Ferroportin inhibitor vamifeport ameliorates ineffective erythropoiesis in a mouse model of b-thalassemia with blood transfusions

β-thalassemia is an inherited anemia characterized by ineffective erythropoiesis. Blood transfusions are required for survival in transfusion-dependent b-thalassemia and are also occasionally needed in patients with non-transfusion-dependent β-thalassemia. Patients with transfusion-dependent b-thalassemia often have elevated transferrin saturation (TSAT) and non-transferrin-bound iron (NTBI) levels, which can lead to organ iron overload, oxidative stress, and vascular damage. Vamifeport is an oral ferroportin inhibitor that was previously shown to ameliorate anemia, ineffective erythropoiesis, and dysregulated iron homeostasis in the Hbb(th3/+) mouse model of b-thalassemia, under non-transfused conditions. Our study aimed to assess the effects of oral vamifeport on iron-related parameters (including plasma NTBI levels) and ineffective erythropoiesis following blood transfusions in Hbb(th3/+) mice. A single dose of vamifeport prevented the transient transfusion-mediated NTBI increase in Hbb(th3/+) mice. Compared with vehicle treatment, vamifeport significantly increased hemoglobin levels and red blood cell counts in transfused mice. Vamifeport treatment also significantly improved ineffective erythropoiesis in the spleens of Hbb(th3/+) mice, with additive effects observed when treatment was combined with repeated transfusions. Vamifeport corrected leukocyte counts and significantly improved iron-related parameters (serum transferrin, TSAT and erythropoietin levels) versus vehicle treatment in Hbb(th3/+) mice, irrespective of transfusion status. In summary, vamifeport prevented transfusion-mediated NTBI formation in Hbb(th3/+) mice. When given alone or combined with blood transfusions, vamifeport also ameliorated anemia, ineffective erythropoiesis, and dysregulated iron homeostasis. Administering vamifeport together with repeated blood transfusions additively ameliorated anemia and ineffective erythropoiesis in this mouse model, providing preclinical proof-of-con-cept for the efficacy of combining vamifeport with blood transfusions in b-thalassemia.