Pfizer has temporarily withdrawn its drug used to treat sickle cell disease from the markets, citing 'safety' and 'well-being' of its patients.

The US biopharmaceutical company said it decided to call back its sickle cell disease drug Oxbryta(voxelotor) from the global markets, after analyzing a new clinical data which found that "the overall benefit of OXBRYTA no longer outweighs the risk."

"The data suggest an imbalance in vaso-occlusive crises and fatal events which require further assessment," the US drug maker said in a statement.

The company has also decided to discontinue all clinical trials and access programs related to the drug.

"The safety and well-being of patients is of the utmost importance to Pfizer, and we believe this action is in the best interest of patients," AidaHabtezion,  Chief Medical Officer and Head of Worldwide Medical and Safety, Pfizer said in a statement.

The drug, which generated a whopping $328 million revenue in 2023, was acquired by Pfizer through its $5.4 billion acquisition of Global Blood Therapeutics in 2022.

Since its approval in 2019, Oxbryta has been used to treat sickle cell disease in people aged 12 and older. In 2021, FDA expanded the approval to include patients aged four and above.

Earlier this year, the European Medicines Agency (EMA), announced that it was starting a review of Pfizer's sickle cell disease drug. The July review found a 'higher number of deaths associated with Oxbryta(eight out of 236)' compared to 'placebo (two out of 236).' Health experts from EMA said the 'total number of deaths was higher than anticipated.'

Pfizer said it has notified regulatory authorities about the temporary withdrawal, and added that it is planning to discontinue distribution and clinical studies until further investigations into the drug's safety are completed.

"We advise patients to contact their physicians to discuss alternative treatment while we continue to investigate the findings from our review of the data," Habtezion said.

Pfizer said it does notexpect the withdrawal to impact its 2024 financial guidance.

Sickle cell disease is an inherited disorder of hemoglobin, the red blood cell protein which helps carrying oxygen to tissues.  Instead of the usual 'flexible disc-shaped'red cells, people affected with sickle cell disease will have a 'misshaped or sickle shaped' caused by a gene mutation. This affects flow of blood to different parts of the body and leads to severe health complications. People affected with sickle cell disease are at higher risks of kidney disease, stroke, eye problems and lung problems and infections. They also often go through severe episodes of pain.

More than 100,000 people in the United States and 8 million people worldwide are affected by the blood disorder, according to the National Heart, Lung, and Blood Institute.