Management of nonviral mixed cryoglobulinemia vasculitis refractory to rituximab: Data from a European collaborative study and review of the literature

Background: Glucocorticoids (GCs) plus rituximab (RTX) represent the first-line treatment of nonviral mixed cryoglobulinemia vasculitis (CryoVas). However, data on therapeutic management and outcome of patients refractory to RTX are lacking. Methods: We conducted a European collaborative retrospective multicenter study of patients with nonviral mixed CryoVas refractory to RTX and performed a literature review. Results: Twenty-six original cases and 7 additional patients from the literature were included. All patients but one had type 2 cryoglobulinemia, and causes were autoimmune disease (51%), malignant hemopathy (12%) or essential CryoVas (42%). CryoVas was primary refractory to RTX in 42%, while 58% had an initial response to RTX before immune escape. After RTX failure, patients received a median of 1 (IQR, 1-3) line of treatment, representing 65 treatment periods during follow-up. Main treatments used were GCs in 92%, alkylating agents in 43%, RTX in combination with other treatments in 46%, and belimumab in 17%. Combination of anti-CD20 plus belimumab, alkylating agents alone and anti-CD20 plus alkylating agents provided the highest rates of clinical response in 100% 82% and 73%, respectively, but showed poor immunological response, in 50%, 30% and 38%, respectively. Rates of severe infection were 57%, 9% and 0% in patients receiving anti-CD20 plus belimumab, alkylating agents alone and anti-CD20 plus alkylating agents, respectively. Conclusion: In patients with nonviral mixed CryoVas refractory to RTX, anti-CD20 plus belimumab, and alkylating agents associated or not with anti-CD20, provide the highest rates of clinical response. However, anti-CD20 plus belimumab was frequently associated with severe infections.