Oxbryta Approved to Treat Sickle Cell Disease

November 25, 2019 – The U.S. FDA has approved OxbrytaTM (voxelotor), manufactured by Global Blood Therapeutics, to treat sickle cell disease in adults and pediatric patients who are at least 12 years of age. It is the first in a new class of drugs known as sickle hemoglobin polymerization inhibitors, and the first medication that addresses the root cause of sickle cell disease to receive FDA approval.

Approximately 100,000 individuals in the United States have sickle cell disease, an inherited blood disorder that affects the hemoglobin in red blood cells (RBCs). Hemoglobin carries oxygen through the body and is usually present as isolated units. However, in sickle cell disease, a genetic mutation causes hemoglobin molecules to stick together when they become deoxygenated. This creates long, stiff chains (polymers) that distort red blood cells into sickle shapes. These sickle-shaped cells clump together and block blood vessels, inhibiting oxygen delivery to the body’s tissues and causing organ damage as well as episodes of severe pain. Sickle cell disease also causes anemia due to the destruction of hemoglobin. Oxbryta works by preventing hemoglobin polymer chains, thus preventing the creation and clumping together of sickle cells.

In a clinical study, 51.1% of patients treated with Oxbryta achieved a greater than 1g/dL increase in hemoglobin (a measurement of improvement in sickle cell disease) compared to 6.5% of patients who received a placebo. Oxbryta also delivered clinically meaningful, statistically significant improvements in hemoglobin levels as well as reduced hemolysis (red blood cell destruction). In nonclinical studies, Oxbryta demonstrated the ability to inhibit red blood cell sickling and improve blood flow. Recommended dosing is 1,500mg taken by mouth once a day with or without food. If the patient has severe hepatic impairment, the recommended dose is 1,000mg per day.

Because the FDA granted Oxbryta accelerated approval, continued approval may be contingent upon verification and description of clinical benefit in confirmatory trials. Oxbryta has launched at a wholesale acquisition cost (WAC) of $125,000 per year.