Sept 26 (Reuters) - U.S. drugmaker Pfizer ( PFE ) said

on Wednesday it was withdrawing its sickle cell disease

treatment Oxbryta from all markets where it is approved, citing

risks of a painful complication and deaths.

Pfizer ( PFE ) bought Oxbryta, also known as voxelotor, as part of

its $5.4 billion buyout of Global Blood Therapeutics in 2022.

It reported $328 million in revenues from the therapy for

the full year 2023.

Pfizer ( PFE ) is also discontinuing all studies and access programs

related to the treatment based on the available clinical data,

which shows that the benefit of the drug no longer outweighs the

risks associated with its use, it said.

The company added that 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 comes ahead of an "extraordinary meeting" on

Thursday of the European health regulator's Committee for

Medicinal Products for Human Use to review Pfizer's ( PFE ) 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 U.S. 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 ( PFE ) 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. The FDA in December last

year 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 ( BLUE )

.

The disease is an inherited blood disorder in which red

blood cells become sickle or crescent shaped and can cause

strokes, organ damage and early death.

Pfizer ( PFE ) said it did not anticipate that the withdrawal would

impact its 2024 financial outlook.