Immunogenicity of anti-tumor necrosis factor antibodies - toward improved methods of anti-antibody measurement

To date, millions of people have been treated with therapeutic monoclonal antibodies (TmAbs) for various indications. It is becoming increasingly clear that TmAbs can be immunogenic, which may reduce efficacy or induce adverse effects. Over the years, the importance of antibody formation has been questioned and sometimes minimized, as few antibody responses to TmAbs (HACA or HAHA) were reported. However, the methods to detect and quantify such antibodies used in the past have been problematic. Only recently, methods have been developed that have adequate sensitivity and are not seriously disturbed by false-positive reactions caused by rheumatoid factors, natural antibodies to Fab or F(ab')(2) fragments, or Fc interactions of IgG4. The large number of treated patients, in combination with these new assays, presents a unique opportunity to study the anti-antilbody immune response in man, possibly allowing us to manipulate immunogenicity in the future.