Maria Höhle, MD¹

¹Orthopedic, Medical, Rheumatologic Center, Hamburg, Germany

Background/Purpose: Tocilizumab (TCZ) leads to a rapid improvement of the clinical course in patients with highly active rheumatoid arthritis (RA). However, a residual rheumatic activity can still be detected.¹ RA is a known risk factor for osteoporosis related bone fractures.² It is well established that TCZ has beneficial effects on bone remodeling.³

The aim of this analysis was to investigate the effects of TCZ on bone mineral density in a real world patient population.

Methods: 50 rheumatoid factor positive patients with RA (17 male, age 20-72 years) who received TCZ as monotherapy since 2008 were prospectively investigated. At baseline and the following 4-6 clinical visits, DAS28 was determined and ultrasound performed. At baseline and every 6 months thereafter, biochemical parameters for bone metabolism and protein diagnostics were recorded. Once a year, the subjects underwent MRI, CT and DXA scan.

Results: In all 50 patients the DAS28 normalized at the latest by the 3^rd infusion cycle of TCZ. The initial RAMRIS score of >5 was reduced to <2 after 6-18 months. Ultrasound revealed a decline of synovialitis and tenodynovialitis after 8 weeks and 12 months, respectively. At baseline in 22 women with early RA, axial QCT/DXA values and lateral DXA values were within reference. 3 patients with early RA had osteopenia, 2 had osteoporosis. Patients with manifest RA had a BMD in the reference range, 3 had osteopenia and 2 were diagnosed with osteoporosis. In 6 male patients, BMD values were within the reference range. 2 men with early RA had osteopenia and 2 had manifest osteoporosis. In 1 male patient with manifest RA, normal BMD values were documented. 2 men with manifest RA hat osteopenia and 4 had osteoporosis. 10 patients had vitamin D3 deficiency and were treated with vitamin D3. 2 patients with osteoporosis were treated with antiresorptive medication. In all patients, BMD values were within the reference range after 1 year of treatment with TCZ, despite 18% of patients presenting with a DAS score > 2.7. 2 patients presented with pustular dermatosis in the palms. No allergic reactions were observed.

Conclusion: Treatment with TCZ leads to a rapid decline of inflammatory activity of the affected joints in patients with RA and minimizes cartilage destruction. TCZ showed a positive effect on bone remodeling and therefore BMD. Thus, the risk for the development of osteoporosis and its related fractures can be minimized by TCZ treatment. Furthermore, TCZ has a positive effect on BMD in manifest RA thus preventing sarcopenia. Temporary elevations of DAS28 during TCZ therapy do not negatively affect BMD.