Single Dose of Anti-CD20 Monoclonal Antibody (Rituximab) Treatment in Adults with Refractory Immune Thrombocytopenic Purpura (ITP).

Refractory Immune Thrombocytopenic Purpura (ITP) is a difficult disease to treat effectively and the mortality approaches nearly 10% over 10 years. Moreover, the side effect profile of chronic steroid administration is undesirable due to the multi-systemic actions of these drugs. Recently, it has been reported in the literature that Rituximab is effective treatment for chronic ITP and it has been used at a dose of 375mg/m² weekly for up to four weeks, as with lymphoma therapy. Rituximab is an expensive treatment, but according to previous data, patients treated with this drug have responded with increased and sustained platelet counts following only one infusion. Based on this, we treated five refractory ITP patients with single-dose Rituximab and all responded well.

Patient 1 is with a 15 year history of ITP and Patient 2 is with a 34 year long history of ITP. Following treatment with Rituximab, although there was an interval of up to 7 months, both eventually responded well. Patient 3 is a 93 year old male who presented to our hospital with an acute presentation of ITP which involved severe gastrointestinal bleeding and this proved to be refractory to both steroids and intravenous immunoglobulins, but responded very quickly to Rituximab within 24 days. Patient 4 is a 75 year old female with diabetes mellitus and three-vessel coronary artery disease who presented with a bleeding diathesis. She was treated with steroids, intravenous immunoglobulins, danazol and azathioprine but with no response. Single-dose Rituximab was effective within 20 days with an improvement in platelet counts. Patient 5 is a 51 year old male with a six year history of ITP who presented to our hospital with massive intraabdominal and gastrointestinal bleeding and after Rituximab therapy his platelet count responded appropriately after 45 days.

These patient responses were not associated with prior response to therapy, age, previous splenectomy, duration of ITP or platelet count. All patients tolerated treatment well except one patient who developed SLE-nephrotic syndrome 15 months later although it cannot be proven that such therapy induced this collagen-vascular diseases because Rituximab can be used to actually treat such conditions. Three patients remained in remission for more than one year after just one dose of the Rituximab therapy. Even from our small number of refractory ITP patients treated with Rituximab, it is our experience that single-dose treatment is also effective in some cases of refractory ITP and its effect may continue to provide long-term remission whereby it is now possible to decrease and even stop long-term steroid treatment in such patients.