FDA OKs Voxelotor (Oxbryta) for Root Cause of Sickle Cell Disease

Megan Brooks

November 25, 2019

The US Food and Drug Administration (FDA) has approved voxelotor oral tablets (Oxbryta, Global Blood Therapeutics) for the treatment of sickle cell disease (SCD) in adults and children aged 12 years and older – a novel therapy that could, according to the president of the SCD Association of America, "change the course of this disease."

Voxelotor is the first approved treatment that directly inhibits sickle hemoglobin polymerization, the root cause of SCD.

"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," 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, said in an agency news release.

The FDA approved voxelotor based on results of the phase 3 HOPE (Hemoglobin Oxygen Affinity Modulation to Inhibit HbS Polymerization) clinical trial involving 274 patients with SCD patients randomly assigned to voxelotor or placebo.

Treatment with voxelotor led to "clinically meaningful and statistically significant" improvements in hemoglobin levels, accompanied by reductions in red blood cell destruction (hemolysis), the company said in a news release.

"After decades of waiting, we now have a treatment option that could change the course of this disease," Beverley Francis-Gibson, president and CEO of the Sickle Cell Disease Association of America, said in the company release.

After 24 weeks of treatment, 51.1% of patients receiving voxelotor achieved a greater than 1 g/dL increase in hemoglobin compared with 6.5% receiving placebo (P < .001).

The most common side effects for patients taking voxelotor were headache, diarrhea, abdominal pain, nausea, fatigue, rash, and pyrexia (fever).

Results from the HOPE Study were published in June in The New England Journal of Medicine and reported by Medscape Medical News at that time

"Every person with SCD 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 in Oakland, California, said in the company release.

With 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," said Vichinsky.

Voxelotor was granted accelerated approval and had fast track and orphan drug designation.

The company expects it to be available through its specialty pharmacy partner network within 2 weeks. More information is available online.

Earlier this month, the FDA approved crizanlizumab (Adakveo, Novartis) to reduce the frequency of vaso-occlusive crisis in patients aged 16 years or older with sickle cell disease, as reported by Medscape Medical News.

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