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RecruitingNCT05953584HIBISCUS 3Updated Sep 10, 2026

A Phase 2 Open-label Study to Evaluate the Activity of Etavopivat on Transcranial Doppler Velocities in Pediatric Patients With Sickle Cell Disease Who Are at Increased Risk for Primary Stroke

A Phase 2 interventional study of Etavopivat and Hydroxyurea in Sickle Cell Disease, sponsored by Forma Therapeutics, Inc.. Recruiting at 9 sites in 3 countries. Open to participants aged 12 Years to 16 Years. Per ClinicalTrials.gov, last updated 2026-09-10.

Sponsored by Forma Therapeutics, Inc. (part of Novo Nordisk A/S) · Phase 2, Interventional, and Treatment

From the registry’s dates

  • Started Jun 2023; still recruiting 3 years 4 months later.
Phase
Phase 2
Study type
Interventional
Enrollment
27
Allocation
Non-randomized
Ages
12 Years to 16 Years
Sex
All
01

Study summary

The study will test a new medicine, etavopivat, for sickle cell disease and see if it is safe and help-ful for participants with sickle cell disease who are at an increased risk of stroke. Participants will be divided into two cohorts depending on their transcranial doppler (TCD) ultrasound results and whether or not they receive hydroxyurea (medication that they may already be taking). In one cohort, participants with conditional transcranial doppler (TCD) or participants with abnormal TCD who are not able to receive hydroxyurea will be included. The study doctor will determine if the TCD result is conditional or abnormal. In another cohort, participants with conditional TCD or participants with abnormal TCD who are receiving a stable dose of hydroxyurea will be included. The study doctor will determine if the TCD result is conditional or abnormal. The participant will start a 52-week (1 year) treatment period. The participant will take 400 milligrams (mg) of etavopivat once a day for the 52 weeks. The dose of 400 mg will be taken as 2 tablets by mouth, each containing 200 mg of etavopivat. Etavopivat may be taken with or without food. Each dose should be taken with a glass of water. As part of the study, the participants will be asked to visit the clinic frequently. The participant will have the opportunity to participate in a 48-week optional extension treatment period. The optional extension treatment period will allow continued as-sessment of safety of etavopivat in paediatric patients. At the end of the study, if deemed appro-priate the participant, the caregiver, and the study doctor, the participant may be offered the op-portunity to participate in a separate study to continue receiving etavopivat. If/when this separate study becomes available, the participant may only transfer to the new study after completion of the 52-week primary treatment period and at any time during the 48-week optional extension treatment period.

02

Conditions studied

  • Sickle Cell Disease

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03

In context

Anemia, Sickle Cell

1,134 studies on the registry are indexed under Anemia, Sickle Cell; 238 are open to participants now.

This study's planned enrollment of 27 is below the median of 40 across 769 interventional studies indexed under Anemia, Sickle Cell.

Browse Anemia, Sickle Cell studies →

Lead sponsor

Forma Therapeutics, Inc. is the lead sponsor of 10 studies on the registry; 2 are open to participants now.

Of its 5 completed or terminated interventional studies of FDA-regulated products, 3 (60%) have results posted.

First submitted after Forma Therapeutics, Inc. became part of Novo Nordisk A/S.

Counted across the registry records on this site, refreshed daily.

04

Who can participate

Ages eligible
12 Years to 16 Years
Sexes eligible
All
Accepts healthy volunteers
No

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.

Inclusion criteria

  1. Patient's parent, legal guardian, or legal representative has provided documented and patients have provided age-appropriate assent

    Age:

  2. 12 to 16 years of age (inclusive) at time of screening

    Type of Participant and Disease Characteristics:

  3. Confirmed diagnosis of SCD

    • Documentation of any SCD genotype (e.g. HbSS, HbSβ0 -thalassemia) based on prior history of laboratory testing. Molecular genotyping is not required. SCD genotype may be determined from the results of electrophoresis, high-performance liquid chromatography, or similar testing.
  4. TAMMV greater than or equal to (≥) 170 cm/s in the ICA and/or MCA during the Screening Period and confirmed on 2 occasions and without history of primary ischemic or hemorrhagic stroke, , or severe central nervous system (CNS) vasculopathy on magnetic resonance angiography (MRA). This includes patients with cTCD (170-199 centimeter per second [cm/s]) or aTCD (≥ 200 cm/s). Patients with aTCD cohort must have refused transfusion therapy.
  5. Hb ≥ 6 grams per deciliter (g/dL) and lesser than or equal to (≤) 9 g/dL at screening
  6. For participants with aTCD and cTCD and already taking HU, the dose of HU milligram per kilogram (mg/kg) must be stable (no more than a 20% change in dosing except for weight-based changes) for at least 90 days prior to start of study treatment with no anticipated need for dose adjustments except for weight-based changes during the study, in the opinion of the Investigator.

