Pfizer withdraws sickle cell disease treatment from global markets

Data indicates that risks associated with OXBRYTA include higher incidence of vaso-occlusive crises and fatal events

Pfizer Inc. (NYSE: PFE) announced on September 25, 2024, that it is voluntarily withdrawing OXBRYTA® (voxelotor), its treatment for sickle cell disease (SCD), from all markets where it is approved.

The decision, which affects patients worldwide, comes after an evaluation of clinical data that raised concerns about the drug’s safety profile.

According to Pfizer, the data now indicates that the risks associated with OXBRYTA, including a higher incidence of vaso-occlusive crises and fatal events, outweigh its benefits for treating SCD.

This action marks a significant shift for the treatment, which was initially seen as a promising advancement for a challenging and life-threatening condition.

As part of this withdrawal, Pfizer is discontinuing all ongoing clinical trials and expanded access programs related to voxelotor, effectively halting the drug’s availability for new and existing patients.

The company has already informed regulatory authorities about the safety concerns and the decision to remove OXBRYTA from the market while a further review is conducted.

Pfizer has urged patients currently on OXBRYTA to consult with their healthcare providers to discuss alternative treatments as soon as possible.

The decision to withdraw OXBRYTA stems from an analysis of safety data, which pointed to an imbalance in the occurrence of vaso-occlusive crises—a severe and painful complication of sickle cell disease—in patients taking the drug.

Additionally, an alarming increase in fatal events was noted in clinical studies.

These findings prompted Pfizer to reevaluate the overall benefit-risk profile of the drug, ultimately concluding that continued use could jeopardize patient safety.

In a pivotal study involving 236 participants, eight deaths were reported among patients treated with OXBRYTA, compared to just two deaths in the placebo group.

This significant difference raised red flags for the company and regulatory authorities alike.

Vaso-occlusive crises, which occur when sickled red blood cells block blood flow to organs and tissues, can lead to severe pain, organ damage, and even death.

The imbalance in such crises, coupled with the fatalities, has led to Pfizer's decision to halt all voxelotor-related activities.

Aida Habtezion, Pfizer’s Chief Medical Officer and Head of Worldwide Medical and Safety, emphasized that patient safety is the company’s top priority: “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. Our primary concern is for patients who suffer from SCD, which remains a very serious and difficult-to-treat disease with limited treatment options.”

Pfizer has taken steps to ensure that all stakeholders, including patients, physicians, and pharmacists, are informed of this withdrawal.

The company is also providing support for patients who need to transition to alternative treatments and has established a hotline for healthcare professionals seeking further guidance.

OXBRYTA was first approved by the US Food and Drug Administration (FDA) in 2019 under an accelerated approval process, specifically for the treatment of hemolytic anemia caused by sickle cell disease in patients aged 12 years and older.

In 2021, the FDA expanded its approval to include children as young as four. The drug has since gained approval in more than 35 countries, including key markets in Europe, the United Kingdom, and the United Arab Emirates.

It was heralded as a groundbreaking treatment, with the ability to prevent the sickling of red blood cells by increasing hemoglobin’s affinity for oxygen.

Pfizer acquired OXBRYTA through its $5.4 billion acquisition of Global Blood Therapeutics (GBT) in 2022, signaling its commitment to expanding its portfolio in rare diseases.

The drug had generated $328 million in revenue for Pfizer in 2023. Despite its early promise, the emerging safety data has cast a shadow over its future.

While the withdrawal of OXBRYTA represents a setback in the treatment of sickle cell disease, Pfizer remains committed to the SCD community.

Habtezion reiterated that the company will continue to assess the data and work on developing safer alternatives for patients living with this debilitating condition.

Sickle cell disease is a hereditary blood disorder that primarily affects individuals of African, Hispanic, Middle Eastern, and South Asian descent.

The condition causes red blood cells to assume a sickle or crescent shape, which impairs blood flow, leading to severe pain, organ damage, and a host of other complications, including stroke.

SCD often manifests in childhood and can lead to a significantly shortened lifespan without adequate treatment.

There are currently limited treatment options for SCD, which makes the loss of a therapy like OXBRYTA particularly impactful for patients and healthcare providers.

The withdrawal of the drug adds to the urgency for the development of new, effective treatments for this population.

The European Medicines Agency (EMA) is scheduled to hold an extraordinary meeting to review OXBRYTA’s safety concerns in light of Pfizer’s decision. Meanwhile, the US FDA and other global regulatory agencies are closely monitoring the situation.

Pfizer has assured patients and healthcare professionals that it will keep them informed of any new developments and future decisions regarding the drug.

In the meantime, Pfizer does not anticipate that the withdrawal will impact its financial guidance for 2024.

Despite the setback with OXBRYTA, the company continues to invest in other areas of research and development within its sickle cell disease portfolio, hoping to address the unmet needs of patients affected by this chronic and life-threatening condition.

For additional information, patients and healthcare providers can contact Pfizer Medical Information at 1-800-438-1985.

This development underscores the challenges of drug development and the balance between innovation and patient safety.

Although OXBRYTA’s withdrawal represents a difficult moment for the sickle cell disease community, it highlights the critical importance of ongoing research to find safer and more effective treatments.