TREATMENT OF ANEMIA DUE TO VERY LOW, LOW OR INTERMEDIATE RISK MYELODYSPLACIC SYNDROMES IN SUBJECTS WITH RINGED SIDEROBLASTS USING AN ACTIVIN-ACTRII LIGAND TRAP

Abstract

The present invention provides a method for treating anemia due to very low-risk, low-risk, or intermediate-risk myelodysplastic syndrome in subjects with ringed sideroblasts by subcutaneous administration of ActRIIA ligand trap or ActRIIB ligand trap.

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of U.S. Provisional Application No. 62 / 753,379, filed October 31, 2018, which is incorporated by reference in its entirety.

[0002] Sequence Listing This application incorporates by reference in its entirety the sequence listing in computer readable form (CRF) submitted herewith in ASCII text format. The text file of the sequence listing submitted herewith is named "14247-343-228_SEQ_LISTING.txt", was created on October 29, 2019, and is 13,087 bytes in size.

[0003] 1.Technical Field The present invention provides a method for treating anemia due to very low, low or moderate risk myelodysplastic syndrome in a subject with ringed sideroblasts, comprising administering to the subject an activin type II receptor signaling inhibitor. [Background technology]

[0004] 2.Background technology Myelodysplastic syndromes (MDS) are a group of hematological malignancies characterized pathologically by the presence of morphological dysplasia and clinically by bone marrow failure, leading to persistent and progressive hematopoietic decline. Both the clinical manifestations and severity of the individual lesions in this syndrome vary considerably, ranging from a relatively mild and painless condition called refractory anemia (RA) to a more severe condition called refractory anemia with blasts (RAEB), which often progresses to acute leukemia (Heaney et al, N Engl J Med, 1999, 340(21):1649-60). Current treatment algorithms are primarily based on risk stratification using the International Prognostic Scoring System (IPSS) (Greenberg et al., Blood, 1997; 89(6):2079-2088 and Erratum in Blood, 1998; 91:110). In subjects with low or intermediate risk group-1 (int-1) according to the IPSS, the goal of treatment is to alleviate hypovolemia (Komrokji et al,Semin Oncol.,2011,38(5):648-57). Subjects with MDS can be classified into one of five risk groups (very low, low, intermediate, high, and very high) based on the cytogenetic, hemoglobin (Hgb), platelet, absolute neutrophil count (ANC) levels, and bone marrow (BM) blast percentages obtained at diagnosis according to the International Prognostic Scoring System-Revised (IPSS-R). See, e.g., Greenberg et al.,Blood,2012;120(12):2454-2465. The five risk groups have significantly different risks of progression to acute myeloid leukemia (AML) and overall survival (OS). Median survival is 8.8 years in subjects with low-risk MDS and as short as 0.8 years in those with very high-risk MDS (Greenberg et al., Blood, 2012; 120(12): 2454-2465).

[0005] Over 90% of subjects diagnosed with MDS will develop anemia during the course of their disease, and 30%-50% of subjects will become transfusion dependent. Red blood cell (RBC) transfusion dependence is an independent poor prognostic factor in MDS (Komrokji et al,Semin Oncol.,2011,38(5):648-57).

[0006] Treatment options for anemia in lower-risk MDS are limited. Response rates for erythropoietin stimulating agents (ESAs) range from 20% to 40%. The use of ESAs (i.e., recombinant erythropoietin [EPO] or darbepoetin [DAR]) is the standard of care for symptomatic anemia patients with low- and intermediate-risk disease according to the IPSS and endogenous serum erythropoietin (sEPO) levels <500 IU / L and is recommended by European and United States (US) treatment guidelines. If necessary, the use of granulocyte colony-stimulating factor (G-CSF) may be employed, and although not required, in some cases the use of G-CSF may further improve the efficacy of ESAs (Fenaux et al., 2014, Annals of Oncology 25(Suppl_3):iii57-iii69; Malcovati et al., 2013, Blood 122(17):2943-64). European guidelines also recommend the use of ESAs for patients with a low RBC transfusion burden (<2 units per month) and / or endogenous sEPO levels <500 IU / L (Fenaux et al., 2014, Annals of Oncology25 (Suppl_3):iii57-iii69; Malcovati et al., 2013, Blood 122(17):2943-64). However, the main favorable prognostic factors for response to ESAs are low or no need for RBC transfusions (<2 units per month) and endogenous sEPO levels <500 IU / L (Fenaux et al., 2013, Blood;121(21):4280-6). Responsiveness to ESAs is highest in patients with low endogenous levels of sEPO (e.g., <500 IU / L), normal blast counts, and lower IPSS / World Health Organization (WHO) Prognostic Scoring System (WPSS) scores (Hellstrom-Lindberg et al., 2003, Br J Haematol; 120(6): 1037-46; Santini, V., 2011, Oncologist; 16(suppl3): 35-42).

[0007] Two related type II receptors, ActRIIA and ActRIIB, have been identified as type II receptors for activin (Mathews and Vale, 1991, Cell 65:973-982; Attisano et al., 1992, Cell 68:97-108). In addition to activin, ActRIIA and ActRIIB can biochemically interact with several other TGF-β family proteins, including BMP7, Nodal, GDF8 and GDF11 (Yamashita et al., 1995, J. Cell Biol. 130:217-226; Lee and McPherron, 2001, Proc. Natl. Acad. Sci. 98:9306-9311; Yeo and Whitman, 2001, Mol. Cell 7:949-957; Oh et al., 2002, Genes Dev. 16:2749-54).

[0008] The ActRIIB ligand wrap, luspatercept, has been described for the treatment of various indications, see, e.g., Patent Application Publication No. 2016090077. Summary of the Invention

[0009] 3. Overview of the Invention Provided herein is a method of treating a human subject who has been or will be diagnosed with anemia due to very low, low or moderate risk myelodysplastic syndrome (MDS), comprising administering to the subject a therapeutically effective dose of luspatercept, also known as ACE-536 (a polypeptide comprising the amino acid sequence of SEQ ID NO: 1), or a polypeptide comprising an amino acid sequence that has at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% sequence identity to sotatercept, also known as ACE-011 (a polypeptide comprising the amino acid sequence of SEQ ID NO: 2), wherein (a) in the subject, at least 15% of erythroblasts are ring sideroblasts, and (b) the subject is: (i) a male subject; (ii) a subject who has been initially diagnosed with MDS within 2-5 years prior to said administration; or (iii) a subject with a baseline platelet count of 100×10 9 / L, or in a specific embodiment, 400 × 10 9 (iv) subjects with a baseline serum erythropoietin (EPO) level of 100-200 IU / L; or (v) subjects who have received 4-6 units of RBC transfusion over a period of 8 weeks prior to said administration.

[0010] Further provided herein is a method of treating a human subject who has been or will be diagnosed with very low, low or moderate risk MDS, or anemia due to very low, low or moderate risk MDS, comprising: (a) determining in the subject that at least 15% of erythroblasts are ring sideroblasts; and (b) determining that the subject is: (i) a male subject; (ii) a subject who has been initially diagnosed with MDS within 2-5 years prior to said administration; (iii) a subject who has a baseline platelet count of 100×10 9 / L super, 150×10 9 / L super, 200×10 9 / L super, 250×10 9 / L super, 300×10 9 / L super, 350×109 / L, or in a specific embodiment, 400 × 10 9 (iv) a subject with a baseline serum erythropoietin (EPO) level of 100-200 IU / L or more; or (v) a subject who has received 4-6 units of RBC transfusions over an 8 week period prior to said treatment; and (c) administering a therapeutically effective amount of a polypeptide comprising an amino acid sequence that has at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100% sequence identity to luspatercept or sotatercept based on a combination of (a) and (b).

[0011] Provided herein is a method of treating a human subject who has been or will be diagnosed with anemia due to very low, low or moderate risk MDS, comprising administering to the subject a therapeutically effective dose of raspatercept or sotatercept, wherein: (a) the subject has one or more mutations in the SF3B1 gene; (b) the subject has at least 5% of its erythroblasts that are ring sideroblasts; and (c) the subject is one of the following: (i) a male subject; (ii) a subject who has been initially diagnosed with MDS within 2-5 years prior to administration of raspatercept or sotatercept; (iii) a subject with a baseline platelet count of 100×10 9 / L super, 150×10 9 / L super, 200×10 9 / L super, 250×10 9 / L super, 300×10 9 / L super, 350×10 9 / L, or in a specific embodiment, 400 × 10 9 (iv) subjects with a baseline serum EPO level of 100-200 IU / L; or (v) subjects who have received 4-6 units of RBC transfusion over a period of 8 weeks prior to said administration.

[0012] Further provided herein is a method of treating a human subject who has been or will be diagnosed with very low, low or moderate risk MDS, or anemia due to very low, low or moderate risk MDS, comprising: (a) determining that the subject has one or more mutations in the SF3B1 gene; (b) determining that the subject has at least 5% of erythroblasts that are ring sideroblasts; and (c) determining that the subject is: (i) a male subject; (ii) a subject who has been initially diagnosed with MDS within 2-5 years prior to said administration; (iii) a subject who has a baseline platelet count of 100×10 9 / L super, 150×10 9 / L super, 200×10 9 / L super, 250×10 9 / L super, 300×10 9 / L super, 350×10 9 / L, or in a specific embodiment, 400 × 10 9 (iv) a subject with a baseline serum erythropoietin (EPO) level of 100-200 IU / L or more; or (v) a subject who has received 4-6 units of RBC transfusions over an 8 week period prior to said treatment; and (d) administering a therapeutically effective amount of a polypeptide comprising an amino acid sequence that has at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100% sequence identity to luspatercept or sotatercept based on a combination of (a), (b) and (c).

[0013] Provided herein is a method of treating a human subject who has been or will be diagnosed with anemia due to very low, low or moderate risk myelodysplastic syndrome (MDS), comprising administering to the subject a therapeutically effective dose of a polypeptide comprising an amino acid sequence that has at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100% sequence identity to SEQ ID NO:3, SEQ ID NO:4 or SEQ ID NO:5, wherein (a) at least 15% of the erythroblasts in the subject are ring sideroblasts, and (b) the subject is: (i) a male subject; (ii) a subject who has been initially diagnosed with MDS within 2-5 years prior to said administration; (iii) a subject who has a baseline platelet count of 100×10 9 / L super, 150×10 9 / L super, 200×10 9 / L super, 250×10 9 / L super, 300×10 9 / L super, 350×10 9 / L, or in a specific embodiment, 400 × 10 9 (iv) subjects with a baseline serum erythropoietin (EPO) level of 100-200 IU / L; or (v) subjects who have received 4-6 units of RBC transfusion over a period of 8 weeks prior to said administration.

[0014] Further provided herein is a method of treating a human subject who has been or will be diagnosed with very low, low or moderate risk MDS, or anemia due to very low, low or moderate risk MDS, comprising: (a) determining in the subject that at least 15% of erythroblasts are ring sideroblasts; and (b) determining that the subject is: (i) a male subject; (ii) a subject who has been initially diagnosed with MDS within 2-5 years prior to said administration; (iii) a subject who has a baseline platelet count of 100×10 9 / L super, 150×10 9 / L super, 200×10 9 / L super, 250×10 9 / L super, 300×10 9 / L super, 350×10 9 / L, or in a specific embodiment, 400 × 10 9 (iv) a subject with a baseline serum erythropoietin (EPO) level of 100-200 IU / L or more; or (v) a subject who has received 4-6 units of RBC transfusions over an 8 week period prior to said treatment; and (c) administering a therapeutically effective amount of a polypeptide comprising an amino acid sequence that has at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100% sequence identity to SEQ ID NO:3, SEQ ID NO:4 or SEQ ID NO:5 based on a combination of (a) and (b).

[0015] Provided herein is a method of treating a human subject who has been or will be diagnosed with anemia due to very low, low or moderate risk MDS, comprising administering to the subject a therapeutically effective dose of SEQ ID NO:3, SEQ ID NO:4 or SEQ ID NO:5, wherein: (a) the subject has one or more mutations in the SF3B1 gene; (b) the subject has at least 5% of its erythroblasts that are ring sideroblasts; and (c) the subject is one of the following: (i) a male subject; (ii) a subject who has been initially diagnosed with MDS within 2-5 years prior to administration of luspatercept or sotatercept; (iii) a subject with a baseline platelet count of 100×10 9 / L super, 150×10 9 / L super, 200×10 9 / L super, 250×10 9 / L super, 300×10 9 / L super, 350×10 9 / L, or in a specific embodiment, 400 × 10 9 (iv) subjects with a baseline serum EPO level of 100-200 IU / L; or (v) subjects who have received 4-6 units of RBC transfusion over a period of 8 weeks prior to said administration.

