Importance of immunogenicity testing for cost-effective management of psoriasis patients treated with adalimumab.

INTRODUCTION:Up to 30% of patients treated with anti-tumor necrosis factor drugs do not respond adequately, and up to 50% lose response over time. Immunogenicity is now known to be one of the main causes of this loss of response. METHODS:Serum levels of adalimumab and anti-drug antibodies (ADAs) were measured in 19 patients with psoriasis. RESULTS:Eighty-nine percent of the patients were responders (Psoriasis Area Severity Index (PASI) > 75) and 11% were partial responders (PASI 50-75). The serum levels of adalimumab were lower than the cutoff in both of the partial responders and the ADAs were high, whereas the other 17 patients had adalimumab levels above the cutoff and low ADA levels. Both partial responders were obese and none of them were taking methotrexate. Both patients switched to ustekinumab, and a PASI 90 response was observed after 16 weeks. CONCLUSION:Immunogenicity is a risk of biological drugs. In this work, the detection of low levels of adalimumab and high levels of ADAs using a sandwich ELISA correlated with loss of clinical response. Testing immunogenicity and the drug pharmacokinetics of biological drugs in psoriasis patients will probably be part of the daily management of these patients in the future.