Luspatercept

1 INDICATIONS AND USAGE REBLOZYL is an erythroid maturation agent indicated for the treatment of: • Anemia in adult patients with beta thalassemia who require regular red blood cell (RBC) transfusions ( 1.1 ). • Anemia without previous erythropoiesis stimulating agent use (ESA-naïve) in adult patients with very low- to intermediate-risk myelodysplastic syndromes (MDS) who may require regular red blood cell (RBC) transfusions ( 1.2 ). • Anemia failing an erythropoiesis stimulating agent and requiring 2 or more RBC units over 8 weeks in adult patients with very low- to intermediate-risk myelodysplastic syndromes with ring sideroblasts (MDS-RS) or with myelodysplastic/myeloproliferative neoplasm with ring sideroblasts and thrombocytosis (MDS/MPN-RS-T) ( 1.3 ). • Limitations of Use: REBLOZYL is not indicated for use as a substitute for RBC transfusions in patients who require immediate correction of anemia ( 1.4 ). 1.1 Beta Thalassemia REBLOZYL is indicated for the treatment of anemia in adult patients with beta thalassemia who require regular red blood cell (RBC) transfusions. 1.2 Myelodysplastic Syndromes Associated Anemia REBLOZYL is indicated for the treatment of anemia without previous erythropoiesis stimulating agent use (ESA-naïve) in adult patients with very low- to intermediate-risk myelodysplastic syndromes (MDS) who may require regular red blood cell (RBC) transfusions. 1.3 Myelodysplastic Syndromes with Ring Sideroblasts or Myelodysplastic/ Myeloproliferative Neoplasm with Ring Sideroblasts and Thrombocytosis Associated Anemia REBLOZYL is indicated for the treatment of anemia failing an erythropoiesis stimulating agent and requiring 2 or more red blood cell units over 8 weeks in adult patients with very low- to intermediate-risk myelodysplastic syndromes with ring sideroblasts (MDS-RS) or with myelodysplastic/myeloproliferative neoplasm with ring sideroblasts and thrombocytosis (MDS/MPN-RS-T). 1.4 Limitations of Use REBLOZYL is not indicated for use as a substitute for RBC transfusions in patients who require immediate correction of anemia.

2 DOSAGE AND ADMINISTRATION • Beta thalassemia: The recommended starting dose is 1 mg/kg once every 3 weeks by subcutaneous injection. Increase dose if patient has no reduction in RBC transfusion burden to a maximum of 1.25 mg/kg ( 2.1 ). • Myelodysplastic Syndromes: The recommended starting dose is 1 mg/kg once every 3 weeks by subcutaneous injection. o For ESA-naïve MDS, increase dose to maintain patient’s hemoglobin concentrations within the target range of 10 g/dL to 12 g/dL to a maximum of 1.75 mg/kg ( 2.2 ). o For ESA-refractory or intolerant MDS, increase dose if patient is not RBC transfusion-free to a maximum of 1.75 mg/kg ( 2.2 ). • Review hemoglobin (Hgb) results prior to each administration ( 2.1 , 2.2 ). • See full prescribing information for preparation and administration instructions ( 2.3 ). 2.1 Recommended Dosage for Beta Thalassemia The recommended starting dose of REBLOZYL is 1 mg/kg once every 3 weeks by subcutaneous injection for patients with beta thalassemia. Prior to each REBLOZYL dose, review the patient’s hemoglobin and transfusion record. Titrate the dose based on responses according to Table 1. Interrupt treatment for adverse reactions as described in Table 2. Discontinue REBLOZYL if no response as described in Table 1 , or if unacceptable toxicity occurs at any time as described in Table 2 . If a planned administration of REBLOZYL is delayed or missed, administer REBLOZYL as soon as possible and continue dosing as prescribed, with at least 3 weeks between doses. Dose Modifications for Response Assess and review hemoglobin results prior to each administration of REBLOZYL. If an RBC transfusion occurred prior to dosing, use the pretransfusion