Low-dose Rituximab and High-dose Dexamethasone as First Line Treatment for Adult Patients With Immune Thrombocytopenic Purpura.

ITP is an autoimmune disorder characterized by formation of autoantibodies against platelet antigens leading platelet destruction and bleeding. Corticosteroids increase the platelet count in about 80 percent of patients.However, many patients have a relapse when the dose of corticosteroid is reduced. Debilitating side effects are common in patients who require long-term corticosteroid therapy to maintain the platelet count. Rituximab, a chimeric anti-CD20 monoclonal antibody, has been shown to be effectively raise the platelet count in some patients with ITP and there is clinical and biological evidence to suggest that, if given early, rituximab may prevent ITP relapses. Rituximab 375 mg/m2 weekly for four weeks has significant activity in patients with immune thrombocytopenia. Furthermore, using lower dose rituximab the level of B-cell depletion and the response rates appear similar to those previously observed with standard dosages in a population of ITP.

The purpose of this study is to determine the response rate and response duration with the combination of low-dose rituximab (100mg IV days 1,8, 15 and 22) and high-dose dexamethasone (40mg PO days 1,2,3,4) in untreated adult patients immune thrombocytopenic purpura.

A complete platelet response is defined as an increase in platelet counts to >150×109/L on two consecutive occasions. A partial response is defined as an increase in the platelet count to between 50 and 150×109/L on two consecutive occasions, 1 week apart. Duration of response is considered from the day of the initial infusion to the first time of relapse (platelet count <30×109/L)or to time of analysis.