A Study of AG-946 in Participants With Anemia Due to Lower-Risk Myelodysplastic Syndromes (LR-MDS)

Myelodysplastic Syndromes Clinical Trial

Official title:

A Phase 2a/2b, Open-label, Proof of Concept (Phase 2a) and Double-blind, Randomized, Placebo-Controlled (Phase 2b), Multicenter, Efficacy, and Safety Study of AG-946 in Participants With Anemia Due to Lower-Risk Myelodysplastic Syndromes

Clinical Trial Details — Status: Active, not recruiting

Administrative data

• NCT number: NCT05490446
• Other study ID #: AG946-C-002
• Secondary ID: 2022-500609-42-0
• Status: Active, not recruiting
• Phase: Phase 2
• Start date: November 7, 2022
• Est. completion date: November 2028

Study information

• Verified date: April 2024
• Source: Agios Pharmaceuticals, Inc.
• Contact: n/a
• Is FDA regulated: No
• Study type: Interventional

Clinical Trial Summary

This purpose of this study is to establish proof of concept of AG-946 in participants with LR-MDS in Phase 2a and to compare the effect of AG-946 versus placebo and to detect a dose response for erythroid response in participants with LR-MDS in Phase 2b.

Recruitment information / eligibility

• Status: Active, not recruiting
• Enrollment: 116
• Est. completion date: November 2028
• Est. primary completion date: November 2025
• Accepts healthy volunteers: No
• Gender: All
• Age group: 18 Years and older

Eligibility

Inclusion Criteria:

Phase 2a

• At least 18 years of age at the time of providing informed consent;
• Documented diagnosis of myelodysplastic syndromes (MDS) according to World Health Organization (WHO) classification (Arber et al, 2016), that meets Revised International Prognostic Scoring System (IPSS-R) classification of lower-risk disease (risk score: =3.5) and <5% blasts as determined by the participant's bone marrow biopsy/aspirate during the Screening Period;
• Nontransfused or with low transfusion burden (LTB), based on transfusion history from the participant's medical record, according to revised International Working Group

(IWG) 2018 criteria:

• Nontransfused (NTD): <3 red blood cell (RBC) units in the 16-week period before administration of the first dose of study drug and no transfusions in the 8-week period before administration of the first dose of study drug, or
• LTB: 3 to 7 RBC units in the 16-week period before administration of the first dose of study drug and <4 RBC units in the 8-week period before administration of the first dose of study drug;
• An hemoglobin (Hb) concentration <11.0 grams per deciliter (g/dL) during the 4-week Screening Period;
• Eastern Cooperative Oncology Group (ECOG) Performance Status score of 0, 1, or 2;
• If taking iron chelation therapy, the iron chelation therapy dose must have been stable and started =56 days before administration of the first dose of study drug;
• Women of childbearing potential (WOCBP) must be abstinent of sexual activities that may result in pregnancy as part of their usual lifestyle or agree to use a highly effective method of contraception from the time of providing informed consent, throughout the study, and for 28 days after the last dose of study drug; if the highly effective method of contraception is hormonal contraception, then an acceptable barrier method must also be used. Men with partners who are WOCBP must be abstinent of sexual activities that may result in pregnancy as part of their usual lifestyle or agree to use a condom from the time of providing informed consent throughout the study and for 28 days after the last dose of study drug;
• Written informed consent from the participant before any study-related procedures are conducted and willing to comply with all study procedures for the duration of the study. Phase 2b
• At least 18 years of age at the time of providing informed consent;
• Documented diagnosis of MDS according to WHO classification (Arber et al, 2016), that meets IPSS-R classification of lower-risk disease (risk score: =3.5) and <5% blasts as determined by the participant's bone marrow biopsy/aspirate during the Screening Period;
• Nontransfused, with LTB, or with high transfusion burden (HTB), based on transfusion

history from the participant's medical record, according to revised IWG 2018 criteria:

