Rituximab in immune thrombocytopenia: gender, age, and response as predictors of long-term response

ObjectivesTo evaluate the efficacy of a salvage treatment with rituximab (RTX) in adults with primary immune thrombocytopenia (ITP), in terms of short-term response and long-term response (LTR, i.e., probability to achieve and maintain response) and to identify biological and clinical predictors of response. MethodsWe retrospectively evaluated the outcome of patients with primary ITP treated with standard dosage RTX (375 mg/m(2) x 4) as salvage therapy in five Italian centers. One hundred and three patients, median age of 46 yr, were included. The median period of observation was 59 months. ResultsResponse (R) and complete response (CR) were documented in 57 (55%) and 37 (36%) patients, respectively. Patients younger than 40 yr had a higher probability to achieve CR (P = 0.025). Younger women (age < 40 yr) had a significantly higher probability to achieve R and CR (P = 0.039 and P = 0.009, respectively). The estimated LTR rate was 36% and 31% after 48 and 72 months, respectively; female sex (P = 0.033) and younger age (P = 0.021) were associated with better LTR. Younger women had the highest LTR rate (P = 0.006). Response duration was associated with the obtainment of CR after RTX (CR vs. partial response, P = 0.002). ConclusionsThe effect of RTX salvage treatment appears higher in younger women, with LTR rate possibly approaching that of splenectomy.