Real-life drug retention rate and safety of rituximab when treating rheumatic diseases: a single-centre Swiss retrospective cohort study

Evaluation of serum Epstein-Barr virus envelope glycoproteins antibodies and their association with systemic autoimmune diseases

Systemic autoimmune diseases (SADs) are a growing spectrum of autoimmune disorders that commonly affect multiple organs. The role of Epstein-Barr virus (EBV) infection or reactivation as a trigger for the initiation and progression of SADs has been established, while the relationship between EBV envelope glycoproteins and SADs remains unclear. Here, we assessed the levels of IgG, IgA, and IgM against EBV glycoproteins (including gp350, gp42, gHgL, and gB) in serum samples obtained from patients with rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE), and found that RA and SLE patients exhibited a statistically significant increase in the levels of 8 and 11 glycoprotein antibodies, respectively, compared to healthy controls (p < 0.05). The LASSO model identified four factors as significant diagnostic markers for RA: gp350 IgG, gp350 IgA, gHgL IgM, and gp42 IgA; whereas for SLE it included gp350 IgG, gp350 IgA, gHgL IgA, and gp42 IgM. Combining these selected biomarkers yielded an area under the curve (AUC) of 0.749 for RA and 0.843 for SLE. We subsequently quantified the levels of autoantibodies associated with SADs in mouse sera following immunization with gp350. Remarkably, none of the tested autoantibody levels exhibited statistically significant alterations. Elevation of glycoprotein antibody concentration suggests that Epstein-Barr virus reactivation and replication occurred in SADs patients, potentially serving as a promising biomarker for diagnosing SADs. Moreover, the absence of cross-reactivity between gp350 antibodies and SADs-associated autoantigens indicates the safety profile of a vaccine based on gp350 antigen.

Cross-Reactivity of Antibodies to Rituximab with Other Therapeutic Anti-CD20 Antibodies

One reason for a lack of response to rituximab as well as infusion-related anaphylactic adverse events is the development of antidrug Abs to rituximab. Besides rituximab, a number of other therapeutic Abs targeting CD20 are nowadays available as alternatives. In this study, we investigated the potential cross-reactivity of (human) anti-rituximab Abs to three other anti-CD20 mAbs: ofatumumab, obinutuzumab, and ocrelizumab. In 25 cases of anti-rituximab Abs, cross-reactivity was examined using both direct binding assays and inhibition immunoassays. Although no cross-reactivity was observed to ofatumumab or obinutuzumab, 8 of 25 samples also showed reactivity toward ocrelizumab in at least one of the two assays. Furthermore, in three cases of anti-ocrelizumab Abs, cross-reactivity to rituximab was observed in an inhibition immunoassay, albeit not in a direct binding assay. Our results suggest that obinutuzumab or ofatumumab are safe anti-CD20 alternatives in case of the presence of anti-rituximab Abs. It is advisable to proceed cautiously if switching from rituximab to ocrelizumab (or vice versa) is considered in case these alternatives may not be available.