The U.S. Food and Drug Administration (FDA) has approved Oxbryta (voxelotor) to treat persons, 12 years and older, with sickle cell disease.

Voxelotor blocks deoxygenated sickle hemoglobin polymerization and thereby inhibits red blood cell for ‘sickling’.

Sickle cell disease is a genetic blood disorder in which red blood cells are abnormally shaped and ‘sticky’, which restricts blood flow and can lead to severe pain and organ damage. It affects approximately 100,000 people in the United States.

In a news release by the FDA, Richard Pazdur, MD, director of the FDA’s Oncology Center of Excellence said, “With Oxbryta (voxelotor), 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. This therapy provides a new treatment option for patients with this serious and life-threatening condition.”

Elliott Vichinsky, MD, director of hematology/oncology at UCSF Benioff Children’s Hospital in Oakland, California added,With today’s approval of Oxbryta (voxelotor), 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 drug’s approval was largely based on a clinical trial involving 274 patients with sickle cell disease randomized to receive voxelotor (900 mg or 1500 mg taken orally once a day) or placebo.  The primary end point was the percentage of patients who had a hemoglobin response, defined as an increase of more than 1.0 g/dl from baseline.

At the end of the 24-week study, 51% of patients in the 1500 mg group showed a hemoglobin response, compared to 6.5% in the placebo group.  Common side effects were headache, diarrhea, abdominal pain, nausea, fatigue, rash and pyrexia. The study was published earlier this year in the New England Journal of Medicine.

Voxelotor was granted Accelerated Approval by the FDA and further clinical trials will likely be required to verify and describe the drug’s clinical benefit.

The medicine is developed by Global Blood Therapeutics, Inc and is expected to be available in specialty pharmacies within two weeks.

To learn more about Sickle Cell Disease and other rare blood disorders, visit