Relapsing or refractory idiopathic thrombotic thrombocytopenic purpura-hemolytic uremic syndrome: the role of rituximab.

Idiopathic thrombotic thrombocytopenic purpura-hemolytic uremic syndrome (TTP-HUS) is a rare disease responsive to treatment with plasma exchange (PE) but with a high percentage of relapse or refractory patients. A severe deficiency of ADAMTS-13 (<5% of normal activity), congenital or caused by an autoantibody, may be specific for TTP and it has been proposed that severe ADAMTS-13 deficiency now defines TTP. B cells play a key role in both the development and the perpetuation of autoimmunity, suggesting that B-cell depletion could be a valuable treatment approach for patients with idiopathic TTP-HUS. This review of the literature focuses on the role of rituximab, a chimeric monoclonal antibody directed against CD20 antigen expressed by B lymphocytes, in patients with relapsing or refractory TTP-HUS with or without ADAMTS-13 deficiency, suggesting that rituximab may produce clinical remission in a significant proportion of patients. Rituximab therapy reduces plasma requirement and avoids complications related to salvage-immunosuppressive therapy. In conclusion, rituximab provides an effective, well-tolerated, and safe treatment option for patients with idiopathic TTP-HUS, thus giving an alternative approach to the current treatment based on PE.

Hepatitis B virus reactivation and alemtuzumab therapy.

Reactivation of hepatitis B virus infection in subjects receiving cytotoxic treatment for heamatological malignancies occurs in 21-53% of chronic HBsAg carriers and in an unknown number of HBsAg negative subjects harbouring occult HBV infection. Immunotherapy with alemtuzumab, a humanized monoclonal antibody against CD52 epitopes on lymphocytes cells produces deep immunosuppression. We describe two subjects with chronic lymphocytic leukaemia and occult HBV infection who developed a virological and biochemical flare of hepatitis B following immunotherapy with alemtuzumab. One of them developed full blown hepatitis with seroreversion from anti-HBs to HBsAg after four weeks of alemtuzumab therapy. Lamivudine (100 mg die) achieved a complete clinical recovery and HBV-DNA clearance from blood within 8 weeks. The second patient (HBsAg and HBV-DNA seronegative, anti-HBs and anti-HBc positive before treatment) was kept under prophylaxis with lamivudine up to three months after alemtuzumab. Two months after withdrawal of lamivudine, clinical and laboratory features of acute hepatitis B developed. Lamivudine therapy was restarted and a prompt recovery was obtained with HBsAg and HBV-DNA clearance.