[Rituximab immunomonitoring in autoimmune diseases: a support tool in clinical practice?]

Immune monitoring of monoclonal antibodies is a helpful tool in optimizing the management of patients treated with TNF blockers, especially in gastroenterology. In contrast, studies evaluating the interest of such monitoring are lacking for other monoclonal antibodies used in autoimmune diseases, including rituximab despite its widespread use in the field for almost 15 years. Hence, we conducted a study whose goal was to describe the clinical and biological characteristics of all patients who had a rituximab immune monitoring.

All the clinical, biological and therapeutic data attached to the demands (from 2015 onwards) we received for immune monitoring of rituximab (measurements of rituximab serum levels and anti-rituximab antibodies using the drug-sensitive assay LISA-TRACKER Duo Rituximab®), were retrospectively reviewed. Suspected cases of hypersensitivity and secondary non-response were included.

Several medical specialities (nephrology, haematology, neurology, rheumatology, internal medicine) were represented among the 18 records included in the study (out of 23 demands), 10 being suspected cases of hypersensitivity and 8 secondary non-responders. All 6 patients whose symptoms were consistent with the classical presentation of serum sickness, as well as half of the secondary non-responders, were positive for antirituximab antibodies.

This detailed real world case study illustrates the potential benefits of rituximab immune monitoring (especially anti-rituximab antibodies) in autoimmune diseases, suggesting it could be helpful in suspected cases of serum sickness, as well as secondary non-response (B-cell non-depletion being an early red flag). Larger and disease-specific studies are warranted to support these findings.