Efficacy and Safety of Luspatercept for the Treatment of Anemia Due to MDS With del5q, Refractory/Resistant/Intolerant to Prior Treatments, RBC-TD

Myelodysplastic syndromes, primarily affecting older adults, are a heterogeneous group of clonal disorders of hematopoietic stem cells characterized by ineffective hematopoiesis that manifest clinically as anemia, neutropenia, and/or thrombocytopenia of variable severity; these often result in RBC- transfusion dependent (TD) anemia, increased risk of infection, and/or hemorrhage, as well as a potential to progress to acute myeloid leukemia (AML). Lenalidomide is approved for red blood cell transfusion-dependent (RBC TD) anemia due to low-risk myelodysplastic syndromes (MDS) with a chromosome 5q deletion (del5q) with or without additional cytogenetic abnormalities. About one third of patients are refractory/resistant/intolerant and will require further treatment options. Luspatercept (ACE-536), an erythroid maturation agent, is a recombinant fusion protein consisting of a modified form of the extracellular domain (ECD) of the human activin receptor type IIB (ActRIIB) linked to the Fc portion of human immunoglobulin G1 (IgG1-Fc). Luspatercept acts on endogenous inhibitors of late-stage erythropoiesis (eg, growth differentiation factor 11, GDF11) to increase release of mature erythrocytes into circulation. Nonclinical data have demonstrated that luspatercept binds to negative regulators governing late-stage erythroid development to inhibit their action, thereby promoting the maturation of erythrocytes in the bone marrow. Luspatercept is indicated for the treatment of adult patients with transfusion-dependent anaemia associated with beta-thalassaemia and due to very low, low and intermediate-risk MDS with ring sideroblasts, who had an unsatisfactory response to or are ineligible for erythropoietin-based-therapy. It is not indicated for other MDS subtypes. Unfortunately, patients with MDS with del5q refractory/resistant/intolerant to lenalidomide are excluded from clinical trials that evaluate novel treatments for the anemia of RBC TD lower risk MDS. Therefore, treatm