A Phase 3 interventional study of Mitapivat Matched Placebo and Mitapivat in Transfusion-dependent Alpha-Thalassemia and Transfusion-dependent Beta-Thalassemia, sponsored by Agios Pharmaceuticals, Inc.. Recruiting at 4 sites in United States. Open to participants aged 1 Year to 17 Years. Per ClinicalTrials.gov, last updated 2026-10-29.
Sponsored by Agios Pharmaceuticals, Inc. · Phase 3, Interventional, and Treatment
The primary objective of this study is to compare the effect of mitapivat versus placebo on transfusion burden in pediatric participants with α- or β-transfusion-dependent thalassemia.
294 studies on the registry are indexed under beta-Thalassemia; 69 are open to participants now.
This study's planned enrollment of 54 is above the median of 40 across 208 interventional studies indexed under beta-Thalassemia.
Browse beta-Thalassemia studies →Agios Pharmaceuticals, Inc. is the lead sponsor of 52 studies on the registry; 6 are open to participants now.
Of its 23 completed or terminated interventional studies of FDA-regulated products, 4 (17%) have results posted.
Compared within beta-Thalassemia, this study's primary condition as ClinicalTrials.gg classifies it; the registry's first condition term is Thalassemia. The counts are of registry records indexed under each term, refreshed daily. How we classify →
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Exclusion Criteria:
Hepatobiliary disorders, including but not limited to:
Any medical, hematological, 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:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
The protein in red blood cells that carries oxygen. A low level is anaemia, which can cause tiredness and breathlessness. Measured in g/dL or g/L (9 g/dL is 90 g/L).
Ways of preventing pregnancy. “Highly effective” methods fail less than 1% of the time a year when used correctly — for example an IUD or an implant.
Criteria usually say which methods count and how long to keep using them after the last dose, sometimes for male participants too. Some studies accept a partner’s vasectomy if it was confirmed successful and that person is the participant’s only sexual partner.
Malignancy means cancer. Criteria about another or earlier malignancy ask whether you have had a different cancer, usually within a set number of years.
Some are commonly allowed, such as treated skin cancers other than melanoma and early cancers removed completely — check the exceptions this study lists.
Judged by the study doctor to matter for your health or for the study. It is a doctor’s decision, so ask the study team if you are unsure whether something counts.
On an ECG, the QT interval is the time the heart’s lower chambers take to activate electrically and recover in each beat. QTc is that time adjusted for heart rate (QTcF by Fridericia’s formula, QTcB by Bazett’s). Some medicines lengthen it, and a long QTc can raise the risk of a dangerous heart rhythm.
The study may name a correction formula and a limit in milliseconds, often around 450–480.
Two enzymes measured in a routine blood test of the liver. Higher levels can mean the liver is under strain or damaged. SGPT and SGOT are older names for ALT and AST.
Criteria usually give a limit as a multiple of the upper limit of normal (ULN), often higher when cancer has spread to the liver.
The top of the normal range for a blood test, as set by the laboratory that runs it. Each lab prints its own range next to your result.
“≤ 2.5 × ULN” means the result can be up to two and a half times that top value.
GFR (glomerular filtration rate) is how much blood the kidneys filter each minute. It is usually estimated from a blood test — eGFR, by formulas such as CKD-EPI or MDRD — and some studies ask for it to be measured directly instead. Usually given in mL/min/1.73 m².
Check the method, the units and the minimum the study states. A value of 90 or above is in the normal-or-high range, but kidney damage can show in other tests too.
Hepatitis B is a virus that infects the liver. These are separate tests: HBsAg positive usually means a current infection (a recent vaccination can briefly cause it too); total anti-HBc (HBcAb) positive means an infection now or in the past; HBV DNA measures how much virus is in the blood.
Some studies accept a past infection if HBV DNA is undetectable, sometimes with antiviral medicine during the study. Check what this study allows.
Hepatitis C is a virus that infects the liver. An HCV antibody test can stay positive after an infection has cleared (and is occasionally positive without one); an HCV RNA test shows whether the virus is there now.
After treatment, hepatitis C counts as cured when HCV RNA is still undetectable 12 weeks or more after the treatment ended. Studies often accept people cured this way.
The human immunodeficiency virus, which weakens the immune system.
Many studies now accept people whose HIV is controlled on treatment, judged by the viral load and the CD4 count. Check the limits this study sets.
A drug or device being studied in a clinical trial.
It may be new, or already approved and being studied for another use, dose or form. Criteria often leave out people who took part in another study of one within a recent period, commonly 30 days or five half-lives.
CYP3A is a group of enzymes, mainly CYP3A4, in the liver and gut that break down many medicines. Some medicines, supplements and foods (grapefruit, St John’s wort) slow them down or speed them up, which changes how much of a study drug stays in the body.
Studies list them so they can be avoided or switched; bring a list of everything you take, including supplements.
A reason a treatment, test or procedure should not be given to a particular person, such as an allergy, another illness or a medicine they take.
