This phase II trial included 465 patients who were inadequately responding to methotrexate (MTX) treatment and who had failed prior treatment with one or more disease-modifying anti-rheumatic drugs.
The study evaluated the efficacy and safety of two doses of Rituxan in combination with MTX and explored the role of corticosteroids. Patients, randomized into one of nine treatment arms, received a stable dose of MTX and varying doses of Rituxan and corticosteroids.
Regardless of dose, the results indicated that Rituxan provided clinically and statistically significant improvement in symptoms of rheumatoid arthritis compared to placebo. The improvement in response rates was shown to be independent of corticosteroids.
The data did not reveal any unexpected safety signals. The most frequently reported adverse events in the study were primarily infusion-related and mild-to-moderate in intensity, including headache, nausea and rigors. Intravenous corticosteroid pre-medication appeared to reduce the incidence and severity of first infusion reactions. Oral corticosteroids did not appear to provide any additional safety benefit.
The reported rate of serious adverse events was higher in the Rituxan groups, but similar to those seen in previous studies of Rituxan in rheumatoid arthritis.
These results follow recent positive findings from a phase III study that evaluated the efficacy and safety of Rituxan in patients with active rheumatoid arthritis who had an inadequate response or were intolerant to prior treatment with one or more anti-TNF therapies.
The companies are planning to evaluate two doses of Rituxan in a phase III study of patients who are inadequately responding to MTX and who have failed prior treatment.
Rituxan is a therapeutic antibody that targets and selectively depletes CD20 positive B cells without targeting stem cells or existing plasma cells. B cells may play multiple roles in the pathophysiology of rheumatoid arthritis. Rituxan is also being investigated in other autoimmune diseases, including lupus, multiple sclerosis and ANCA-associated vasculitis.