• NTD: <3 RBC units in the 16-week period before randomization and no transfusions in the 8-week period before randomization, or
• LTB: 3 to 7 RBC units in the 16-week period before randomization and <4 RBC units in the 8-week period before randomization, or
• HTB: =8 RBC units in the 16-week period before randomization and =4 RBC units in the 8-week period before randomization;
• An Hb concentration <11.0 g/dL during the 4-week Screening Period;
• Up to 2 prior therapies including erythropoiesis-stimulating agents (ESAs) (eg, erythropoietin [EPO], EPO + granulocyte colony-stimulating factor [G-CSF]) and/or luspatercept;
• ECOG Performance Status score of 0, 1, or 2;
• If taking iron chelation therapy, the iron chelation therapy dose must have been stable and started =56 days before randomization;
• WOCBP must be abstinent of sexual activities that may result in pregnancy as part of their usual lifestyle or agree to use a highly effective, from the time of providing informed consent throughout the study and for 28 days after the last dose of study drug; if the highly effective method of contraception is hormonal contraception, then an acceptable barrier method must be used. Men with partners who are WOCBP must be abstinent of sexual activities that may result in pregnancy as part of their usual lifestyle or agree to use a condom from the time of providing informed consent throughout the study and for 28 days after the last dose of study drug;
• Written informed consent from the participant before any study-related procedures are conducted and willing to comply with all study procedures for the duration of the study. Exclusion Criteria: Phase 2a
• Known history of acute myeloid leukemia (AML);
• Secondary MDS, defined as MDS that is known to have arisen as a result of chemical injury or treatment with chemotherapy and/or radiation for other diseases;
• Prior exposure to a pyruvate kinase activator and/or disease-modifying agents for

underlying MDS:

• Immunomodulatory drugs (IMiDs) such as lenalidomide; at the Investigator's discretion and in consultation with the Medical Monitor, participants who received =1 week of treatment with IMiDs may not be excluded, provided their last dose was =8 weeks before administration of the first dose of study drug
• Hypomethylating agents (HMAs); at the Investigator's discretion and in consultation with the Medical Monitor, participants who received =2 doses of HMAs may not be excluded, provided that their last dose was =8 weeks before administration of the first dose of study drug
• Isocitrate dehydrogenase (IDH) inhibitors
• Immunosuppressive therapy (IST)
• Allogeneic or autologous stem cell transplant;
• Currently receiving treatment with ESAs±G-CSF and/or luspatercept. Treatment with ESAs±G-CSF must have been stopped for =28 days before administration of the first dose of study drug; treatment with luspatercept must have been stopped for =65 days before administration of the first dose of study drug;
• History of active and/or uncontrolled cardiac or pulmonary disease within 6 months

before providing informed consent, including but not limited to:

• New York Heart Association Class III or IV heart failure or clinically significant dysrhythmia
• Myocardial infarction, unstable angina pectoris, or unstable hypertension; high risk thrombosis; hemorrhagic, embolic, or thrombotic stroke; deep venous thrombosis; or pulmonary or arterial embolism
• Heart rate-corrected QT interval using Fridericia's method of =470 milliseconds for female participants and =450 milliseconds for male participants, except for right or left bundle branch block
• Severe pulmonary fibrosis as defined by severe hypoxia, evidence of right-sided heart failure, and radiographic pulmonary fibrosis >50%
• Severe pulmonary hypertension as defined by severe symptoms associated with hypoxia, right-sided heart failure, and oxygen indicated;
• History of hepatobiliary disorders, as defined by:
• Serum aspartate aminotransferase (AST) >2.5 × upper limit of normal (ULN) (unless due to hemolysis and/or hepatic iron deposition) and alanine aminotransferase (ALT) >2.5 × ULN (unless due to hepatic iron deposition)
• Serum bilirubin >ULN, if the elevation is associated with clinically symptomatic choledocholithiasis, cholecystitis, biliary obstruction, or hepatocellular disease;
• Renal dysfunction, as defined by an estimated glomerular filtration rate (eGFR) <45 milliliters per minute (mL/min)/1.73 m^2;
• Active infection requiring systemic antimicrobial therapy at the time of providing informed consent. If antimicrobial therapy is required during the Screening Period, screening procedures should not be performed while antimicrobial therapy is being administered, and the last dose of antimicrobial therapy must be administered =7 days before administration of the first dose of study drug;
• Major surgery within 12 weeks before administration of the first dose of study drug. Participants must have completely recovered from any previous surgery before administration of the first dose of study drug;
• For any malignancy except MDS: History of malignancy (active or treated) =5 years before providing informed consent for nonmelanomatous skin cancer in situ, cervical carcinoma in situ, or breast carcinoma in situ;
• Positive test for hepatitis C virus (HCV) antibody (Ab) with evidence of active HCV infection, or positive test for hepatitis B surface antigen (HBsAg);
• Positive test for HIV-1 Ab or HIV-2 Ab;
• Absolute neutrophil count (ANC) <500/microliter (µL) (0.5 × 109/L);
• Platelet count =75,000/µL during Screening (75 × 109/L) platelet transfusions within 28 days before Screening or during Screening;
• Nonfasting triglyceride concentration >500 mg/dL;
• Receiving inhibitors of P-glycoprotein (P-gp) that have not been stopped for =5 days or a time frame equivalent to 5 half-lives (whichever is longer) before administration of the first dose of study drug;
• Current enrollment or past participation (within 4 weeks or a time frame equivalent to 5 half-lives of the investigational study drug before administration of the first dose of study drug or, whichever is longer) in any other clinical study involving an investigational treatment or device;
• Known allergy to AG-946 or its excipients;
• Pregnant or breastfeeding;
• Any medical, hematologic, psychological, or behavioral condition(s) or prior or current therapy that, in the opinion of the Investigator, may confer an unacceptable risk to participating in the study and/or could confound the interpretation of the

