What the trial was testing
The trial enrolled 274 patients with sickle cell disease. The study was sponsored by Global Blood Therapeutics and tracked outcomes across the full group of patients who matched the trial's eligibility profile.
It was a large trial designed to confirm whether the treatment works well enough for wider use. Trials at this stage are designed to produce evidence regulators and physicians can act on — not just observations to follow up later.
What the results showed
Meaningful increases in hemoglobin across patients regardless of genotype.
Blood · 2025 · NCT04195633
These findings — that showed a hemoglobin increase of more than 1 g/dL after treatment with voxelotor — were published in the Blood and represent the headline result of the study.
Researchers tracked outcomes across 274 patients enrolled in the trial. The result was consistent enough across the group that the team felt confident reporting it.
What this means for patients
For patients with sickle cell disease, this result changes the calculus on what to ask their care team about. Whether it changes day-to-day care depends on factors like disease subtype, prior treatments, and where the patient is in their care journey.
What you can do now
Voxelotor (Oxbryta) received FDA approval for sickle cell disease. Ask your hematologist whether it is appropriate for your situation and genotype.
Eligibility for the treatments mentioned above depends on specific test results and clinical history. Bring this summary, the trial name, and your most recent labs or pathology report to your next visit.
Open sickle cell disease trials
Early Screening and Treatment of Heart Complication in Sickle Cell Disease
This study tests whether early heart screening and treatment for iron overload in subjects with sickle cell disease can prevent heart problems and reduce hospitalizations.
A Research Study Looking at Long-term Treatment With Etavopivat in People With Sickle Cell Disease or Thalassaemia
Etavopivat is a new medicine under development for treating blood disorders like sickle cell disease and thalassaemia. Sickle cell disease and thalassaemia are inherited blood disorders that affect haemoglobin. Haemoglobin is the protein that carries oxygen through the body. This study is looking into how safe treatment with etavopivat is and how well it works over a long period of time. The study will last for up to 264 weeks, but it will end earlier if etavopivat is approved in the participant's country.