The efficacy and safety of tocilizumab, an anti-IL-6 receptor monoclonal antibody, was examined as a monotherapy in patients with active RA who had inadequate responses to MTX. In this Japanese study, RA patients previously treated with MTX received either tocilizumab 8 mg/kg every 4 weeks + a MTX placebo (tocilizumab group) or a tocilizumab placebo + MTX 8 mg/week (MTX group) for 24 weeks. Study endpoints included ACR20, 50, and 70 improvement rates, DAS28, EULAR response, and the numeric index of ACR response (ACR-N) area under the curve (AUC) at 24 weeks.

There were 61 patients in the tocilizumab group and 64 patients in the MTX group. After 24 weeks of treatment, ACR20 (80.3% vs 25.0%, p<0.001), ACR50 (49.2% vs 10.9%, p<0.001), and ACR70 (29.5% vs 6.3%, p<0.001) response rates were significantly higher in the tocilizumab group than in the MTX group. Consistent improvements were observed in the EULAR response criteria as well as ACR-N AUC index.

Fewer patients withdrew from the tocilizumab group (n = 7) compared with the MTX group (n = 31) indicating a greater tolerance for tocilizumab. The safety profiles of the two groups were similar. The most common adverse event was nasopharyngitis in both groups (tocilizumab 18.0% and MTX 10.9%).

This study indicates that tocilizumab is an efficacious and safe treatment in RA patients with inadequate response to MTX.