Chimeric anti-tumor necrosis factor-alpha monoclonal antibody treatment of patients with rheumatoid arthritis receiving methotrexate therapy.

OBJECTIVE: To evaluate the safety and efficacy of single and multiple doses of a chimeric anti-TNF-alpha monoclonal antibody (infliximab) in patients with rheumatoid arthritis (RA) who had active disease despite therapy with methotrexate (MTX).

METHODS: Twenty-eight patients with active RA despite receiving therapy with 10 mg/week of MTX were randomized to receive a single, blinded infusion of either placebo or 5, 10, or 20 mg/kg infliximab. Twenty-three patients who completed the blinded study entered an open, multiple dose extension study in which they received up to 3 additional infusions of 10 mg/kg infliximab at Weeks 12, 20, and 28. Safety, efficacy, and pharmacokinetics were evaluated during the blinded and open trial.

RESULTS: There were no serious infusion related reactions. In the blinded phase, 17 (81.0%) of 21 patients receiving infliximab achieved an American College of Rheumatology (ACR) 20% response at some point during the 12 weeks of followup compared to one (14.3%) of 7 patients receiving placebo (p = 0.003). Clinical improvement was evident by the first week and was sustained through Week 12. For the 19 patients who received infliximab during the blinded part of the trial and continued into the open label trial, 53% maintained an ACR 20% response with multiple infusions of 10 mg/kg infliximab through Week 40. Three patients withdrew from the trial during the open continuation phase because of adverse events: cellulitis, infusion related dizziness and headache, and vasculitic rash. Infliximab in doses of 5 to 20 mg/kg had a mean terminal half-life ranging from 9 to 12 days and was detectable in sera from most patients 8 to 12 weeks after dosing.

CONCLUSION: Infliximab is generally well tolerated during 40 weeks of therapy. A single infusion of 5 to 20 mg/kg infliximab significantly decreases the signs and symptoms of RA compared to placebo in patients with active disease receiving MTX. Multiple doses of infliximab produce sustained clinical benefit for up to 40 weeks.