Tocilizumab monotherapy versus adalimumab monotherapy for treatment of rheumatoid arthritis (ADACTA): a randomised, double-blind, controlled phase 4 trial

Background: Roughly a third of patients with rheumatoid arthritis treated with biological treatments receive them as monotherapy. Tocilizumab--an inhibitor of interleukin 6 receptor signalling--has been studied as monotherapy in several clinical trials. We assessed the efficacy and safety of tocilizumab monotherapy compared with adalimumab monotherapy for patients with rheumatoid arthritis.

Methods: We did this randomised, double-blind, parallel-group, phase 4 superiority study in 76 centres in 15 countries in North and South America, Australasia, and Europe. We enrolled patients who were aged at least 18 years, had severe rheumatoid arthritis for 6 months or more, and were intolerant to methotrexate or were inappropriate for continued methotrexate treatment. Patients were randomly assigned (1:1; block size of four) to receive tocilizumab 8 mg per kg bodyweight intravenously every 4 weeks plus placebo subcutaneously every 2 weeks or adalimumab 40 mg subcutaneously every 2 weeks plus placebo intravenously every 4 weeks for 24 weeks. Investigators, patients, and sponsor personnel were masked to assignment. The primary endpoint was change in disease activity score using 28 joints (DAS28) from baseline to week 24. This trial is registered with ClinicalTrials.gov, number NCT01119859.

Findings: We screened 452 patients and enrolled 326 patients. The intention-to-treat population contained 325 patients (163 assigned to tocilizumab, 162 assigned to adalimumab). Week 24 mean change from baseline in DAS28 was significantly greater in the tocilizumab group (-3·3) than in the adalimumab group (-1·8) patients (difference -1·5, 95% CI -1·8 to -1·1; p<0·0001). 16 of 162 (10%) patients in the adalimumab group versus 19 of 162 (12%) in the tocilizumab group had serious adverse events. More patients in the tocilizumab group than in the adalimumab group had increased LDL-cholesterol, increased alanine aminotransferase concentrations, and reduced platelet and neutrophil counts.

Interpretation: Tocilizumab monotherapy was superior to adalimumab monotherapy for reduction of signs and symptoms of rheumatoid arthritis in patients for whom methotrexate was deemed inappropriate. The adverse event profiles of tocilizumab and adalimumab were consistent with previous findings.

Funding: F Hoffmann-La Roche.