Abbreviations: Imids, immunomodulatory agents, e.g., thalidomide, lenalidomide, pomalidomide. ActRIIA ligand traps, activin receptor type IIA ligand traps, e.g., sotatercept, luspatercept; HMAs, hypomethylating agents, e.g., azacitidine, decitabine; HDAC inhibitors, histone deacetylase inhibitors, e.g., panobinostat, pracinostat; PI3 kinase inhibitors, phophsatidylinositol-3-kinase inhibitors, e.g., buparlisib, INCB050465.