study data. Also excluded are:

• Participants who are institutionalized by regulatory or court order;
• Participants with any condition(s) that could create undue influence (including but not limited to incarceration, involuntary psychiatric confinement, and financial or familial affiliation with the Investigator or Sponsor). Phase 2b
• Known history of AML;
• Secondary MDS, defined as MDS that is known to have arisen as a result of chemical injury or treatment with chemotherapy and/or radiation for other diseases;
• Prior exposure to a pyruvate kinase activator, including exposure to AG-946 in the

Phase 2a part of this study, and/or disease-modifying agents for underlying MDS:

• IMiDs such as lenalidomide; at the Investigator's discretion and in consultation with the Medical Monitor, participants who received =1 week of treatment with IMiDs may not be excluded, provided their last dose was =8 weeks before randomization
• HMAs; at the Investigator's discretion and in consultation with the Medical Monitor, participants who received =2 doses of HMAs may not be excluded, provided that their last dose was =8 weeks before randomization
• IDH inhibitors
• IST
• Allogeneic or autologous stem cell transplant;
• Currently receiving treatment with ESAs±G-CSF and/or luspatercept. Treatment with ESAs±G-CSF must have been stopped for =28 days before randomization; treatment with luspatercept must have been stopped for =65 days before randomization;
• History of active and/or uncontrolled cardiac or pulmonary disease within 6 months

before providing informed consent, including but not limited to:

• New York Heart Association Class III or IV heart failure or clinically significant dysrhythmia
• Myocardial infarction, unstable angina pectoris, or unstable hypertension; high risk thrombosis; hemorrhagic, embolic, or thrombotic stroke; deep venous thrombosis; or pulmonary or arterial embolism
• Heart rate-corrected QT interval using Fridericia's method of =470 milliseconds for female participants and =450 milliseconds for male participants, except for right or left bundle branch block
• Severe pulmonary fibrosis as defined by severe hypoxia, evidence of right-sided heart failure, and radiographic pulmonary fibrosis >50%
• Severe pulmonary hypertension as defined by severe symptoms associated with hypoxia, right-sided heart failure, and oxygen indicated;
• History of hepatobiliary disorders, as defined by:
• Serum AST >2.5 × ULN (unless due to hemolysis and/or hepatic iron deposition) and ALT >2.5 × ULN (unless due to hepatic iron deposition)
• Serum bilirubin >ULN, if the elevation is associated with clinically symptomatic choledocholithiasis, cholecystitis, biliary obstruction, or hepatocellular disease;
• Renal dysfunction, as defined by an eGFR <45 mL/min/1.73 m^2;
• Active infection requiring systemic antimicrobial therapy at the time of providing informed consent. If antimicrobial therapy is required during the Screening Period, screening procedures should not be performed while antimicrobial therapy is being administered, and the last dose of antimicrobial therapy must be administered =7 days before randomization;
• Major surgery within 12 weeks before randomization. Participants must have completely recovered from any previous surgery before randomization;
• For any malignancy except MDS: History of malignancy (active or treated) =5 years before providing informed consent, except for nonmelanomatous skin cancer in situ, cervical carcinoma in situ, or breast carcinoma in situ.;
• Positive test for HCV Ab with evidence of active HCV infection, or positive test for HBsAg;
• Positive test for HIV-1 Ab or HIV-2 Ab;
• ANC <500/µL (0.5 × 109/L);
• Platelet count <50,000/µL (50 × 109/L) during Screening; platelet transfusions within 28 days before Screening or during Screening;
• Nonfasting triglyceride concentration >500 mg/dL;
• Receiving inhibitors of P-gp that have not been stopped for =5 days or a time frame equivalent to 5 half-lives (whichever is longer) before randomization;
• Current enrollment or past participation (within 4 weeks or a time frame equivalent to 5 half-lives of the investigational study drug before randomization or, whichever is longer) in any other clinical study involving an investigational treatment or device;
• Known allergy to AG-946 or its excipients, including placebo;
• Pregnant or breastfeeding;
• Any medical, hematologic, psychological, or behavioral condition(s) or prior or current therapy that, in the opinion of the Investigator, may confer an unacceptable risk to participating in the study and/or could confound the interpretation of the