The other ingredients in a medicine besides the active drug, such as fillers, colours or preservatives.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Hemoglobin (Hb)
The protein in red blood cells that carries oxygen. A low level is anaemia, which can cause tiredness and breathlessness. Measured in g/dL or g/L (9 g/dL is 90 g/L).
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Contraception
Ways of preventing pregnancy. “Highly effective” methods fail less than 1% of the time a year when used correctly — for example an IUD or an implant.
Criteria usually say which methods count and how long to keep using them after the last dose, sometimes for male participants too. Some studies accept a partner’s vasectomy if it was confirmed successful and that person is the participant’s only sexual partner.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Cancer (malignancy)
Malignancy means cancer. Criteria about another or earlier malignancy ask whether you have had a different cancer, usually within a set number of years.
Some are commonly allowed, such as treated skin cancers other than melanoma and early cancers removed completely — check the exceptions this study lists.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Clinically significant
Judged by the study doctor to matter for your health or for the study. It is a doctor’s decision, so ask the study team if you are unsure whether something counts.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
QT and QTc
On an ECG, the QT interval is the time the heart’s lower chambers take to activate electrically and recover in each beat. QTc is that time adjusted for heart rate (QTcF by Fridericia’s formula, QTcB by Bazett’s). Some medicines lengthen it, and a long QTc can raise the risk of a dangerous heart rhythm.
The study may name a correction formula and a limit in milliseconds, often around 450–480.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
ALT and AST (liver enzymes)
Two enzymes measured in a routine blood test of the liver. Higher levels can mean the liver is under strain or damaged. SGPT and SGOT are older names for ALT and AST.
Criteria usually give a limit as a multiple of the upper limit of normal (ULN), often higher when cancer has spread to the liver.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
ULN (upper limit of normal)
The top of the normal range for a blood test, as set by the laboratory that runs it. Each lab prints its own range next to your result.
“≤ 2.5 × ULN” means the result can be up to two and a half times that top value.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
GFR and eGFR (kidney filtering)
GFR (glomerular filtration rate) is how much blood the kidneys filter each minute. It is usually estimated from a blood test — eGFR, by formulas such as CKD-EPI or MDRD — and some studies ask for it to be measured directly instead. Usually given in mL/min/1.73 m².
Check the method, the units and the minimum the study states. A value of 90 or above is in the normal-or-high range, but kidney damage can show in other tests too.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Hepatitis B tests
Hepatitis B is a virus that infects the liver. These are separate tests: HBsAg positive usually means a current infection (a recent vaccination can briefly cause it too); total anti-HBc (HBcAb) positive means an infection now or in the past; HBV DNA measures how much virus is in the blood.
Some studies accept a past infection if HBV DNA is undetectable, sometimes with antiviral medicine during the study. Check what this study allows.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Hepatitis C tests
Hepatitis C is a virus that infects the liver. An HCV antibody test can stay positive after an infection has cleared (and is occasionally positive without one); an HCV RNA test shows whether the virus is there now.
After treatment, hepatitis C counts as cured when HCV RNA is still undetectable 12 weeks or more after the treatment ended. Studies often accept people cured this way.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
HIV
The human immunodeficiency virus, which weakens the immune system.
Many studies now accept people whose HIV is controlled on treatment, judged by the viral load and the CD4 count. Check the limits this study sets.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Investigational drug or device
A drug or device being studied in a clinical trial.
It may be new, or already approved and being studied for another use, dose or form. Criteria often leave out people who took part in another study of one within a recent period, commonly 30 days or five half-lives.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
CYP3A (CYP3A4) inhibitors and inducers
CYP3A is a group of enzymes, mainly CYP3A4, in the liver and gut that break down many medicines. Some medicines, supplements and foods (grapefruit, St John’s wort) slow them down or speed them up, which changes how much of a study drug stays in the body.
Studies list them so they can be avoided or switched; bring a list of everything you take, including supplements.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Contraindication
A reason a treatment, test or procedure should not be given to a particular person, such as an allergy, another illness or a medicine they take.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Excipients
The other ingredients in a medicine besides the active drug, such as fillers, colours or preservatives.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Participants will receive oral mitapivat twice daily (BID), with dose determined by age and weight, for 48 weeks during the double blind (DB) period. Enrollment is conducted sequentially by age cohort, beginning with the oldest cohort. Cohort 1: 12 to \<18 years Cohort 2: 6 to \<12 years Cohort 3: 1 to \<6 years Participants who complete the DB period may continue receiving mitapivat in the open label extension (OLE) period for up to 144 weeks.
Drug: Mitapivat
Participants will receive oral placebo matching mitapivat, administered BID, with dosing based on age and weight, for 48 weeks during the DB period. Enrollment is conducted sequentially by age cohort, beginning with the oldest cohort. Cohort 1: 12 to \<18 years Cohort 2: 6 to \<12 years Cohort 3: 1 to \<6 years Participants who complete the DB period may transition to receive mitapivat in the OLE period for up to 144 weeks.
