This clinical trial is for men and women who have been diagnosed with clonal cytopenias of uncertain significance (CCUS) that is clinically significant.

The purpose of this study is to learn whether luspatercept is successful in improving blood counts in patients with clonal cytopenias of uncertain significance (CCUS). Luspatercept is a U.S. Food and Drug Administration (FDA) -approved drug for myelodysplastic syndrome (MDS) but is not approved for CCUS.

During this study, participants will need to come to the study clinic every 3 weeks to receive the luspatercept injection under their skin (subcutaneously) and have evaluations to assess for safety and response of their disease on treatment.

Participation in the study is expected to last four years. The active treatment phase will last approximately two years. After this, participants will be followed for survival for another two years by the study team. Participants are not required to do any study-related procedures or visits after they stop receiving the study drug.