study data. Also excluded are:

• Participants who are institutionalized by regulatory or court order
• Participants with any condition(s) that could create undue influence (including but not limited to incarceration, involuntary psychiatric confinement, and financial or familial affiliation with the Investigator or Sponsor).

Related Conditions & MeSH terms

• Anemia
• Myelodysplastic Syndromes
• Preleukemia
• Syndrome

Intervention

Drug:
• AG-946
AG-946 Tablet
• Placebo
Matching-placebo Tablet

Locations

Country	Name	City	State
Australia	Monash Health, Monash Medical Centre	Clayton	Victoria
Austria	Ordensklinikum Linz GmbH Elisabethinen	Linz	Oberösterreich
Czechia	Fakultni nemocnice Ostrava	Ostrava
France	CHU Angers	Angers	Maine-et-Loire
France	CHRU Lille	Lille
France	Hôpital de La Conception	Marseille	Bouches-du-Rhône
France	Hôpital Saint Louis	Paris
Germany	Universitatsklinikum Dusseldorf	Düsseldorf	Nordrhein-Westfalen
Germany	Medizinische Hochschule Hannover	Hannover	Niedersachsen
Germany	Universitatsklinikum Leipzig	Leipzig	Sachsen
Greece	University Hospital of Alexandroupolis	Alexandroupolis
Greece	Attikon University General Hospital	Athens
Greece	University General Hospital of Patras	Patras
Greece	Hippokration Hospital	Thessaloniki
Israel	Shaare Zedek Medical Center	Jerusalem
Israel	Tel Aviv Sourasky Medical Center PPDS	Tel Aviv
Italy	Fondazione IRCCS Cà Granda Ospedale Maggiore Policlinico	Milano	Lombardia
Italy	Fondazione IRCCS Policlinico San Matteo di Pavia	Pavia	Lombardia
Italy	Fondazione PTV Policlinico Tor Vergata	Roma
Italy	Istituto Clinico Humanitas	Rozzano	Lombardia
Italy	Azienda Ospedaliera Ordine Mauriziano di Torino	Torino	Piemonte
Korea, Republic of	Kyungpook National University Hospital	Daegu
Korea, Republic of	Asan Medical Center - PPDS	Seoul
Korea, Republic of	The Catholic University of Korea, Seoul St. Mary's Hospital	Seoul
Poland	Pratia Onkologia Katowice - PRATIA - PPDS	Katowice	Slaskie
Poland	SPZOZ MiSWiA z Warminsko-Mazurskim Centrum Onkologii w Olsztynie	Olsztyn	Warminsko-mazurskie
Poland	MTZ Clinical Research Powered by PRATIA - PPDS	Warszawa	Mazowieckie
Spain	C.H. Regional Reina Sofia - PPDS	Cordoba
Spain	Hospital Universitario HM Sanchinarro - CIOCC	Madrid
Spain	Hospital Universitario La Paz - PPDS	Madrid
Spain	Complejo Asistencial Universitario de Salamanca - H. Clinico	Salamanca
Spain	Hospital Universitario Virgen del Rocio - PPDS	Sevilla
United Kingdom	Aberdeen Royal Infirmary - PPDS	Aberdeen	Aberdeen City
United Kingdom	Western General Hospital Edinburgh - PPDS	Edinburgh
United Kingdom	Kings College Hospital	London
United Kingdom	Churchill Hospital-NHS Oxford	Oxford
United States	Duke Adult Blood and Marrow Clinic	Durham	North Carolina
United States	Mayo Clinic Jacksonville - PPDS	Jacksonville	Florida
United States	Innovative Clinical Research Institute Whittier	Lakewood	California
United States	Memorial Sloan Kettering Cancer Center	Long Island City	New York
United States	David Geffen School of Medicine at UCLA	Los Angeles	California
United States	Emad Ibrahim, MD, Inc.	Redlands	California
United States	Washington University School of Medicine	Saint Louis	Missouri
United States	Edward H. Kaplan MD & Associates	Skokie	Illinois

