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Phase 3 Study of Mitapivat to Reduce Transfusions in Children with Alpha or Beta Transfusion‑Dependent Thalassemia

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What is this trial about?

A plain-language summary of the goals, design and what participants do

The study looks at children with Transfusion-Dependent Alpha- or Beta-Thalassemia, a rare inherited condition where the body makes abnormal hemoglobin and needs regular blood transfusions. The investigational medicine being tested is MITAPIVAT, taken by mouth as a tablet or granules. Some participants will receive a matching placebo instead of the active drug.

The aim is to see whether the drug can lower the amount of blood that must be given compared with the placebo. The trial is a phase 3 study that is double‑blind (neither the children nor the doctors know which treatment is given) and randomized (children are assigned to one group or the other by chance). The study also looks at how the drug moves through the body (pharmacokinetics) and whether it is safe.

Children will be screened, then start taking the study medication for about a year, with regular clinic visits to check blood counts, transfusion records, iron levels, growth, and bone health. Blood tests will be done to monitor for any side effects, to measure drug levels, and to assess changes in iron overload, a condition where excess iron builds up in the body. The study ends after the last visit, when all data are collected.

The research process

The trial runs in 10 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Randomization to study treatment

    After enrollment, you will be assigned by a computer system to receive either mitapivat or a matching placebo. the assignment is blinded, meaning you and the study staff will not know which product you receive.

  2. Step 2

    Receiving the study medication

    If assigned to mitapivat, you will receive either a tablet containing 200 mg of the drug or granules containing 150 mg of the drug. the form provided will be specified by the study pharmacist.

    If assigned to placebo, you will receive a matching tablet or granules that contain no active ingredient.

  3. Step 3

    Starting daily oral dosing

    The medication is taken by mouth (oral use) once each day.

    The dose (200 mg tablet or 150 mg granules) is taken at the same time each day, with or without food, as instructed in the dosing booklet.

    Treatment continues for up to 48 weeks unless the study doctor decides to stop it early for safety reasons.

  4. Step 4

    Recording transfusion information

    You will keep a diary of every blood transfusion you receive, noting the date, volume of red blood cells transfused, and any related details.

    This information is used to assess the effect of the study medication on your transfusion burden.

  5. Step 5

    Clinic visit at week 4

    A safety assessment is performed, including physical examination, vital signs, and laboratory tests.

    A blood sample is taken to measure the concentration of mitapivat in your plasma (pharmacokinetic assessment).

  6. Step 6

    Clinic visit at week 13

    Efficacy assessments begin, focusing on the amount of transfused red blood cells compared with your historical transfusion record.

    Additional laboratory tests evaluate iron metabolism and other safety parameters.

  7. Step 7

    Clinic visit at week 24

    The study team reviews transfusion records for weeks 13–24 to determine whether a ≥50 % reduction in transfused volume has occurred.

    Continued monitoring of safety, growth parameters, and laboratory values is performed.

  8. Step 8

    Clinic visit at week 36

    The study team evaluates transfusion data for weeks 25–36 for the same ≥50 % reduction criterion.

    Additional assessments of iron overload, hormone levels, and bone health are conducted.

  9. Step 9

    Final clinic visit at week 48

    The primary efficacy endpoint is evaluated, comparing transfusion volume over the entire 48‑week period with your historical baseline.

    Comprehensive safety assessments, including adverse‑event reporting, laboratory tests, and bone‑density measurement, are completed.

    The study medication is discontinued after this visit, and a final follow‑up schedule is provided.

  10. Step 10

    Post‑treatment follow‑up

    After stopping the study medication, you may be asked to attend a short follow‑up visit or provide a final safety blood sample, as directed by the study doctor.

Who can join the trial?

6 criteria

  • Provide written informed consent (or assent if you are a child) and agree to follow all study procedures for the entire study period.
  • Be between 1 year old and younger than 18 years old, and weigh at least 7 kg (about 15 pounds) at the time you sign the consent.
  • Have a confirmed diagnosis of thalassemia (either alpha‑type, beta‑type, HbE/β‑thalassemia, or α‑thalassemia/HbH disease) based on blood tests such as hemoglobin electrophoresis, high‑performance liquid chromatography, or DNA testing. These tests look at the type of hemoglobin you have and the genes that produce it.
  • Be transfusion dependent, meaning you have received 6 to 20 blood transfusion episodes in the 24 weeks before the study start and you have not gone more than 6 weeks without a transfusion during that time.
  • If you are taking the medicine hydroxyurea, your dose must have stayed the same for at least 16 weeks before you join the study.
  • Female participants who have started their periods (menarche) must either avoid any sexual activity that could lead to pregnancy or agree to use two forms of birth control, one of which must be a highly effective method, from the time you sign the consent until 28 days after the last dose of the study drug.

Who cannot join the trial?

