Monoclonal antibody treatment of mixed cryoglobulinemia resistant to interferon α with an anti-CD20

A controlled study has been carried out to assess the efficacy of rituximab, a chimeric antibody that binds to the B-cell surface antigen CD20, in 20 patients With mixed cryoglobulinemia (MC) and hepatitis C virus (HCV)-positive chronic active liver disease, resistant to interferon alpha (IFN-alpha) therapy. They received an intravenous infusion of 375 mg/m(2) rituximab once a week for 4 consecutive weeks. Infusion of rituximab had a good safety profile and no severe side effects were reported. Sixteen patients (80%) showed a complete response (CR), characterlied by rapid improvement of clinical signs (disappearance of purpura and weakness arthralgia and improvement of peripheral neuropathy), and decline of cryocrit. CR was associated with a significant reduction of rheumatoid factor (RF) activity and anti-HCV antibody titers. Decline of IgG anti-HCV titers in the cryoprecipitates was Usually associated with a favorable response (r = 0.81; P < .005). No differences in the dynamics of B-cell depletion and recovery were found between responders and nonresponders. Molecular monitoring of the B-cell response revealed disappearance/deletion of peripheral clones in the responders and great stability in the nonresponders. Rituximab had a deep impact on hepatitis C viremia; HCV ANA increased approximately twice the baseline levels in the responders, Whereas it remained much the same in the nonresponders. Twelve (75%) of 16 responders remained in remission throughout the follow-up. The results indicate that rituximab has clinical and biologic activity in patients with HCV+ MC. However, in view of the increased viremia in the responders, additional modes of application and combination of rituximab with other agents need to be investigated. (C) 2663 by The American Society of Hematology.