[0016] Further provided herein is a method of treating a human subject who has been or will be diagnosed with very low, low or moderate risk MDS, or anemia due to very low, low or moderate risk MDS, comprising: (a) determining that the subject has one or more mutations in the SF3B1 gene; (b) determining that the subject has at least 5% of erythroblasts that are ring sideroblasts; and (c) determining that the subject is: (i) a male subject; (ii) a subject who has been initially diagnosed with MDS within 2-5 years prior to said administration; (iii) a subject who has a baseline platelet count of 100×10 9 / L super, 150×10 9 / L super, 200×10 9 / L super, 250×10 9 / L super, 300×10 9 / L super, 350×10 9 / L, or in a specific embodiment, 400 × 10 9 (iv) a subject with a baseline serum erythropoietin (EPO) level of 100-200 IU / L or more; or (v) a subject who has received 4-6 units of RBC transfusions over an 8 week period prior to said treatment; and (d) administering a therapeutically effective amount of a polypeptide comprising an amino acid sequence that has at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100% sequence identity to SEQ ID NO:3, SEQ ID NO:4 or SEQ ID NO:5 based on a combination of (a), (b) and (c).

[0017] Provided herein is a method of treating a human subject who has been or will be diagnosed with anemia due to very low, low or moderate risk myelodysplastic syndrome (MDS), comprising administering to the subject a therapeutically effective dose of a polypeptide comprising an amino acid sequence that has at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100% sequence identity to a fragment of SEQ ID NO:3, SEQ ID NO:4, or SEQ ID NO:5, wherein (a) at least 15% of the erythroblasts in the subject are ring sideroblasts, and (b) the subject is: (i) a male subject; (ii) a subject who has been initially diagnosed with MDS within 2-5 years prior to said administration; (iii) a subject who has a baseline platelet count of 100×10 9 / L super, 150×10 9 / L super, 200×10 9 / L super, 250×10 9 / L super, 300×10 9 / L super, 350×10 9 / L, or in a specific embodiment, 400 × 10 9 (iv) a subject with a baseline serum erythropoietin (EPO) level of 100-200 IU / L or (v) a subject who has received 4-6 units of RBC transfusion over an 8 week period prior to said administration. In certain embodiments, the fragment of SEQ ID NO:3 is SEQ ID NO:5.

[0018] Further provided herein is a method of treating a human subject who has been or will be diagnosed with very low, low or moderate risk MDS, or anemia due to very low, low or moderate risk MDS, comprising: (a) determining in the subject that at least 15% of erythroblasts are ring sideroblasts; and (b) determining that the subject is: (i) a male subject; (ii) a subject who has been initially diagnosed with MDS within 2-5 years prior to said administration; (iii) a subject who has a baseline platelet count of 100×10 9 / L super, 150×10 9 / L super, 200×109 / L super, 250×10 9 / L super, 300×10 9 / L super, 350×10 9 / L, or in a specific embodiment, 400 × 10 9 (iv) a subject with a baseline serum erythropoietin (EPO) level of 100-200 IU / L or (v) a subject who has received 4-6 units of RBC transfusions over an 8 week period prior to said treatment; and (c) administering a therapeutically effective amount of a polypeptide comprising an amino acid sequence that has at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100% sequence identity to SEQ ID NO:3, SEQ ID NO:4 or a fragment of SEQ ID NO:5 based on a combination of (a) and (b). In certain embodiments, the fragment of SEQ ID NO:3 is SEQ ID NO:5.

[0019] Provided herein is a method of treating a human subject who has been or will be diagnosed with anemia due to very low, low or moderate risk MDS, comprising administering to the subject a therapeutically effective dose of a fragment of SEQ ID NO:3, SEQ ID NO:4 or SEQ ID NO:5, wherein: (a) the subject has one or more mutations in the SF3B1 gene; (b) the subject has at least 5% of its erythroblasts that are ring sideroblasts; (c) the subject is one of the following: (i) a male subject; (ii) a subject who has been initially diagnosed with MDS within 2-5 years prior to administration of luspatercept or sotatercept; (iii) a subject with a baseline platelet count of 100×10 9 / L super, 150×10 9 / L super, 200×10 9 / L super, 250×10 9 / L super, 300×10 9 / L super, 350×10 9 / L, or in a specific embodiment, 400 × 10 9(iv) a subject with a baseline serum EPO level of 100-200 IU / L or (v) a subject who has received 4-6 units of RBC transfusion over an 8 week period prior to said administration. In certain embodiments, the fragment of SEQ ID NO:3 is SEQ ID NO:5.

[0020] Further provided herein is a method of treating a human subject who has been or will be diagnosed with very low, low or moderate risk MDS, or anemia due to very low, low or moderate risk MDS, comprising: (a) determining that the subject has one or more mutations in the SF3B1 gene; (b) determining that the subject has at least 5% of erythroblasts that are ring sideroblasts; and (c) determining that the subject is: (i) a male subject; (ii) a subject who has been initially diagnosed with MDS within 2-5 years prior to said administration; (iii) a subject who has a baseline platelet count of 100×10 9 / L super, 150×10 9 / L super, 200×10 9 / L super, 250×10 9 / L super, 300×10 9 / L super, 350×10 9 / L, or in a specific embodiment, 400 × 10 9 (iv) a baseline serum erythropoietin (EPO) level of 100-200 IU / L or (v) a subject who has received 4-6 units of RBC transfusions over an 8 week period prior to said treatment; and (d) administering a therapeutically effective amount of a polypeptide comprising an amino acid sequence that has at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100% sequence identity to SEQ ID NO:3, SEQ ID NO:4 or a fragment of SEQ ID NO:5 based on a combination of (a), (b) and (c). In certain embodiments, the fragment of SEQ ID NO:3 is SEQ ID NO:5.

[0021] In certain embodiments of any of the above methods, the very low, low or intermediate risk MDS is classified using the International Prognostic Scoring System-Revised (IPSS-R).

[0022] In certain embodiments of any of the above methods, the subject has less than 5 percent blasts in the bone marrow.

[0023] In certain embodiments of any of the above methods, the subject is in need of a red blood cell (RBC) transfusion.

[0024] In certain embodiments of any of the above methods, the method is for (i) reducing the percentage of erythroblasts in the subject that are ring sideroblasts for an extended period of time, more particularly for 8 weeks or more, compared to the initial percentage of erythroblasts in the subject that are ring sideroblasts, and / or (ii) increasing the hemoglobin level in the subject for an extended period of time, more particularly for 8 weeks or more, compared to the hemoglobin level in the subject at a period of time prior to administering the first of the administrations to the subject.

[0025] In certain embodiments of any of the above methods, the percentage of erythroblasts in the subject prior to said administration, e.g., prior to administration of luspatercept or sotatercept, that are ring sideroblasts is at least 15%, at least 16%, at least 17%, at least 18%, at least 19%, or at least 20%. In certain embodiments, the subject treated prior to said administration has at least 15% of the erythroblasts in the subject that are ring sideroblasts. In certain embodiments, the subject treated prior to said administration (i) has one or more mutations in the SF3B1 gene and (ii) has at least 5%, at least 6%, at least 7%, at least 8%, at least 9%, at least 10%, at least 11%, at least 12%, at least 13%, at least 14%, at least 15%, at least 16%, at least 17%, at least 18%, at least 19%, or at least 20% of the erythroblasts that are ring sideroblasts.

[0026] In certain embodiments of any of the above methods, the pharma- ceutically effective dose of luspatercept or sotatercept is between 1.0 mg / kg and 1.75 mg / kg. In certain embodiments of any of the above methods, the pharma- tically effective dose of raspatercept or sotatercept is 0.45 mg / kg, 0.50 mg / kg, 0.60 mg / kg, 0.70 mg / kg, 0.80 mg / kg, 0.90 mg / kg, 1.00 mg / kg, 1.05 mg / kg, 1.10 mg / kg, 1.15 mg / kg, 1.20 mg / kg, 1.25 mg / kg, 1.30 mg / kg, 1.33 mg / kg, 1.35 mg / kg, 1.40 mg / kg, 1.45 mg / kg, 1.50 mg / kg, 1.55 mg / kg, 1.60 mg / kg, 1.65 mg / kg, 1.70 mg / kg, or 1.75 mg / kg.

[0027] In certain embodiments of any of the above methods, the raspatercept or sotatercept is administered subcutaneously.

[0028] In certain embodiments of any of the above methods, the subject can be refractory to prior treatment with erythropoietin stimulating agent (ESA).In certain embodiments of any of the above methods, the subject can be intolerant to prior treatment with ESA.In certain embodiments of any of the above methods, the subject can be ineligible for treatment with ESA.

[0029] In certain embodiments of any of the above methods, a subject who is refractory to prior treatment with an ESA can be a subject who was refractory to a prior regimen that included an ESA, either as a single agent or in combination with other agents, or who became unresponsive to this regimen at any time after induction due to intolerance or adverse events.

[0030] In certain embodiments of any of the above methods, the subject is intolerant to prior treatment with an ESA. In certain embodiments, the prior regimen, which includes an ESA, either alone or in combination with other agents, has been discontinued in the subject at some point after induction due to intolerance or adverse events.

[0031] In certain embodiments of any of the above methods, the subject has high endogenous serum erythropoietin (EPO) levels and is therefore unlikely to respond to treatment with an ESA. In certain embodiments of any of the above methods, the subject has not previously been treated with an ESA and has a serum EPO level of greater than 200 IU / L.

[0032] In certain embodiments of any of the above methods, the ESA-containing regimen also includes granulocyte-colony stimulating factor (G-CSF).

[0033] In certain embodiments, the outcome of any of the above methods is (a) a period of red blood cell transfusion independence (RBC-TI) in the treated subject of 8 weeks or more following said administration, (b) RBC-TI in the treated subject of 12 weeks or more following said administration, or (c) an altered red blood cell response (mHI-E) in the treated subject, which in certain embodiments is an increase in mean hemoglobin of 1.5 g / dL or more over an 8 week period or a decrease in transfused red blood cells of 4 units or more over an 8 week period following said administration. [Brief description of the drawings]

[0034] 4. Brief description of the drawings [Figure 1] Demographic and baseline characteristics of the intent-to-treat (ITT) population are shown.

[0035] [Diagram 2] Past transfusion history of the ITT population is shown.

[0036] [Diagram 3] For the ITT population, medical history data were compiled using frequency tables by system organ class and preferred term from the Medical Dictionary for Regulatory Activities (MedDRA).

[0037] [Figure 4] For the ITT population, frequency tables are used to show the history of previous MDS diagnoses.

[0038] [Diagram 5] Frequency distribution tables are used to demonstrate RBC transfusion dependency.

[0039] [Figure 6] Past history of treatment with ESAs, use of GCSF / GMCSF, and treatment with iron chelation therapy in the ITT population is shown.

[0040] [Figure 7A] Part A of the subgroup analysis by forest plot of RBC-TI ≥8 weeks during weeks 1 to 24 in the ITT population is shown.

[0041] [Figure 7B] Part B of the subgroup analysis by forest plot of RBC-TI ≥8 weeks during weeks 1-24 in the ITT population is shown.

[0042] [Figure 8A] Part A of the subgroup analysis by forest plot of RBC-TI ≥12 weeks during weeks 1 to 24 in the ITT population is shown.

[0043] [Figure 8B] Part B of the subgroup analysis by forest plot of RBC-TI ≥12 weeks during weeks 1-24 in the ITT population is shown.

[0044] [Figure 9A] Part A of the subgroup analysis by forest plot of RBC-TI ≥12 weeks during weeks 1 to 48 in the ITT population is shown.

[0045] [Figure 9B] Part B of the subgroup analysis by forest plot of RBC-TI ≥12 weeks during weeks 1 to 48 in the ITT population is shown.

[0046] [Figure 10A] Part A of the subgroup analysis by forest plot for HI-E during weeks 1 to 24 in the ITT population is shown.

[0047] [Figure 10B]Part B of the subgroup analysis by forest plot for HI-E during weeks 1 to 24 in the ITT population is shown.

[0048] [Figure 11A] Part A of the subgroup analysis by forest plot for HI-E from weeks 1 to 48 in the ITT population is shown.

[0049] [Figure 11B] Part A of the subgroup analysis by forest plot for HI-E from weeks 1 to 48 in the ITT population is shown. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0050] 5. Detailed Description of the Invention 5.1 Overview The present invention provides a method for treating anemia due to very low, low or moderate risk myelodysplastic syndrome (MDS) in subjects with ringed sideroblasts using activin-ActRIIA or activin-ActRIIB ligand trap. To demonstrate efficacy, statistical analysis was performed on the intent-to-treat (ITT) population, including subgroup analysis by age, sex, race, baseline characteristics (e.g., baseline serum EPO level), medical history (e.g., time since initial diagnosis) and baseline RBC transfusion dependency. See Section 6.1.2.

[0051] 5.2 Terms and Abbreviations As used herein, "ActRII" refers to activin receptor type II. As used herein, "ActRIIA" refers to activin receptor type IIA. See, for example, Mathews and Vale, 1991, Cell 65:973-982. GenBank™ Accession No. NM_001278579.1 provides an exemplary human ActRIIA nucleic acid sequence. GenBank™ Accession No. NP_001265508.1 provides an exemplary human ActRIIA amino acid sequence.

[0052] As used herein, "ActRIIB" refers to activin receptor type IIB. See, for example, Attisano et al., 1992, Cell 68:97-108. GenBank™ Accession No. NM_001106.3 provides an exemplary human ActRIIB nucleic acid sequence. GenBank™ Accession No. NP_001097.2 provides an exemplary human ActRIIB amino acid sequence.

