Long-term safety and effectiveness of romiplostim for chronic idiopathic thrombocytopenic purpura in real-world settings

Idiopathic thrombocytopenic purpura (ITP), an autoimmune hematologic disorder characterized by severe platelet count reduction, can be treated with romiplostim. However, post-marketing safety and effectiveness data for romiplostim in Japan are scarce. This prospective, observational, post-marketing Specified Use-Results Survey evaluated the real-world safety and effectiveness of romiplostim for 2 years. All patients treated with romiplostim during the survey period were eligible. Of the 1622 patients in the safety analysis set, 94.08% (1526/1622) had chronic ITP. The mean single dose of romiplostim was stable after 12 weeks and remained < 6 μg/kg in approximately 70% of patients until 104 weeks. Within 2 years, 14.92% of patients discontinued romiplostim because of adverse events, while 6.47% discontinued because of suspected adverse drug reactions. In contrast, 14.00% of patients discontinued romiplostim because of symptom improvement. Before romiplostim initiation, platelet count was < 2.0 × 10⁴/µL in 60.54% of patients, and the mean platelet count was 2.84 ± 5.76 × 10⁴/µL. Platelet count was 9.19 ± 13.01 × 10⁴/µL after 4 weeks, and remained between 10.34 ± 10.72 and 12.38 ± 12.63 × 10⁴/µL from 8 to 104 weeks of treatment. No specific concerns were revealed regarding the safety and effectiveness of romiplostim in chronic ITP; the findings demonstrated a favorable risk–benefit balance for romiplostim in this population. Trial registration: UMIN000047864 (www.​umin.​ac.​jp/​ctr).