A multi-centre, single-arm, open-label study evaluating the safety and efficacy of fixed dose rituximab in patients with refractory, relapsed or chronic idiopathic thrombocytopenic purpura (R-ITP1000 study)

The efficacy of a fixed-dose rituximab schedule was prospectively explored in primary/acute refractory, relapsed or chronic (platelet count >10x10(9)/l and 50x10(9)/l) idiopathic thrombocytopenic purpura (ITP). Patients received two doses of rituximab (1000mg) on days 1 and 15 and were followed-up on weeks 1-8, 12, 26, 39 and 52. A total of 122 patients were included in the safety population; efficacy was analysed in 108 patients. Overall response rate (ORR) at week 8, defined as the proportion of patients achieving complete response (CR; platelet count >150x10(9)/l) or partial response (PR; platelet count >50x10(9)/l) was 44%. Therapeutic response, defined as achieving a response at week 8, with at least a minor response (MR; platelet count >30x10(9)/l), sustained up to weeks 26 and 52 and accompanied by a reduction in ITP medications, was achieved in 44% (week 26) and 35% (week 52) of patients, respectively. Treatment was well tolerated with no safety concerns. While this study failed to meet its primary endpoint of an ORR of 50%, the efficacy of two fixed doses of rituximab appear to provide similar efficacy to the standard 375mg/m(2) four-dose schedule in relapsed/chronic ITP.