Kena Betancur | Corbis News | Getty Images A version of this article first appeared in CNBC's Healthy Returns newsletter, which brings the latest health-care news straight to your inbox. Subscribe here to receive future editions. Hello and happy Tuesday! Today, we're unpacking a shocking move from Pfizer .

The pharmaceutical giant last week announced it would voluntarily withdraw its sickle cell disease therapy , Oxbryta, from worldwide markets — to the surprise of doctors, patients and investors. Here's why the drug is important: Oxbryta is one of at least six treatments for the inherited blood disorder. The drug first won accelerated approval from the U.

S. Food and Drug Administration in 2019, which requires further trials to confirm its benefits to patients. Oxbryta was one of the centerpieces of Pfizer's $5.

4 billion acquisition of Global Blood Therapeutics in 2022. Sickle cell disease causes red blood cells to become misshapen half-moons that get stuck inside blood vessels, which can restrict blood flow and cause what are known as pain crises . It impacts roughly 100,000 people in the U.

S., many of whom are Black, according to data from the Centers for Disease Control and Prevention. The company on Wednesday said the decision to withdraw Oxbryta was based on data showing a higher risk of deaths and complications in patients treated with the once-daily pill.

In a release , Pfizer said the "totality of clinical data" on Oxbryta now indicates that its overall benefit "no .