November 25, 2019
1 min read

FDA approves Oxbryta for sickle cell disease

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Elliott Vichinsky, MD
Elliott Vichinsky

The FDA granted accelerated approval to voxelotor for the treatment of sickle cell disease.

The approval applies to use of the therapy for patients aged 12 years and older.

Voxelotor (Oxbryta, Global Blood Therapeutics) — an oral agent taken once daily — is the first approved treatment that directly inhibits sickle hemoglobin polymerization, the root cause of sickle cell disease.

“Every person with sickle cell disease experiences hemoglobin polymerization and suffers from varying severity of anemia and hemolysis,” Elliott Vichinsky, MD, director of hematology/oncology at UCSF Benioff Children’s Hospital, said in a Global Blood Therapeutics-issued press release. “With today’s approval of Oxbryta, we now have a therapy that significantly improves hemoglobin levels, has a favorable safety profile and reduces the anemia and hemolysis that inevitably leads to the long-term and often undetected detrimental effects associated with this chronic genetic condition.”

The FDA based the approval in part on results of the randomized, placebo-controlled HOPE trial, which included 274 patients (median age, 24 years; range, 12-64) with sickle cell disease.

All patients had baseline hemoglobin of 5.5 g/DL to 10.5 g/DL. Two-thirds (65%) of study participants were taking hydroxyurea at study entry, and patients on stable hydroxyurea doses continued the drug throughout the trial.

In the double-blind, multicenter trial, researchers assigned patients to voxelotor dosed at 1,500 mg daily (n = 90), 900 mg daily (n = 92) or placebo (n = 92).

Hemoglobin response rate — defined as hemoglobin increase of at least 1 g/dL from baseline to week 24 — served as the primary efficacy outcome measure.

Researchers reported response rates of 51.1% with voxelotor and 6.5% with placebo (P < .0001).

Results also showed improved efficacy with the recommended 1,500-mg voxelotor dose vs. placebo with regard to mean change in hemoglobin (1.14 g/dL vs. – 0.08 g/dL), percent change in indirect bilirubin (– 29.08% vs. – 3.16%) and percent reticulocyte count (– 19.93% vs. 4.54%).

The most common adverse events reported among voxelotor-treated patients included headache, diarrhea, abdominal pain, nausea, rash, fatigue and pyrexia.