Sponsors (1)

Lead Sponsor	Collaborator
Agios Pharmaceuticals, Inc.

Countries where clinical trial is conducted

United States,  Australia,  Austria,  Czechia,  France,  Germany,  Greece,  Israel,  Italy,  Korea, Republic of,  Poland,  Spain,  United Kingdom, 

Outcome

Type	Measure	Description	Time frame	Safety issue
Primary	Phase 2a: Number of Participants With Hemoglobin (Hb) Response	Hb response is defined as a =1.5-grams per deciliter (g/dL) increase from baseline in the average Hb concentration from Week 8 through Week 16.	Baseline, Week 8 through Week 16
Primary	Phase 2a: Number of Participants With Transfusion Independence During the Core Period	Transfusion Independence is defined as transfusion-free for =8 consecutive weeks during the Core Period (participants With Low Transfusion Burden [LTB] only).	Up to 16 weeks
Primary	Phase 2b: Number of Participants With Modified Hematologic Improvement-erythroid (mHI-E) Response	mHI-E Response is defined as: =1.5-g/dL increase from baseline in Hb concentration for =8 consecutive weeks during the Double-blind Period (participants who are nontransfused [NTD]); Transfusion independence, defined as transfusion-free for =8 consecutive weeks during the Double-blind Period (participants with LTB only); =50% reduction in total transfused RBC units for =8 consecutive weeks during the Double-blind Period compared with baseline (participants with high transfusion burden [HTB] only)	Up to 24 weeks
Secondary	Phase 2a: Number of Participants With Adverse Events (AEs), Serious Adverse Events (SAEs), and AEs Leading to Discontinuation During the Core Period	An AE is any untoward medical occurrence in a patient or clinical investigation participant administered a pharmaceutical product that does not necessarily have a causal relationship with this treatment. An SAE is any AE or suspected adverse reaction that results in death, is immediately life-threatening, requires inpatient hospitalization or prolongation of existing hospitalization, results in persistent or significant incapacity or substantial disruption of the ability to conduct normal life functions, results in congenital anomaly/birth defect, or is considered an important medical event.	Up to 16 weeks
Secondary	Phase 2a: Number of Participants With Laboratory Abnormalities During the Core Period		Up to 16 weeks
Secondary	Phase 2a: Number of Participants With Hb 1.0+ Response	Hb 1.0+ response is defined as a =1.0-g/dL increase from baseline in the average Hb concentration from Week 8 through Week 16	Baseline, Week 8 through Week 16
Secondary	Phase 2a: Change From Baseline in Hb Concentration During the Core Period		Baseline up to 16 weeks
Secondary	Phase 2a: Number of Participants With =1.5-g/dL increase From Baseline in the Hb Concentration at =2 Consecutive Time Points From Week 8 through Week 16		Baseline, Week 8 through Week 16
Secondary	Phase 2a: Change from Baseline in Total Transfused Red Blood Cell (RBC) Units During the Core Period		Baseline up to 16 weeks
Secondary	Phase 2a: Number of Participants With =50% Reduction in Total Transfused RBC Units for =8 Consecutive Weeks During the Core Period Compared With Baseline		Baseline up to 16 weeks
Secondary	Phase 2a: Plasma Concentration of AG-946 During the Core Period		Day 1 and Week 8 (=60 minutes predose and 0.5, 1, 2, 3, 4, 6, and 8 hours postdose) and at Weeks 2, 4, 12, and 16 (=60 minutes predose)
Secondary	Phase 2a: Maximum (Peak) Concentration (Cmax) of AG-946 During the Core Period		Day 1 and Week 8 (=60 minutes predose and 0.5, 1, 2, 3, 4, 6, and 8 hours postdose) and at Weeks 2, 4, 12, and 16 (=60 minutes predose)
