Dupixent Sales Surge Amid Growing CTCL Cancer Lawsuit Allegations

Immunotherapy drug has quickly become a worldwide blockbuster medication, even as evidence continues to raise concerns about the failure to warn that side effects of Dupixent may cause cutaneous T-cell lymphoma (CTCL).

The makers of the immunotherapy drug Dupixent say the medication raked in nearly $5 billion in the third quarter of 2025 alone, as questions begin to mount about whether a push for increased sales caused Sanofi to withhold critical safety information about potential cancer risks associated with the medication.

Sanofi announced its results for the third quarter of 2025 last week, indicating its profits exceeded projections, primarily on the strength of Dupixent sales, which increased by more than 26% over the past year, having already topped $15 billion in 2024, according to the company.

Dupixent (dupilumab) is an injectable immunotherapy first approved in 2017 to treat asthma and other inflammatory conditions affecting the skin and respiratory system. The drug has since gained approval for a range of chronic diseases, including chronic rhinosinusitis, eosinophilic esophagitis, prurigo nodularis, and chronic urticaria, making it one of Sanofi’s most profitable products worldwide.

However, as the drug’s use has expanded rapidly, there are now growing questions about whether Sanofi failed to adequately warn about a potential link between Dupixent and T-cell lymphomas, with a number of recent studies finding that users may be more likely to develop cutaneous T-cell lymphoma (CTCL) and peripheral T-cell lymphoma (PTCL).

A JAMA Dermatology study published in April 2024 found that Dupixent users were more than four times as likely to develop CTCL compared to non-users. A follow-up analysis of TriNetX network data reported a 350% increased risk of T-cell lymphoma among Dupixent users, while a European Respiratory Journal study in June 2025 linked Dupixent to a 4.5-fold higher risk of CTCL among asthma patients, with the risk climbing to 14-fold for those treated 16 weeks or longer. However, no information about the potential risk is included on the drug warning label.

As a result, Sanofi now faces a growing potential for Dupixent cancer lawsuits being pursued for former users of the medication, alleging that they may have avoided a CTCL diagnosis if earlier information and warnings had been provided for patients and the medical community.

Claims raised in lawsuits and medical studies align with mounting safety signals reported to the FDA. Since 2017, the agency’s adverse event database has received nearly 300 reports of lymphoma among Dupixent users, including 138 cases of CTCL and more than 100 additional lymphomas of unspecified type. 

The FDA confirmed earlier this year that it has opened a formal safety review into Dupixent’s potential cancer risks and is evaluating whether stronger warnings may be required.

Despite those concerns, surging prescriptions of Dupixent helped Sanofi reach $14.55 billion in global third-quarter sales. The company had only projected to make $14.46 billion.

Analysts say a significant part of that success has been the drug’s approval for numerous indications. Just last week, Dupixent was approved for use in Canada for treatment of adults with inadequately controlled chronic obstructive pulmonary disease (COPD), which is the fifth leading cause of death in that country.

Dupixent was originally only approved for atopic dermatitis, and now has indications for COPD, asthma, chronic rhinosinusitis, eosinophilic esophagitis, prurigo nodularis, chronic spontaneous urticaria and bullous pemphigoid. Sanofi estimates that the drug will bring in nearly $14.5 billion in sales per year by 2031, when it loses patent protections.

Dupixent T-Cell Lymphoma Lawsuits

Whether Dupixent’s blockbuster status stays on that arc may rely significantly on the effects of potential Dupixent T-cell lymphoma lawsuits.

While many former users continue to remain unaware that a prior CTCL diagnosis may have been caused or accelerated by side effects of Dupixent, as more information is disclosed by regulators and independent researchers the size and scope of the litigation may increase dramatically in the coming months and years.

Dupixent cancer lawyers are currently investigating claims by individuals who were prescribed the drug for any of its approved uses, and were later diagnosed with:

• Cutaneous T-cell lymphoma (CTCL)
• Mycosis fungoides
• Sézary syndrome
• Other T-cell lymphoma subtypes

To receive a free consultation to determine if you or a loved one may be eligible to file a lawsuit, submit information for review by a Dupixent lawyer.