Sept 25 (Reuters) - U.S. drugmaker Pfizer ( PFE ) said

on Wednesday it is 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 shows an imbalance in

vaso-occlusive crises, a complication of the disease and "fatal

events" that requires 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 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.

Pfizer ( PFE ) said it will 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.

The U.S. Food and Drug Administration granted an

accelerated approval to the therapy in 2019. It is also approved

in Europe, United Kingdom and United Arab Emirates.

Oxbryta is used to treat an inherited blood disorder in

which red blood cells become sickle or crescent shaped and can

cause strokes, organ damage and early death.

The company said it does not anticipate that the

withdrawal will impact its full-year 2024 financial outlook.