hemoglobin for dose evaluation. Dose modifications for response are provided in Table 1. Do not increase the dose beyond the maximum dose of 1.25 mg/kg. In absence of transfusion, if hemoglobin increase is greater than 2 g/dL within 3 weeks or the predose hemoglobin is greater than or equal to 11.5 g/dL, reduce the dose or interrupt treatment with REBLOZYL as described in Table 1. Table 1: Beta Thalassemia - REBLOZYL Dose Titration for Response * Do not increase the dose if the patient is experiencing an adverse reaction as described in Table 2. REBLOZYL Dosing Recommendation* Starting Dose • 1 mg/kg every 3 weeks Dose Increases for Insufficient Response If after at least 2 consecutive doses (6 weeks) at 1 mg/kg, a patient: • Has no reduction in RBC transfusion burden • Increase the dose to 1.25 mg/kg every 3 weeks If after 3 consecutive doses (9 weeks) at 1.25 mg/kg, a patient: • Has no reduction in RBC transfusion burden • Discontinue treatment Dose Modifications for Predose Hemoglobin Levels or Rapid Hemoglobin Rise Predose hemoglobin is greater than or equal to 11.5 g/dL in absence of transfusion • Interrupt treatment • Restart at same dose when the hemoglobin is no more than 11 g/dL Increase in hemoglobin greater than 2 g/dL within 3 weeks in absence of transfusion and • current dose is 1.25 mg/kg • current dose is 1 mg/kg • current dose is 0.8 mg/kg • current dose is 0.6 mg/kg • Reduce dose to 1 mg/kg • Reduce dose to 0.8 mg/kg • Reduce dose to 0.6 mg/kg • Discontinue treatment Dose Modifications for Toxicity For patients experiencing Grade 3 or higher adverse reactions, modify treatment as described in Table 2. Table 2: Beta Thalassemia - REBLOZYL Dosing Modifications for Adverse Reactions * Grade 1 is mild, Grade 2 is moderate, Grade 3 is severe, and Grade 4 is life-threatening. **Per Table 1 dose reductions above. REBLOZYL Dosing Recommendation* Grade 3 or 4 hypersensitivity reactions • Discontinue treatment Other Grade 3 or 4 adverse reactions • Interrupt treatment • When the adverse reaction resolves to no more than Grade 1, restart treatment at the next lower dose level** • If the dose delay is greater than 15 consecutive weeks, discontinue treatment Extramedullary hematopoietic (EMH) masses causing serious complications • Discontinue treatment 2.2 Recommended Dosage for Myelodysplastic Syndromes Associated Anemia The recommended starting dosage of REBLOZYL is 1 mg/kg once every 3 weeks by subcutaneous injection for the treatment of anemia of MDS. Prior to each REBLOZYL dose, review the patient’s hemoglobin and transfusion record. Titrate the dose based on responses according to Table 3 and Table 4 . Interrupt treatment for adverse reactions as described in Table 5 . Discontinue REBLOZYL if no response as described in Table 3 and Table 4 , or if unacceptable toxicity occurs at any time as described in Table 5 . If a planned administration of REBLOZYL is delayed or missed, administer REBLOZYL as soon as possible and continue dosing as prescribed, with at least 3 weeks between doses. Dose Modifications for Response Assess and review hemoglobin results prior to each administration of REBLOZYL. If an RBC transfusion occurred prior to dosing, use the pretransfusion hemoglobin for dose evaluation. Dose modifications for response are provided in Table 3 and Table 4 . Do not increase the dose more frequently than every 6 weeks (2 doses) or beyond the maximum dose of 1.75 mg/kg. If, upon dose reduction, the patient loses response (i.e., requires a transfusion) or hemoglobin concentration drops by 1 g/dL or more in 3 weeks in absence of transfusion, increase the dose by one dose level as described in Table 3 and 4 . Wait a minimum of 6 weeks between dose increases. For ESA-naïve MDS, appropriate dose adjustments should be