Pfizer said it is voluntarily withdrawing all lots of its sickle cell drug Oxbryta in all markets where it is approved, two years after acquiring its parent company Global Blood Therapeutic in a $5.4 billion deal.

The healthcare company on Wednesday said that the decision is based on clinical data that now indicate the overall benefit of Oxbryta no longer outweighs the risk in the approved sickle cell patient population.

Pfizer said it has notified regulatory authorities about its latest findings about Oxbryta.

The company doesn't expect the pulling of Oxbryta to negatively affect its full-year guidance.

Chief Medical Officer Aida Habtezion said the company advises patients to contact their physicians to discuss alternative treatment while it continues to investigate its data.

The news come about two years after Pfizer agreed to buy Global Blood Therapeutic to give it access to the treatment of sickle-cell disease market and bolster its rare-diseases business.

Pfizer had tried to develop its own sickle cell drug, but it failed. In 2019, Global Blood Therapeutics won approval in the U.S. for Oxbryta.

Sickle cell is an inherited blood disorder that affects about 100,000 people in the U.S., of which more than 90% are non-Hispanic Black or African American, according to the Centers for Disease Control and Prevention.