We report the long-term outcome results of 57 consecutive adult patients with immune thrombocytopenia after being treated with rituximab. According to the different period of therapy, patients received either standard dose (SD) rituximab (i.e., 375 mg/m(2) weekly for 4 weeks) or low dose (LD) rituximab (i.e., 100 mg flat dose weekly for 4 weeks). Overall (OR) and complete response (CR) rates were 60 and 40%, respectively. Patients' median follow-up was 52 months, 82 months in the SD, and 44 months in the LD group; 15 out of 34 responsive patients (44%) relapsed, with median response duration of 24 months (range 3-120). The estimated 4-years event-free survival (EFS, considering events the non response status at month 2 or relapses in responders) was 30%. Patients who received SD vs. LD rituximab had better outcome with regard to short term response (OR 66 vs. 52%, CR 50 vs. 28%), relapse rate (38 vs. 54%), probability to achieve and maintain long-term response (41 vs. 24%) and estimated 4-years EFS (35 vs. 23%). Patients with a longer interval between diagnosis and rituximab therapy had worse EFS [HR = 1.005; 95%IC: (1.002-1.009), P = 0.019]. Three patients developed short-term adverse events, two-serum sickness, and one interstitial pneumonia. Four cases of malignancies and two herpes zoster reactivations were registered during long-term follow-up; one patient died for cerebral bleeding. Rituximab SD appears a safe and active agent allowing in nearly 40% of cases to achieve long-term response and splenectomy sparing effect.
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