observed in the patients receiving low doses of oral corticosteroids. Conclusion: In this 1-year prospective open study, patients with active RA receiving TCZ and MTX had no change in BMD, a decrease in serum DKK-1 and an increase in bone formation marker. © 2014 Société française de rhumatologie.