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Study on the Effectiveness of Decitabine and Tetrahydrouridine in Patients with Sickle Cell Disease Not Eligible for Hydroxyurea Treatment

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What is this trial about?

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

This clinical trial is focused on studying the effects of a new treatment for sickle cell disease, a condition that affects the red blood cells and can cause pain and other serious health problems. The treatment being tested is a combination of two substances, decitabine and tetrahydrouridine, which are taken as a capsule. The study will compare this treatment to a placebo to see how well it works in improving hemoglobin levels in patients who cannot use another medication called hydroxycarbamide.

The purpose of the study is to evaluate the effectiveness and safety of the decitabine-tetrahydrouridine combination. Participants will take the medication orally over a period of time, and their health will be monitored regularly. The study will last for several weeks, during which changes in hemoglobin and other health markers will be observed. The goal is to determine if the new treatment can help improve the condition of people with sickle cell disease.

Throughout the study, participants will undergo various assessments to track their progress. These assessments will include measuring the concentration of the medication in the blood and observing any changes in the number of painful episodes or other complications related to sickle cell disease. The study aims to provide valuable information on whether this new treatment can offer a better option for managing sickle cell disease in patients who are not eligible for existing treatments.

The research process

The trial runs in 7 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Joining the study

    Upon joining the study, eligibility is confirmed based on specific criteria such as age, diagnosis of sickle cell disease, and recent medical history.

    The study is designed for individuals who are not eligible for hydroxyurea treatment.

  2. Step 2

    Initial assessment

    An initial assessment is conducted to establish baseline health metrics, including haemoglobin levels and reticulocyte count.

    This assessment helps in measuring changes throughout the study.

  3. Step 3

    Medication administration

    Participants receive either the Decitabine/Tetrahydrouridine combination or a placebo.

    The medication is administered orally in the form of hard capsules.

    The dosage is 5 mg of Decitabine and 250 mg of Tetrahydrouridine.

  4. Step 4

    Treatment period

    The treatment period lasts for 24 weeks.

    During this time, regular monitoring of haemoglobin levels and other health indicators is conducted.

  5. Step 5

    Follow-up assessments

    Follow-up assessments occur at specified intervals to evaluate the maximum concentration of Decitabine and Tetrahydrouridine in the blood.

    Other health metrics, such as foetal haemoglobin levels and the number of vaso-occlusive crises, are also monitored.

  6. Step 6

    End of treatment evaluation

    At the end of the 24-week treatment period, a comprehensive evaluation is conducted.

    This includes measuring changes in haemoglobin levels and assessing any adverse events.

  7. Step 7

    Extended monitoring

    Participants are monitored for an additional 24 weeks to track long-term effects and any further health changes.

    The study concludes with a final assessment to gather all necessary data.

Who can join the trial?

6 criteria

  • Must be **18 years or older** at the time of signing the consent form.
  • Must have a **confirmed diagnosis of sickle cell disease**. This includes different types like HbSS, HbSC, HbSβ0 thalassemia, HbSβ+ thalassemia, or other variants.
  • Must have had **2 to 10 episodes** of a condition called **VOCs** (vaso-occlusive crises) in the last 12 months before the screening visit. VOCs are painful episodes that occur in sickle cell disease.
  • Must have a **hemoglobin level** between **5.0 g/dL and 10.5 g/dL** at the first visit. Hemoglobin is a protein in red blood cells that carries oxygen.
  • Must have an **absolute reticulocyte count** above the **ULN** (Upper Limit of Normal) at the first visit. Reticulocytes are young red blood cells, and this count helps assess bone marrow activity.
  • Must have a **body weight** between **40 kg and 125 kg** (inclusive).

Who cannot join the trial?

4 criteria

  • Patients who are eligible for treatment with **hydroxyurea (HU)** cannot participate. **Hydroxyurea** is a medication used to treat sickle cell disease.
  • Patients who do not have **sickle cell disease** cannot participate. **Sickle cell disease** is a group of inherited red blood cell disorders.
  • Patients who are not within the specified age range for the study cannot participate. The study is for certain age groups only.
  • Patients who are part of a vulnerable population cannot participate. A vulnerable population includes groups that may need special protection.
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Investigated drugs

Decitabine-Tetrahydrouridine (NDec) is a combination medication being studied for its potential to improve hemoglobin levels in patients with sickle cell disease. This medication is taken orally and is being evaluated for its effectiveness in patients who are not eligible for treatment with hydroxyurea. The goal of the trial is to determine if this combination can provide a beneficial effect on hemoglobin levels, which is a critical factor in managing sickle cell disease.

What is already known about the treatment

Decitabine-Tetrahydrouridine (NDec) – This medication is administered orally and is currently being evaluated in clinical trials for its effectiveness in treating sickle cell disease. It is not yet widely used in standard medical practice, as it is still under investigation. The main therapeutic indication for this medication is to improve hemoglobin levels in patients with sickle cell disease who are not eligible for hydroxyurea treatment. At the molecular level, decitabine works by incorporating into DNA and inhibiting DNA methylation, which can lead to changes in gene expression. Tetrahydrouridine is included to enhance the effectiveness of decitabine by inhibiting its breakdown. This combination falls under the pharmacological classification of antimetabolites.

Investigated diseases

Sickle Cell Disease – Sickle cell disease is a genetic disorder that affects the red blood cells, causing them to become rigid and shaped like a sickle or crescent. These abnormally shaped cells can block blood flow in small blood vessels, leading to pain and potential organ damage. The disease is characterized by episodes of pain, known as vaso-occlusive crises, and can also cause anemia due to the rapid breakdown of the sickle cells. Over time, sickle cell disease can lead to complications such as acute chest syndrome, stroke, and increased risk of infections. The severity and frequency of symptoms can vary widely among individuals. The condition is inherited in an autosomal recessive pattern, meaning both copies of the gene in each cell have mutations.
Trial detailsLast updated 2 Oct 2026
Age18+ yearsPhasePhase IITrial ID2023-508506-22-00Protocol codeNN7533-4470Estimated enrolment87 patientsSponsorNovo Nordisk A/S

sourced from the EU Clinical Trials Register and site verification

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