made to maintain patient’s hemoglobin concentrations within the target range of 10 g/dL to 12 g/dL (see Table 3). Table 3: MDS Associated Anemia - REBLOZYL Dose Titration for Response of ESA-naïve patients * Do not increase the dose if the patient is experiencing an adverse reaction as described in Table 5 . REBLOZYL Dosing Recommendation* Starting Dose • 1 mg/kg every 3 weeks Dose Increases for Insufficient Response If after at least 2 consecutive doses (6 weeks) at 1 mg/kg, a patient: • Is not RBC transfusion-free, or • Has a hemoglobin concentration less than 10 g/dL with hemoglobin increase less than 1 g/dL since last dose • Increase the dose to 1.33 mg/kg every 3 weeks If after at least 2 consecutive doses (6 weeks) at 1.33 mg/kg, a patient: • Is not RBC transfusion-free, or • Has a hemoglobin concentration less than 10 g/dL with hemoglobin increase less than 1 g/dL since last dose • Increase the dose to 1.75 mg/kg every 3 weeks If after at least 3 consecutive doses (9 weeks) at 1.75 mg/kg, a patient: • Has no reduction in RBC transfusion burden including no increase from baseline hemoglobin • Discontinue treatment Dose Modifications for Predose Hemoglobin Levels or Rapid Hemoglobin Rise Predose hemoglobin is greater than or equal to 12 g/dL in absence of transfusion • Interrupt treatment • Restart at same dose when the hemoglobin is less than or equal to 11 g/dL Increase in hemoglobin greater than 2 g/dL within 3 weeks in absence of transfusion and • current dose is 1.75 mg/kg • current dose is 1.33 mg/kg • current dose is 1 mg/kg • current dose is 0.8 mg/kg • current dose is 0.6 mg/kg • Reduce dose to 1.33 mg/kg • Reduce dose to 1 mg/kg • Reduce dose to 0.8 mg/kg • Reduce dose to 0.6 mg/kg • Discontinue treatment Table 4: MDS Associated Anemia - REBLOZYL Dose Titration for Response of ESA-refractory or intolerant patients * Do not increase the dose if the patient is experiencing an adverse reaction as described in Table 5. REBLOZYL Dosing Recommendation* Starting Dose • 1 mg/kg every 3 weeks Dose Increases for Insufficient Response If after at least 2 consecutive doses (6 weeks) at 1 mg/kg, a patient: • Is not RBC transfusion-free • Increase the dose to 1.33 mg/kg every 3 weeks If after at least 2 consecutive doses (6 weeks) at 1.33 mg/kg, a patient: • Is not RBC transfusion-free • Increase the dose to 1.75 mg/kg every 3 weeks If after at least 3 consecutive doses (9 weeks) at 1.75 mg/kg, a patient: • Has no reduction in RBC transfusion burden including no increase from baseline hemoglobin • Discontinue treatment Dose Modifications for Predose Hemoglobin Levels or Rapid Hemoglobin Rise Predose hemoglobin is greater than or equal to 11.5 g/dL in absence of transfusion • Interrupt treatment • Restart at same dose when the hemoglobin is less than or equal to 11 g/dL Increase in hemoglobin greater than 2 g/dL within 3 weeks in absence of transfusion and • current dose is 1.75 mg/kg • current dose is 1.33 mg/kg • current dose is 1 mg/kg • current dose is 0.8 mg/kg • current dose is 0.6 mg/kg • Reduce dose to 1.33 mg/kg • Reduce dose to 1 mg/kg • Reduce dose to 0.8 mg/kg • Reduce dose to 0.6 mg/kg • Discontinue treatment Dose Modifications for Toxicity For patients experiencing Grade 3 or higher adverse reactions, modify treatment as described in Table 5 . Table 5: MDS Associated Anemia - REBLOZYL Dosing Modifications for Adverse Reactions * Grade 1 is mild, Grade 2 is moderate, Grade 3 is severe, and Grade 4 is life-threatening. **Per Table 3 and Table 4 dose reductions above. REBLOZYL Dosing Recommendation* Grade 3 or 4 hypersensitivity reactions • Discontinue treatment Other Grade 3 or 4 adverse reactions • Interrupt treatment • When the adverse reaction resolves to no more than Grade 1, restart treatment at the next lower