Combined use of GDF traps and erythropoietin receptor activators to increase red blood cell levels

摘要

Compositions for increasing red blood cell levels or treatment of anemia comprising erythropoietin receptor activators and a variant Activin RIIB (ActRIIB) polypeptide having a leucine residue replaced by a acidic amino acid residue, where the variant ActRIIB polypeptide has a reduced affinity for activin B and may be called a GDF trap. Methods for the use of these compositions.