A Prospective Randomized Study of Rituximab and Dexamethasone vs Dexamethasone Alone in ITP.

Previous uncontrolled studies have highlighted the potential activity of Rituximab in patients with idiopathic thrombocytopenic purpura (ITP) relapsed or refractory to standard treatments. To better address this effect, a prospective randomized, multicenter, phase III study comparing treatment with Dexamethasone alone (arm A) vs Dexamethasone plus Rituximab (arm B) was started in July 2005 for adult patients with ITP according to the ASH guidelines. Main inclusion criteria were: age ≥ 18 years, untreated ITP, platelet (PLT) count ≤ 20 x10⁹/L, HIV- HCV-HbsAg negativity, informed consent. Patients randomized to arm A received a single course of Dexamethasone 40 mg po on days +1, +2, +3, +4, while patients randomized to arm B received Dexamethasone (as in arm A) in association with Rituximab 375 mg/m² iv on days +7, +14, +21, +28. Patients in arm A who failed to achieve a sustained response (SR) could be rescued with arm B treatment. The primary objective of the study was to compare SR, i.e. PLT ≥ 50 x 10⁹/L at month + 6 of treatment. The secondary objectives were: the initial overall (OR= PLT ≥ 50 x10⁹/L) and complete response (CR= PLT ≥ 100 x 10⁹/L) by day 30 after starting treatment, respectively; the toxic profile. The statistical plan considered three interim analyses, after the first 50, 100 and 150 enrolled patients, with an estimated sample size of 198 patients (99 per arm). Table 1 summarizes the main demographic data and the results of efficacy and toxicity according to an intention to treat analysis of the first interim analysis. The toxic profile was characterized by only grade 3 adverse events (AE); no patient died during the study period. 16 patients of arm A were rescued with arm B. For this group SR was 81% and no patient experienced SAE or ≥ grade 3 AE. In accordance with the initial statistical plan of the study, which stated that patients’ recruitment would ceased if a ≥ 50% difference in sustained response was demonstrated, enrolment has been stopped in June 2007 with a total number of 103 randomized patients. This preliminary report indicates a significantly higher SR for arm B of treatment with no difference in toxicity profile. A final report will be prepared when the results on the entire study group will be available.