A Study of Luspatercept in People With Anemia

Inclusion Criteria: Documentation of Anemia due to CKD * Patients must have a Hb ≤ 9.5 g/dL on two separate occasions within 4 weeks prior to enrollment. * Do not anticipate red cell transfusion within the following 4 weeks and no history of red cell transfusion in three weeks prior to enrollment. * Ferritin ≥100 ng/mL and iron transferrin saturation (TSAT) ≥ 20%. * Serum folate \> 4 ng/mL * Serum vitamin B12 \> 250 pg/mL * Patients may have received iron, B12 and folic acid repletion if initiated \> 6 weeks prior to enrollment. Patients who are already on iron, B12 and folic acid repletion can continue throughout the trial. * TSH, T4 within institutional normal limits. Documentation of Chronic Kidney Disease * Chronic kidney disease defined as a GFR between 30-60 mL/min/1.73m2 for ≥ 3 months calculated by the 2021 CKD-EPI creatinine equation for eGFR, the 2021 CKD-EPI creatinine-cystatin C equation, or creatinine clearance measured by a 24-hour urine collection. Prior Treatment with Erythrocyte Stimulating Agents (ESA) * Eligible patients will not have had recent (within past 3 weeks) erythrocyte stimulating agents (ESA) prior to enrollment unless they are hyporesponsive to ESA therapy. * Patients are eligible if they are either hyporesponsive to ESA therapy or unwilling to accept ESAs. defined by the Kidney Disease Outcomes Quality Initiative (KDOQI) as the inability to achieve/maintain a desired hemoglobin (herein defined as a hemoglobin of \> 9.0 g/dL) using a maximum…