Final results of the international, open –label phase III study evaluating the safety and efficacy of romiplostim (Nplate™) in adults with primary immune thrombocytopenia (ITP) were presented at conference.

The study evaluated the incidence of adverse events and antibody formation in 407 adults (51% had previously undergone a splenectomy) who were treated with romiplostim once weekly, with dose adjustments to maintain platelet counts of greater than or equal to 50,000 platelets/microlitre.

Over the course of the study, a median of 44 weeks, a doubling of the platelet count to greater than or equal to 50,000 platelets/microlitre was achieved by 91% of patients who received romiplostim. A platelet count increase of greater than or equal to 20,000 platelets/microlitre from baseline (secondary outcome) was achieved by 93% of patients who received romiplostim. Median time to response was one to two weeks.

In the study, incidence and type of adverse events in treated patients were consistent with those reported in previous studies with the most common ones being headache, arthralgia and fatigue.