Assessments
This post hoc analysis of MEDALIST evaluated the cumulative mean number of RBC transfusion units and RBC transfusion visits through 144 weeks of treatment according to baseline RBC transfusion burden level (low vs high). Low and high baseline RBC transfusion burden levels were defined as having < 6 RBC transfusion units or ≥ 6 RBC transfusion units over 8 weeks, respectively. The cumulative mean number of RBC transfusion units and RBC transfusion visits required during the treatment period according to baseline RBC transfusion burden level was also evaluated by luspatercept response at week 25. Patients in the luspatercept arm who achieved RBC-TI for ≥ 8 weeks by week 25 were defined as luspatercept responders; those who did not were defined as initial luspatercept nonresponders. The cumulative mean number of RBC transfusion units or RBC transfusion visits required was estimated using Nelson–Aalen nonparametric estimators with robust variance estimate for each treatment group with a 95% confidence interval.This post hoc analysis also evaluated the effect of continuing luspatercept treatment beyond the first 24 weeks. Assessment of clinical benefit was conducted up to the data cutoff date of July 1, 2019 (144 weeks of treatment). Clinical benefit indicators included RBC transfusion burden, hemoglobin and serum ferritin levels, and hematologic improvement-erythroid (HI-E) response. HI-E response was assessed per modified IWG 2006 criteria [