dose level** • If the dose delay is greater than 12 consecutive weeks, discontinue treatment 2.3 Preparation and Administration REBLOZYL should be reconstituted and administered by a healthcare professional. Reconstitute REBLOZYL with Sterile Water for Injection, USP only. Table 6: Reconstitution Volumes Vial Size Amount of Sterile Water for Injection, USP required for reconstitution Final Concentration Deliverable Volume 25 mg vial 0.68 mL 25 mg/0.5 mL (50 mg/mL) 0.5 mL 75 mg vial 1.6 mL 75 mg/1.5 mL 1.5 mL (50 mg/mL) Reconstitute the number of REBLOZYL vials to achieve the appropriate dose based on the patient’s weight. Use a syringe with suitable graduations for reconstitution to ensure accurate dosage. Reconstitution Instructions 1. Reconstitute with Sterile Water for Injection, USP using volumes described in Table 6 (Reconstitution Volumes) with the stream directed onto the lyophilized powder. Allow to stand for one minute. 2. Discard the needle and syringe used for reconstitution. The needle and syringe used for reconstitution should not be used for subcutaneous injections. 3. Gently swirl the vial in a circular motion for 30 seconds. Stop swirling and let the vial sit in an upright position for 30 seconds. 4. Inspect the vial for undissolved particles in the solution. If undissolved powder is observed, repeat step 3 until the powder is completely dissolved. 5. Invert the vial and gently swirl in an inverted position for 30 seconds. Bring the vial back to the upright position, and let it sit for 30 seconds. 6. Repeat step 5 seven more times to ensure complete reconstitution of material on the sides of the vial. 7. Parenteral drug products should be inspected visually for particulate matter and discoloration prior to administration whenever solution and container permit. REBLOZYL is a colorless to slightly yellow, clear to slightly opalescent solution which is free of foreign particulate matter. Do not use if undissolved product or foreign particulate matter are observed. 8. If the reconstituted solution is not used immediately: • Store at room temperature at 20°C to 25°C (68°F to 77°F) in the original vial for up to 8 hours. Discard if not used within 8 hours of reconstitution. • Alternatively, store refrigerated at 2°C to 8°C (36°F to 46°F) for up to 24 hours in the original vial. Remove from refrigerated condition 15 to 30 minutes prior to injection to allow solution to reach room temperature for a more comfortable injection. Discard if not used within 24 hours of reconstitution. • Do not freeze the reconstituted solution. Discard any unused portion. Do not pool unused portions from the vials. Do not administer more than 1 dose from a vial. Do not mix with other medications. Instructions for Subcutaneous Administration Calculate the exact total dosing volume of 50 mg/mL solution required for the patient. Slowly withdraw the dosing volume of the reconstituted REBLOZYL solution from the single-dose vial(s) into a syringe. Divide doses requiring larger reconstituted volumes (i.e., greater than 1.2 mL) into separate similar volume injections and inject into separate sites. If multiple injections are required, use a new syringe and needle for each subcutaneous injection. Administer the injection subcutaneously into the upper arm, thigh, and/or abdomen.

