Immunogenicity of golimumab and its clinical relevance in patients with rheumatoid arthritis, psoriatic arthritis and ankylosing spondylitis

Objective. Golimumab immunogenicity was extensively studied during clinical development. As anti-drug antibody (ADA) detection with the standard bridging EIA (original-EIA) can yield false-negative results or underestimate ADA incidence and titres due to drug interference, a more sensitive assay was needed to determine clinical impact. Methods. A highly sensitive drug-tolerant EIA (DT-EIA) was developed and cross-validated against the original-EIA. Samples from phase-3 subcutaneous golimumab rheumatological trials (GO-FORWARD-rheumatoid arthritis, GOREVEAL-psoriatic arthritis, GO-RAISE-ankylosing spondylitis) were then retested. Associations between ADAs and golimumab pharmacokinetics, efficacy and safety were assessed. Results. The DT-EIA was more sensitive than the original-EIA and capable of detecting ADAs amid golimumab concentrations far exceeding those in immunogenicity test samples. Consequently, an 8-fold increase in the incidence of ADAs was observed with the DT-EIA (31.7%) vs original-EIA (4.1%) in the studies. Most ADA-positive patients identified by the DT-EIA had lower antibody titres, while most with higher titres were previously identified as ADA-positive by the original-EIA. With the DT-EIA, ADA-positive patients generally had lower trough serum golimumab concentrations than ADA-negative patients; however, ADA impact on serum golimumab concentrations was more notable at higher ADA titres (>= 100). No impact of ADAs on clinical efficacy or injection-site reactions was evident. Conclusion. ADA incidence was expectedly higher using the DT-EIA vs original-EIA; newly detected ADAs were characterized mostly by low titres, with no impact on clinical efficacy or injection-site reactions, consistent with previously observed original-EIA results. Golimumab immunogenicity with the DT-EIA is consistent with existing knowledge regarding the clinical relevance of ADAs detected with the original-EIA in patients with rheumatological disorders.