On September 25, 2024, Pfizer Inc. (NYSE: PFE) announced the voluntary global withdrawal of OXBRYTA® (voxelotor), its treatment for sickle cell disease (SCD), due to safety concerns.

This decision follows a review of clinical data that raised alarms about the drug’s safety, particularly the increased risk of vaso-occlusive crises and fatal events. Pfizer concluded that the risks now outweigh the benefits of using OXBRYTA for treating SCD, marking a major shift for a drug initially seen as a breakthrough for this serious condition.

Pfizer is discontinuing all ongoing clinical trials and expanded access programs for OXBRYTA. Regulatory authorities have been notified, and the company urges patients currently on the drug to consult with healthcare providers for alternative treatments.

The decision stems from an analysis of safety data that revealed an imbalance in vaso-occlusive crises—a severe complication of SCD—and a concerning rise in fatal cases during clinical studies. In one key study involving 236 patients, eight deaths occurred in the OXBRYTA group, compared to only two in the placebo group, prompting Pfizer to halt the drug’s use.

Pfizer’s Chief Medical Officer, Aida Habtezion, emphasized the company’s commitment to patient safety, stating, “Our priority is the well-being of patients, and this decision reflects that commitment. SCD is a challenging disease with few treatment options, and we remain dedicated to finding safer alternatives.”

OXBRYTA was initially approved by the US FDA in 2019 for treating hemolytic anemia caused by SCD, with approvals later expanding to younger age groups and multiple international markets. Pfizer had acquired OXBRYTA through its 2022 acquisition of Global Blood Therapeutics (GBT).

While the withdrawal represents a setback for SCD treatment, Pfizer remains committed to developing safer solutions for this patient population. Regulatory agencies, including the European Medicines Agency (EMA) and the US FDA, are reviewing the drug’s safety concerns, and Pfizer has promised to keep patients and healthcare professionals updated on future decisions.

Despite the withdrawal, Pfizer does not anticipate any impact on its 2024 financial outlook. The company will continue to invest in research and development to address the unmet needs of patients living with SCD.

For more information, patients and healthcare providers can contact Pfizer Medical Information at 1-800-438-1985. This development highlights the challenges of balancing drug innovation with patient safety in the ongoing search for effective treatments.