Type II mixed cryoglobulinemia (MC) is a systemic vasculitis, associated in most cases with hepatitis C virus (HCV) infection, sustained by proliferation of oligoclonal cells. Systemic B cell depletion and clinical remission can be achieved in non-Hodgkin lymphoma by human/mouse chimeric monoclonal antibody that specifically reacts with the CD20 antigen (rituximab). Similar effects could be expected in type II MC. Twelve patients, mean age 61.9 years (range 37-76), 11 with HCV infection genotype 2a2c (4 cases) or 1b (6 cases) and 3 (1 case) and symptomatic type II MC with systemic manifestations, including renal involvement, marrow clonal restriction, large necrotizing ulcers, and polyneuropathy, were considered eligible for rituximab therapy because of resistance or intolerance to conventional therapy or important bone marrow infiltration. Rituximab was administered intravenously at a dose of 375 mg/m2 on days 1, 8, 15, and 22. Two more doses were administered 1 and 2 months later. No other immunosuppressive drugs were added. Response was evaluated by assessing the changes in clinical signs, symptoms, and laboratory parameters. Levels of proteinuria, hematuria, erythrocyte sedimentation rate, cryocrit, rheumatoid factor, and IgM decreased while C4 values increased and HCV viral load remained stable during short- and medium-term observation. Bone marrow abnormalities were found to reverse to normal. Constitutional symptoms disappeared or ameliorated. No acute or delayed side effects were seen. Based on this experience and a number of reports published in the last 5 years, Rituximab appears to be a safe and effective therapeutic option in symptomatic patients with HCV-associated MC with signs of systemic vasculitis.

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Background: In a prospective, single-center open study, we evaluated the very long-term effects of rituximab (RTX) administered to patients with severe mixed cryoglobulinemia (MC). Methods: RTX was administered to 31 patients with MC (type II in 29 cases and type III in 2) with diffuse membranoproliferative glomerulonephritis (16 cases), peripheral neuropathy (26) and large skin ulcers (7). All but 4 patients had serum anti-hepatitis C virus antibodies. RTX was administered at a dose of 375 mg/m², according to a ‘4 + 2' protocol (days 1, 8, 15 and 22 plus 1 dose 1 and 2 months later). No other immunosuppressive drugs were added. Response was evaluated over a very long-term follow-up (mean 72.47 months, range 30-148). Results: Complete remission of pretreatment active manifestations was observed in all cases of purpuric lesions and non-healing vasculitic ulcers, and in 80% of the peripheral neuropathies. Cryoglobulinemic nephropathy significantly improved during follow-up, starting from the 2nd month after RTX (serum creatinine from 2.1 ± 1.7 to 1.5 ± 1.6 mg/dl, p ≤ 0.05; 24-hour proteinuria from 2.3 ± 2.1 to 0.9 ± 1.9 g/24 h, p ≤ 0.05). Improvement of cryoglobulinemic serological hallmarks, such as cryocrit and low complement C4, were observed. No clinically relevant side effects were recorded. Re-induction with RTX was carried out in 9 relapsed patients after a mean of 31.1 months (12-54), again with beneficial effects. The survival rate was 75% at 6 years and the probability of remaining symptom-free for 10 years without any therapy was of about 60% after a single ‘4 + 2' infusion cycle, while the probability of living symptom-free 5 years after relapsing was 80% if given the same treatment. Conclusion: In this open, prospective study, RTX appeared to be very effective and safe in the treatment of the most severe cases of MC.

A promising role of RTX in an intensified protocol of induction therapy can be envisaged in patients for whom avoiding immunosuppressive maintenance therapy and sparing steroids are particularly appealing. Moreover, our data confirm in one of the longest follow-up available, the opportunity to reconsider the regimens of BL depletion in the treatment of the most severe or refractory forms of SLE despite the disappointing results of RCTs.

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