Drug: Mitapivat Matched Placebo · Drug: Mitapivat
Tablets or Granules
Tablets or Granules
Also known as: AG-348, Mitapivat sulfate
Percentage of Participants Who Achieved Transfusion Reduction Response (TRR) Through Week 48
TRR is defined as ≥50 percent (%) reduction in transfused red blood cells (RBC) volume (normalized by weight) in any consecutive 12-week period through Week 48 compared with historical RBC transfusion volume (normalized by weight) and standardized to 12 weeks.
Time frame: Baseline, through Week 48
Percentage of Participants Who Achieved TRR2 From Week 13 to Week 24
TRR2 is defined as ≥50% reduction in transfused RBC volume (normalized by weight) from week 13 to week 24 compared with historical RBC transfusion volume (normalized by weight) and standardized to 12 weeks.
Time frame: Baseline, Week 13 through Week 24
Percentage of Participants Who Achieved TRR3 From Week 25 to Week 36
TRR3 is defined as ≥50% reduction in transfused RBC volume (normalized by weight) from week 25 to week 36 compared with historical RBC transfusion volume (Normalized by Weight) and standardized to 12 weeks.
Time frame: Baseline, Week 25 through Week 36
Percentage of Participants Who Achieved TRR4 From Week 37 to Week 48
TRR4 is defined as ≥50% reduction in transfused RBC volume (normalized by weight) from week 37 to week 48 compared with historical RBC transfusion volume (normalized by weight) and standardized to 12 weeks.
Time frame: Baseline, Week 37 through Week 48
Percentage of Participants Who Achieved TRR5 From Week 25 to Week 48
TRR5 is defined as ≥50% reduction in transfused RBC volume (normalized by weight) from week 25 to week 48 compared with historical RBC transfusion volume (normalized by weight) and standardized to 24 weeks.
Time frame: Baseline, Week 25 through Week 48
Percent Change in Transfused RBC Volume (Normalized by Weight) From Week 13 Through Week 48 Compared With Historical Transfusion Volume (Normalized by Weight) and Standardized to 36 Weeks
Time frame: Baseline, Week 13 through Week 48
Percentage of Participants Who Achieved Transfused Independence Through Week 48
Transfusion independence is defined as transfusion-free for greater than or equal to 8 consecutive weeks through Week 48.
Time frame: Baseline, through Week 48
Change in the Number of Transfusion Episodes From Week 13 Through Week 48 Compared With Historical Number of Transfusion Episodes Standardized to 36 Weeks
Time frame: Baseline, Week 13 through Week 48
Change From Baseline in Serum Iron at Week 48
Time frame: Baseline, Week 48
Change From Baseline in Total Iron-Binding Capacity at Week 48
Time frame: Baseline, Week 48
Change From Baseline in Transferrin at Week 48
Time frame: Baseline, Week 48
Change From Baseline in Transferrin Saturation at Week 48
Time frame: Baseline, Week 48
Change From Baseline in Serum Ferritin Levels at Week 48
Time frame: Baseline, Week 48
Cohort 1: Change From Baseline in Estradiol Through Week 48
Time frame: Baseline, through Week 48
Cohort 1: Change From Baseline in Estrone Through Week 48
Time frame: Baseline, through Week 48
Cohort 1: Change From Baseline in Total Testosterone Through Week 48
Time frame: Baseline, through Week 48
Cohort 1: Change From Baseline in Free Testosterone Through Week 48
Time frame: Baseline, through Week 48
Cohort 1: Change From Baseline in Luteinizing Hormone Through Week 48
Time frame: Baseline, through Week 48
Cohort 1: Change From Baseline in Sexual Maturity Rating With Tanner Stage Through Week 48
Time frame: Baseline, through Week 48
Cohort 1: Percentage of Female Participants With Newly Developed Ovarian Cysts Through Week 48
Time frame: Baseline, through Week 48
Change From Baseline Over Time in Height-for-age Z-Score, Weight-for-age Z-Score, and Body Mass Index (BMI)-for-age Z-Score Through Week 48
Time frame: Baseline, through Week 48
Change from Baseline in Bone Mineral Density (BMD) Through Week 48
Time frame: Baseline, through Week 48
Number of Participants With Treatment Emergent Adverse Events (AEs) and Serious Adverse Events (SAEs)
Time frame: From first dose of study drug up to end of study (up to Week 196)
Plasma Concentration of Mitapivat
Time frame: Pre-dose, and at multiple timepoints (up to 7 hours post-dose) at Week 4
Area Under the Plasma Concentration-Time Curve From Time Zero to Last Quantifiable Concentration (AUC0-last) of Mitapivat
Time frame: Pre-dose, and at multiple timepoints (up to 7 hours post-dose) at Week 4
Maximum Observed Plasma Concentration (Cmax) of Mitapivat
Time frame: Pre-dose, and at multiple timepoints (up to 7 hours post-dose) at Week 4
Time to Reach Maximum Observed Plasma Concentration (Tmax) of Mitapivat
Time frame: Pre-dose, and at multiple timepoints (up to 7 hours post-dose) at Week 4
Plan to share: No
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From the registry record's own update history. This site started tracking changes on Sep 25, 2026; for anything earlier, see the record history on ClinicalTrials.gov ↗
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Studies of the drug tested here: Mitapivat