Emerging Pathogenetic Mechanisms and New Drugs for Anemia in Myelofibrosis and Myelodysplastic Syndromes.

Anemia in myeloid neoplasms is multifaceted, with heterogeneous pathogenetic mechanisms that include ineffective erythropoiesis, hepcidin-induced iron-restricted erythropoiesis, and abnormal inflammatory cytokine production. Current management of anemia is challenged by limited approved drugs that specifically treat anemia in myelofibrosis (MF) and myelodysplastic syndrome (MDS). Newer therapies target the transforming growth factor beta (TGF-β)-bone morphogenic protein/sons of mothers against decapentaplegic (BMP-SMAD) signaling pathway, which plays a significant role in ineffective erythropoiesis (SMAD 2/3) and abnormal hepcidin production (SMAD 1/5/8). These include TGF-β ligand traps (luspatercept, elritercept), activin A receptor type 1 (ACVR1)/activin receptor-like kinase 2 (ALK2) inhibitors (momelotinib, zilurgisertib), and anti-hemojuvelin antibody-based therapies (DISC-0974). Luspatercept and momelotinib are approved for anemia related to lower-risk MDS and MF, respectively, and represent an important addition to the treatment armamentarium, along with imetelstat, a telomerase inhibitor, recently ratified for anemia in lower-risk MDS. A promising strategy to overcome the limitations of existing anemia-directed therapies includes the use of drug combinations with complementary mechanisms (luspatercept + erythropoiesis stimulating agents, luspatercept + momelotinib, DISC-0974 + momelotinib), and harnessing the erythropoietic potential of sodium-glucose co-transporter-2 inhibitors (SGLT-2I). Future research should address the complex pathophysiology of anemia, standardize definitions for anemia with gender-specified cutoffs, implement uniform erythroid response criteria, and consider early therapeutic intervention in clinical trials for anemia-directed therapies.