6 ADVERSE REACTIONS The following clinically significant adverse reactions are described elsewhere in the labeling: • Thrombosis/Thromboembolism [see Warnings and Precautions ( 5.1 )] • Hypertension [see Warnings and Precautions ( 5.2 )] • Extramedullary Hematopoietic Masses [see Warnings and Precautions ( 5.3 )] The most common (>10%) adverse reactions were fatigue, headache, musculoskeletal pain, arthralgia, dizziness/vertigo, nausea, diarrhea, cough, abdominal pain, dyspnea, COVID-19, edema peripheral, hypertension, and hypersensitivity ( 6.1 ). To report SUSPECTED ADVERSE REACTIONS, contact Bristol-Myers Squibb at 1-888-423-5436 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch. 6.1 Clinical Trials Experience Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice. The data in the WARNINGS AND PRECAUTIONS reflect exposure to REBLOZYL as a single agent administered across a range of doses (0.125 mg/kg to 1.75 mg/kg) in 571 patients in 4 trials. Beta Thalassemia The safety of REBLOZYL in patients with beta thalassemia was evaluated in the BELIEVE trial [see Clinical Studies ( 14.1 )] . Key eligibility criteria included adult patients with beta thalassemia (with the exception of patients with hemoglobin S or alpha-thalassemia disease) without major organ damage or recent DVT stroke and platelet counts less than or equal to 1000 x 10 9 /L. Patients received a starting dose of REBLOZYL 1 mg/kg subcutaneous injection every 3 weeks. Overall, 53% of patients had their dose increased to 1.25 mg/kg (46% REBLOZYL, n = 223) or placebo (66%, n = 109). The median duration of treatment was similar between the REBLOZYL and placebo arms (63.3 weeks vs. 62.1 weeks, respectively). Per protocol, patients in the REBLOZYL and placebo arms were to remain on therapy for at least 48 weeks in the double-blind phase of the trial. Among patients receiving REBLOZYL, 94% were exposed for 6 months or longer and 72% were exposed for greater than one year. The median age of patients who received REBLOZYL was 30 years (range: 18, 66); 59% female; 54% White and 36% Asian. Serious adverse reactions occurred in 3.6% of patients on REBLOZYL. Serious adverse reactions reported in 1% of patients were cerebrovascular accident and deep vein thrombosis. A fatal adverse reaction occurred in one patient treated with REBLOZYL who died due to an unconfirmed case of AML (M6). Permanent discontinuation due to an adverse reaction (Grades 1-4) occurred in 5.4% of patients who received REBLOZYL. Most frequent adverse reactions requiring permanent discontinuation in patients who received REBLOZYL included arthralgia (1%), back pain (1%), bone pain (<1%), and headache (<1%). Dosage reductions due to an adverse reaction occurred in 2.7% of patients who received REBLOZYL. Most frequent adverse reactions requiring dosage reduction in >0.5% of patients who received REBLOZYL included hypertension and headache. Dosage interruptions due to an adverse reaction occurred in 15.2% of patients who received REBLOZYL. Most frequent adverse reactions requiring dosage interruption in >1% of patients who received REBLOZYL included upper respiratory tract infection, ALT increase, and cough. The most common adverse reactions (at least 10% for REBLOZYL and 1% more than placebo) were headache (26%), bone pain (20%), arthralgia (19%), fatigue (14%), cough (14%), abdominal pain (14%), diarrhea (12%), and dizziness (11%). Table 7 summarizes the adverse reactions in BELIEVE. Table 7: Adverse Drug Reactions (>5%) in Patients with Beta Thalassemia Receiving REBLOZYL with a Difference Between Arms of 1% in BELIEVE Trial Body System REBLOZYL (N=223) Placebo (N=109) Adverse Reaction All Grades n (%) Grades ≥3 a n (%) All Grades n (%) Grades ≥3 n (%) a Limited to Grade 3 reactions with the exception of 4 events of Grade 4 hyperuricemia. b Grouped term includes abdominal pain and abdominal pain upper. c Grouped term includes essential hypertension, hypertension, and hypertensive crisis. Musculoskeletal and connective tissue disorders Bone Pain 44 (20) 3 (1) 9 (8) 0 (0) Arthralgia 43 (19) 0 (0) 13 (12) 0 (0) Infections and infestation Influenza 19 (9) 0 (0) 6 (6) 0 (0) Viral Upper Respiratory Infection 14 (6) 1 (0.4) 2 (2) 0 (0) Nervous system disorders Headache 58 (26) 