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
Myeloablative Conditioning, Prophylactic Defibrotide and Haplo AlloSCT for Patients With Sickle Cell Disease
This is a follow-up trial to NYMC 526 (NCT01461837) to assess the safety, efficacy and toxicity of administering Defibrotide prophylaxis for high-risk sickle cell or beta thalassemia patients undergoing a familial haploidentical or MUD allogeneic stem cell transplantation with CD34 enrichment and T-cell addback. This patient population historically has a risk of developing sinusoidal obstructive syndrome (SOS) and Defibrotide has demonstrated efficacy in treatment of SOS. The Funding Source is FDA OOPD.
A Trial to Assess Haploidentical T-depleted Stem Cell Transplantation in Patients With SCD
HSCT is currently the only curative option for SCD but less than 20% of SCD patients have a MD donor available. So far, all curative approaches beyond a MSD HSCT at young age are non-satisfactory. With the lack of a suitable donor for the vast majority of patients, the major question of this trial is, if a haploidentical αß/CD19+ T-cell depleted HSCT can be a valid alternative to a MSD HSCT. The main challenge in non-malignant diseases is to offer a safe and GvHD-free HSCT without rejection.