Serum concentrations of infliximab in patients with Behçet's disease

Abstract

AbstractPurpose We investigated the relationship between the serum concentrations of infliximab (IFX), an anti‐tumor necrosis factor‐alpha monoclonal antibody, and its therapeutic effect in patients with Behçet's disease (BD) who were receiving IFX therapy.Methods Nine BD patients (7 males and 2 females) with uveitis who were receiving IFX therapy for 1 years or longer were included in this study. IFX (5‐6 mg/kg) was administered at weeks 0, 2, and 6 and thereafter every 8 weeks. After informed consent was obtained, peripheral blood samples were collected before the IFX infusion. The serum concentrations of IFX were measured by enzyme‐linked immunosorbent assay.Results In the 6 patients who did not develop any uveitis attacks, the mean serum concentration of IFX was 3.6‐13.5 μg/ml, while the mean concentration was < 0.1‐1.58 μg/ml in three patients who had uveitis attacks. We speculate that the uveitis attacks occurred in the three patients because of the low IFX concentrations, and shortened the IFX administration interval from 8 weeks to 6 or 7 weeks. Thereafter, two of the three patients did not have any uveitis attacks. The serum concentration of IFX in the two patients was increased from 0.1 to 5.5 μg/ml and 0.2 to 3.6 μg/ml, respectively, whereas the concentration in one patient who had uveitis attacks was <0.1 μg/ml, and the neutralizing antibody titre to IFX was negative. The serum concentration of IFX was correlated with its efficacy.Conclusion Measurement of IFX serum concentration is useful to predict treatment efficacy in BD patients.