20 criteria

  • Pregnant or breastfeeding: You cannot be pregnant or nursing a baby during the study.
  • History of sickle‑cell or HbC hemoglobin: If you have ever been diagnosed with sickle‑cell disease (HbS) or HbC disease, you cannot take part.
  • Previous gene therapy or bone‑marrow/stem‑cell transplant: Having had gene therapy, a bone‑marrow transplant, a stem‑cell transplant, or very strong chemotherapy that destroys bone‑marrow cells excludes you.
  • Other conditions affecting puberty: Any medical problem, besides thalassemia, that could change normal sexual development prevents participation.
  • Current use of luspatercept: If you are taking the drug luspatercept, or have taken it within the past 36 weeks, you are excluded.
  • Current use of hematopoietic stimulating agents: Taking medicines that stimulate blood‑cell production, or having taken them within the past 36 weeks, excludes you.
  • Recent cancer: A diagnosis of cancer (active or treated) within the last 5 years disqualifies you, except for very early skin, cervical, or breast cancers that have not spread.
  • Active or uncontrolled heart or lung disease, or abnormal heart rhythm (QT prolongation): Ongoing serious heart or lung problems, or a heart‑beat pattern that is unusually long, within the past 6 months, prevent enrollment.
  • Serious liver or gallbladder problems: Includes liver cirrhosis or severe scarring, painful gallstones or gallbladder inflammation, drug‑induced liver damage, or liver enzyme levels (AST or ALT) more than 2.5 times the normal limit (unless caused by blood‑cell breakdown or iron buildup).
  • Kidney dysfunction: If your kidney function test (estimated glomerular filtration rate) is below 60 mL/min/1.73 m², you cannot join.
  • High blood triglycerides: A non‑fasting triglyceride level higher than 215 mg/dL (5 mmol/L) excludes you.
  • Active infection needing antibiotics: Having an infection that requires treatment with medicines taken by mouth or injection, or having taken such antibiotics within the 7 days before randomisation, disqualifies you.
  • Active hepatitis B or C infection: Ongoing infection with hepatitis B or hepatitis C viruses (which affect the liver) prevents participation.
  • Known HIV infection: If you are infected with HIV, the virus that attacks the immune system, you cannot take part.
  • Recent major surgery: Any major operation, including removal of the spleen, performed within 6 months before consent, or any major surgery planned during the study, excludes you.
  • Recent participation in another clinical trial: Being enrolled in, or having finished, another study with an experimental drug or device within the past 12 weeks (or the time it takes for the drug to leave the body, whichever is longer) disqualifies you.
  • Use of strong CYP3A4/5‑affecting medicines: Taking drugs that strongly block or speed up the body’s CYP3A4/5 enzymes (which process many medicines) without stopping them for the required time (at least 5 days for blockers or 4 weeks for inducers, or the equivalent based on the drug’s half‑life) excludes you.
  • Use of anabolic steroids: Taking anabolic steroids without stopping them at least 4 weeks before randomisation excludes you. Stable testosterone replacement for low hormone levels is allowed if the dose has not changed for at least 12 weeks.
  • Allergy to mitapivat or its ingredients: If you are known to be allergic to the study drug mitapivat or any of its inactive components (such as microcrystalline cellulose, croscarmellose sodium, sodium stearyl fumarate, mannitol, magnesium stearate, or the film coating ingredients), you cannot participate.
  • Other medical, blood, mental, or behavioral conditions: Any health problem, mental health issue, or previous/current treatment that the study doctor believes makes participation unsafe or could affect the study results excludes you. This also includes people who are institutionalized by court order, incarcerated, involuntarily confined for psychiatric reasons, or who have financial or family ties that could unduly influence the study.
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Investigated drugs

Mitapivat is an oral medication that helps red blood cells work better by activating a natural enzyme inside them. In children with α‑ or β‑transfusion‑dependent thalassemia, this can improve the cells’ ability to carry oxygen and may lower the number of blood transfusions they need. In the study, participants took Mitapivat either as a tablet or as granules, but both forms contain the same active medicine. The trial is looking at how well Mitapivat works to reduce transfusion needs and how safe it is for young patients.

What is already known about the treatment

MITAPIVAT - MITAPIVAT is taken by mouth as either a 200 mg tablet or a 150 mg granule, usually once daily. It is already approved in several countries for the rare disease pyruvate kinase deficiency and is being studied as an orphan drug for transfusion‑dependent alpha‑ or beta‑thalassemia. The medicine works by binding to and activating the enzyme pyruvate kinase in red blood cells, which helps the cells produce more energy and live longer. Because of this action it is classified as a pyruvate kinase activator, a type of oral small‑molecule therapy used to treat blood disorders.

Investigated diseases

Transfusion-Dependent Alpha- or Beta-Thalassemia - Transfusion-Dependent Alpha- or Beta-Thalassemia is an inherited disorder that reduces the body’s ability to make normal hemoglobin. The lack of functional hemoglobin leads to chronic anemia, causing fatigue and reduced physical stamina. Because the blood cells break down quickly, people need regular red blood cell transfusions to maintain adequate oxygen levels. Over time the continual need for transfusions can result in excess iron buildup in organs, which may affect growth and development. The condition usually becomes apparent in early childhood and may evolve with increasing transfusion requirements as the child grows.
Trial detailsLast updated 7 Oct 2026
Age0-17PhasePhase IIITrial ID2025-524707-71-00Protocol codeAG348-C-029Estimated enrolment54 patientsSponsorAgios Pharmaceuticals Inc.

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