[0053] As used herein, "BL" refers to baseline.

[0054] As used herein, "DAR" refers to darbepoetin.

[0055] As used herein, "ECD" refers to the extracellular domain.

[0056] As used herein, "EPO" refers to erythropoietin.

[0057] As used herein, "sEPO" refers to serum erythropoietin.

[0058] As used herein, "ESA" refers to erythropoietin stimulating agent.

[0059] As used herein, "G-CSF" refers to granulocyte colony-stimulating factor.

[0060] As used herein, "GM-CSG" refers to granulocyte-macrophage colony-stimulating factor.

[0061] As used herein, "Hb" refers to hemoglobin.

[0062] As used herein, "HI-E" refers to red blood cell hematological improvement. In certain embodiments, HI-E is as defined by the IWG. In certain embodiments, HI-E is as defined by the IWG Criteria (2006 Revised). In certain embodiments, HI-E in patients with low transfusion burden is an increase in the patient's hemoglobin concentration of at least 1.5 g / dL for at least 8 weeks. In certain embodiments, HI-E in patients with high transfusion burden is a reduction in RBC transfusions of at least 4 units over an 8-week period.

[0063] As used herein, "HTB" refers to high transfusion burden. In certain embodiments, a subject with HTB is one who receives 4 or more units of RBC transfusions in an 8 week period.

[0064] As used herein, "IgG" refers to immunoglobulin G.

[0065] As used herein, "IPSS-R" refers to the International Prognostic Scoring System-Revised. See Section 5.4.

[0066] As used herein, "IWG" refers to the International Working Group. See, e.g., Cheson et al. Blood. 2000 96:3671-3674. In certain embodiments, IWG refers to the 2006 revised criteria. See, e.g., Cheson et al., 2006, Blood, 108(2).

[0067] As used herein, "LTB" refers to low transfusion burden. In certain embodiments, an LTB subject is one who receives less than 4 units of RBC transfusions in an 8 week period.

[0068] As used herein, "ITT" refers to intent-to-treat.

[0069] As used herein, "MedDRA" refers to the Medical Dictionary for Regulatory Activities.

[0070] As used herein, "MDS" refers to myelodysplastic syndromes.

[0071] As used herein, "PD" refers to pharmacodynamics.

[0072] As used herein, "PK" refers to pharmacokinetics.

[0073] As used herein, "RA" refers to refractory anemia.

[0074] As used herein, "RAEB" refers to refractory anemia with excess blasts.

[0075] As used herein, "RBC" refers to red blood cells.

[0076] As used herein, "RBC-TI" refers to red blood cell transfusion independence.

[0077] As used herein, "RCMD-RS" refers to refractory cytopenia with multilineage dysplasia with ringed sideroblasts.

[0078] As used herein, "RS" refers to ringed sideroblasts.

[0079] As used herein, "SC" refers to subcutaneous.

[0080] As used herein, "SF3B1" refers to splicing factor 3B1. GenBank™ Accession Nos. NM_012433.3, NM_001005523.2, and NM_001308824.1 provide exemplary nucleic acid sequences for human SF3B1. GenBank™ Accession Nos. NP_001295753.1, NP_001005526.1, and NP_036565.2 provide exemplary amino acid sequences for human SF3B1.

[0081] As used herein, "WPSS" refers to the World Health Organization (WHO) Prognostic Scoring System.

[0082] As used herein, "raspatercept" refers to a polypeptide comprising the amino acid sequence of SEQ ID NO:1.

[0083] As used herein, "sotatercept" refers to a polypeptide comprising the amino acid sequence of SEQ ID NO:2.

[0084] 5.3 Treatment method In one aspect, the present invention provides a method of treating very low, low or moderate risk MDS or anemia due to very low, low or moderate risk MDS in a subject, comprising administering to the subject a pharmacologic effective dose (0.1 mg / kg to 2.0 mg / kg) of an ActRII signaling inhibitor if at least 5%, at least 6%, at least 7%, at least 8%, at least 9%, at least 10%, at least 11%, at least 12%, at least 13%, at least 14%, at least 15%, at least 16%, at least 17%, at least 18%, at least 19%, or at least 20% of the subject's erythroblasts are ring sideroblasts. For patient populations and subpopulations that can be treated with the methods provided herein, see Section 5.4. In certain embodiments, the subject has one or more mutations in the SF3B1 gene. In certain embodiments, the percentage of erythroblasts in the subject that are ring sideroblasts is first determined. In certain embodiments, the first refers to within 1 day, within 2 days, within 3 days, within 4 days, within 5 days, within 6 days, within 1 week, within 2 weeks, within 3 weeks, within 4 weeks, within 5 weeks, within 6 weeks, within 7 weeks, within 8 weeks, within 3 months, within 4 months, within 5 months, within 6 months, within 1 year, within 2 years, within 3 years, within 4 years, and within 5 years of administering a pharma- ceutical effective dose of an ActRII signaling inhibitor to the subject.

[0085] Provided herein is a method for treating very low, low or moderate risk MDS, or anemia due to very low, low or moderate risk MDS, in a subject, by administering to the subject a pharmacologic effective dose of an activin receptor type II (ActRII) signaling inhibitor to (i) reduce the percentage of erythroblasts in the subject that are ring sideroblasts for a prolonged period of time relative to the initial percentage of erythroblasts in the subject that are ring sideroblasts, and / or (ii) reduce the percentage of erythroblasts in the subject that are ring sideroblasts for a period of time prior to administering a first dose of the ActRII signaling inhibitor to the subject. The method includes administering a therapeutically effective dose of 0.1 mg / kg to 2.0 mg / kg for a period of time that elevates the subject's hemoglobin level above the subject's hemoglobin level for an extended period of time, wherein the pharmacologic effective dose is between 0.1 mg / kg and 2.0 mg / kg, and wherein the initial percentage of erythroblasts in the subject that are ring sideroblasts is at least 5%, at least 6%, at least 7%, at least 8%, at least 9%, at least 10%, at least 11%, at least 12%, at least 13%, at least 14%, at least 15%, at least 16%, at least 17%, at least 18%, at least 19%, or at least 20%.

[0086] In certain embodiments, the ActRII signaling inhibitor is administered once a week, once every two weeks, once every three weeks, once every four weeks, once every five weeks, or once every six weeks.In certain embodiments, the ActRII signaling inhibitor is administered once every 21 days.In certain embodiments, the ActRII signaling inhibitor is administered subcutaneously.

[0087] In certain embodiments, the ActRII signaling inhibitor is raspatercept (a polypeptide comprising the amino acid sequence of SEQ ID NO: 1). In certain embodiments, the ActRII signaling inhibitor is sotatercept (a polypeptide comprising the amino acid sequence of SEQ ID NO: 2). In certain embodiments, the ActRII signaling inhibitor is a polypeptide comprising the amino acid sequence of SEQ ID NO: 3. In certain embodiments, the ActRII signaling inhibitor is a polypeptide comprising a fragment of the amino acid sequence of SEQ ID NO: 3. In certain embodiments, the ActRII signaling inhibitor is a polypeptide comprising the amino acid sequence of SEQ ID NO: 4. In certain embodiments, the ActRII signaling inhibitor is a polypeptide comprising a fragment of the amino acid sequence of SEQ ID NO: 4. In certain embodiments, the ActRII signaling inhibitor is a polypeptide comprising the amino acid sequence of SEQ ID NO: 5. In certain embodiments, the ActRII signaling inhibitor is a humanized fusion protein consisting of the extracellular domain of ActRIIA and a human IgG1 Fc domain. In certain embodiments, the ActRII signaling inhibitor is a humanized fusion protein consisting of the extracellular domain of ActRIIB and a human IgG1 Fc domain.

[0088] In certain embodiments, the ActRII signaling inhibitor is a signaling inhibitor of ActRIIB. In certain embodiments, the ActRIIB signaling inhibitor is a polypeptide comprising an amino acid sequence selected from the group consisting of: (a) an amino acid sequence 90% identical to SEQ ID NO:1, (b) an amino acid sequence 91% identical to SEQ ID NO:1, (c) an amino acid sequence 92% identical to SEQ ID NO:1, (d) an amino acid sequence 93% identical to SEQ ID NO:1, (e) an amino acid sequence 94% identical to SEQ ID NO:1, (f) an amino acid sequence 95% identical to SEQ ID NO:1, (g) an amino acid sequence 96% identical to SEQ ID NO:1, (h) an amino acid sequence 97% identical to SEQ ID NO:1, (i) an amino acid sequence 98% identical to SEQ ID NO:1, (j) an amino acid sequence 99% identical to SEQ ID NO:1, and (k) an amino acid sequence 100% identical to SEQ ID NO:1.

[0089] In certain embodiments, the ActRII signaling inhibitor is a signaling inhibitor of ActRIIA. In certain embodiments, the ActRIIA signaling inhibitor is a polypeptide comprising an amino acid sequence selected from the group consisting of: (a) an amino acid sequence 90% identical to SEQ ID NO:2, (b) an amino acid sequence 91% identical to SEQ ID NO:2, (c) an amino acid sequence 92% identical to SEQ ID NO:2, (d) an amino acid sequence 93% identical to SEQ ID NO:2, (e) an amino acid sequence 94% identical to SEQ ID NO:2, (f) an amino acid sequence 95% identical to SEQ ID NO:2, (g) an amino acid sequence 96% identical to SEQ ID NO:2, (h) an amino acid sequence 97% identical to SEQ ID NO:2, (i) an amino acid sequence 98% identical to SEQ ID NO:2, (j) an amino acid sequence 99% identical to SEQ ID NO:2, and (k) an amino acid sequence 100% identical to SEQ ID NO:2.

[0090] In certain embodiments, the ActRII signaling inhibitor is a signaling inhibitor of ActRIIB. In certain embodiments, the ActRIIB signaling inhibitor is a polypeptide comprising an amino acid sequence selected from the group consisting of: (a) an amino acid sequence 90% identical to SEQ ID NO:3, (b) an amino acid sequence 91% identical to SEQ ID NO:3, (c) an amino acid sequence 92% identical to SEQ ID NO:3, (d) an amino acid sequence 93% identical to SEQ ID NO:3, (e) an amino acid sequence 94% identical to SEQ ID NO:3, (f) an amino acid sequence 95% identical to SEQ ID NO:3, (g) an amino acid sequence 96% identical to SEQ ID NO:3, (h) an amino acid sequence 97% identical to SEQ ID NO:3, (i) an amino acid sequence 98% identical to SEQ ID NO:3, (j) an amino acid sequence 99% identical to SEQ ID NO:3, and (k) an amino acid sequence 100% identical to SEQ ID NO:3.

[0091] In certain embodiments, the ActRII signaling inhibitor is a signaling inhibitor of ActRIIA. In certain embodiments, the ActRIIA signaling inhibitor is a polypeptide comprising an amino acid sequence selected from the group consisting of: (a) an amino acid sequence 90% identical to SEQ ID NO:4, (b) an amino acid sequence 91% identical to SEQ ID NO:4, (c) an amino acid sequence 92% identical to SEQ ID NO:4, (d) an amino acid sequence 93% identical to SEQ ID NO:4, (e) an amino acid sequence 94% identical to SEQ ID NO:4, (f) an amino acid sequence 95% identical to SEQ ID NO:4, (g) an amino acid sequence 96% identical to SEQ ID NO:4, (h) an amino acid sequence 97% identical to SEQ ID NO:4, (i) an amino acid sequence 98% identical to SEQ ID NO:4, (j) an amino acid sequence 99% identical to SEQ ID NO:4, and (k) an amino acid sequence 100% identical to SEQ ID NO:4.

[0092] In certain embodiments, the ActRII signaling inhibitor is a signaling inhibitor of ActRIIB. In certain embodiments, the ActRIIB signaling inhibitor is a polypeptide comprising an amino acid sequence selected from the group consisting of: (a) an amino acid sequence 90% identical to SEQ ID NO:5, (b) an amino acid sequence 91% identical to SEQ ID NO:5, (c) an amino acid sequence 92% identical to SEQ ID NO:5, (d) an amino acid sequence 93% identical to SEQ ID NO:5, (e) an amino acid sequence 94% identical to SEQ ID NO:5, (f) an amino acid sequence 95% identical to SEQ ID NO:5, (g) an amino acid sequence 96% identical to SEQ ID NO:5, (h) an amino acid sequence 97% identical to SEQ ID NO:5, (i) an amino acid sequence 98% identical to SEQ ID NO:5, (j) an amino acid sequence 99% identical to SEQ ID NO:5, and (k) an amino acid sequence 100% identical to SEQ ID NO:5.

