Efficacy of tocilizumab monotherapy after response to combined tocilizumab and methotrexate in patients with rheumatoid arthritis: the randomised JUST-ACT study

Objective The aim of the JUST-ACT study was to assess whether the add-on effect of tocilizumab (TCZ) to background methotrexate (MTX) observed in MTX-inadequate responders with active rheumatoid arthritis (RA), would be sustained when MTX is withdrawn. Methods A double-blind, parallel-group, phase 3 study in biologic-naive RA patients with a disease activity score 28 (DAS28)>3.2 despite MTX which were treated with TCZ+MTX for an initial 16-week period. Patients who at week 16 achieved low disease activity (LDA) (DAS28 <= 3.2) were randomised to continue with TCZ+MTX or switch to TCZ + placebo (PBO) for an additional 12 weeks. The primary endpoint was the change in DAS28-ESR from the randomisation at week 16 to week 28. Non-inferiority was confirmed if the upper limit of the two-sided 95%CI for the treatment difference between TCZ+MTX and TCZ monotherapy groups was lower than the selected non-inferiority margin of 0.6. Results 261 patients completed the first 16 weeks of TCZ+MTX treatment and 165 were randomised (83 to TCZ+MTX and 82 to TCZ+PBO). For the primary endpoint, the adjusted treatment difference (95% CI) in mean change of DAS28-ESR was -0.06 (-0.40 to 0.27), and therefore the non-inferiority of switching to TCZ monotherapy versus continuing with TCZ+MTX was demonstrated. In both treatment groups, the percentage of patients in clinical remission from 16 to 28 weeks was similar as were the improvements in disease activity, functional disability and quality of life. Conclusion In MTX non-responder patients achieving LDA with TCZ+MTX, switching to TCZ monotherapy is non-inferior to continuing the combination.