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Effect of mitapivat versus placebo on transfusion burden in patients with sickle cell disease

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What is this trial about?

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

sickle cell disease is a hereditary condition in which red blood cells are abnormally shaped and break down quickly, often causing chronic anemia. The study is testing an oral tablet called mitapivat to see if it can lower the number of blood transfusions that people with this condition need. The purpose of the study is to determine whether mitapivat reduces the need for transfusions compared with a placebo.

Participants are assigned by chance to receive either the study drug or a matching placebo, and neither the participants nor the doctors know which one is given (this is called “double‑blind”). The treatment period lasts for about one year, with the first month serving as a baseline and the remaining weeks used to track how often transfusions are required. Throughout the study, volunteers attend regular visits where simple blood tests and health checks are performed to monitor safety and any changes in transfusion needs. The term “transfusion burden” simply refers to the total number of blood transfusions a person receives.

The research process

The trial runs in 6 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Randomization and receipt of study medication

    After enrollment you will be randomly assigned to receive either mitapivat tablets (200 mg each) or matching placebo tablets that look the same. the assignment is done by the study team and you will not know which one you receive.

  2. Step 2

    Start taking study medication

    You will begin taking the assigned tablet by mouth as directed by the study staff. the tablet is taken for the entire double‑blind period that lasts 52 weeks.

  3. Step 3

    Initial follow‑up visit (week 4, day 29)

    Approximately four weeks after starting the medication (day 29) you will attend a study visit. during this visit blood samples are taken and any red blood cell transfusions you have received are recorded. this visit marks the start of the period used to evaluate the primary outcome.

  4. Step 4

    Regular monitoring visits

    Throughout the 52‑week double‑blind period you will attend scheduled visits (often monthly or as specified by the study team). at each visit you will:

    - report any side effects or health changes

    - have blood drawn for laboratory tests

    - have any red blood cell transfusions you receive documented.

  5. Step 5

    Transfusion tracking (week 4 through week 52)

    From week 4 (day 29) until the end of week 52 you will be monitored for the need for red blood cell transfusion. the number of transfusion units you receive during this time is recorded and will be compared between the mitapivat and placebo groups.

  6. Step 6

    Final assessment (week 52)

    At the end of the 52‑week period you will have a final study visit. the study team will evaluate whether you remained free of transfusions from week 4 through week 52 and will also review the total number of transfusion units received. if you discontinue the study before week 52, you will be considered a non‑responder for the primary outcome.

Who can join the trial?

12 criteria

  • Must be at least 12 years old.
  • Must have a confirmed diagnosis of sickle cell disease, which includes types such as HbSS, HbSC, HbS/β0‑thalassemia, HbS/β+‑thalassemia, or other similar forms.
  • Must have had ten or fewer sickle cell pain episodes (crises) in the 12 months before agreeing to join the study.
  • Must have received at least one blood transfusion of packed red blood cells in the past 12 months.
  • Must have a hemoglobin level (the protein that carries oxygen in the blood) between 5.5 and 10.5 g/dL, measured as the average of at least two tests taken at least one week apart.
  • Must show evidence of increased red blood cell breakdown (hemolysis) in lab tests, such as any of the following during screening:
    • Hemoglobin less than 8 g/dL,
    • Absolute reticulocyte count higher than the normal upper limit (more young red cells than usual),
    • Indirect bilirubin higher than normal (a waste product from broken red cells), or
    • LDH (lactate dehydrogenase) higher than normal (an enzyme that rises when cells are damaged).
    • If you are taking the medicine hydroxyurea, the dose must have been unchanged for at least 90 days, or you must stop the medicine at least 90 days before joining the study.
    • Women who can become pregnant and girls who have started menstruating must either avoid sexual activity that could lead to pregnancy or agree to use a highly effective birth‑control method during the study and for 28 days after the last dose; if hormonal birth control is used, a barrier method (such as condoms) must also be used.
    • Must provide written informed consent (or, if under 18, have a parent/guardian sign and give your agreement) before any study procedures and be willing to follow all study requirements for its duration.

Who cannot join the trial?