[0093] In certain embodiments, the ActRII signaling inhibitor is a signaling inhibitor of ActRIIB. In certain embodiments, the ActRIIB signaling inhibitor is an inhibitor of (a) an amino acid sequence 70% identical to a fragment of SEQ ID NO: 3, (b) an amino acid sequence 71% identical to a fragment of SEQ ID NO: 3, (c) an amino acid sequence 72% identical to a fragment of SEQ ID NO: 3, (d) an amino acid sequence 73% identical to a fragment of SEQ ID NO: 3, (e) an amino acid sequence 74% identical to a fragment of SEQ ID NO: 3, (f) an amino acid sequence 75% identical to a fragment of SEQ ID NO: 3, (g) an amino acid sequence 76% identical to a fragment of SEQ ID NO: 3, (h) an amino acid sequence 77% identical to a fragment of SEQ ID NO: 3, (i) an amino acid sequence 78% identical to a fragment of SEQ ID NO: 3, (ii) an amino acid sequence 79% identical to a fragment of SEQ ID NO: 3, (iii) an amino acid sequence 71% identical to a fragment of SEQ ID NO: 3, (iv) an amino acid sequence 72% identical to a fragment of SEQ ID NO: 3, (v) an amino acid sequence 73% identical to a fragment of SEQ ID NO: 3, (vi) an amino acid sequence 74% identical to a fragment of SEQ ID NO: 3, (vi) an amino acid sequence 75% identical to a fragment of SEQ ID NO: 3, (vi) an amino acid sequence 76% identical to a fragment of SEQ ID NO: 3, (vi) an amino acid sequence 77% identical to a fragment of SEQ ID NO: 3, (vi) an amino acid sequence 78% identical to a fragment of SEQ ID NO: 3, (vi) an amino acid sequence 79% identical to a fragment of SEQ ID NO: 3, (vi) an amino acid sequence 79% identical to a fragment of SEQ ID (i) an amino acid sequence that is 77% identical to a fragment of SEQ ID NO:3, (j) an amino acid sequence that is 79% identical to a fragment of SEQ ID NO:3, (k) an amino acid sequence that is 80% identical to a fragment of SEQ ID NO:3, (l) an amino acid sequence that is 81% identical to a fragment of SEQ ID NO:3, (m) an amino acid sequence that is 82% identical to a fragment of SEQ ID NO:3, (n) an amino acid sequence that is 83% identical to a fragment of SEQ ID NO:3, (o) an amino acid sequence that is 84% ​​identical to a fragment of SEQ ID NO:3, (p) an amino acid sequence that is 85% identical to a fragment of SEQ ID NO:3. (q) an amino acid sequence that is 86% identical to a fragment of SEQ ID NO:3, (r) an amino acid sequence that is 87% identical to a fragment of SEQ ID NO:3, (s) an amino acid sequence that is 88% identical to a fragment of SEQ ID NO:3, (t) an amino acid sequence that is 89% identical to a fragment of SEQ ID NO:3, (u) an amino acid sequence that is 90% identical to a fragment of SEQ ID NO:3, (v) an amino acid sequence that is 91% identical to a fragment of SEQ ID NO:3, (w) an amino acid sequence that is 92% identical to a fragment of SEQ ID NO:3, (x) an amino acid sequence that is 93% identical to a fragment of SEQ ID NO:3, A polypeptide comprising an amino acid sequence selected from the group consisting of: (y) an amino acid sequence that is 94% identical to a fragment of SEQ ID NO:3; (z) an amino acid sequence that is 95% identical to a fragment of SEQ ID NO:3; (aa) an amino acid sequence that is 96% identical to a fragment of SEQ ID NO:3; (ab) an amino acid sequence that is 97% identical to a fragment of SEQ ID NO:3; (ac) an amino acid sequence that is 98% identical to a fragment of SEQ ID NO:3; (ad) an amino acid sequence that is 99% identical to a fragment of SEQ ID NO:3; and (ae) an amino acid sequence that is 100% identical to a fragment of SEQ ID NO:3.

[0094] In certain embodiments, the ActRII signaling inhibitor is a signaling inhibitor of ActRIIA. In certain embodiments, the ActRIIA signaling inhibitor is an amino acid sequence having (a) an amino acid sequence 70% identical to a fragment of SEQ ID NO: 4, (b) an amino acid sequence 71% identical to a fragment of SEQ ID NO: 4, (c) an amino acid sequence 72% identical to a fragment of SEQ ID NO: 4, (d) an amino acid sequence 73% identical to a fragment of SEQ ID NO: 4, (e) an amino acid sequence 74% identical to a fragment of SEQ ID NO: 4, (f) an amino acid sequence 75% identical to a fragment of SEQ ID NO: 4, (g) an amino acid sequence 76% identical to a fragment of SEQ ID NO: 4, (h) an amino acid sequence 77% identical to a fragment of SEQ ID NO: 4, (i) an amino acid sequence 78% identical to a fragment of SEQ ID NO: 4, (ii) an amino acid sequence 79% identical to a fragment of SEQ ID NO: 4, (iii) an amino acid sequence 71% identical to a fragment of SEQ ID NO: 4, (iv) an amino acid sequence 72% identical to a fragment of SEQ ID NO: 4, (v) an amino acid sequence 73% identical to a fragment of SEQ ID NO: 4, (vi) an amino acid sequence 74% identical to a fragment of SEQ ID NO: 4, (vi) an amino acid sequence 75% identical to a fragment of SEQ ID NO: 4, (vi) an amino acid sequence 76% identical to a fragment of SEQ ID NO: 4, (vii) an amino acid sequence 77% identical to a fragment of SEQ ID NO: 4, (v) an amino acid sequence 78% identical to a fragment of SEQ ID NO: 4, (vii) an amino acid sequence 79% identical to a fragment of SEQ ID NO: 4, (v) an amino acid sequence 79% identical to a fragment (i) an amino acid sequence that is 77% identical to a fragment of SEQ ID NO:4, (j) an amino acid sequence that is 79% identical to a fragment of SEQ ID NO:4, (k) an amino acid sequence that is 80% identical to a fragment of SEQ ID NO:4, (l) an amino acid sequence that is 81% identical to a fragment of SEQ ID NO:4, (m) an amino acid sequence that is 82% identical to a fragment of SEQ ID NO:4, (n) an amino acid sequence that is 83% identical to a fragment of SEQ ID NO:4, (o) an amino acid sequence that is 84% ​​identical to a fragment of SEQ ID NO:4, (p) an amino acid sequence that is 85% identical to a fragment of SEQ ID NO:4. (q) an amino acid sequence that is 86% identical to a fragment of SEQ ID NO:4; (r) an amino acid sequence that is 87% identical to a fragment of SEQ ID NO:4; (s) an amino acid sequence that is 88% identical to a fragment of SEQ ID NO:4; (t) an amino acid sequence that is 89% identical to a fragment of SEQ ID NO:4; (u) an amino acid sequence that is 90% identical to a fragment of SEQ ID NO:4; (v) an amino acid sequence that is 91% identical to a fragment of SEQ ID NO:4; (w) an amino acid sequence that is 92% identical to a fragment of SEQ ID NO:4; (x) an amino acid sequence that is 93% identical to a fragment of SEQ ID NO:4. A polypeptide comprising an amino acid sequence selected from the group consisting of: (y) an amino acid sequence that is 94% identical to a fragment of SEQ ID NO:4; (z) an amino acid sequence that is 95% identical to a fragment of SEQ ID NO:4; (aa) an amino acid sequence that is 96% identical to a fragment of SEQ ID NO:4; (ab) an amino acid sequence that is 97% identical to a fragment of SEQ ID NO:4; (ac) an amino acid sequence that is 98% identical to a fragment of SEQ ID NO:4; (ad) an amino acid sequence that is 99% identical to a fragment of SEQ ID NO:4; and (ae) an amino acid sequence that is 100% identical to a fragment of SEQ ID NO:4.

[0095] In certain embodiments, the ActRII signaling inhibitor is a signaling inhibitor of ActRIIB. In certain embodiments, the ActRIIB signaling inhibitor is an inhibitor of (a) an amino acid sequence 70% identical to a fragment of SEQ ID NO:5, (b) an amino acid sequence 71% identical to a fragment of SEQ ID NO:5, (c) an amino acid sequence 72% identical to a fragment of SEQ ID NO:5, (d) an amino acid sequence 73% identical to a fragment of SEQ ID NO:5, (e) an amino acid sequence 74% identical to a fragment of SEQ ID NO:5, (f) an amino acid sequence 75% identical to a fragment of SEQ ID NO:5, (g) an amino acid sequence 76% identical to a fragment of SEQ ID NO:5, (h) an amino acid sequence 77% identical to a fragment of SEQ ID NO:5, (i) an amino acid sequence 78% identical to a fragment of SEQ ID NO:5, (ii) an amino acid sequence 79% identical to a fragment of SEQ ID NO:5, (iii) an amino acid sequence 71% identical to a fragment of SEQ ID NO:5, (iv) an amino acid sequence 72% identical to a fragment of SEQ ID NO:5, (v) an amino acid sequence 73% identical to a fragment of SEQ ID NO:5, (vi) an amino acid sequence 74% identical to a fragment of SEQ ID NO:5, (vi) an amino acid sequence 75% identical to a fragment of SEQ ID NO:5, (vi) an amino acid sequence 76% identical to a fragment of SEQ ID NO:5, (vi) an amino acid sequence 77% identical to a fragment of SEQ ID NO:5, (vi) an amino acid sequence 78% identical to a fragment of SEQ ID NO:5, (vi) an amino acid sequence 79% identical to a fragment of SEQ ID NO:5, (vi) an amino acid sequence 79% identical to a fragment of SEQ ID NO:5, (vi) an amino acid sequence 79% identical to a fragment (i) an amino acid sequence that is 77% identical to a fragment of SEQ ID NO:5, (i) an amino acid sequence that is 78% identical to a fragment of SEQ ID NO:5, (j) an amino acid sequence that is 79% identical to a fragment of SEQ ID NO:5, (k) an amino acid sequence that is 80% identical to a fragment of SEQ ID NO:5, (l) an amino acid sequence that is 81% identical to a fragment of SEQ ID NO:5, (m) an amino acid sequence that is 82% identical to a fragment of SEQ ID NO:5, (n) an amino acid sequence that is 83% identical to a fragment of SEQ ID NO:5, (o) an amino acid sequence that is 84% ​​identical to a fragment of SEQ ID NO:5, (p) an amino acid sequence that is 85% identical to a fragment of SEQ ID NO:5. (q) an amino acid sequence that is 86% identical to a fragment of SEQ ID NO:5, (r) an amino acid sequence that is 87% identical to a fragment of SEQ ID NO:5, (s) an amino acid sequence that is 88% identical to a fragment of SEQ ID NO:5, (t) an amino acid sequence that is 89% identical to a fragment of SEQ ID NO:5, (u) an amino acid sequence that is 90% identical to a fragment of SEQ ID NO:5, (v) an amino acid sequence that is 91% identical to a fragment of SEQ ID NO:5, (w) an amino acid sequence that is 92% identical to a fragment of SEQ ID NO:5, (x) an amino acid sequence that is 93% identical to a fragment of SEQ ID NO:5, A polypeptide comprising an amino acid sequence selected from the group consisting of: (y) an amino acid sequence that is 94% identical to a fragment of SEQ ID NO:5; (z) an amino acid sequence that is 95% identical to a fragment of SEQ ID NO:5; (aa) an amino acid sequence that is 96% identical to a fragment of SEQ ID NO:5; (ab) an amino acid sequence that is 97% identical to a fragment of SEQ ID NO:5; (ac) an amino acid sequence that is 98% identical to a fragment of SEQ ID NO:5; (ad) an amino acid sequence that is 99% identical to a fragment of SEQ ID NO:5; and (ae) an amino acid sequence that is 100% identical to a fragment of SEQ ID NO:5.

[0096] In certain embodiments, the dose of the ActRII signaling inhibitor is 0.1 to 2.25 mg / kg. In certain embodiments, the dose of the ActRII signaling inhibitor is 0.1 to 2.0 mg / kg. In certain embodiments, the dose of the ActRII signaling inhibitor is 0.7 to 2.0 mg / kg. In certain embodiments, the dose of the ActRII signaling inhibitor is about 0.1 mg / kg, about 0.125 mg / kg, about 0.3 mg / kg, about 0.5 mg / kg, about 0.7 mg / kg, about 1.0 mg / kg, about 1.25 mg / kg, about 1.33 mg / kg, about 1.5 mg / kg, about 1.75 mg / kg, about 2.0 mg / kg, or about 2.25 mg / kg. In certain embodiments, the dose of the ActRII signaling inhibitor is 0.1 mg / kg to 0.5 mg / kg, 0.3 mg / kg to 0.7 mg / kg, 0.5 mg / kg to 1.0 mg / kg, 0.7 mg / kg to 1.25 mg / kg, 1.0 mg / kg to 2.0 mg / kg or 1.5 to 2.25 mg / kg.

[0097] In certain embodiments, the ActRII signaling inhibitor is administered once every 21 days. In certain embodiments, the ActRII signaling inhibitor is administered subcutaneously. In certain embodiments, the treatment period is up to 24 months. In certain embodiments, the maximum total dose per administration is less than 168 mg.

