The effect of tocilizumab on bone mineral density in patients with methotrexate-resistant active rheumatoid arthritis

Objective. The aim of this study was to analyse the effects of therapy with tocilizumab (TCZ), an anti-IL-6 receptor antibody, on BMD of the lumbar spine and femoral neck in patients with RA. Methods. Eighty-six patients with active RA (indicated by a 28-joint DAS ESR > 3.2) despite treatment with MTX 12 mg/week were included in this open-label prospective study and started on TCZ (8 mg/kg every 4 weeks). All patients used a stable dosage of MTX and were not allowed to use steroids or bisphosphonates during the study period. BMD of the lumbar spine and femoral neck was measured by dual-energy X-ray absorptiometry at baseline and 52 weeks after initiating TCZ. Results. Seventy-eight patients completed this study. BMD of the lumbar spine and femoral neck remained stable after 1 year of TCZ treatment. In 33 patients who had osteopenia at baseline, there was a significant increase in BMD of the lumbar spine [mean 0.022 (s.d.) 0.042, P < 0.05] and femoral neck [0.024 (0.0245), P < 0.05]. Conclusion. TCZ affects BMD in patients who had active RA despite treatment with MTX. BMD of the lumbar spine and femoral neck in patients with normal BMD at baseline was stable. TCZ increased the BMD of patients who had osteopenia at baseline.