21 criteria

  • You are currently pregnant, breastfeeding, or have just given birth.
  • You need regular red blood cell transfusions (ongoing schedule) or have had a transfusion within the last 60 days before signing consent.
  • You were admitted to the hospital for a sickle cell pain crisis or similar event within the past 14 days.
  • You are taking disease‑modifying medicines for sickle cell disease such as voxelotor, crizanlizumab, or L‑glutamine (hydroxyurea is allowed) or have taken them within the last 90 days.
  • You have had cancer (other than early‑stage skin, cervical, or breast cancer) or received cancer treatment within the past 5 years.
  • heart or lung condition that is not well controlled and has been present in the last 6 months.
  • You have a liver or bile‑duct disorder (hepatobiliary disorder).
  • Your kidney function is low, with an estimated filtration rate below 30 mL/min/1.73 m².
  • You have an active, uncontrolled infection that requires systemic antibiotic treatment.
  • You test positive for active hepatitis B (HBsAg) or hepatitis C infection.
  • You test positive for HIV‑1 or HIV‑2 antibodies.
  • You have had major surgery (including removal of the spleen) within the past 16 weeks or plan to have major surgery during the study.
  • You are currently enrolled in, or have participated in, another clinical trial with an experimental drug within the past 90 days (or the time it takes for the drug to halve).
  • You have previously taken the study drug mitapivat in another trial.
  • You have received gene therapy or a bone marrow or stem cell transplant before.
  • You are taking, or have taken within the last 90 days, medicines that stimulate blood‑cell production (hematopoietic stimulating agents).
  • CYP3A4 enzyme and have not stopped them for the required time (5 days for inhibitors, 28 days for inducers).
  • You are using anabolic steroids and have not stopped them for at least 4 weeks before randomization (testosterone replacement therapy is allowed if stable).
  • You are known to be allergic to mitapivat or any of its tablet ingredients (microcrystalline cellulose, croscarmellose sodium, sodium stearyl fumarate, mannitol, magnesium stearate, Opadry Blue II film‑coat components).
  • alcohol use disorder) or are on treatments that the investigator believes pose an unacceptable risk or could confuse the study results.
  • You are taking herbal or dietary supplements that have not been on a stable dose and preparation for at least 8 weeks before randomization.
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Investigated drugs

MITAPIVAT is an oral tablet being tested as a new treatment for people with sickle cell disease. In the study, participants take this medication to see if it can lower the number of blood transfusions they need. MITAPIVAT works by helping red blood cells produce more energy, which can make the cells less likely to become stiff and stick together—a common problem in sickle cell disease. By improving the health of red blood cells, the drug aims to reduce complications that often require transfusion therapy. This medication is considered an orphan drug, meaning it is being developed for a condition that affects a relatively small number of patients.

What is already known about the treatment

  • Placebo

    The placebo is an oblong blue film‑coated tablet that looks like a 100 mg drug and is taken by mouth, but it contains no active ingredient. It is used only as a control to compare the effects of the real medication in the study. Because it has no pharmacological action, it has no therapeutic use, no mechanism of action, and is not listed in medical literature as a treatment. It simply mimics the appearance of the test drug to keep the trial blind.

  • Mitapivat

    Mitapivat is an oral tablet taken at a dose of 200 mg once daily, designed to treat anemia in people with sickle cell disease. It works by activating the enzyme pyruvate kinase in red blood cells, which improves the cells’ energy production and helps them survive longer. The drug is classified as a pyruvate kinase activator and is recognized as an orphan drug for rare blood disorders; it is already approved in some regions for pyruvate kinase deficiency and is now being studied for sickle cell disease. Clinical trials are evaluating its ability to reduce the need for blood transfusions in this patient group.

Investigated diseases

Anemia in sickle cell disease - It is a low red blood cell count that occurs in people who have sickle cell disease, a genetic disorder that makes hemoglobin abnormal. The abnormal hemoglobin causes red cells to become stiff and break down faster than normal, leading to reduced oxygen‑carrying capacity. Over time, the body may produce fewer new red cells, and the anemia can become more persistent. Episodes of increased red cell destruction can cause sudden drops in hemoglobin. The condition can worsen with infections, dehydration, or stress. It may require regular monitoring of blood counts.
Trial detailsLast updated 7 Oct 2026
Age18+ yearsPhasePhase IIITrial ID2026-526778-18-00Protocol codeAG348-C-030Estimated enrolment159 patientsSponsorAgios Pharmaceuticals Inc.

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