1 (<1) 26 (24) 1 (1) Dizziness 25 (11) 0 (0) 5 (5) 0 (0) General disorders and administration site conditions Fatigue 30 (14) 0 (0) 14 (13) 0 (0) Gastrointestinal disorders Abdominal Pain b 31 (14) 0 (0) 13 (12) 0 (0) Diarrhea 27 (12) 1 (<1) 11 (10) 0 (0) Nausea 20 (9) 0 (0) 6 (6) 0 (0) Vascular disorders Hypertension c 18 (8) 4 (2) 3 (3) 0 (0) Metabolism and nutrition disorders Hyperuricemia 16 (7) 6 (3) 0 (0) 0 (0) Respiratory, thoracic and mediastinal disorders Cough 32 (14) 0 (0) 12 (11) 0 (0) Clinically relevant adverse reactions in <5% of patients include vertigo/vertigo positional, syncope/presyncope, injection site reactions, hypersensitivity, extramedullary hematopoietic masses, and spinal cord compression. Liver function abnormalities in the BELIEVE trial are shown in Table 8. Table 8: Liver Function Laboratory Abnormalities in Patients with Beta Thalassemia in the BELIEVE Trial REBLOZYL N = 223 n (%) Placebo N = 109 n (%) ALT ≥ 3 × ULN 26 (12) 13 (12) AST ≥ 3 × ULN 25 (11) 5 (5) ALP ≥ 2 × ULN 17 (8) 1 (<1) Total bilirubin ≥ 2 × ULN 143 (64) 51 (47) Direct bilirubin ≥ 2 × ULN 13 (6) 4 (4) Treatment of Myelodysplastic Syndromes Associated Anemia in ESA-naïve Patients The safety of REBLOZYL in patients with very low‑ to intermediate‑risk myelodysplastic syndromes was evaluated in the COMMANDS trial in 356 randomized patients [see Clinical Studies ( 14.2 )] . Key eligibility criteria included adult patients who were ESA‑naïve with endogenous sEPO levels of < 500 U/L and who required regular RBC transfusions. The median time on treatment with REBLOZYL was 41.6 weeks (range, 0 – 165 weeks); 71.3% of patients were exposed for 24 weeks and 45.5% completed 48 weeks of treatment. Among the 178 patients treated with REBLOZYL, 17 (9.6%) discontinued due to an adverse reaction, 48 (27%) had a dose interruption due to an adverse reaction, and 5 (2.8%) had a dose reduction due to an adverse reaction. The most common (>10%) all‑grade adverse reactions included diarrhea, fatigue, hypertension, edema peripheral, nausea, and dyspnea. The most common (>2%) Grade > 3 adverse reactions included hypertension and dyspnea. Selected laboratory abnormalities that changed from Grade 0‑2 at baseline to Grade > 2 at any time during the studies in at least 10% of patients were glomerular filtration rate and total bilirubin increased. Table 9 shows the most common adverse reactions for patients treated with REBLOZYL or epoetin alfa in the COMMANDS trial [see Clinical Studies ( 14.2 )] . Table 9: Adverse Reactions (≥5%) in Patients Receiving REBLOZYL in COMMANDS Trial a Reaction includes similar/grouped terms. b Includes asthenic conditions. Body System /Adverse Reaction REBLOZYL (N=178) Epoetin Alfa (N=176) All Grades n (%) Grade ≥3 n (%) All Grades n (%) Grade ≥3 n (%) General disorders and administration site conditions Fatigue a,b 38 (22) 0 (0) 12 (7) 0 (0) Edema peripheral 23 (13) 0 (0) 12 (7) 0 (0) Non-cardiac chest pain 9 (5) 1 (1) 6 (3) 0 (0) Pyrexia 9 (5) 1 (1) 12 (7) 1 (1) Gastrointestinal disorders Diarrhea 26 (15) 0 (0) 20 (11) 0 (0) Nausea 21 (12) 0 (0) 13 (7) 0 (0) Vascular disorders Hypertension a 25 (14) 17 (10) 13 (7) 9 (5) Respiratory, thoracic and mediastinal disorders Dyspnea 21 (12) 7 (4) 13 (7) 2 (1) Dyspnea exertional 9 (5) 0 (0) 1 (1) 0 (0) Nervous system disorders Dizziness 16 (9) 1 (1) 15 (9) 0 (0) Headache 15 (8) 0 (0) 12 (7) 1 (1) Musculoskeletal and connective tissue disorders Back Pain 16 (9) 2 (1) 13 (7) 3 (2) Arthralgia 10 (6) 0 (0) 14 (8) 0 (0) Myalgia 9 (5) 0 (0) 5 (3) 0 (0) Osteoarthritis 9 (5) 1 (1) 4 (2) 0 (0) Infections and infestations COVID-19 19 (11) 6 (3) 17 (10) 2 (1) Urinary tract infection 13 (7) 0 (0) 7 (4) 0 (0) Pneumonia 8 (5) 7 (4) 15 (9) 11 (6) Metabolism and nutrition disorders Hyperuricemia 12 (7) 