Luspatercept: A New Tool for the Treatment of Anemia Related to β-Thalassemia, Myelodysplastic Syndromes and Primary Myelofibrosis

Anemia is a common feature of both benign and malignant hematologic diseases. Beta-thalassemia (β-thalassemia) syndromes are a group of hereditary disorders characterized by ineffective erythropoiesis, due to a genetic deficiency in the synthesis of the beta chains of hemoglobin, often accompanied by severe anemia and the need for red blood cell (RBC) transfusions. Myelodysplastic syndromes (MDS) are characterized by cytopenia(s) and ineffective hematopoiesis, despite a hypercellular bone marrow. Primary myelofibrosis (PMF) is a clonal myeloproliferative neoplasm characterized by reactive fibrosis of the bone marrow, accompanied by extramedullary hematopoiesis. Luspatercept, previously known as ACE-536, is a fusion protein that combines a modified activin receptor IIB (ActRIIB), a member of the transforming growth factor-β (TGF-β) superfamily, with the Fc domain of human immunoglobulin G (IgG1). It has shown efficacy in the treatment of anemia due to beta β-thalassemia, MDS and PMF and recently gained approval by the Federal Drug Agency (FDA) and the European Medicines Agency (EMA) for transfusion-dependent (TD) patients with β-thalassemia and very low to intermediate-risk patients with MDS with ringed sideroblasts who have failed to respond to, or are ineligible for, an erythropoiesis-stimulating agent. In this review, we describe the key pathways involved in normal hematopoiesis and the possible mechanism of action of luspatercept, present its development and data from the most recent clinical trials in β-thalassemia, MDS and PMF, and discuss its potential use in the treatment of these hematological disorders.