Pfizer (PFE.US) withdraws sickle cell disease treatment drug Oxbryta due to safety concerns

Pfizer (PFE.US) announced it is voluntarily withdrawing all batches of its Sickle Cell Disease (SCD) treatment Oxbryta (voxelotor) from the markets where it has already been approved, and will also stop all ongoing clinical trials and global expanded access programs for Oxbryta.

Pfizer said in a statement that its decision was based on clinical data that showed the overall benefit of Oxbryta in SCD patients no longer outweighed the risks. The data showed an imbalance in the number of patients experiencing vaso-occlusive crises and fatal events, which needed further evaluation.

Pfizer said it had informed regulators of the findings and decided to voluntarily withdraw Oxbryta from the market and stop its distribution and clinical studies, while further reviewing existing data and analyzing the results. The company added that it expects the withdrawal will not impact its full-year 2024 financial guidance.

According to the information, Oxbryta is a once-daily oral therapy developed by Pfizer's subsidiary Global Blood Therapeutics for SCD patients, which works by increasing the affinity of hemoglobin for oxygen to inhibit the aggregation of sickle hemoglobin that causes hemolysis and hemolytic anemia and the resulting red blood cell sickling and red blood cell destruction.

In November 2019, the U.S. Food and Drug Administration (FDA) accelerated the approval of Oxbryta for the treatment of adult and 12-year-old and older children with SCD. In December 2021, the FDA expanded the indication of Oxbryta to 4-year-old and older SCD patients. Since its first approval in 2019, Oxbryta has been approved for sale in more than 35 countries worldwide. According to Pfizer's financial report, Oxbryta's global sales in 2023 were US$328 million.

It is worth noting that other approved SCD treatment drugs include Lyfgenia from bluebird bio (BLUE.US) and Casgevy from Vertex Pharmaceuticals (VRTX.US) and CRISPR Therapeutics (CRSP.US), which was co-developed. The above news affected bluebird bio, which rose more than 6% after-hours on Wednesday, and CRISPR Therapeutics, which rose more than 2%, while Vertex Pharmaceuticals remained flat.