1 (1) 10 (6) 1 (1) Decreased appetite 8 (5) 0 (0) 11 (6) 0 (0) Blood and lymphatic system disorders Thrombocytopenia 11 (6) 7 (4) 3 (2) 1 (1) Neutropenia 9 (5) 7 (4) 13 (7) 10 (6) Psychiatric disorders Insomnia 9 (5) 0 (0) 6 (3) 0 (0) Other clinically relevant adverse reactions reported in <5% of patients are injection site reactions, including erythema, pruritus, and rash. Shifts from Grades 0‑2 at baseline to Grades 2‑3 abnormalities for selected laboratory tests in the COMMANDS trial are shown in Table 10. Table 10: Selected Treatment‑Emergent Laboratory Abnormalities in COMMANDS Trial that Shift to Grades 2‑3 a Number of patients at Grades 0-1 at baseline. b GFR= glomerular filtration rate (mL/min) Parameter REBLOZYL Epoetin Alfa N a n (%) N a n (%) Total bilirubin 171 38 (22) 165 19 (12) GFR b 171 60 (35) 167 36 (22) Myelodysplastic Syndromes with Ring Sideroblasts or Myelodysplastic / Myeloproliferative Neoplasm with Ring Sideroblasts and Thrombocytosis Associated Anemia in ESA-refractory or -intolerant patients The safety of REBLOZYL at the recommended dose and schedule was evaluated in 242 patients with MDS with ring sideroblasts (n=192) or other myeloid neoplasms (n=50) in the MEDALIST trial. The safety population included 63% males and 37% females of median age 72 years (range, 30 – 95 years); of these patients, 81% were White, 0.4% Black, 0.4% Other, and race was not reported in 18.2% of patients. The median time on treatment with REBLOZYL was 50.4 weeks (range, 3 – 221 weeks); 67% of patients were exposed for 6 months or longer and 49% were exposed for greater than one year. Among the 242 patients treated with REBLOZYL, 5 (2.1%) had a fatal adverse reaction, 11 (4.5%) discontinued due to an adverse reaction, and 7 (2.9%) had a dose reduction due to an adverse reaction. The most common (≥10%) all-grade adverse reactions included fatigue, musculoskeletal pain, dizziness, diarrhea, nausea, hypersensitivity reactions, hypertension, headache, upper respiratory tract infection, bronchitis, and urinary tract infection. The most common (≥2%) Grade ≥ 3 adverse reactions included fatigue, hypertension, syncope and musculoskeletal pain. Selected laboratory abnormalities that changed from Grade 0-1 at baseline to Grade ≥ 2 at any time during the studies in at least 10% of patients included creatinine clearance decreased, total bilirubin increased, and ALT increased. Table 11 shows the most common adverse reactions for patients treated with REBLOZYL or placebo through the first 8 cycles in the MEDALIST trial [see Clinical Studies ( 14.3 )] . Table 11: Adverse Reactions (≥5%) in Patients Receiving REBLOZYL with a Difference Between Arms of >2% in MEDALIST Trial Through Cycle 8 Body System /Adverse Reaction REBLOZYL (N=153) Placebo (N=76) All Grades n (%) Grade 3 n (%) All Grades n (%) Grade 3 n (%) a Includes asthenic conditions. b Reaction includes similar/grouped terms. General disorders and administration site conditions Fatigue a, b 63 (41) 11 (7) 17 (22) 2 (3) Musculoskeletal and connective tissue disorders Musculoskeletal pain b 30 (20) 3 (2) 11 (14) 0 (0) Nervous system disorders Dizziness/vertigo 28 (18) 1 (<1) 5 (7) 1 (1) Headache b 21 (14) 0 (0) 5 (7) 0 (0) Syncope / presyncope 8 (5) 5 (3) 0 (0) 0 (0) Gastrointestinal disorders Nausea b 25 (16) 1 (<1) 8 (11) 0 (0) Diarrhea b 25 (16) 0 (0) 7 (9) 0 (0) Respiratory, thoracic and mediastinal disorder Dyspnea b 20 (13) 2 (1) 4 (5) 1 (1) Immune system disorders Hypersensitivity reactions b 15 (10) 1 (<1) 5 (7) 0 (0) Renal and urinary disorders Renal impairment b 12 (8) 3 (2) 3 (4) 0 (0) Cardiac disorders Tachycardia b 12 (8) 0 (0) 1 (1) 0 (0) Injury poisoning and procedural complications Injection site reactions 10 (7) 0 (0) 3 (4) 0 (0) Infections and infestations Upper