Patient disposition. In the luspatercept (including crossover) group and placebo group, treatment discontinuations occurred in 39 of 134 (29.1%) and 31 of 49 (63.3%) patients, respectively. The main reasons for study drug discontinuation in the luspatercept and placebo groups, respectively, were lack of efficacy (2/134 [1.5%] and 17/49 [34.7%]), withdrawal by patient (23/134 [17.2%] and 10/49 [20.4%]), and AEs (8/134 [6.0%] and 4/49 [8.2%]). AEs leading to study drug discontinuation in patients receiving luspatercept (including crossover) were arthralgia, hemolytic anemia, and lupus-like syndrome (1 patient); spinal cord compression and EMH masses (1 patient); pulmonary arterial hypertension (1 patient); myocardial infarction (1 patient); transient ischemic attack (1 patient); back pain, bone pain, and palpitations (1 patient each). In the placebo group, AEs that led to study drug discontinuation were fatigue and diffuse large B-cell lymphoma (1 patient), and hypotension, asthenia, and hepatocellular carcinoma (1 patient each). ∗As of last patient last visit date (28 November 2022).