Nearly half (43.9%) of rheumatoid arthritis (RA) patients receiving tocilizumab 8mg/kg, in addition to ongoing methotrexate therapy experienced a 50% (ACR50) improvement in symptoms at 24 weeks and more than one fifth achieved a 70% symptom improvement, according to results of a European study presented at EULAR 2007, the Annual European Congress of Rheumatology in Barcelona, Spain. This study is the first phase III trial of tocilizumab.
Lead researcher Dr Josef Smolen of the Medical University of Vienna for Internal Medicine commented, "These data show the potential of tocilizumab as a novel and attractive approach to treating RA. The symptom improvements observed across both 4mg/kg and 8mg/kg doses show that tocilizumab offers significant promise to patients with moderate and severe RA."
Significant improvement in symptoms was observed in all patients receiving tocilizumab and methotrexate compared to placebo and methotrexate. At 24 weeks, an ACR70 (70% symptom improvement) was observed in 22%, an ACR50 (50% symptom improvement) in 43.9% and an ACR20 (20% symptom improvement) in 58.5% of patients receiving 8mg/kg tocilizumab plus methotrexate compared to placebo (2.0% p=<0.0001; 10.8% p=<0.0001 and 26.5% p=<0.0001 respectively). An ACR20 was equally noted in 47.9% of patients receiving 4mg/kg tocilizumab plus methotrexate compared to placebo (26.5% p=<0.0001).
A significantly higher proportion of patients treated with tocilizumab and methotrexate achieved a good/moderate EULAR response, observed in 79.5% of patients receiving tocilizumab 8mg/kg and 61.9% patients receiving 4mg/kg tocilizumab, versus 34.8% on placebo.
A reduction in Disease Activity Score (DAS28) was also observed from two weeks onwards in both tocilizumab groups, with a significant change from baseline to week 24 in patients treated with tocilizumab 8mg/kg (-3.43) and 4mg/kg (-2.68) compared to placebo (-1.55, p=0.0001).
The study involved 623 patients with sustained moderate to severe RA despite long standing treatment with methotrexate. Patients received 4mg/kg, 8mg/kg tocilizumab or placebo intravenously every four weeks for a period of 24 weeks. Patients were permitted concurrent treatment with methotrexate at their pre-study dose (10-25mg weekly). Treatment with all other disease modifying anti-rheumatic drugs (DMARDs) was discontinued at the beginning of the trial.
Tocilizumab is a novel humanised anti human interleukin 6 (IIL-6) receptor monoclonal antibody. IL-6 is a cytokine involved in the pathogenesis of RA and by targeted blockage of this receptor, tocilizumab slows down the progression of rheumatoid arthritis.
Adverse Events (AEs) were recorded throughout the duration of the trial with a similar AE profile reported in all three groups (8mg/kg, 4mg/kg and placebo). The AE profile of tocilizumab is consistent with data presented in previous studies with the treatment being generally well tolerated.
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