Pfizer Pulls Sickle Cell Treatment Over Deadly Complication Risks

Pfizer (NYSE: PFE) has voluntarily withdrawn all global lots of its sickle cell disease (SCD) treatment, Oxbryta (voxelotor), halting all clinical trials and access programs for the drug. Citing clinical data that shows the risks of Oxbryta outweigh its benefits, the company has informed regulatory authorities of the decision. Despite this action, Pfizer does not anticipate any impact on its full-year 2024 financial guidance.

Risks of Increased Vaso-Occlusive Crises and Fatal Events Outweigh Treatment Benefits

Pfizer has announced the voluntary withdrawal of its SCD drug, Oxbryta, from global markets. This decision marks a significant setback for Pfizer, following its $5.4 billion acquisition two years ago. The company will halt distribution, recall all produced lots, and discontinue all ongoing clinical trials and access programs for Oxbryta.

The company based its decision on recent clinical data indicating that the overall benefits of Oxbryta no longer outweigh the risks for approved SCD patients. New patient outcome data revealed an “imbalance” in vaso-occlusive crises and fatalities, which Pfizer believes “require further assessment.” As a result, the company has taken this precautionary measure.

“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,” stated Aida Habtezion, M.D., chief medical officer at Pfizer. Oxbryta received FDA accelerated approval in late 2019 and European Commission marketing authorization in 2022, based on prior data showing significant improvements in hemoglobin levels. However, the latest findings prompted Pfizer to reassess its position on the drug.

Oxbryta Withdrawal Amid Strategic Reevaluation and Evolving Market Landscape

Oxbryta served as a central component in Pfizer’s $5.4 billion acquisition of Global Blood Therapeutics (GBT) in 2022, amid a post-COVID merger and acquisition surge. At that time, Pfizer projected that Oxbryta and GBT’s pipeline for SCD could collectively generate over $3 billion in peak annual sales. However, earlier this year, Pfizer discontinued one of two late-stage trials for a GBT candidate, inclacumab, due to difficulties in patient recruitment.

In the previous year, Oxbryta generated $328 million in global sales. Despite this market withdrawal, Pfizer stated that it does not anticipate any impact on its financial guidance for 2024. Subsequently, the pharma giant has informed regulatory authorities about the market withdrawal and continues to investigate the new clinical findings. Additionally, Habtezion urged patients to consult their physicians regarding alternative treatment options during this transition.

SCD is a lifelong inherited blood disorder characterized by hemoglobin S polymerization, leading to red blood cell sickling. This process causes vascular inflammation and hemolytic anemia, which can result in acute pain crises and progressive organ damage, including strokes. Complications often begin in early childhood and contribute to a reduced life expectancy. Consequently, early intervention can help modify the disease’s progression, alleviate symptoms, and prevent long-term organ damage. Historically, there has been a significant unmet need for therapies addressing the root causes of SCD. Although rare in developed nations, approximately 4.5 million people worldwide live with SCD, alongside more than 45 million with the sickle cell trait. SCD primarily affects individuals of sub-Saharan African descent, but it also occurs in those with Hispanic, South Asian, Southern European, and Middle Eastern ancestry.

Recall Follows FDA Approval of Two Gene Therapies for SCD

Oxbryta’s withdrawal follows the recent FDA approvals of two gene therapies for SCD. Vertex and CRISPR Therapeutics received approval for Casgevy, while bluebird bio launched Lyfgenia. These therapies demonstrated the ability to reduce or eliminate vaso-occlusive crises in sickle cell patients based on clinical data. 

These FDA approvals of gene therapies Casgevy and Lyfgenia mark a significant advancement in treating SCD. Both therapies aim to provide a potential cure for the over 100,000 affected individuals in the United States, predominantly among the Black population. Furthermore, Casgevy utilizes the groundbreaking CRISPR gene-editing technology, which holds immense promise for curing various diseases. Both therapies target individuals aged 12 and older, with Casgevy priced at $2.2 million and Lyfgenia costing $3.1 million, raising concerns about accessibility and insurance coverage.

Notably, earlier this year, the Institute for Clinical and Economic Review indicated that both Vertex and bluebird’s therapies would be cost-effective if priced between $1.35 million and $2.05 million. This pricing strategy contrasts with traditional gene therapies, which typically exceed $1 million and can reach up to $3.5 million, as seen with CSL Behring and uniQure’s Hemgenix for hemophilia B. Meanwhile, interim data suggest that these new therapies can effectively reduce painful vaso-occlusive crises, presenting fresh hope for patients living with the debilitating effects of SCD.

Author

Bernice Lottering