Levels of interleukin-1 beta can predict response to tocilizumab therapy in rheumatoid arthritis: the PETITE (predictors of effectiveness of tocilizumab therapy) study

Predicting the responses of patients with rheumatoid arthritis (RA) to tocilizumab is difficult, because inflammatory markers such as C-reactive protein rapidly normalize regardless of clinical efficacy. We aimed to identify factors that could predict response to tocilizumab. Sixty-five patients completed 52 weeks of tocilizumab therapy. Serum fibrinogen, D-dimer and interleukin (IL)-1β levels were measured at baseline and after 4 weeks of therapy. Clinical responses to tocilizumab were assessed using disease activity score 28-erythrocyte sedimentation rate and the clinical disease activity index at baseline and after 52 weeks of therapy (UMIN Clinical Trials Registry No. UMIN000002246). Mean age was 60.5 years (range 22–85 years). Mean disease duration was 11.2 years (range 0–45 years). All patients had moderate-to-severe disease activity and were resistant to disease-modifying anti-rheumatic drugs and/or other biologics. Baseline IL-1β levels were significantly lower in responders than in non-responders (p = 0.045), but multiple logistic regression analysis found no significant difference (adjusted odds ratio 2.74; 95 % confidence interval 0.84–8.95; p = 0.096). Low D-dimer and IL-1β levels at 4 weeks predicted greater decrease in disease activity after 52 weeks of treatment (p = 0.005 and p < 0.001, respectively). Effects of tocilizumab at 52 weeks could be predicted from D-dimer and IL-1β levels after 4 weeks of tocilizumab treatment. These markers might be more useful than current inflammatory markers for early-stage prediction of response to tocilizumab in RA.