The purpose of this study is to evaluate the efficacy and safety of AMG 531 compared with placebo in thrombocytopenic Japanese subjects with immune (idiopathic) thrombocytopenic purpura (ITP) .
The efficacy and safety of romiplostim, a thrombopoietin-mimetic peptibody, were evaluated in a double-blind, placebo-controlled, randomized trial of Japanese patients with chronic immune thrombocytopenia (ITP). Thirty-four ITP patients received romiplostim (n = 22) or placebo (n = 12) for 12 weeks, with a starting romiplostim dose of 3 μg/kg weekly. The primary end point was the number of weeks with platelet response, defined as a platelet count ≥50 × 10(9)/L (not including the 4 weeks after rescue medication administration). Patients received a median of 4 (range 1-19) prior ITP therapies including splenectomy in 44%. On study, 68% also received concomitant ITP therapy. Weekly responses occurred for a median of 11 weeks with romiplostim as compared to 0 weeks with placebo (p < 0.0001). Most romiplostim-treated patients (95%) achieved platelet responses; two showed extended responses after the treatment period. The use of rescue medication was required in 9% of romiplostim-treated patients as compared with 17% of placebo-treated patients. Both treatment groups had similar incidences of adverse events (91% romiplostim, 92% placebo). Adverse events that occurred more frequently (>10%) in romiplostim-treated patients included nasopharyngitis, headache, peripheral edema, back pain, and extremity pain. In conclusion, romiplostim significantly increased and maintained platelet counts and was well tolerated in Japanese patients with ITP.
A safety analysis of pooled data from clinical studies of romiplostim, a thrombopoietin (TPO) receptor agonist, in which patients with immune thrombocytopaenia (ITP) received romiplostim, placebo, or medical standard of care (SOC) Rodeghiero et al. (Eur J Haematol 91:423-436, 2013), has been updated. Included are data from 14 trials spanning 2002-2011; placebo- and SOC-arm data are pooled. Most patients (n = 1059) were female (61 %) and Caucasian (85 %); 38 % had undergone splenectomy; 23 were children. Mean (SD) baseline platelet count was 20.6 (16.5) × 10(9)/L. Mean (SD) weekly dose of romiplostim was 4.2 (2.8) µg/kg; total exposure was 1520 patient-years. Overall, 921 patients received romiplostim only, 65 received placebo/SOC only, and 73 received placebo/SOC followed by romiplostim. Rates of haemorrhage (romiplostim, 205/100 patient-years; placebo/SOC, 263/100), thrombosis (both, 5.5/100 patient-years), haematological malignancy/myelodysplastic syndrome (romiplostim, 0.5/100 patient-years; placebo/SOC, 2.7/100), and non-haematological tumours (romiplostim, 2.2/100 patient-years; placebo/SOC, 3.6/100) were comparable among groups. Bone marrow reticulin was reported in 17 patients and collagen in one patient receiving romiplostim; one patient receiving placebo/SOC had reticulin reported. Three patients developed neutralizing antibodies to romiplostim, but not to endogenous TPO. This integrated analysis of the safety profile of romiplostim in patients with ITP is consistent with previously reported studies; no new safety concerns emerged.
The purpose of this study is to evaluate the efficacy and safety of AMG 531 compared with placebo in thrombocytopenic Japanese subjects with immune (idiopathic) thrombocytopenic purpura (ITP) .