Secondary	Phase 2a: Time to Cmax (tmax) of AG-946 During the Core Period		Day 1 and Week 8 (=60 minutes predose and 0.5, 1, 2, 3, 4, 6, and 8 hours postdose) and at Weeks 2, 4, 12, and 16 (=60 minutes predose)
Secondary	Phase 2a: Area Under the Concentration-time Curve From 0 to t Hours (AUC0-t) of AG-946 During the Core Period		Day 1 and Week 8 (=60 minutes predose and 0.5, 1, 2, 3, 4, 6, and 8 hours postdose) and at Weeks 2, 4, 12, and 16 (=60 minutes predose)
Secondary	Phase 2a: Area Under the Concentration-time Curve From 0 to the End of the Dosing Interval (AUC0-t) of AG-946 During the Core Period		Day 1 and Week 8 (=60 minutes predose and 0.5, 1, 2, 3, 4, 6, and 8 hours postdose) and at Weeks 2, 4, 12, and 16 (=60 minutes predose)
Secondary	Phase 2a: Apparent Terminal Elimination Half-life (t½) of AG-946 During the Core Period		Day 1 and Week 8 (=60 minutes predose and 0.5, 1, 2, 3, 4, 6, and 8 hours postdose) and at Weeks 2, 4, 12, and 16 (=60 minutes predose)
Secondary	Phase 2a: Whole Blood Concentrations of 2,3-diphosphoglycerate (2,3-DPG) During the Core Period		Day 1 and Week 8 (=60 minutes predose and 0.5, 1, 2, 3, 4, 6, and 8 hours postdose) and at Weeks 2, 4, 12, and 16 (=60 minutes predose)
Secondary	Phase 2a: Whole Blood Concentrations of Adenosine Triphosphate (ATP) During the Core Period		Day 1 and Week 8 (=60 minutes predose and 0.5, 1, 2, 3, 4, 6, and 8 hours postdose) and at Weeks 2, 4, 12, and 16 (=60 minutes predose)
Secondary	Phase 2b: Number of Participants With Adverse Events (AEs), Serious Adverse Events (SAEs), and AEs Leading to Discontinuation During the Double-blind Period	An AE is any untoward medical occurrence in a patient or clinical investigation participant administered a pharmaceutical product that does not necessarily have a causal relationship with this treatment. An SAE is any AE or suspected adverse reaction that results in death, is immediately life-threatening, requires inpatient hospitalization or prolongation of existing hospitalization, results in persistent or significant incapacity or substantial disruption of the ability to conduct normal life functions, results in congenital anomaly/birth defect, or is considered an important medical event.	Up to 24 weeks
Secondary	Phase 2b: Change From Baseline in Hb Concentration During the Double-Blind Period		Baseline up to 24 weeks
Secondary	Phase 2b: Change From Baseline in Total Transfused RBC Units From Week 8 Through Week 24		Baseline, Week 8 through Week 24
Secondary	Phase 2b: Number of Participants With Transfusion Independence during the Double-blind Period	Transfusion independence is defined as transfusion-free for =8 consecutive weeks during the Double-blind Period.	Baseline up to 24 weeks
Secondary	Phase 2b: Time to First mHI-E Response During the Double-blind Period	mHI-E Response is defined as: =1.5-g/dL increase from baseline in Hb concentration for =8 consecutive weeks during the Double-blind Period (participants who are NTD); Transfusion independence, defined as transfusion-free for =8 consecutive weeks during the Double-blind Period (participants with LTB only); =50% reduction in total transfused RBC units for =8 consecutive weeks during the Double-blind Period compared with baseline (participants with HTB only)	Baseline up to 24 weeks
