Transforming growth factor-β superfamily ligand trap ACE-536 corrects anemia by promoting late-stage erythropoiesis

Rajasekhar Suragani et al . show that a modified activin receptor IIB ligand trap increases red blood cell numbers in mice, rats and monkeys and ameliorates anemia in mice and rats, including in a mouse model of myelodysplastic syndromes. The ligand trap binds to the cytokine GDF11 and acts by inhibiting Smad2/3 signaling, thereby reversing ineffective erythropoiesis. Also in this issue, Michael Dussiot et al . show related findings using a wild-type activin receptor IIA ligand trap.