Efficacy of tocilizumab on MRI-determined bone oedema in rheumatoid arthritis

The aim of this study was to assess the impact of tocilizumab on bone oedema in rheumatoid arthritis (RA) as shown by magnetic resonance imaging (MRI). In this longitudinal study, patients with rheumatoid arthritis according to the American College of Rheumatology (ACR) 2009 criteria with inadequate response or intolerance to disease-modifying anti-rheumatic drugs (DMARDs), treated with tocilizumab, were included. Sociodemographic characteristics and clinical and laboratory data for the disease were collected at baseline (M0) and 06 months (M6) of treatment. Disease activity was assessed using disease activity score in 28 joints (DAS28), simplified disease activity index (SDAI) and clinical disease activity index (CDAI). MRI of the dominant hand was performed at baseline and M6 of treatment. The primary outcome measure was the assessment of bone oedema by rheumatoid arthritis MRI scoring system (RAMRIS) bone oedema. Secondary outcomes included RAMRIS synovitis, DAS28, C-reactive protein (CRP) and SDAI at baseline and M6. Twenty-two patients with RA were included, 19 females (86.4 %), with a mean of age 42 ± 13.7. The mean disease duration was 8 ± 5.2 years. The mean DAS28 was 5.78 ± 0.87. The median CRP was 16 mg/l (6.7 to 36.3). The average SDAI was 90 ± 34. Three patients were excluded from the study for serious side effects. At baseline, bone oedema was present in 41 % of patients (N = 9), with a median bone oedema RAMRIS 0 (0 to 7.2). At M6, bone oedema decreased or disappeared in 32 % (N = 7) with a significant improvement in the RAMRIS bone oedema score (p = 0.04). Moreover, there is a significant improvement in RAMRIS synovitis (p < 0.0001) as well as in activity parameters: DAS28 (p < 0.0001), CRP (p < 0.0001) and SDAI (p < 0.0001). This study suggests that tocilizumab is associated with a significant improvement on MRI-determined bone oedema in the short term. This improvement in bone oedema is correlated with improved parameters of disease activity, in which early structural effect could be discussed. Further studies are needed to confirm these results.