[0098] In certain embodiments, the outcome of any of the above methods is (a) a period of red blood cell transfusion independence (RBC-TI) of 8 weeks or more following said administration, (b) a period of RBC-TI of 12 weeks or more following said administration, or (c) an altered red blood cell response (mHI-E) in the treated subject, which in certain embodiments is an increase in mean hemoglobin of 1.5 g / dL or more following an 8 week period or a decrease in transfused red blood cells of 4 units or more following an 8 week period following said administration.

[0099] 5.4 Patient population The subject treated according to the methods described herein can be any mammal, such as a rodent, a domestic animal, such as a dog or a cat, or a primate, for example a non-human primate. In a preferred embodiment, the subject is a human. In certain embodiments, the methods described herein can be used to treat anemia in a subject due to very low risk, low risk, or medium risk myelodysplastic syndrome (MDS), to reduce transfusion burden in an anemic subject, or to monitor said treatment, and / or to select a subject to treat according to the methods provided herein in any mammal, such as a rodent or a primate, in a preferred embodiment, a human subject.

[0100] In certain embodiments, the subject treated according to the methods described herein is a female. In certain embodiments, the subject treated according to the methods described herein is a male. In certain embodiments, the subject treated according to the methods described herein can be a subject of any age. In certain embodiments, the subject treated according to the methods described herein is under 18 years old. In a specific embodiment, the subject treated according to the methods described herein is under 13 years old. In another specific embodiment, the subject treated according to the methods described herein is under 12 years old, under 11 years old, under 10 years old, under 9 years old, under 8 years old, under 7 years old, under 6 years old, or under 5 years old. In another specific embodiment, the subject treated according to the methods described herein is 1-3 years old, 3-5 years old, 5-7 years old, 7-9 years old, 9-11 years old, 11-13 years old, 13-15 years old, 15-20 years old, 20-25 years old, 25-30 years old, or over 30 years old. In another specific embodiment, the subject treated according to the methods described herein is 30-35 years old, 35-40 years old, 40-45 years old, 45-50 years old, 50-55 years old, 55-60 years old, or over 60 years old. In another specific embodiment, the subject treated according to the methods described herein is 18-64 years old, 65-74 years old, or over 75 years old.

[0101] In certain embodiments, the subject treated according to the methods provided herein has been diagnosed with MDS as defined by IPSS-R. IPSS-R refers to the International Prognostic Scoring System-Revised, which has been used to assess the prognosis of myelodysplastic syndromes. See, for example, Greenberg et al., Blood, 2012;120(12):2454-2465. The IPSS-R uses a criteria point system to characterize the outcome of myelodysplastic syndrome patients as very low risk (risk score: 0-1.5, median survival: 8.8 years), low risk (risk score: 1.5-3.0, median survival: 5.3 years), moderate risk (points: 3.0-4.5, median survival: 3.0 years), high risk (points: 4.5-6.0, median survival: 1.6 years), or very high risk (risk score: >6, median survival: 0.8 years). The point system was based on (i) the percentage of myeloblasts in the subject, and (ii) the cytogenetic values ​​(hemoglobin concentration (g / dL), absolute neutrophil count (×10 9 / L and platelet count (×10 9 / L) is evaluated.

[0102] In certain embodiments, the subject treated according to the method provided herein has MDS. In certain embodiments, the MDS is very low-risk MDS according to the IPSS definition. In certain embodiments, the MDS is low-risk MDS according to the IPSS-R definition. In certain embodiments, the MDS is intermediate-risk MDS according to the IPSS-R definition. In certain embodiments, the subject treated according to the method provided herein has MDS-refractory cytopenia with multilineage dysplasia (MDS-RCMD).

[0103] In certain embodiments, a subject treated according to the methods described herein has an Eastern Cooperative Oncology Group (ECOG) score of 0. In certain embodiments, a subject treated according to the methods described herein has an ECOG score of 1. In certain embodiments, a subject treated according to the methods described herein has an ECOG score of 2.

[0104] In certain embodiments, the percentage of erythroblasts that are ring sideroblasts in a subject treated according to the methods provided herein is at least 5%, at least 6%, at least 7%, at least 8%, at least 9%, at least 10%, at least 11%, at least 12%, at least 13%, at least 14%, at least 15%, at least 16%, at least 17%, at least 18%, at least 19%, or at least 20%. In certain embodiments, the percentage of erythroblasts that are ring sideroblasts in a subject treated according to the methods provided herein is at least 15%. In certain embodiments, the percentage of erythroblasts that are ring sideroblasts in a subject treated according to the methods provided herein is about 15%. In certain embodiments, the percentage of erythroblasts that are ring sideroblasts in a subject treated according to the methods provided herein is about 15% to about 20%. In certain embodiments, the percentage of erythroblasts that are ring sideroblasts in a subject treated according to the methods provided herein is about 5%-20%. In certain embodiments, a subject treated according to the methods provided herein has a ratio of ring sideroblasts to normal erythroblasts of at least 1:20, at least 1:7, or at least 1:5.

[0105] In certain embodiments, a subject with anemia due to very low, low or moderate risk MDS requires regular red blood cell transfusions for the rest of his / her life. In certain embodiments, a subject with anemia due to very low, low or moderate risk MDS requires transfusions of 0-4 red blood cell units in an 8 week period. In certain embodiments, a subject with anemia due to very low, low or moderate risk MDS requires transfusions of 4-6 red blood cell units in an 8 week period. In certain embodiments, a subject with anemia due to very low, low or moderate risk MDS requires transfusions of less than 6 red blood cell units in an 8 week period. In certain embodiments, a subject with anemia due to very low, low or moderate risk MDS requires transfusions of more than 6 red blood cell units in an 8 week period. In certain embodiments, a subject with anemia due to very low, low or moderate risk MDS has a high transfusion burden. In certain embodiments, a high transfusion burden is a load of 12 or more units of red blood cells in a 24 week period prior to treatment with the methods provided herein. In certain embodiments, a subject treated with the methods provided herein has a low transfusion burden. In certain embodiments, a subject with a low transfusion burden and treated with the methods provided herein requires a maximum of 0, 1, 2 or 3 units of red blood cells per 8 weeks. In certain embodiments, a subject treated with the methods provided herein has a high transfusion burden. In certain embodiments, a subject with a high transfusion burden and treated with the methods provided herein requires at least 4 units, at least 5 units, at least 6 units, at least 7 units, at least 8 units, at least 9 units, at least 10 units, at least 11 units, at least 12 units or at least 13 units of red blood cells per 8 weeks.

[0106] In certain embodiments, the subject to be treated has one or more mutations in the SF3B1 gene. In certain embodiments, the one or more mutations in the SF3B1 gene are confirmed by genetic analysis. In certain embodiments, the one or more mutations are mutations in a non-coding region. In certain embodiments, SF3B1 is a gene encoding SB3B1. In certain embodiments, the one or more mutations are mutations in a coding region. In certain embodiments, SF3B1 is a SF3B1 protein. In certain embodiments, the one or more mutations in the SF3B1 protein are selected from the group consisting of E622D, R625C, H662Q, H662D, K66N, K666T, K666Q, K666E, A672D, K700E, I704N. In certain embodiments, the subject to be treated according to the methods provided herein expresses a SF3B1 protein with the mutation E622D. In certain embodiments, subjects treated according to the methods provided herein express an SF3B1 protein with a mutation R625C. In certain embodiments, subjects treated according to the methods provided herein express an SF3B1 protein with a mutation H662Q. In certain embodiments, subjects treated according to the methods provided herein express an SF3B1 protein with a mutation H662D. In certain embodiments, subjects treated according to the methods provided herein express an SF3B1 protein with a mutation K66N. In certain embodiments, subjects treated according to the methods provided herein express an SF3B1 protein with a mutation K666T. In certain embodiments, subjects treated according to the methods provided herein express an SF3B1 protein with a mutation K666Q. In certain embodiments, subjects treated according to the methods provided herein express an SF3B1 protein with a mutation K666E. In certain embodiments, subjects treated according to the methods provided herein express an SF3B1 protein with the A672D mutation. In certain embodiments, subjects treated according to the methods provided herein express an SF3B1 protein with the K700E mutation.In certain embodiments, subjects treated according to the methods provided herein express an SF3B1 protein with a mutation I704N. In specific embodiments, subjects treated according to the methods provided herein express one or more mutations in SRSF2. In specific embodiments, subjects treated according to the methods provided herein express one or more mutations in DNMT3A. In specific embodiments, subjects treated according to the methods provided herein express one or more mutations in TET2. In specific embodiments, subjects treated according to the methods provided herein express one or more mutations in SETBP1.

[0107] In certain embodiments, a subject treated according to the methods provided herein (i) has anemia due to very low, low or moderate risk MDS, (ii) at least 15% of the subject's erythroblasts are ring sideroblasts. In certain embodiments, a subject treated according to the methods provided herein (i) has anemia due to very low, low or moderate risk MDS, (ii) at least 5% of the subject's erythroblasts are ring sideroblasts, and (iii) expresses one or more SF3B1 mutations.

[0108] In certain embodiments, the subject treated according to the methods provided herein has thrombocytopenia. In certain embodiments, the subject treated according to the methods provided herein has thrombocytopenia of 100×10 platelets per liter or less. 9 In certain embodiments, subjects treated according to the methods provided herein have a platelet count of 100-400×10 per liter. 9 In certain embodiments, a subject treated according to the methods provided herein has a platelet count of 400×10 9 In certain embodiments, the subject treated according to the methods provided herein is neutropenic. In certain embodiments, the subject treated according to the methods provided herein is neutropenic. In certain embodiments, the subject treated according to the methods provided herein is neutrophil counts greater than 1×10 9 is less than.

[0109] In certain embodiments, a subject treated according to the methods provided herein has less than 13,000 white blood cells per μL, less than 12,000 white blood cells per μL, less than 11,000 white blood cells per μL, less than 10,000 white blood cells per μL, less than 7,500 white blood cells per μL, or less than 500 white blood cells per μL.

[0110] In certain embodiments, subjects treated according to the methods provided herein have hemoglobin levels below 10 g / dL, below 9 g / dL, below 8 g / dL, or below 7 g / dL. In certain embodiments, subjects treated according to the methods provided herein have hemoglobin levels between 7 g / dL and 7.5 g / dL, between 7.5 g / dL and 8 g / dL, between 8 g / dL and 8.5 g / dL, between 8.5 g / dL and 9.0 g / dL, between 9.0 g / dL and 9.5 g / dL, or between 9.5 g / dL and 10.0 g / dL.

[0111] In certain embodiments of any of the above methods, the subject can be refractory to prior treatment with erythropoietin stimulating agent (ESA).In certain embodiments of any of the above methods, the subject can be intolerant to prior treatment with ESA.In certain embodiments of any of the above methods, the subject can be ineligible for treatment with ESA.

[0112] In certain embodiments of any of the above methods, a subject who is refractory to prior treatment with an ESA can be a subject who was refractory to a prior regimen that included an ESA, either as a single agent or in combination with other agents, or who became unresponsive to that prior regimen at any time after induction due to intolerance or adverse events.

[0113] In certain embodiments of any of the above methods, the subject is intolerant to prior treatment with an ESA. In certain embodiments, a prior regimen that includes an ESA, either alone or in combination with other agents, has been discontinued in the subject at some point after induction due to intolerance or adverse events.

[0114] In certain embodiments of any of the above methods, the subject is intolerant to previous treatment with ESA.In certain embodiments, the subject has high endogenous serum erythropoietin (EPO) levels, and is therefore unlikely to respond to treatment with ESA.In certain embodiments of any of the above methods, the subject has never been previously treated with ESA, and has serum EPO levels greater than 200IU / L.

[0115] In certain embodiments, the subject treated according to the methods provided herein has been previously treated with one or more ESAs or is currently treated with one or more ESAs. In certain embodiments, the subject treated according to the methods provided herein is non-responsive to treatment with one or more ESAs. In certain embodiments, the subject treated according to the methods provided herein is refractory to treatment with one or more ESAs. In certain embodiments, the subject treated according to the methods provided herein is refractory to treatment with one or more ESAs. In certain embodiments, the subject treated according to the methods provided herein is refractory to prior treatment with an ESA. In certain embodiments, a subject who is refractory to ESA prior treatment has documented refractory or become unresponsive to a prior regimen that includes an ESA, either alone or in combination with other agents (e.g., G-CSF), and the ESA regimen must be (a) recombinant human erythropoietin greater than 40,000 IU per week for at least 8 doses or equivalent, or (b) darbepoetin alfa greater than 500 μg once every 3 weeks for at least 4 doses or equivalent. In certain embodiments, a subject who is treated according to the methods provided herein is intolerant to prior ESA treatment. In certain embodiments, a subject who is intolerant to prior ESA treatment has documented a prior regimen that includes an ESA, either alone or in combination (e.g., with G-CSF), that was discontinued at any time after initiation due to intolerance or adverse events. In certain embodiments, a subject who is treated according to the methods provided herein is ESA-ineligible. In certain embodiments, subjects who are ineligible for an ESA are unlikely to respond to an ESA based on endogenous serum erythropoietin levels of greater than 200 IU / L in subjects not previously treated with an ESA.

