Patient baseline characteristics, RBC-TI ≥8 weeks and mHI-E response. Baseline characteristics of patients in the MEDALIST trial by transfusion burden (A). Rates of RBC-TI for ≥8 weeks and mHI-E response during weeks 1 to 48, overall and by transfusion burden (B). Time to first response and duration of RBC-TI ≥8 weeks and mHI-E response (C). mHI-E response was defined according to IWG 2006 criteria¹⁷ as a mean hemoglobin increase ≥1.5 g/dL among patients with a baseline RBC transfusion burden <4 units per 8 weeks or a reduction of ≥4 RBC units among patients with baseline RBC transfusion burden ≥4 units per 8 weeks, sustained over a consecutive 56-day period. ∗Last value measured on or before the date and time of the first dose of luspatercept per placebo. †Highest value within 35 days before the first dose of luspatercept per placebo. ‡Only 2 patients with HTB who received placebo achieved RBC-TI; therefore, a median duration could not be reliably estimated. IWG, International Working Group; mHI-E, modified hematologic improvement-erythroid; SD, standard deviation; sEPO, serum erythropoietin; SF3B1, splicing factor 3b subunit 1.