Long-term follow-up analysis after rituximab therapy in children with refractory symptomatic ITP: identification of factors predictive of a sustained response

We report the long-term follow-up (median 39.5 months) of 49 paediatric patients (33 females and 16 males) with refractory symptomatic immune thrombocytopenic purpura (ITP) treated with rituximab. The overall response rate was 69% (34/49 patients). Twenty-one responders had a platelet count >50 x 10(9)/l at a median 20.2 months from treatment. Kaplan-Meier analysis showed a probability of relapse-free survival (RFS) of 60% at 36 months from the first rituximab infusion. The number of infusions and a previous splenectomy did not influence overall response rate. Patients who achieved complete response were significantly older at diagnosis and first rituximab infusion than partial responders (P = 0.027). Older children displayed a significantly greater probability of sustained response (RFS) at 36 months than younger children (88.9% vs. 56.7%, P = 0.037). Earlier responses (within 20 d from treatment) were significantly associated with both complete (P = 0.004) and sustained response (P = 0.002). Only mild and transient side-effects were observed in 9/49 children; no major infections nor delayed toxicities were recorded during the follow-up.