Pfizer is withdrawing its sickle cell disease treatment Oxbryta from all markets where it has been approved, citing risks of a painful complication and deaths.
Pfizer bought Oxbryta, also known as voxelotor, as part of its $5.4 bn buyout of Global Blood Therapeutics in 2022.
Reuters reports that the company is also discontinuing all studies and access programmes related to the treatment based on the available clinical data, which show that the benefit of the drug no longer outweighs the risks associated with its use.
The company said the data showed an imbalance in vaso-occlusive crises, a complication of the disease and “fatal events” that required further assessment.
Vaso-occlusive crisis in patients with the disease occurs when blood flow gets blocked, depriving a tissue of oxygen and triggering an inflammatory response.
The withdrawal preceded an “extraordinary meeting” last Thursday of the European health regulator’s Committee for Medicinal Products for Human Use to review the drug.
In a study of 236 people, there were eight deaths in patients taking Oxbryta and two deaths in the placebo arm.
“The initiation of the review follows an imbalance of deaths between voxelotor and placebo observed in clinical trials,” the European Medicines Agency said in an agenda of the meeting posted on its website.
The US Food and Drug Administration (FDA) granted an accelerated approval to Oxbryta in 2019. It is also approved in Europe, the United Kingdom and United Arab Emirates.
Pfizer said it would further review the available data and had notified regulatory authorities about its findings. It said it had advised patients to contact their physicians to discuss alternative treatment.
Other treatments for sickle cell disease include regular blood transfusions and established hydroxycarbamide, also known as hydroxyurea, to reduce the risk of blood vessels becoming blocked.
But new options have been launched. In December last year, the FDA approved two gene therapies for the disease, pitched as one-time treatments, one by an alliance of Vertex and CRISPR Therapeutics, the other by Bluebird Bio.
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