Long-term safety and effectiveness of romiplostim in patients with refractory aplastic anemia: a nationwide, all-case, post-marketing surveillance study in Japan

This all-case post-marketing surveillance study in Japan evaluated the safety and effectiveness of romiplostim, a thrombopoietin receptor agonist, in patients with aplastic anemia (AA), a rare disease characterized by pancytopenia. All patients with refractory AA who initiated romiplostim from June 2019 to September 2021 were registered. Romiplostim was administered subcutaneously once weekly for 52 weeks. Observation lasted 52 weeks or until 4 weeks after discontinuation. Occurrences of bone marrow fibrosis and hematopoietic tumors were monitored for up to 2 years after romiplostim initiation. Data from 470 patients at 220 institutions were analyzed. The mean age ± standard deviation was 66.27 ± 16.89 years, and 43.40% were male. Romiplostim was discontinued in 219/470 patients (46.60%). Adverse events (AEs) occurred in 57.02% of patients, and adverse drug reactions (ADRs) occurred in 18.09%. AEs of special interest classified as ADRs included thromboembolism (1.49%), hematopoietic tumor (1.28%), and hemorrhage (0.46%). During follow-up, hematopoietic tumors as ADRs were observed in 2/310 patients (0.65%). Hematological response was achieved in 257/327 patients (78.59%) at 27 weeks and 205/244 patients (84.02%) at 52 weeks. Platelet transfusion independence or reduced requirement was achieved in 164/213 patients (77.00%) at 27 weeks and 133/160 patients (83.13%) at 52 weeks, while red blood cell transfusion independence or reduced requirement was achieved in 194/247 patients (78.54%) and 162/186 patients (87.10%), respectively. Long-term romiplostim treatment was safe and effective in patients with refractory AA in a real-world setting. Registration: University Hospital Medical Information Network (UMIN000056465), 16 December, 2024.