[0116] In certain embodiments, the subject treated according to the methods described herein has MDS. In certain embodiments, the subject treated according to the methods described herein has MDS and has an intact chromosome 5 long arm. In certain embodiments, the subject treated according to the methods provided herein has MDS and has an intact chromosome 5 long arm and has not documented treatment failure with lenalidomide. In certain embodiments, the subject treated according to the methods provided herein has MDS and has an intact chromosome 5 long arm and has documented treatment failure with lenalidomide. In certain embodiments, the subject treated according to the methods described herein has MDS with deletion of the chromosome 5 long arm. MDS with deletion of the long arm of chromosome 5 includes deletion of the long arm of chromosome 5 and is characterized by macrocytic anemia with, among other things, oval macrocytes, normal or slightly decreased white blood cell count, normal or increased platelet count, and less than 5% blasts in bone marrow and blood. In certain embodiments, the subject treated according to the methods provided herein has MDS with deletion of the long arm of chromosome 5 and has not documented failure of treatment with lenalidomide. In certain embodiments, the subject treated according to the methods provided herein has MDS with deletion of the long arm of chromosome 5 and has documented failure of treatment with lenalidomide. In certain embodiments, failure of treatment with lenalidomide includes loss of response to lenalidomide, failure to respond to lenalidomide after 4 months of treatment with lenalidomide, intolerance to treatment with lenalidomide, or cytopenias that are not treatable with lenalidomide.

[0117] In certain embodiments, a subject treated according to the methods provided herein has an EPO serum concentration greater than 500 IU / L. In certain embodiments, a subject treated according to the methods provided herein has an EPO serum concentration between 200 and 500 IU / L. In certain embodiments, a subject treated according to the methods provided herein has an EPO serum concentration between 100 and 200 IU / L. In certain embodiments, a subject treated according to the methods provided herein has an EPO serum concentration less than 100 IU / L.

[0118] In certain embodiments, subjects treated according to the methods provided herein have a renal clearance rate of creatinine between 40 and 60 mL / min. In certain embodiments, subjects treated according to the methods provided herein have a renal clearance rate of creatinine greater than 60 mL / min.

[0119] In certain embodiments, subjects treated according to the methods provided herein have a baseline platelet count of 100×10 9 In certain embodiments, subjects treated according to the methods provided herein have a baseline platelet count of 100-400×10 9 / L. In certain embodiments, subjects treated according to the methods provided herein have a baseline platelet count of 400×10 9 / L.

[0120] In certain embodiments, subjects treated according to the methods provided herein are initially diagnosed with MDS 0-2 years prior to administration of raspatercept or sotatercept. In certain embodiments, subjects treated according to the methods provided herein are initially diagnosed with MDS 2-5 years prior to administration of raspatercept or sotatercept. In certain embodiments, subjects treated according to the methods provided herein are initially diagnosed with MDS more than 5 years prior to administration of raspatercept or sotatercept.

[0121] In certain embodiments, the present invention provides a method of treating a human subject who has been or will be diagnosed with anemia due to very low risk, low risk, or moderate risk myelodysplastic syndrome (MDS), comprising administering to the subject a therapeutically effective dose of luspatercept or sotatercept, wherein (a) the subject has at least 15% of erythroblasts that are ring sideroblasts, and (b) the subject is a male subject.

[0122] In certain embodiments, the present invention provides a method of treating a human subject who has been or will be diagnosed with anemia due to very low-risk, low-risk, or intermediate-risk myelodysplastic syndrome (MDS), comprising administering to the subject a therapeutically effective dose of raspatercept or sotatercept, wherein (a) the subject has at least 15% of its erythroblasts that are ring sideroblasts, and (b) the subject has been initially diagnosed with MDS within 2-5 years prior to administration of raspatercept or sotatercept.

[0123] In certain embodiments, the present invention provides a method of treating a human subject who has been diagnosed with or will be diagnosed with anemia due to very low, low, or intermediate risk myelodysplastic syndrome (MDS), comprising administering to the subject a therapeutically effective dose of raspatercept or sotatercept, wherein: (a) the subject has at least 15% erythroblasts that are ring sideroblasts; and (b) the subject has a baseline platelet count of 400×10 or greater. 9 / L.

[0124] In certain embodiments, the present invention provides a method of treating a human subject who has been or will be diagnosed with anemia due to very low-risk, low-risk, or moderate-risk myelodysplastic syndrome (MDS), comprising administering to the subject a therapeutically effective dose of luspatercept or sotatercept, wherein: (a) the subject has at least 15% erythroblasts that are ring sideroblasts; and (b) the subject has a baseline serum erythropoietin (EPO) level of 100-200 IU / L.

[0125] In certain embodiments, the present invention provides a method of treating a human subject who has been or will be diagnosed with anemia due to very low-risk, low-risk, or moderate-risk myelodysplastic syndrome (MDS), comprising administering to the subject a therapeutically effective dose of raspatercept or sotatercept, where (a) the subject has at least 15% of its erythroblasts that are ring sideroblasts, and (b) the subject has received 4-6 units of RBC transfusions in an 8-week period prior to administration of raspatercept or sotatercept.

[0126] In certain embodiments, the present invention provides a method of treating a human subject who has been or will be diagnosed with anemia due to very low risk, low risk, or moderate risk myelodysplastic syndrome (MDS), comprising administering to the subject a therapeutically effective dose of luspatercept or sotatercept, wherein: (a) the subject has one or more mutations in the SF3B1 gene; (b) the subject has at least 5% of erythroblasts that are ring sideroblasts; and (c) the subject is a male subject.

[0127] In certain embodiments, the present invention provides a method of treating a human subject who has been or will be diagnosed with anemia due to very low, low or intermediate risk myelodysplastic syndrome (MDS), comprising administering to the subject a therapeutically effective dose of raspatercept or sotatercept, where (a) the subject has one or more mutations in the SF3B1 gene, (b) the subject has at least 5% of erythroblasts that are ring sideroblasts, and (c) the subject has received an initial diagnosis of MDS within 2 to 5 years prior to administration of raspatercept or sotatercept.

[0128] In certain embodiments, the present invention provides a method of treating a human subject who has been or will be diagnosed with anemia due to very low, low, or intermediate risk myelodysplastic syndrome (MDS), comprising administering to the subject a therapeutically effective dose of raspatercept or sotatercept, wherein: (a) the subject has one or more mutations in the SF3B1 gene; (b) the subject has at least 5% of erythroblasts that are ring sideroblasts; and (c) the subject has a baseline platelet count of 400×10 or greater. 9 / L.

[0129] In certain embodiments, the present invention provides a method of treating a human subject who has been or will be diagnosed with anemia due to very low, low, or moderate risk myelodysplastic syndrome (MDS), comprising administering to the subject a therapeutically effective dose of luspatercept or sotatercept, wherein: (a) the subject has one or more mutations in the SF3B1 gene; (b) the subject has at least 5% erythroblasts that are ring sideroblasts; and (c) the subject has a baseline serum EPO level of 100-200 IU / L.

[0130] In certain embodiments, the present invention provides a method of treating a human subject who has been or will be diagnosed with anemia due to very low-risk, low-risk, or moderate-risk myelodysplastic syndrome (MDS), comprising administering a therapeutically effective dose of raspatercept or sotatercept to the subject, where (a) the subject has one or more mutations in the SF3B1 gene, (b) the subject has at least 5% of its erythroblasts that are ring sideroblasts, and (c) the subject has received 4-6 units of RBC transfusions in an 8-week period prior to administration of raspatercept or sotatercept. EXAMPLES

[0131] 6. Working Example 6.1 Example 1: A Phase 3, Double-Blind, Randomized, Placebo-Controlled, Multicenter Study to Evaluate the Safety and Efficacy of Luspatercept (a Polypeptide Comprising the Amino Acid Sequence of SEQ ID NO: 1) for Treating Anemia Due to Myelodysplastic Syndromes at Very Low, Low, or Intermediate Risk Per IPSS-R in Subjects with Ringed Sideroblasts and Requiring Red Blood Cell Transfusions 6.1.1 Introduction This example presents a Phase 3, double-blind, randomized, placebo-controlled, multicenter study to evaluate the safety and efficacy of luspatercept for treating anemia due to IPSS-R very low, low, or intermediate risk myelodysplastic syndromes in subjects with ringed sideroblasts and requiring red blood cell transfusions.

[0132] 6.1.2 Results 229 subjects with MDS who passed screening were enrolled into the randomized intent-to-treat (ITT) population. Of the 229 MDS subjects, 153 were enrolled in the treatment group and received luspatercept starting at a dose level of 1 mg / kg, which could be titrated up to a maximum of 1.75 mg / kg. Of the 229 MDS subjects, 76 were enrolled in the placebo control group.

[0133] The primary endpoint, response rate, was calculated by dividing the number of responders by the total number of subjects in the intent-to-treat (ITT) population. The study achieved its primary endpoint in a statistically significant manner with the proportion of subjects who were red blood cell transfusion independent for at least 8 weeks after treatment being higher in the luspatercept group than in the placebo group. Secondary objectives were (i) to evaluate the effect of luspatercept on RBC transfusion independence (RBC-TI) for at least 12 weeks, (ii) to evaluate the effect of luspatercept on hemoglobin increase, (iii) to evaluate the effect of luspatercept on duration of RBC-TI, (iv) to evaluate the effect of luspatercept on time to RBC-TI, and (v) to evaluate the effect of luspatercept on red blood cell hematological improvement (HI-E). The study also achieved statistical significance for secondary efficacy endpoints of RBC-TI ≥ 12 weeks, and mHI-E during study periods 1-24 weeks and 1-48 weeks. Additionally, the study showed a non-significant trend toward improvement in median overall RBC-TI duration (among patients who responded in the first 24 weeks).

[0134] Subject age, weight, and baseline characteristics were summarized using descriptive statistics, while sex, race, and other categorical variables were presented using frequency tables by dose cohort. See Figure 1. Past transfusion history was summarized. See Figure 2. Medical history data was summarized using frequency tables by Medical Dictionary for Regulatory Activities (MedDRA) organ system class and preferred term. See Figure 3. Diagnosis of myelodysplastic syndrome (MDS) and RBC transfusion dependency were summarized using frequency tables. See Figures 4 and 5.

[0135] Efficacy analyses were performed in the ITT population. Efficacy outcomes were defined as (i) red blood cell transfusion independence (RBC-TI) ≥8 weeks, (ii) mean hemoglobin gain ≥1.0 g / dL, (iii) duration of RBC-TI, (iv) time to RBC-TI, and (v) red blood cell response (HI-E). Results of the primary efficacy outcome showed that a statistically significant higher proportion of subjects in the treatment group had RBC-TI ≥8 weeks over the 1-24 week period compared to the placebo group. See Figure 6. Analysis of key secondary outcomes showed that a statistically significant higher proportion of subjects in the treatment group had RBC-TI ≥12 weeks.

[0136] Subgroup analysis by forest plot for RBC-TI duration ≥8 weeks in the ITT population, with gender, race, and other categorical variables, was performed. The results showed stronger effects in certain subgroups. See Figures 7A and 7B.

[0137] Similarly, subgroup analysis was performed for the ITT population with RBC-TI duration ≥12 weeks during weeks 1-24 by forest plot for sex, race, and other categorical variables, with strong effects observed in certain subgroups (see Figures 8A and 8B).

[0138] In addition, subgroup analysis was performed by forest plot for RBC-TI duration ≥12 weeks in the ITT population, with gender, race, and other categorical variables. The results showed strong effects in certain subgroups. See Figures 9A and 9B.

[0139] Additionally, subgroup analysis of the altered erythroid response (mHI-E) over the 1-24 week period was performed using forest plots to show gender, race, and other categorical variables, with stronger effects observed in certain subgroups. See Figures 10A and 10B.

[0140] Similarly, subgroup analysis of altered erythroid responses (mHI-E) from weeks 1 to 48 was performed using forest plots to show gender, race, and other categorical variables, with stronger effects observed in certain subgroups. See Figures 11A and 11B.

[0141] 6.1.3 Study Design Subjects received luspatercept subcutaneously (initial dose 1 mg / kg) on ​​day 1 of each 21-day treatment cycle. Control subjects received placebo subcutaneously on day 1 of each 21-day treatment cycle. Treatment duration was up to 24 months. The study was divided into (i) a screening period, (ii) a treatment period, and (iii) a post-treatment follow-up period.

[0142] (a) Screening Period Once subjects provided written informed consent, they entered a screening period to determine eligibility. Subjects were assigned an identification (ID) number via the Interactive Response Technology (IRT) system. Subject screening occurred up to 28 days prior to the first dose. During the screening period, subjects underwent safety and other evaluations to determine eligibility for the study. Rescreening was permitted and new subject ID numbers were assigned.

[0143] Laboratory review of bone marrow aspirate smears, bone marrow biopsy specimens, peripheral blood smears, and cytogenetic values ​​was used to confirm the diagnosis and WHO classification of MDS and to determine baseline IPSS-R risk category (Greenberg et al., Blood, 2012;120(12):2454-2465). RBC transfusion history must be obtained for at least 16 weeks prior to and including the date of enrollment, and data must include hemoglobin (Hgb) values ​​at the time of transfusion (i.e., pre-transfusion Hgb values).

