A Phase 4 interventional study of Hydroxyurea in Sickle Cell Disease and Stroke, sponsored by Vanderbilt University Medical Center. Recruiting at 2 sites in Nigeria. Open to participants aged 5 Years to 12 Years. Per ClinicalTrials.gov, last updated 2026-03-05.
Sponsored by Vanderbilt University Medical Center · Phase 4, Interventional, and Prevention
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Among 59 studies testing hydroxyurea in Anemia, Sickle Cell — 8 open to participants now, 14 under way, 1 of them phase 3. Hydroxyurea · Anemia, Sickle Cell.
Among the 59 studies testing hydroxyurea in Anemia, Sickle Cell, this one is the 8th largest by planned enrollment of the 57 interventional ones that give a count, is the only one that started in 2024, is one of 5 in phase 4, reaches primary completion later than 11 of the 13 other live ones, and was the 56th registered.
1,134 studies on the registry are indexed under Anemia, Sickle Cell; 238 are open to participants now.
Browse Anemia, Sickle Cell studies →8 of the 59 studies testing hydroxyurea in Anemia, Sickle Cell are open now, in 6 countries. Recruiting first, the newest first:
St. Jude Children's Research Hospital · Sites in United States
Ages up to 22
Children's Hospital Medical Center, Cincinnati · Sites in Uganda
Ages 11–18
Theravia · Sites in France, French Guiana
Ages 9 mo–11 yrs
Brown University · Sites in Angola
Ages 6 mo–12 yrs
Barau Dikko Teaching Hospital · Sites in Nigeria
Ages 2–16
By country, each count listing its studies:
Hydroxyurea: first FDA approval 1967 (DROXIA), first EMA approval 2007. What it is approved for, and how studies give it, is on its page →
Of the 177 Anemia, Sickle Cell studies recruiting now, 64 (36%) set no upper age limit and 97 (55%) stop at 75 or younger; 127 take children under 18; 29 take healthy volunteers.
This study: 5 Years to 12 Years · all sexes · no healthy volunteers.
The full table on the hub →This tab as a report to print or save as PDF → With an account.
59 studies; the count open now beside each. This study's row is marked.
A study in two phases is counted once above. Listed by phase, each with its combined phases: Phase 1 15 · Phase 2 29 · Phase 3 12 · Phase 4 5
First in 1984; this study’s year is marked. 1 started in 2024.
By drug class, each counting the studies that test any of its medicines:
This study's planned enrollment of 220 is above the median of 40 across 769 interventional studies indexed under Anemia, Sickle Cell.
Median enrollment 50 across the 57 interventional studies. Of the 43 that completed or were terminated, 18 (42%) have results posted.
This tab as a report to print or save as PDF → With an account.
5 of 59 have an industry lead sponsor. The 10 most frequent:
Vanderbilt University Medical Center is the lead sponsor of 835 studies on the registry; 155 are open to participants now.
Of its 126 completed or terminated interventional studies of FDA-regulated products, 92 (73%) have results posted.
14 studies in Anemia, Sickle Cell by Vanderbilt University Medical Center: 1 open now, 5 under way, none of them phase 3. Of 9 finished, 3 (33%) have results posted.
Among the 14 studies in Anemia, Sickle Cell by Vanderbilt University Medical Center, this one is one of 2 that started in 2024, is the only one in phase 4, and was the 14th registered.
Vanderbilt University Medical Center’s Anemia, Sickle Cell studies by the year they started, since 2013.
4 of the studies testing hydroxyurea in Anemia, Sickle Cell that are under way reach primary completion within a year, 0 of them phase 3. Phase 3 first, then by date:
| Study | Primary completion |
|---|---|
| NCT01962415Paul SzabolcsReduced Intensity Conditioning for Non-Malignant Disorders Undergoing UCBT, BMT or PBSCT | 2026-11 |
| NCT02286154Children's Hospital Medical Center, CincinnatiTherapeutic Response Evaluation and Adherence Trial (TREAT) | 2026-12 |
| NCT05662098Children's Hospital Medical Center, CincinnatiAlternative Dosing And Prevention of Transfusions (ADAPT) | 2026-12-31 |
| NCT06171217Children's Hospital Medical Center, CincinnatiRealizing Effectiveness Across Continents With Hydroxyurea | 2027-10-04 |
Add all 4 to your calendar (.ics) → With an account.
Among the 59 studies testing hydroxyurea in Anemia, Sickle Cell, from their registry updates:
Among Vanderbilt University Medical Center’s 14 in Anemia, Sickle Cell:
Nothing recorded among them since 2026-09-25.
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The primary goal of this study is to complete a multicenter single-arm, type I hybrid trial to assess the effectiveness of hydroxyurea therapy for primary stroke prevention in high-risk children with sickle cell anemia (SCA) living in Nigeria in routine care settings.
