Diamond Blackfan Anemia(DBA)is a bone marrow failure disorder characterized by low red blood cell count but normal levels of platelets and white blood cells.Ribosomal mutations in RPS19,RPS26,RPL5,and RPL11 have been identified in approximately 50% of all DBA cases.Corticosteriod therapy and bone marrow transplantion are the most common treatment options for DBA patients.However,corticosteroids have severe side effects and bone marrow transplantation is risky;thus,novel therapeutics for DBA are needed.Sotatercept(ACE-011),an activin receptor IIA ligand trap which rapidly increased hemoglobin and hematocrit in both pharmacologic models and in healthy volunteers,is currently being evaluated in diseases of ineffective erythropoiesis such as ?-thalassemia and MDS.Non-clinical studies in mice have demonstrated that RAP-011,a murine ortholog of sotatercept,stimulates RBC parameters in mice through stimulating expansion of late-stage erythroblasts through a mechanism distinct from EPO.Here,we evaluated the effect of RAP-011 in zebrafish models of ribosome insufficiency in RPS19 and RPL11 that recapitulate the anemic phenotype seen in DBA patients.Treatment with RAP-011 treatment dramatically restored hemoglobin levels compromised by ribosome stress.