[0144] (b) Treatment period Subjects entered the treatment period after completing the required evaluations during the screening period and also fulfilling the eligibility criteria. After subjects were enrolled through the IRT system, they received their first dose of luspatercept or placebo (first dose, day 1) within 3 days of enrollment, which could have been administered on the day of enrollment if they met the eligibility criteria. Subjects received luspatercept or placebo on day 1 of each 21-day treatment cycle. Best supportive care (BSC) was administered in conjunction with study treatment when clinically indicated by the investigator. Best supportive care included, but was not limited to, blood transfusions, iron chelators, antibiotics, antiviral and / or antifungal therapy, and nutritional support, as needed. Best supportive care in this study excluded the use of ESAs.

[0145] (c) Post-treatment follow-up period Investigators recorded all adverse events (AEs) from the time subjects signed informed consent until 42 days after the last dose of luspatercept or placebo, as well as any serious adverse events (SAEs) noted by the investigator at any time thereafter that were suspected to be related to luspatercept or placebo. Transfusion data collection continued 42 days after the last dose of study product or until the end of the study.

[0146] 6.1.4 Test objectives Table 1: Study objectives for subjects with MDS treated with laspatercept [Table 1] TIFF0007663502000002.tif240170TIFF0007663502000003.tif217170

[0147] 6.1.5 Inclusion Criteria Subjects met the following study entry criteria: (i) subjects were 18 years of age or older at the time of signing the Informed Consent Document (ICF); (ii) subjects understood and voluntarily signed the ICF before undergoing any study-related evaluations / procedures; (iii) subjects documented an institutional diagnosis of MDS meeting the IPSS-R classification of very low-risk, low-risk, or intermediate-risk MDS according to the WHO / French American British (FAB) classification (Greenberg et al., Blood, 2012; 120(12): 2454-2465); (iv) subjects must have 15% or more of their erythroid precursors in the bone marrow as ring sideroblasts, or 5% or more (but less than 15%) if the subject has one or more mutations in the SF3B1 gene; (v) subjects must have less than 5% blasts in the bone marrow. (vi) Subjects must have a peripheral blood white blood cell (WBC) count less than 13,000 / μL. (vii) Subjects must require red blood cell (RBC) transfusions. (viii) Subjects must have an Eastern Cooperative Oncology Group (ECOG) score of 0, 1, or 2. (ix) Subjects were refractory, intolerant, or ineligible for prior ESA therapy. Subjects who were refractory to prior ESA therapy could be those who were refractory to a prior regimen containing an ESA, either alone or in combination with other agents, or who lost sustained responsiveness at any time point after induction due to intolerance or adverse events. Subjects who were intolerant to prior ESA therapy could be those whose prior regimen containing an ESA, either alone or in combination with other agents, was discontinued at any time point after induction due to intolerance or adverse events. Subjects who were ineligible for prior ESA therapy could be those who are unlikely to respond to treatment with an ESA due to high endogenous serum erythropoietin (EPO) levels. In certain embodiments of any of the above methods, the subject has not been previously treated with an ESA and has a serum EPO level greater than 200 IU / L.

[0148] 6.1.6 Exclusion criteria Subjects were excluded from enrollment if they had any of the following: (i) previous treatment with a disease-modifying treatment (e.g., immunomodulatory, hypomethylating, or immunosuppressive) for the underlying MDS disease. (Subjects previously treated with hypomethylating agents (HMA) or lenalidomide may be enrolled at the investigator's discretion, provided that the subject had received no more than two doses of HMA or no more than one calendar week of treatment with lenalidomide, the last dose of which must have occurred more than 5 weeks prior to the date of randomization.) (ii) previous treatment with either luspatercept or sotatercept; (iii) MDS associated with a cytogenetic abnormality due to del 5q; (iv) secondary MDS, i.e. MDS known to be due to chemical injury or chemotherapy and / or radiation treatment for another disease; (v) iron, vitamin B 12or known clinically significant anemia due to folate deficiency, autoimmune or hereditary hemolytic anemia, or gastrointestinal bleeding and iron deficiency as determined by serum ferritin ≤15 μg / L and, if clinically indicated, additional testing (e.g., transferrin saturation calculation [iron / total iron binding capacity <20%] or iron staining of bone marrow aspirate); (vi) Previous allogeneic or autologous stem cell transplant; (vii) Known diagnosis of acute myeloid leukemia (AML). (viii) Use of any of the following within 5 weeks prior to randomization: anticancer cytotoxic chemotherapy agents, anticancer cytotoxic chemotherapy treatments, corticosteroids (except for subjects who received stable or tapering doses of corticosteroids for a condition other than MDS at least 1 week prior to randomization), or iron chelators (except for subjects who received stable or tapering doses of other RBC hematopoietic growth factors (e.g., interleukin-3), investigational drugs, investigational devices, or investigational approved therapies at least 8 weeks prior to randomization), unless the half-life of the previous investigational product is known and the use occurred 5 or fewer times within the half-life or 5 weeks prior to randomization, whichever is longer. (ix) Uncontrolled hypertension (defined as repeated elevations in diastolic blood pressure (DBP) to 100 mmHg or greater despite adequate treatment). (x) Absolute neutrophil count (ANC) of 500 / μL (0.5 × 10 9 / L), (xi) History of a previous malignancy other than MDS, unless the subject has been free of the disease for ≥5 years (including completion of any active or adjuvant treatment for the previous malignancy) (subjects with a history / comorbidities of basal cell carcinoma of the skin, squamous cell carcinoma of the skin, cervical intraepithelial carcinoma, and breast intraepithelial carcinoma, and incidental histologic evidence of prostate cancer (T1a or T1b using the tumor, node, metastasis [TNM] clinical staging system) are permitted), or (xii) Major surgery within 8 weeks prior to randomization (subjects must have fully recovered from any surgery prior to randomization).

[0149] 6.1.7 Treatment Dose, Administration and Schedule Luspatercept for injection was formulated as a sterile lyophilized cake / sterile lyophilized powder without preservatives. Luspatercept for injection was available in two strengths, which when reconstituted consisted of 50 mg / mL of luspatercept in a 10 mM citrate buffer-based solution (10 mM citrate, pH=6.5, 9% sucrose, 0.02% polysorbate 80). The drug product was supplied in 3 mL glass vials in the following strengths:

[0150] (i) 25 mg / vial: A 25 mg / vial designation contained 37.5 mg of luspatercept. After reconstitution with 0.68 mL of water for injection (WFI), each vial delivers at least 0.5 mL (25 mg) of 50 mg / mL luspatercept.

[0151] (ii) 75 mg / vial: A formulation labeled 75 mg / vial contained 87.5 mg of luspatercept. After reconstitution with 1.6 mL of WFI, each vial delivers at least 1.5 mL (75 mg) of 50 mg / mL luspatercept.

[0152] Study staff at the clinical site administered luspatercept or placebo to subjects by subcutaneous (SC) injection. Subjects underwent hemoglobin, blood pressure, and weight assessments prior to each dose. Clinical site staff also identified whether subjects had received any blood transfusions (including those at any outside study sites between study visits) prior to each dose by utilizing subject diaries or procedures performed at other study sites.

[0153] SC injections were given in the upper arm, thigh, and / or abdomen. Dose calculations requiring reconstituted volumes greater than 1.2 mL were divided into comparable volumes for injection into separate locations using the same anatomical site but on opposite sides of the body (e.g., left thigh and right thigh). The maximum volume for a single SC injection was 1.2 mL.

[0154] Injection sites were rotated according to the investigator's discretion, and injections could be given in the following order as needed, for example: (i) right upper arm, (ii) left upper arm, (iii) right upper thigh, and (iv) left upper thigh.

[0155] The maximum total dose per administration is to be less than 168 mg, resulting in a maximum total volume after reconstitution of 3.36 mL.

[0156] Subjects began treatment after eligibility was confirmed by the sponsor. Subjects were required to begin treatment within 28 days of signing the ICF. Safety laboratory tests and physical examinations were not repeated on cycle 1 day 1 (C1D1), except for blood pressure measurements and blood tests, if the screening evaluation was performed within 72 hours of C1D1.

[0157] On day 1 of each treatment cycle, subjects received luspatercept or placebo subcutaneously.

[0158] (a) Dose Modifications: Dose Escalation, Dose Reduction, and Dose Delay If the subject met all of the following criteria: (i) the subject had ≥ 1 RBC transfusion event (for a pre-transfusion Hgb < 9.0 g / dL) during the last 2 prior treatment cycles (approximately 6 weeks); (ii) the last 2 prior treatment cycles evaluated must be at the same dose level; and (iii) the subject must not have met any protocol dose delay and / or dose reduction criteria during the last 2 prior treatment cycles (except for dose delays necessitated by the effects of RBC transfusion), then starting immediately on Day 1 of Cycle 3 and with evaluation by the investigator prior to each subsequent treatment cycle, the subject could gradually increase the dose level from a starting dose of 1.0 mg / kg to 1.33 mg / kg, up to a maximum of 1.75 mg / kg, but the maximum total dose must not exceed 168 mg.

[0159] If all of the above criteria were met, the dose could be increased by one dose level. The dose levels were titrated individually for each subject, not to exceed 1.75 mg / kg. For reference, the dose increments and decrements are shown below (Table 3), along with the starting dose.

[0160] Table 2: Starting Dose Levels, Dose Reductions, and Dose Escalations in Subjects with MDS [Table 2]

[0161] (b) Concomitant medications and treatments In this study, additional medications were occasionally provided to manage the status of the subject's condition (including side effects from study treatment or disease progression). Supportive care (including but not limited to antiemetics) was provided at the discretion of the investigator.

[0162] Permitted concomitant medications and treatments included the following: (i) Granulocyte colony-stimulating factors (i.e., G-CSF, GM-CSF) were allowed only in the case of neutropenic fever or when clinically indicated in the product label. (ii) Concomitant use of corticosteroids for conditions other than MDS was allowed if the subject had been taking a stable or tapering dose for at least 1 week prior to randomization. (iii) Administration of attenuated vaccines (e.g., influenza vaccine) was allowed at the investigator's discretion if clinically indicated. (iv) With regard to iron chelation therapy, subjects who were using iron chelation therapy at the time of randomization had to have been on a stable or tapering dose for at least 8 weeks, and concomitant treatment with iron chelation therapy during the treatment period of this study was allowed at the investigator's discretion and was recommended to be used in accordance with the product label. (vii) With regard to RBC transfusions, concomitant treatment with transfusions for anemia was permitted at the investigator's discretion for low hemoglobin levels, symptoms associated with anemia (e.g., hemodynamic or pulmonary compromise requiring treatment), or comorbidities.

[0163] Each subject had a "pre-transfusion hemoglobin threshold" at which they would require a transfusion during the study, based on their transfusion history. The baseline pre-transfusion hemoglobin threshold was the average of all documented pre-transfusion hemoglobin values ​​between the first dose on Day 1 and the preceding 16 weeks. During treatment, if the pre-transfusion hemoglobin level rose by 1 g / dL or more compared to the subject's pre-transfusion hemoglobin threshold (at the time of the next predicted transfusion event), transfusions were delayed for a minimum of 7 days and / or the number of units transfused was reduced by 1 RBC unit or more. Subjects could receive transfusions for anemia-related symptoms or other needs (e.g., infection) at the discretion of the investigator.

[0164] (c) Prohibited Concomitant Medications and Prohibited Concomitant Treatments The following concomitant medications were specifically excluded across studies: (i) cytotoxic agents / therapy, chemotherapeutic agents / therapy, targeted agents / therapy or investigational agents / therapy, (ii) azacitidine, decitabine or other hypomethylating agents, (iii) lenalidomide, thalidomide and other immunomodulatory drugs (IMiDs), (iv) ESAs and other RBC hematopoietic growth factors (e.g. interleukin-3), (v) G-CSF or GM-CSF (except in cases of neutropenic fever), (vi) hydroxyurea, (vii) androgens (except for treatment of hypogonadism), (viii) oral retinoids (topical retinoids were allowed), (ix) arsenic trioxide, and (x) interferons (IFNs).

[0165] 7. Sequence details Table 3: Sequence information [Table 3]

[0166] 8. Equivalents Although the present invention has been described in detail with reference to specific embodiments thereof, it will be understood that functionally equivalent variations are within the scope of the present invention. Indeed, various modifications of the invention in addition to those shown and described herein will become apparent to those skilled in the art from the foregoing description and accompanying drawings. Such modifications are intended to be within the scope of the appended claims. Those skilled in the art will recognize, or be able to ascertain using no more than routine experimentation, many equivalents to the specific embodiments of the invention described herein. Such equivalents are intended to be encompassed by the following claims.