respiratory tract infection 10 (7) 1 (<1) 2 (3) 0 (0) Influenza / influenza like illness 9 (6) 0 (0) 2 (3) 0 (0) Other clinically relevant adverse reactions reported in <5% of patients include bronchitis, urinary tract infection, and hypertension [see Warnings and Precautions ( 5.2 )] . Shifts from Grades 0-1 to Grades 2-4 abnormalities for selected laboratory tests during the first 8 cycles in the MEDALIST trial are shown in Table 12. Table 12: Selected Grades 2-4 Treatment-Emergent Laboratory Abnormalities Through Cycle 8 in the MEDALIST Trial a Number of patients at Grades 0-1 at baseline. Parameter REBLOZYL Placebo N a n (%) N a n (%) ALT elevated 151 13 (9) 74 5 (7) AST elevated 152 6 (4) 76 0 (0) Total bilirubin elevated 140 17 (12) 66 3 (5) Creatinine clearance reduced 113 30 (27) 62 13 (21)

12.3 Pharmacokinetics Luspatercept-aamt exhibited linear pharmacokinetics (PK) over the dose range of 0.2 to 1.25 mg/kg (0.2 to 1.25 times the recommended starting dosage) in patients with beta thalassemia, and from 0.125 mg/kg to 1.75 mg/kg (0.125 to 1.75 times the recommended starting dosage) in patients with MDS. The geometric mean (% coefficient of variation [%CV]) steady-state AUC at the starting dose of 1 mg/kg was 126 (35.9%) day•µg/mL for patients with beta thalassemia and 154 (37.4%) day•µg/mL for patients with MDS. Luspatercept-aamt serum concentration reached steady state after 3 doses when administered every 3 weeks. The accumulation ratio of luspatercept-aamt was approximately 1.5. Absorption The median [range] time to maximum concentration (T max ) of luspatercept-aamt was observed at approximately 5 [3 to 8] days post-dose in adult patients with beta thalassemia or 6 [3 to 7] days post-dose in adult patients with MDS. The absorption of luspatercept-aamt was not significantly affected by the subcutaneous injection sites (upper arm, thigh, or abdomen). Distribution The geometric mean (%CV) apparent volume of distribution (V d /F) of luspatercept-aamt was 7.1 (26.7%) L for patients with beta thalassemia and 9.6 (26.7%) L for patients with MDS. Elimination The geometric mean (%CV) half-lives (t 1/2 ) of luspatercept-aamt were approximately 11 (25.7%) days in patients with beta thalassemia and 14 (31.7%) days in patients with MDS. The geometric mean (%CV) apparent total clearance (CL/F) of luspatercept-aamt was 0.44 (38.5%) L/day in patients with beta thalassemia and 0.47 (42.9%) L/day in patients with MDS. Metabolism Luspatercept-aamt is expected to be catabolized into small peptides and amino acids by general catabolic degradation processes in multiple tissues. Specific Populations No clinically significant differences in the luspatercept-aamt PK were observed based on age (18 to 95 years), sex, race/ethnicity (Asian, White), mild to severe hepatic impairment (total bilirubin ≤ ULN and AST or ALT > ULN, or total bilirubin > ULN and any AST or ALT), mild to moderate renal impairment (estimated glomerular filtration rate [eGFR] 30 to 89 mL/min), baseline albumin (30 to 56 g/L), baseline serum erythropoietin (2.4 to 2920 U/L), red blood cell (RBC) transfusion burden (0 to 43 units/24 weeks), beta thalassemia genotype (β0/β0 vs. non-β0/β0), splenectomy, and ring sideroblasts status in MDS (negative vs. positive). The effect of AST or ALT >3 x ULN and the effect of severe renal impairment (eGFR <30 mL/min) on luspatercept-aamt PK is unknown. Body Weight The apparent CL/F and V d /F of luspatercept-aamt increased with increasing body weight in patients with beta thalassemia (34 to 97 kg) and in patients with MDS (33 to 124 kg). Drug Interaction Studies Effect of Iron-chelating Agents on Luspatercept-aamt No clinically significant differences in luspatercept-aamt PK were observed when used concomitantly with iron-chelating agents.