Background:Biological drugs are protein derivatives that, as such, are highly immunogenic. In recent years there have been many conflicting opinions about the role of drug immunogenicity in clinical practice.Objectives:To evaluate the drug immunogenicity of TNF-alpha blocking drugs (etanercept and adalimumab) used to treat patients with rheumatoid arthritis. To determine whether their presence can alter the effect of treatment and to evaluate their role in the clinical practice of rheumatologists.Methods:121 patients with rheumatoid arthritis, as well as 31 healthy controls, similar in sex and age, were examined. They were all monitored at 0, 6, 12 and 24 months from the start of TNF-alpha blocker treatment. Demographics, vital signs, markers of inflammation such as C-reactive protein (CRP), erythrocyte sedimentation rate (ESR) and disease activity indices were examined at each visit, respectively. Drug-induced neutralizing antibodies, as well as drug bioavailability in patients treated with adalimumab, were examined by ELISA.Results:Drug-induced neutralizing antibodies to adalimumab were detected in 11.57% of patients at 6 month, in 17.64% of patients at 12 month, and 24.8% at 24 month. Drug-induced neutralizing antibodies to etanercept were not detected at 6 months, at 7.77% at 12 months, at 9.63% of patients at 24 months. Of the adalimumab patients who were having drug-induced antibodies, 92.59% had low drug bioavailability, while the remaining 7.41% of patients showed normal drug bioavailability despite the presence of drug-induced neutralizing antibodies. In terms of worsening of the disease activity, a positive correlation was found with the presence of drug antibodies - Pearson Correlation = 0.701, p = 0.001. Patients with poor clinical response and available drug antibodies receiving adalimumab were slightly more than those treated with etanercept at 12 and 24 months but the difference is non-significant-U = 0.527, p> 0.05 and U = 0.623, p> 0.05, respectively.Conclusion:Presence of drug-induced neutralizing antibodies in patients treated with adalimumab and etanercept has been associated with poor clinical response and worsening of the patient’s condition. Testing of drug-induced neutralizing antibodies as well as the drug bioavailability of the drug used can be used as reliable biomarkers in clinical rheumatology.References:[1]Benucci M., F.Li Gobbi, M. Meacii et al., “Antidrug antibodies against TNF-blocking agents: correlations between disese activity, hypersensitivity reactions, and different classes of immunoglobulins”, Biologics and Targets and Therapy, 2015: 9 7 -2.[2]Chen D., Y. Chen, W. Tsai et al., “ Significant associations of antidrug antibody levels with serum drug trough levels and therapeutic response of adalimumab and etanercept treatment in rheumatoid arthritis”, Ann Rheum Dis. 2015 Mar; 74 (3).[3]Kalden J. and H. Schulze-Koops, “ Immunogenicity and loss of response to TNF inhibitors: implications for rheumatoid arthritis treatment ”, Nature Reviews Rheumatology, 2017 volume 13, 707–718.[4]Wolf-Henning Boehnck, N. Brembilla, “ Immunogenicity of biological therapies: causes and consequences, ” Expert Review of Clinical Immunology, Vol 14, 2018, Issue 6, 513-523Disclosure of Interests:None declared
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