The Food and Drug Administration (FDA) has approved Oxbryta (voxelotor; Global Blood Therapeutics) for the treatment of sickle cell disease (SCD) in adults and pediatric patients 12 years of age and older. The indication is approved under accelerated approval based on increase in hemoglobin (Hb); continued approval may be contingent upon verification and description of clinical benefit in confirmatory trials.

Voxelotor is a sickle hemoglobin (HbS) polymerization inhibitor that binds to HbS and exhibits preferential partitioning to red blood cells. “With Oxbryta, sickle cells are less likely to bind together and form the sickle shape, which can cause low hemoglobin levels due to red blood cell destruction,” said Richard Pazdur, MD, director of the FDA’s Oncology Center of Excellence and acting director of the Office of Oncologic Diseases in the FDA’s Center for Drug Evaluation and Research. “This therapy provides a new treatment option for patients with this serious and life-threatening condition.”

The approval was based on data from the phase 3 HOPE study that evaluated the safety and efficacy of Oxbryta vs placebo in 274 patients with SCD (median age: 24 years; median baseline Hb: 8.5g/dL). The primary end point of the study was Hb response rate defined as the proportion of patients with an Hb increase of >1g/dL from baseline to Week 24. 

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Results showed the response rate for Oxbryta was 51.1% compared with 6.5% for placebo (P<.001). Additionally, the adjusted mean change from baseline to Week 24 in Hb was 1.14g/dL in the Oxbryta group vs -0.08g/dL for the placebo group (P<.001). With regard to safety, the most common treatment-emergent adverse reactions included headache, diarrhea, abdominal pain, nausea, fatigue, rash and pyrexia.

Oxbryta is supplied as 500mg tablets and is expected to be available through specialty pharmacies within 2 weeks.

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