Additional Relevant Details Study DesignData from two Phase 2 studies will be presented at the conference: the completed dose-escalation study in which patients received treatment with luspatercept for three months and the ongoing long-term extension study in which patients receive treatment with luspatercept for up to an additional 24 months. In both the 3-month study and the long-term extension study, red blood cell (RBC) transfusion dependent patients (≥ 4 units RBC / 8 weeks) and non-transfusion dependent patients ( < 4 units RBC / 8 weeks) were enrolled and treated with open-label luspatercept, dosed subcutaneously once every 3 weeks. The primary outcome measure of the base study was the proportion of patients who have an erythroid response, defined as 1) a hemoglobin increase of ≥ 1.5 g/dL from baseline for ≥ 14 days (in the absence of RBC transfusions) in non-transfusion dependent patients, or 2) ≥ 20% reduction in RBC transfusion burden compared to pretreatment in transfusion dependent patients. The primary outcome measure of the long-term extension was the safety and tolerability assessed by adverse events.EfficacyResults in Transfusion Dependent (TD) Beta-Thalassemia Patients   RBC transfusion reduction
over any 12 weeks versus 12
weeks pre-treatment   Response rate (% of patients)   3-month base study(n=30)Long-term extension study(n=24)≥ 20%   80% (24/30)96% (23/24)≥ 33%   67% (20/30)83% (20/24)≥ 50%   53% (16/30)67% (16/24) Durability of Response:In the long-term extension study, the duration of the reduction in transfusion burden of ≥ 33% ranged from 12 to 48+ weeks.Results in Non-Transfusion Dependent (NTD) Beta-Thalassemia Patients   Hemoglobin (Hb) response over
any 12 weeks versus 12
weeks pre-treatment   Response rate (% of patients)in patients treated with ≥ 0.6 mg/kg   3-month base study(n=22)Long-term extension study(n=27)Increase in mean Hb ≥ 1.0 g/dL   64% (14/22)78% (21/27)Increase in mean Hb ≥ 1.5 g/dL   36% (8/22)56% (15/27) Durability of Response:In the long-term extension study, the duration of hemoglobin increase (≥ 1.0 g/dL) ranged from 113 to 505+ days.Improvement in patient-reported quality of life (QoL) measures in NTD patients:

• Increases in mean hemoglobin over a 12-week period correlated (r=0.67, p=0.001) with increases in
  FACIT-F, a patient-reported outcome (PRO) questionnaire used to assess anemia related symptoms

Safety Results in TD and NTD PatientsTD Patients

• There were no related serious adverse events and related grade 3 adverse events included: bone pain (n=2 base, n=1 extension), asthenia (n=2 base) and myalgia (n=1 extension)
• The most common related adverse events (all grades) were bone pain, myalgia, arthralgia, headache, asthenia, and musculoskeletal pain

NTD Patients

• There were no related serious adverse events and one grade 3 related adverse event of headache (n=1) in the extension study
• The most common related adverse events were bone pain, headache, musculoskeletal pain and arthralgia

Luspatercept is an investigational product that is not approved for use in any country.The BELIEVE Trial, a global Phase 3 study in regularly transfused beta-thalassemia patients, is currently enrolling.