To determine the frequency and correlates of autoantibody formation in patients with rheumatic diseases treated with infliximab in a routine clinical setting.
All patients receiving at least 5 infusions of infliximab, and with anticipated continuation, were prospectively evaluated for the development of the following antibodies: antinuclear antibody (ANA), anti-DNA, anti-Sm, anti-RNP, anti-SSA and anti-SSB. Correlates with pharmacologic treatments, response to infliximab, and adverse events were assessed.
Seventy-six percent of 42 patients receiving prolonged treatment with infliximab developed new autoantibodies, and these persisted in 57%. The most common new autoantibody was ANA in 45%, followed by anti-DNA in 33%, anti-Sm in 31%, and anti-RNP in 29%. New autoantibody formation was associated with both a greater number of infusions (p = 0.015) and a higher total dose of infliximab infused (p = 0.047). No other treatment, disease characteristic, or loss of efficacy to infliximab discriminated between those developing antibodies compared to those without new antibody formation. No patient developed clinical signs of a new connective tissue disease.
Autoantibody formation is seen commonly in patients receiving prolonged treatment with infliximab. Concomitant immunosuppressive treatments did not preclude the formation of antibodies. The clinical significance of antibody formation remains to be determined.