The influence of tocilizumab immunogenicity markers on the effectiveness of treating rheumatoid arthritis

Purpose. The study assesses the impact of tocilizumab immunogenicity markers on clinical response to conducted treatment in patients with rheumatoid arthritis. Materials and methods. A total of 17 patients with the confirmed diagnosis of RA receiving tocilizumab therapy for more than 1 year were enrolled into the study. Blood serum samples were collected once every six months before every drug injection during 2.5 years of treatment. The concentration of antibodies to tocilizumab and level of tocilizumab was determined using the ELISA. Additionally, DAS28 values were measured at the first and the last patient visit during the course of study, whereas levels of C-reactive protein (CRP), white blood cells, platelets, rheumatoid factor, and circulating immune complexes were only measured at the last examination. Results. Positive correlations between the antibodies to tocilizumab and the last point DAS28 values were found, as well as a negative correlation of tocilizumab level and the level of DAS28. Conclusions. The data obtained indicate a significant effect of serum levels of tocilizumab, as well as of the concentration of antibodies to tocilizumab on the effectiveness of RA treatment. A routine study of these biomarkers might be useful for individualizing treatment approaches for RA patients and determining the causes of tocilizumab resistance.