Secondary	Phase 2b: Maximum Duration of mHI-E Response for Participants Who Achieved an mHI-E Response During the Double-blind Period	mHI-E Response is defined as: =1.5-g/dL increase from baseline in Hb concentration for =8 consecutive weeks during the Double-blind Period (participants who are NTD); Transfusion independence, defined as transfusion-free for =8 consecutive weeks during the Double-blind Period (participants with LTB only); =50% reduction in total transfused RBC units for =8 consecutive weeks during the Double-blind Period compared with baseline (participants with HTB only)	Baseline up to 24 weeks
Secondary	Phase 2b: Plasma Concentration of AG-946 During the Double-blind Period		Day 1 and Week 8 (=60 minutes predose and 0.5, 1, 2, 3, 4, 6, and 8 hours postdose) and at Weeks 2, 4, 12, and 16 (=60 minutes predose)
Secondary	Phase 2b: Maximum (Peak) Concentration (Cmax) of AG-946 During the Double-blind Period		Day 1 and Week 8 (=60 minutes predose and 0.5, 1, 2, 3, 4, 6, and 8 hours postdose) and at Weeks 2, 4, 12, and 16 (=60 minutes predose)
Secondary	Phase 2b: Time to Cmax (tmax) of AG-946 During the Double-blind Period		Day 1 and Week 8 (=60 minutes predose and 0.5, 1, 2, 3, 4, 6, and 8 hours postdose) and at Weeks 2, 4, 12, and 16 (=60 minutes predose)
Secondary	Phase 2b: Area Under the Concentration-time Curve From 0 to t Hours (AUC0-t) of AG-946 During the Double-blind Period		Day 1 and Week 8 (=60 minutes predose and 0.5, 1, 2, 3, 4, 6, and 8 hours postdose) and at Weeks 2, 4, 12, and 16 (=60 minutes predose)
Secondary	Phase 2b: Area Under the Concentration-time Curve From 0 to the End of the Dosing Interval (AUC0-t) of AG-946 During the Double-blind Period		Day 1 and Week 8 (=60 minutes predose and 0.5, 1, 2, 3, 4, 6, and 8 hours postdose) and at Weeks 2, 4, 12, and 16 (=60 minutes predose)
Secondary	Phase 2b: Apparent Terminal Elimination Half-life (t½) of AG-946 During the Double-blind Period		Day 1 and Week 8 (=60 minutes predose and 0.5, 1, 2, 3, 4, 6, and 8 hours postdose) and at Weeks 2, 4, 12, and 16 (=60 minutes predose)
Secondary	Phase 2b: Whole Blood Concentrations of 2,3-diphosphoglycerate (2,3-DPG) During the Double-blind Period		Day 1 and Week 8 (=60 minutes predose and 0.5, 1, 2, 3, 4, 6, and 8 hours postdose) and at Weeks 2, 4, 12, and 16 (=60 minutes predose)
Secondary	Phase 2b: Whole Blood Concentrations of Adenosine Triphosphate (ATP) During the Double-blind Period		Day 1 and Week 8 (=60 minutes predose and 0.5, 1, 2, 3, 4, 6, and 8 hours postdose) and at Weeks 2, 4, 12, and 16 (=60 minutes predose)
Secondary	Phase 2b: Correlation Between AG-946 Plasma Concentration/exposure and Percentage of Participants With mHI-E Response During the Double-blind Period, as Assessed by Regression Analysis	mHI-E Response is defined as: =1.5-g/dL increase from baseline in Hb concentration for =8 consecutive weeks during the Double-blind Period (participants who are NTD); Transfusion independence, defined as transfusion-free for =8 consecutive weeks during the Double-blind Period (participants with LTB only); =50% reduction in total transfused RBC units for =8 consecutive weeks during the Double-blind Period compared with baseline (participants with HTB only)	Baseline up to 24 weeks
Secondary	Phase 2b: Correlation Between AG-946 Plasma Concentration/exposure and Change From Baseline in Hb Concentration During the Double-blind Period, as Assessed by Regression Analysis		Baseline up to 24 weeks
Secondary	Phase 2b: Correlation Between AG-946 Plasma Concentration/exposure and Percentage of Participants Having AEs of Clinical Interest During the Double-blind Period, as Assessed by Regression Analysis	AEs of special interest will be determined during the study.	Baseline up to 24 weeks