Strokes in sickle cell anemia (SCA), particularly in children living in Africa, are associated with significant morbidity and an increased risk of premature death. In the US, primary stroke prevention in children with SCA involves screening for elevated Transcranial Doppler ultrasound (TCD) velocity coupled with regular blood transfusion therapy for persons with elevated velocities. However, regular blood transfusion therapy is not a viable option for children with SCA in Nigeria for several reasons, including 1) inadequate supply of blood (still donor exchange system; 2) availability and cost of monthly blood transfusions for preventive therapy as opposed to emergency therapy; 3) unsafe blood supplies with a high probability of blood-borne infections and alloimmunization; and 4) children that receive regular blood transfusion will ultimately require daily iron chelation an unaffordable undertaking in low-income countries.
This multicenter open-label, single-arm type I hybrid trial will assess the effectiveness of Hydroxyurea therapy for primary stroke prevention in children with sickle cell anemia (SCA) living in Nigeria. A recently completed double-blind, parallel-group phase III randomized controlled trial (SPRING), involved comparing low-dose to moderate-dose hydroxyurea for primary stroke prevention in children with SCA and abnormal transcranial Doppler (TCD) velocities (>200 cm/sec). Children with abnormal TCD velocities have a high stroke risk of approximately 10.7 events per 100 person-years (observation arm in the STOP trial). In the low- (n=109) and moderate-dose (n=111) hydroxyurea groups, the stroke incidence rates were 1.2 and 1.9 per 100 person-years, respectively, p=0.77 (combined incidence rate 1.5 per 100 person-years). Despite equal efficacy for stroke prevention in both treatment groups, moderate- when compared to low-dose hydroxyurea, was more effective in preventing severe acute pain and all-cause hospitalizations. Our findings supported the American Society of Hematology's evidence-based guidelines for hydroxyurea therapy for primary stroke prevention in low-income settings. The hypothesis to be tested in the SPRING-2 study is in a multicenter single-arm type I hybrid trial, for children with abnormal TCD velocities treated with hydroxyurea, the stroke incidence rate will be non-inferior to the SPRING trial results, with an upper non-inferiority margin of 4 strokes per 100-person-years. The point estimate method was used to determine the non-inferiority margin based on the Nigerian pediatrician's judgment of what maximum stroke rate would be clinically meaningful to demonstrate the effectiveness and justify treatment for the high-risk stroke group. A non-inferiority test with an overall sample size of 220 will achieve 91% power at a 0.050 significance level to detect non-inferiority when the expected proportion of strokes is 0.035, a minimum follow-up period of 2.5 years and a loss to follow-up of 10% per year. The study will follow standard of care procedures, including clinic visits every 3 months and complete blood cell counts every 6 months. The following aims will be conducted as part of the trial: 1) Determine the incidence of the first stroke in children with abnormal TCD velocities treated with hydroxyurea for 2.5 years in the type 1 hybrid trial; 2) Evaluate the implementation and sustainability of the intervention within the extended RE-AIM framework; 3) Evaluate the cost-effectiveness of low- compared to a higher dose of hydroxyurea for primary stroke prevention in children with abnormal TCD velocities. Capacity building for three Nigerian Multiple Principal Investigators, statisticians, and nurses will be focused on three areas-: 1) developing a Nigerian data coordinating center and the required skills to support a clinical trial; 2) developing a regional TCD course for nurses, enhancing task shifting and reach, and 3) performing cost-effective analysis for the type I hybrid trial comparing low-and moderate dose hydroxyurea.
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.
The inclusion criteria for the SPRING-2 Trial will consist of:
Exclusion Criteria:
The exclusion criteria will be the following:
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.
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.
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 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.
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.
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).
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.
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.
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.
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.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
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.
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.
Initial treatment with Hydroxyurea at 10 mg/kg/day (range 7 to 15 mg/kg/day) for primary stroke prevention. Subsequent treatment with moderate-dose hydroxyurea (20 mg/kg/day (range 17.5 - 26 mg/kg/day)) based after at least two severe pain events requiring physician contact during the trial.
Drug: Hydroxyurea
The study intervention will include initial treatment with low-dose hydroxyurea therapy at 10 mg/kg/day (range 7 - 15 mg/kg/day), with subsequent increase to moderate dose hydroxyurea therapy at 20 mg/kg/day (range 17.5 - 26 mg/kg/day) after at least two severe events requiring physician contact.
Also known as: Hydrea
Incidence Rate of Clinical Stroke or TIA
The incidence rate of clinical stroke or TIA in participants treated with low- or moderate-dose hydroxyurea.
Time frame: 5 years
Incidence of All-Cause Hospitalizations
To evaluate all-cause hospitalizations with low-dose or moderate-dose hydroxyurea during clinic visits. Participants will be interviewed to determine the number of interim hospitalizations.
Time frame: 5 years
Plan to share: No
Started Aug 2024 (actual). Primary completion is estimated for Dec 2029, 64 months after the start.
Of 20 phase 4 interventional studies under Anemia, Sickle Cell, half reached primary completion within 24 months of starting (the median), counting those still running; a quarter within 13 and three quarters within 41. This study's planned 64 months is above that.
How these figures are worked out, and which studies are left out of them.
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Studies of the drug tested here: Hydroxyurea
Vanderbilt University Medical Center →