Background/Purpose: Tocilizumab is a humanized monoclonal antibody that binds to IL-6 receptor, blocking its effects. The efficacy and safety of tocilizumab in rheumatoid arthritis (RA) patients were evaluated in a comprehensive global clinical development program with several phase III studies, following the initial development in Japan. The long-term efficacy of tocilizumab was also established based on the follow-up of prior pivotal studies. Although efficacy and safety of the drug is consistent in the literature, efficacy and safety data in Brazilian population are scarce. The RITMO study collected the long-term safety and efficacy of tocilizumab associated with methotrexate in patients with RA with inadequate response to disease-modifying antirheumatic drugs (DMARD) therapy. The Brazilian cohort of RITMO study followed patients over a period of 2 years. Therefore, the aim of the present study is to evaluate safety and efficacy of tocilizumab 8 mg/kg associated with methotrexate in the treatment of Brazilian patients with moderate to severe RA with inadequate response DMARDs therapy. 

Methods: RITMO was an open-label, phase 3,  single-arm study conducted in 10 countries from Latin America to evaluate follow-up of intravenous tocilizumab, in association with methotrexate, in patients with moderate to severe active RA with inadequate response to DMARDs. Brazilian patients were enrolled to the extension study and were followed during 2 years, receiving treatment for 96 weeks. Efficacy and safety-related outcomes were analyzed. This analysis includes only Brazil data. (Clinicaltrials.gov NCT00754572).

Results: 98 patients were included in this analysis. Patients presented early response to the study drug with rapid improvement, of which 32% of the patients achieved ACR20 response in the second week of treatment. In addition, the functional disability in patients decreased during the study, through reduction of HAQ-DI mean value from 1.6 ± 0.7 to 0.80 ± 0.40. After 24 weeks of treatment, patients achieved response rate of 77%, 57% and 39% for ACR20, ACR50 and ACR70, respectively; these response rates remained stable after this period. After 96 weeks, 46.1% of the patients met DAS28 remission criteria. Prevalence of adverse events was 115.6 events/100 patients-year, with 14 serious adverse events (2/100 patients-year); 145 infections in 63 patients (20.2/100 patients-year) were reported, of which 6 were serious infections (0.8/100 patients-year).

Conclusion: Tocilizumab associated with methotrexate in RA patients with inadequate response to DMARDs therapy was safe and effective. The analysis of the Brazilian cohort of RITMO study was consistent with prior reported phase III studies.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/tocilizumab-in-combination-with-methotrexate-in-the-treatment-of-rheumatoid-arthritis-in-patients-who-have-failed-to-disease-modifying-antirheumatic-drugs-long-term-results-of-the-brazilian-cohort/