Flare of a mixed cryoglobulinaemic vasculitis after obinutuzumab infusion.

OBJECTIVES: Obinutuzumab (OBZ) is a new humanised type II anti-CD20 monoclonal antibody (mAb) approved in onco-haematology. Its use as an alternative to rituximab (RTX) in case of immunisation in autoimmune diseases has not been fully assessed yet. Here we report the case of a patient suffering from a refractory cryoglobulinaemic vasculitis (CV) associated to Sjögren's syndrome (SS) and treated with OBZ.

METHODS: Since the patient was immunised against RTX, she was treated with OBZ at relapse. Three days after the infusion of OBZ, she presented a vasculitis flare. Rheumatoid factor level, complement level and cryoprecipitation were evaluated on consecutive serum samples of the patients and after RTX and OBZ addition in vitro.

RESULTS: No evidence for cross-reactivity between anti-RTX Abs and OBZ was found. However, we could observe in vitro that cryoprecipitation was worsened by the simultaneous presence of anti-RTX Abs and RTX. We suggest that the flare of CV after OBZ infusion could be linked to a large release of immune complexes following B cells lysis induced by OBZ.

CONCLUSIONS: Based on our report, we think that the use of OBZ needs to be carefully discussed in patients with mixed CV.