Multicenter, prospective study to evaluate the efficacy of biweekly romiplostim administration in patients with immune thrombocytopenia

Abstract

Multicenter, prospective study was conducted to evaluate the efficacy of biweekly romiplostim in maintaining platelet >/= 30 x 10(9)/L for at least 4 weeks. Treatment was started with a weekly injection (1 mcg/kg), and the dose was escalated until a titrated dose was achieved that maintained a platelet 50-200 x 10(9)/L for four consecutive weeks. Patients were scheduled to a biweekly schedule, and returned to a weekly schedule if platelets fell to <30 x 10(9)/L. Eighteen patients were enrolled (median platelet, 14 x 10(9)/L). After the first weekly schedule, ten of eighteen (55.6 %) attained a median titrated dose of 3 mcg/kg and proceeded to the first biweekly schedule. However, all failed to maintain a platelet >/= 30 x 10(9)/L for at least 4 weeks, and returned to a second weekly schedule, where eight of the ten achieved a titrated dose (median, 5 mcg/kg) and moved to a second schedule of biweekly romiplostim. Three of the eight (37.5 %) showed platelet >/= 30 x 10(9)/L for 4, 8, and 10 weeks, but all eight patients eventually experienced a drop in platelets. Lengthening the dose interval of romiplostim to greater than a week is not feasible to maintain stable platelet count.