Pfizer has announced the voluntary withdrawal of all lots of Oxbryta (voxelotor) from the market worldwide, a drug used in the treatment of sickle cell disease (SCD). This decision follows a review of clinical data that suggested the overall benefit of Oxbryta no longer outweighs the risk for the approved patient population.
The data indicated a potential imbalance in vaso-occlusive crises and fatal events, which necessitates further assessment. Vaso-occlusive crises are a common and painful complication of SCD, where sickled red blood cells block blood flow in small vessels.
Safety Concerns and Regulatory Actions
Pfizer has notified regulatory authorities about these findings and its decision to voluntarily withdraw Oxbryta from the market. The company is also discontinuing all active voxelotor clinical trials and expanded access programs worldwide while further reviewing the available data and investigating the findings.
"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," said Aida Habtezion, Chief Medical Officer and Head of Worldwide Medical and Safety at Pfizer. She advised patients to contact their physicians to discuss alternative treatment options.
Impact on Sickle Cell Disease Treatment
Oxbryta (voxelotor) is an oral, once-daily therapy designed to increase hemoglobin's affinity for oxygen, thereby inhibiting sickle hemoglobin polymerization and reducing red blood cell sickling and destruction. It received accelerated approval from the U.S. FDA in 2019 for adults and children 12 years and older, which was expanded in December 2021 to include patients 4 years of age and older.
The withdrawal of Oxbryta leaves a gap in the treatment landscape for SCD, a lifelong inherited blood disorder affecting approximately 4.5 million people globally. SCD is characterized by vascular inflammation and hemolytic anemia, leading to acute pain crises and progressive organ damage.
Pfizer's Next Steps
Pfizer has stated that it will keep patients, regulatory authorities, investigators, and clinicians informed about actions and appropriate next steps for Oxbryta. Despite the withdrawal, the company does not anticipate that this event will impact its full-year 2024 financial guidance.