    Sex and Requirements

  7. Patients, who if female and of , are using acceptable methods of contraception and agree not to donate ova from study start to 90 days after the last dose of study drug, and who if male, are willing to use acceptable methods of contraception and agree not to donate sperm, from study start to 90 days after the last dose of study drug

Exclusion criteria

Exclusion Criteria:

Medical Conditions

  1. Female who is breast feeding or pregnant
  2. History of seizure disorder
  3. Prior overt stroke (a focal neurological deficit of acute onset) by history or significant concerns for history of overt stroke based on Screening MRL, history of , focal neurological deficit on standardized neurological examination, or concern for moderate or severe neurological deficit (which could be due to stroke) based on a positive "10 questions" screening. Patients with significant or suggestive severe CNS vasculopathy (ie, moya moya) of Grade 4 or higher based on MRA read locally.
  4. Significant cytopenias ( [ANC] \< 1.5 × 10\^3/microliter (µL), \< 150,000/µL, reticulocytes \< 80,000/µL)
  5. Severe renal dysfunction (estimated at the Screening visit; calculated by the local laboratory \< 30 mL/min/1.73 m\^2) or on chronic dialysis
  6. Hepatic dysfunction characterized by (ALT) > 4 × (ULN) and/or direct > 3 × ULN
  7. Patients with bacterial, fungal, parasitic, or viral infection requiring systemic therapy or history of such infections leading to significant neurological impairment:

    • Patients with acute bacterial, fungal, parasitic, or viral infection requiring systemic therapy should delay screening/enrollment until active therapy has been completed.
    • Patients with acute viral infections (eg, coronavirus disease 2019 [COVID-19]) should delay screening/enrollment until the acute infection has resolved.
    • Patients enrolled in areas where malaria is prevalent must be on malaria prophylaxis based on regional guidance and resistance results. Note: Infection prophylaxis is allowed (see concomitant medication restrictions).
  8. Known (HIV) positivity
  9. Known infection with virus (hepatitis B surface antigen [HepBsAg] and hepatitis B core antibody [HepBcAb] positive.
Terms in these criteria, in plain language(14)

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.

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.

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).

TIA (transient ischaemic attack)

A “mini-stroke”: temporary stroke-like symptoms caused by reduced blood flow to part of the brain, spinal cord or eye, without signs of a new stroke on a scan.

Stroke symptoms need emergency care at once, even if they go away.

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.

Childbearing potential

Able to become pregnant: from the first period until menopause, unless permanently unable to through surgery (removal of the womb, or of both ovaries or both fallopian tubes).

Criteria for people of childbearing potential usually ask for a negative pregnancy test and for contraception during the study and for a time after it.

Absolute neutrophil count (ANC)

The number of neutrophils, white blood cells that help fight infection, in a given amount of blood. Too few raises the risk of infection.

It is a count, not a percentage of the white cells. Limits are written in units that mean the same: ≥ 1.5 × 10⁹/L is ≥ 1,500 per mm³ (µL). Each lab has its own reference range.

Platelets

Blood cells that help blood clot. Too few raises the risk of bleeding and bruising. A usual adult range is about 150–400 × 10⁹/L (150,000–400,000 per µL); each lab has its own reference range.

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.

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.

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.

Bilirubin

A yellow substance made when red blood cells are broken down, which the liver clears. A high level can mean a problem with the liver or the bile ducts.

Criteria often allow more for people with Gilbert’s syndrome, a harmless inherited condition that raises bilirubin.

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.

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.

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.

05

Study design

Phase
Phase 2
Primary purpose
Treatment
Allocation
Non-randomized
Intervention model
Parallel assignment
Masking
None (open label)
Enrollment
27 participants (estimated)

Study arms

  • Experimental
    Etavopivat

    Participants will receive Etavopivat 400 mg once daily (QD) orally.

    Drug: Etavopivat

  • Experimental
    Etavopivat with HU

    Participants will receive Etavopivat 400 mg QD orally in combination with HU. The dose of HU (mg/kg) will be stable (no more than a 20% change in dosing except for weight-based changes) during the study, in the opinion of the Investigator.

    Drug: Etavopivat · Drug: Hydroxyurea

Interventions

  • Participants will receive a dose of 400 mg (two 200 mg oral tablets) etavopivat once daily.

  • Participants will receive a stable dose of HU.

06

What researchers measure

Primary outcomes

  1. Change in the highest TAMMV in any of the L/R internal carotid artery [ICA] and L/R middle cerebral artery [MCA], whichever is highest, as measured by TCD

    Time frame: Baseline and Week 12

Secondary outcomes

  1. Change in the highest TAMMV in any of the L/R internal carotid artery [ICA] and L/R middle cerebral artery [MCA], whichever is highest, as measured by TCD

    Time frame: Baseline, Weeks 2,4, 24 and 52

  2. Incidence of conversion to normal (< 170 cm/s), conditionally abnormal (170-199 cm/s), and abnormal (≥ 200 cm/s) TCD velocities

    Time frame: Weeks 2, 4, 12, 24, and 52

07

Study locations

4 of 9 sites recruiting
08

References and documents

Individual participant data

Plan to share: Yes — According to the Novo Nordisk disclosure commitment on novonordisk-trials.com

Data sharing details ↗ · novonordisk-trials.com

No publications or documents are linked to this record.

09

Updates

Tracking since Sep 25, 2026
No changes since tracking began. The registry record was last updated on Sep 10, 2026, before this site started recording changes on Sep 25, 2026. Its history is on ClinicalTrials.gov ↗
10

Registry details

Key details

Study ID
NCT05953584
Responsible party
Sponsor
First posted
Jul 20, 2023
Start date
Jun 20, 2023
Primary completion
Aug 20, 2027 (estimated)
Completion
Jun 28, 2028 (estimated)
Last update
Sep 10, 2026

Study contacts

Novo Nordisk
Contact
clinicaltrials@novonordisk.com
(+1) 866-867-7178
Clinical Transparency (dept. 2834)
study director · Novo Nordisk A/S

Oversight

FDA-regulated drug
Yes
FDA-regulated device
No
View the source record on ClinicalTrials.gov ↗

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