RARE Daily

FDA Approves Novel Treatment to Target Abnormality in Sickle Cell Disease

November 26, 2019

The U.S. Food and Drug Administration granted accelerated approval to Global Blood Therapeutics’ Oxbryta for the treatment of sickle cell disease in adults and pediatric patients 12 years of age and older.

It is the second marketing approval of a treatment for sickle cell disease in one week, the first being granted to Novartis for Adakveo to reduce the frequency of vaso-occlusive crises, a common and painful complication of sickle cell disease that occurs when blood circulation is obstructed by sickled red blood cells.

Sickle cell disease (SCD) is a lifelong, inherited blood disorder in which red blood cells are abnormally shaped in a crescent, or “sickle” shape, which restricts the flow in blood vessels and limits oxygen delivery to the body’s tissues, leading to severe pain and organ damage. It is also characterized by severe and chronic inflammation that worsens vaso-occlusive crises (VOCs) during which patients experience episodes of extreme pain and organ damage.

Approximately 100,000 people in the United States have sickle cell disease. People of African ancestry make up 90 percent of the population with sickle cell disease in the United States. However, sickle cell disease is also prevalent among people of Hispanic, South Asian, Southern European, and Middle Eastern ancestry. Sickle cell disease occurs in about 1 in 365 African American births and 1 in 16,300 Hispanic-American births.

Oxbryta is an inhibitor of deoxygenated sickle hemoglobin polymerization, the main abnormality in SCD. Nonclinical studies have demonstrated that Oxbryta inhibits red blood cell sickling, improves red blood cell deformability, and improves the blood’s ability to flow.

“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. This therapy provides a new treatment option for patients with this serious and life-threatening condition,” said Richard Pazdur, 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.

The approval was based on the results of a clinical trial with 274 patients with sickle cell disease. In the study, 90 patients received 1500 mg of Oxbryta, 92 patients received 900 mg of Oxbryta and 92 patients received a placebo. Effectiveness was based on an increase in hemoglobin response rate in patients who received 1500 mg of Oxbryta, which was 51.1 percent for these patients compared to 6.5 percent in the placebo group.

Common side effects for patients taking Oxbryta were headache, diarrhea, abdominal pain, nausea, fatigue, rash and fever.

Oxbryta, which had Fast Track designation, was granted Accelerated Approval, which enables the FDA to approve drugs for serious conditions to fill an unmet medical need based on a result that is reasonably likely to predict a clinical benefit to patients. Further clinical trials are required to verify and describe Oxbryta’s clinical benefit.

Oxbryta also received Orphan Drug designation, which provides incentives to assist and encourage the development of drugs for rare diseases.

Author: Rare Daily Staff

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