Background Tocilizumab (TCZ) is an interleukin 6 (IL-6) inhibitor that is used in Rheumatoid Arthritis (RA) treatment (1). Although, IL-6 plays a role in viral immunosurveillance
Objectives We studied the effect of TCZ on the evolution in viral load for the Epstein Barr Virus (EBV), Cytomegalovirus (CMV) and Varicella Zoster Virus (VZV) in patients with RA.
Methods This was a prospective monocenter study of RA patients taking TCZ. Demographic, clinical and laboratory data were collected on each patient. Viral loads (VL) were determined in whole blood (using the EBV R-gene quantification kit, Abbott Real Time CMV kit, and Biomérieux VZV R-Gene kit) at TCZ initiation and during treatment follow-up. A difference between two viral loads of 0.5log10 copies/ml of whole blood was considered significant.
Results 22 patients were evaluated. There were 20 (89%) women of a mean age of 57.8±11.2 with seropositive (68%) and erosive (74%) RA that had been progressing for a mean of 11.3±9.7 years. TCZ was administered alone (36.7%) or in combination with methotrexate (MTX) (50%).
When TCZ was introduced, the EBV VL was positive in eight patients with a mean VL value of 1777.2±3518.3 (3.5±0.4 log10) copies/ml. Only one patient had a positive CMV VL. The VZV VL was negative in all patients. After 9.2±4.8 months had lapsed, EBV VL and CMV VL became negative in six of eight patients (p=0.02) and did not significantly vary in the remaining two patients. No VL (EBV, CMV, VZV) became positive. A positive EBV VL did not correlate with RA activity (DAS28ESR, DAS28CRP) or with inflammatory biomarkers (ESR and CRP). RA activity significantly declined after six months of TCZ treatment (DAS28ESR after six months 2.8±1.1 vs. 5.14±0.9 [p<0.001]). In our study, TCZ did not increase the VL of EBV, CMV or VZV. No other data is available for RA patients. However, in Juvenile Idiopathic Arthritis patients, Kawada et al. did not demonstrate any change in EBV or CMV VL in patients treated with MTX and TCZ, but the study was only on four patients (2). Our EBV results are identical to those that we reported on anti-TNF, which were found by other teams as well (3, 4). Nevertheless, although we did not demonstrate any changes in CMV or VZV VL in patients taking TCZ, there was one reported case of CMV pneumonia (5), one case of lethal EBV-related macrophage activation syndrome (6) and one severe case of Shingles (7).
Conclusions EBV, CMV and VZV viral loads do not seem to significantly increase with the introduction of TCZ treatment. Studies involving larger patient populations are necessary.
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Disclosure of Interest None declared