Prevention of Complete TTP Relapses by Immediate Initiation of Rituximab Treatment.

Plasma exchange (PE) is the treatment of choice in thrombotic thrombocytopenic purpura (TTP) patients. The use of PE has decreased the mortality rate of TTP from 90 to 10–30%. However PE is costly, technically demanding and often associated with serious complications such as infection and/or transfusions reactions. Some patients are also unresponsive to PE. In recent studies patients with refractory TTP have achieved sustained remission after Rituximab treatment. Patients with chronic TTP are very often afraid of PE. We cared for 4 anxious patients, who refused PE treatment on the one side and demanded treatment in their early phase of relapse on the other side. Therefore we treated 4 patients with a beginning relapse of TTP with Rituximab (375 mg/m²/week) before onset of symptoms. The 4 patients had already suffered from 10, 3, 4 and 5 relapses. Due to close control of laboratory data in an 8 or 12 weekly interval it was possible to detect deterioration of laboratory data (decrease of platelets <50.000, increase of LDH>500 U/l, decrease of ADAMTS-13 activity to <6.5%, increase of inhibitor to ADAMTS-13 >4BU and detection of schistocytes in the blood smear). Already after the first or second Rituximab dose a significant effect on the laboratory data was seen (increase of platelets >100.000, decrease of LDH to normal values, increase and normalization of ADAMTS-13 activity, decrease of inhibitor titer and disappearance of schistocytes). In the mean observation time (3–12 months) no deterioration of laboratory data and no TTP symptoms were observed. No side effects of Rituximab occurred. Based on our experience we recommend close control of laboratory parameters and an immediate treatment before onset of symptoms in patients with impending relapses. Up to now the reasons for these rapid effects of Rituximab are not fully understood. Other mechanisms of Rituximab treatment in TTP compared to lymphoma therapy might be possible.