Rituximab therapy in adult patients with relapsed or refractory immune thrombocytopenic purpura: long-term follow-up results

OBJECTIVE: To evaluate the long-term activity and toxicity profile of rituximab in adult patients with idiopathic immune thrombocytopenic purpura (ITP). PATIENTS AND METHODS: Twenty-six patients with active and symptomatic ITP relapsed or refractory received weekly infusions of rituximab 375 mg/m(2) for 4 wk. Median time from diagnosis to rituximab was 34.5 months. The following parameters of efficacy and toxicity were considered: complete response (CR) and partial response (PR), relapse rate, relapse-free survival (RFS), therapy-free survival (TFS), short- and long-term toxicity. RESULTS: CR and PR were 14/26 (54%) and 4/26 (15%), respectively. Median time of observation was 56.5 months (range 39-77). Nine of the 18 responding patients relapsed after a median of 21 months (range 8-66); 9/26 patients (35%) maintained the response, with a median follow-up of 57 months (range 39-69), and 11/26 (42%) did not necessitate further therapy; estimated 5 yr RFS and TFS were 61% and 72%, respectively. Younger age and shorter interval from diagnosis to rituximab appeared indicators of better outcome. Rituximab administration was associated with two episodes of short-term toxicity, with one case of serum sickness syndrome; no infectious or other significant long-term complications were documented. CONCLUSION: Rituximab therapy may achieve long-lasting remission in nearly one-third of patients with relapsed or refractory ITP, with a good safety profile.