[0167] All publications, patents, and patent applications mentioned in this specification are herein incorporated by reference to the same extent as if each individual publication, patent, or patent application was specifically and individually indicated to be incorporated by reference in its entirety. The present application provides the following aspects of the invention. (Aspect 1) 1. A method of treating a human subject who has been diagnosed with or will be diagnosed with anemia due to very low, low or intermediate risk myelodysplastic syndrome (MDS), comprising administering to the subject a therapeutically effective dose of raspatercept or sotatercept, wherein: (a) the subject has at least 15% erythroblasts that are ring sideroblasts; and (b) the subject has: (i) Male subjects; (ii) a subject who has been initially diagnosed with MDS within 2 to 5 years prior to the administration of luspatercept or sotatercept; (iii) Baseline platelet count of 400 × 10 9 / L or more, (iv) subjects with baseline serum erythropoietin (EPO) levels between 100 and 200 IU / L; and (v) Subjects who have received 4 to 6 units of RBC transfusion within an 8-week period prior to administration of luspatercept or sotatercept; The method according to the present invention corresponds to one of the following groups: (Aspect 2) 1. A method of treating a human subject who has been diagnosed with or will be diagnosed with anemia due to very low, low or intermediate risk myelodysplastic syndrome (MDS), comprising administering to said subject a therapeutically effective dose of raspatercept or sotatercept, wherein: (a) said subject has one or more mutations in the SF3B1 gene; (b) said subject has at least 5% of erythroblasts that are ring sideroblasts; and (c) said subject has (i) Male subjects; (ii) a subject who has been initially diagnosed with MDS within 2 to 5 years prior to the administration of luspatercept or sotatercept; (iii) Baseline platelet count of 400 × 10 9 / L or more, (iv) subjects with baseline serum EPO levels between 100 and 200 IU / L; and (v) Subjects who have received 4 to 6 units of RBC transfusion within an 8-week period prior to administration of luspatercept or sotatercept; The method according to the present invention corresponds to one of the following groups: (Aspect 3) The method of embodiment 1 or 2, wherein said very low risk, low risk or intermediate risk MDS is classified using the International Prognostic Scoring System-Revised (IPSS-R). (Aspect 4) The method of embodiment 1 or 2, wherein the subject has less than 5 percent blasts in the bone marrow. (Aspect 5) The method of embodiment 1 or 2, wherein the subject is in need of an RBC transfusion. (Aspect 6) The method of any one of claims 1 to 2, wherein the method is for (i) reducing the percentage of erythroblasts in the subject that are ring sideroblasts for a longer period of time than the initial percentage of erythroblasts in the subject that are ring sideroblasts, and / or (ii) increasing the hemoglobin level of the subject for a longer period of time than the hemoglobin level of the subject at a period of time prior to administering a first dose of the ActRII signaling inhibitor to the subject. (Aspect 7) The method of embodiment 6, wherein the extended period is a period of 8 weeks or more. (Aspect 8) The method of any one of claims 1 to 2, wherein the method is for (i) achieving a red blood cell transfusion independence (RBC-TI) period of 8 weeks or more in the subject after administration of raspatercept or sotatercept, (b) achieving an RBC-TI period of 12 weeks or more in the subject after administration of raspatercept or sotatercept, or (c) modifying the red blood cell response (mHI-E) in the subject after administration of raspatercept or sotatercept. (Aspect 9) The method of embodiment 8, wherein said mHI-E is an increase in mean hemoglobin of 1.5 g / dL or more for 8 weeks or a decrease in transfused red blood cells of 4 units or more for 8 weeks following said administration. (Aspect 10) The method of embodiment 1, wherein the percentage of erythroblasts that are ring sideroblasts in the subject prior to said administration of luspatercept or sotatercept is at least 15%, at least 16%, at least 17%, at least 18%, at least 19%, or at least 20%. (Aspect 11) The method of embodiment 2, wherein the percentage of erythroblasts that are ring sideroblasts in the subject prior to administration of luspatercept or sotatercept is at least 5%, at least 6%, at least 7%, at least 8%, at least 9%, at least 10%, at least 11%, at least 12%, at least 13%, at least 14%, or at least 15%. (Aspect 12) The method according to aspect 1 or 2, wherein the pharma- ceutically effective dose of luspatercept or sotatercept is 0.5 mg / kg to 1.75 mg / kg. (Aspect 13) 3. The method of embodiment 1 or 2, wherein the dose is about 0.45 mg / kg, about 0.50 mg / kg, about 0.60 mg / kg, about 0.70 mg / kg, about 0.80 mg / kg, about 0.90 mg / kg, about 1.00 mg / kg, about 1.05 mg / kg, about 1.10 mg / kg, about 1.15 mg / kg, about 1.20 mg / kg, about 1.25 mg / kg, about 1.30 mg / kg, about 1.33 mg / kg, about 1.35 mg / kg, about 1.40 mg / kg, about 1.45 mg / kg, about 1.50 mg / kg, about 1.55 mg / kg, about 1.60 mg / kg, about 1.65 mg / kg, about 1.70 mg / kg, or about 1.75 mg / kg. (Aspect 14) The method of embodiment 1 or 2, wherein the luspatercept or sotatercept is administered subcutaneously. (Aspect 15) The method of embodiment 1 or 2, wherein the subject is refractory to prior erythropoietin stimulating agent (ESA) treatment. (Aspect 16) The method of embodiment 1 or 2, wherein the subject is intolerant to prior treatment with an ESA. (Aspect 17) The method of embodiment 1 or 2, wherein the subject is ineligible for treatment with an ESA. (Aspect 18) The method according to any one of aspects 15 to 17, wherein the treatment with an ESA is a treatment using a regimen containing an ESA. (Aspect 19) Method 18, wherein the ESA-containing regimen includes granulocyte colony-stimulating factor (G-CSF). (Aspect 20) A pharmaceutical formulation of laspatercept comprising: (i) laspatercept in the form of a preservative-free sterile lyophilized cake or sterile lyophilized powder before reconstitution; and (ii) laspatercept in a reconstituted form having a concentration of 50 mg / mL in a 10 mM citrate buffer-based solution (10 mM citrate, pH=6.5, 9% sucrose, 0.02% polysorbate 80). (Aspect 21) 1. A single dose pharmaceutical formulation comprising: (i) laspatercept in the form of a preservative-free sterile lyophilized cake or sterile lyophilized powder before reconstitution; (ii) laspatercept in the form of a reconstituted form having a concentration of 50 mg / mL in a 10 mM citrate buffer-based solution (10 mM citrate, pH=6.5, 9% sucrose, 0.02% polysorbate 80); and (iii) a 3 mL glass vial package containing 37.5 mg of laspatercept, said glass vial package delivering at least 0.5 mL (25 mg / vial) of 50 mg / mL laspatercept after reconstitution with 0.68 mL of water for injection (WFI). (Aspect 22) A single dose pharmaceutical formulation comprising: (i) laspatercept in the form of a preservative-free sterile lyophilized cake or sterile lyophilized powder before reconstitution; (ii) laspatercept in the form after reconstitution, having a concentration of 50 mg / mL in a 10 mM citrate buffer-based solution (10 mM citrate, pH=6.5, 9% sucrose, 0.02% polysorbate 80); and (iii) a 3 mL glass vial package containing 87.5 mg of laspatercept, said glass vial package delivering at least 1.5 mL (75 mg / vial) of 50 mg / mL laspatercept after reconstitution with 1.6 mL of WFI. (Aspect 23) The method according to any one of aspects 1 to 19, wherein luspatercept or sotatercept is used as the pharmaceutical formulation according to any one of aspects 20 to 22.

Claims

1. 1. A pharmaceutical composition comprising luspatercept for treating a human subject diagnosed with anemia due to very low, low or moderate risk myelodysplastic syndrome (MDS), comprising: (a) at least 15% of erythroblasts in the subject that are ring sideroblasts; and (b) the subject has a baseline platelet count of 400×10 or greater. ９ / L, and (c) the pharmaceutical composition comprises laspatercept at a concentration of 50 mg / mL, 10 mM citrate, 9% sucrose, and 0.02% polysorbate 80, and the pharmaceutical composition has a pH of 6.

5.

2. 1. A pharmaceutical composition comprising luspatercept for treating a human subject diagnosed with anemia due to very low, low or moderate risk myelodysplastic syndrome (MDS), wherein: (a) the subject has one or more mutations in the SF3B1 gene; (b) the subject has at least 5% of erythroblasts that are ring sideroblasts; and (c) the subject has a baseline platelet count of 400×10 ９ / L, and (d) the pharmaceutical composition comprises laspatercept at a concentration of 50 mg / mL, 10 mM citrate, 9% sucrose, and 0.02% polysorbate 80, and the pharmaceutical composition has a pH of 6.

5.

3. 3. The pharmaceutical composition of claim 1 or 2, wherein the very low risk, low risk or moderate risk MDS is classified using the International Prognostic Scoring System-Revised (IPSS-R).

4. The pharmaceutical composition of claim 1 or 2, wherein the subject has less than 5 percent blasts in the bone marrow.

5. The pharmaceutical composition of claim 1 or 2, wherein the subject is in need of an RBC transfusion.

6. 3. The pharmaceutical composition of claim 1 or 2, wherein the treatment is effective to (i) reduce the percentage of erythroblasts in the subject that are ring sideroblasts for a longer period of time than the initial percentage of erythroblasts in the subject that are ring sideroblasts, and / or (ii) increase the hemoglobin level of the subject for a longer period of time than the hemoglobin level of the subject at a period of time prior to administering a first dose of luspatercept to the subject.

7. The pharmaceutical composition of claim 6, wherein the extended period is a period of 8 weeks or more.

8. 3. The pharmaceutical composition of claim 1 or 2, wherein the treatment is effective to (i) achieve a period of red blood cell transfusion independence (RBC-TI) of 8 weeks or more in the subject following administration of raspatercept, (ii) achieve a period of RBC-TI of 12 weeks or more in the subject following administration of raspatercept, or (iii) modify the red blood cell response (mHI-E) in the subject following administration of raspatercept.

9. The pharmaceutical composition of claim 8, wherein the mHI-E is an increase in mean hemoglobin of 1.5 g / dL or more in the subject over an 8-week period following administration of luspatercept, or a decrease in red blood cells transfused to the subject of 4 or more units over an 8-week period.

10. 2. The pharmaceutical composition of claim 1, wherein the percentage of erythroblasts in the subject that are ring sideroblasts prior to administration of raspatercept to the subject is at least 16%, at least 17%, at least 18%, at least 19% or at least 20%.

11. 3. The pharmaceutical composition of claim 2, wherein the percentage of erythroblasts in the subject that are ring sideroblasts prior to administration of raspatercept to the subject is at least 5%, at least 6%, at least 7%, at least 8%, at least 9%, at least 10%, at least 11%, at least 12%, at least 13%, at least 14% or at least 15%.

12. The pharmaceutical composition according to claim 1 or 2, characterized in that luspatercept is administered to the subject at a dose of 0.5 mg / kg to 1.75 mg / kg.

13. 3. The pharmaceutical composition of claim 1 or 2, wherein luspatercept is administered to the subject at a dose of about 0.45 mg / kg, about 0.50 mg / kg, about 0.60 mg / kg, about 0.70 mg / kg, about 0.80 mg / kg, about 0.90 mg / kg, about 1.00 mg / kg, about 1.05 mg / kg, about 1.10 mg / kg, about 1.15 mg / kg, about 1.20 mg / kg, about 1.25 mg / kg, about 1.30 mg / kg, about 1.33 mg / kg, about 1.35 mg / kg, about 1.40 mg / kg, about 1.45 mg / kg, about 1.50 mg / kg, about 1.55 mg / kg, about 1.60 mg / kg, about 1.65 mg / kg, about 1.70 mg / kg or about 1.75 mg / kg.

14. The pharmaceutical composition according to claim 1 or 2, characterized in that luspatercept is administered subcutaneously to the subject.

15. The pharmaceutical composition of claim 1 or 2, wherein the subject is refractory to prior erythropoietin stimulating agent (ESA) treatment.

16. 3. The pharmaceutical composition of claim 1 or 2, wherein the subject is intolerant to prior treatment with an ESA.

17. The pharmaceutical composition of claim 1 or 2, wherein the subject is ineligible for treatment with an ESA.

18. The pharmaceutical composition according to any one of claims 15 to 17, wherein the treatment with ESA is in combination with granulocyte colony-stimulating factor (G-CSF).

19. The pharmaceutical composition of claim 1 or 2, wherein the subject is a male.

20. The pharmaceutical composition of claim 1 or 2, wherein the subject has received an initial diagnosis of MDS within 2 to 5 years prior to administration of luspatercept.

21. The pharmaceutical composition of claim 1 or 2, wherein the subject has a baseline serum erythropoietin (EPO) level of 100-200 IU / L.

22. 3. The pharmaceutical composition of claim 1 or 2, wherein the subject has received 4-6 units of RBC transfusion in an 8 week period prior to administration of luspatercept.

23. The pharmaceutical composition comprises: a) 37.5 mg of luspatercept in a 3 mL glass vial package reconstituted with 0.68 mL of water for injection from a preservative-free sterile lyophilized cake or powder form; or b) 87.5 mg of raspatercept in a 3 mL glass vial package reconstituted with 1.6 mL of water for injection from a preservative-free sterile lyophilized cake or powder form.

3. The pharmaceutical composition according to claim 1 or 2, which is a single dose pharmaceutical formulation comprising:

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