Dupixent T-Cell Lymphoma Lawsuit

What Is This Lawsuit About?

The Dupixent T-cell lymphoma lawsuit is emerging litigation against Sanofi and Regeneron Pharmaceuticals alleging that their blockbuster drug Dupixent (dupilumab) causes cutaneous T-cell lymphoma (CTCL) at an alarmingly elevated rate — 30 times higher than other medications — and that the manufacturers failed to adequately warn patients and healthcare providers about this serious cancer risk.

Dupixent was approved by the FDA in March 2017 and has become one of the top-selling drugs in the world, prescribed for conditions including atopic dermatitis (eczema), asthma, and nasal polyps. However, FDA adverse event data has revealed a striking pattern: out of 181,575 adverse event reports, the rate of cutaneous T-cell lymphoma in Dupixent patients is 30 times higher than in patients taking comparable medications.

In March 2025, the FDA placed Dupixent on its list of medications with potentially serious risks. Lawsuits began filing in late 2025, including a wrongful death case in Tennessee (October 2025), an individual claim in Illinois (December 2025), and additional cases in January 2026. In February 2026, a petition was filed to consolidate these cases into a multidistrict litigation (MDL) in the Northern District of Georgia.

If you or a loved one took Dupixent and were diagnosed with CTCL or another lymphoma, you may be eligible to file a claim. This litigation shares similarities with other pharmaceutical lawsuits where cancer risks emerged after FDA approval, such as the hair relaxer cancer lawsuit and the Ozempic stomach paralysis lawsuit.

Who Qualifies?

You may qualify for the Dupixent lymphoma lawsuit if you took the drug and were diagnosed with CTCL or another lymphoma. An experienced attorney can evaluate your specific case during a free consultation.

CTCL Risk: 30x Higher Than Other Drugs

Cutaneous T-cell lymphoma is a rare cancer of the T-cells that primarily manifests in the skin. What makes the Dupixent connection particularly concerning — and particularly dangerous — is that CTCL symptoms can closely mimic eczema, the very condition Dupixent is most commonly prescribed to treat. This means patients may have their cancer misdiagnosed as a flare-up of their underlying skin condition, delaying life-saving treatment.

Lawsuit Timeline

The Dupixent lymphoma litigation is in its earliest stages, with cases filed beginning in late 2025 and an MDL petition submitted in February 2026. Here are the key milestones:

Settlement Amounts & Projections

Because the Dupixent lymphoma litigation is in its very early stages, no settlements have been reached yet. However, based on comparable pharmaceutical mass tort cases involving cancer, legal analysts project the following potential settlement ranges:

Key factors that will influence settlement amounts include the severity of the lymphoma diagnosis, the stage at which CTCL was detected, the patient's overall health outcome, and the strength of medical evidence linking Dupixent use to the cancer. For context on how pharmaceutical settlements are structured, see our guide on mass tort settlement amounts. Related pharmaceutical litigation like the Tepezza hearing loss lawsuit provides comparable reference points.

How to File a Claim

Filing a Dupixent lymphoma claim involves several steps. An experienced mass tort attorney can guide you through the process at no upfront cost.

Named Defendants

Dupixent is jointly developed and marketed by two pharmaceutical companies. Both are named as defendants in the emerging litigation:

Plaintiffs allege that both Sanofi and Regeneron knew or should have known about the elevated CTCL risk from post-market surveillance data and FDA adverse event reports, but failed to update Dupixent's prescribing information or provide adequate warnings to patients and their doctors.

Scientific & Medical Evidence

The connection between Dupixent and cutaneous T-cell lymphoma is supported by FDA adverse event data and emerging scientific research:

• FDA Adverse Event Data: Out of 181,575 adverse event reports associated with Dupixent, the rate of cutaneous T-cell lymphoma is 30 times higher than the rate seen with other comparable medications. This disproportionate signal prompted the FDA to flag the drug in March 2025.
• FDA Serious Risk Designation (March 2025): The FDA placed Dupixent on its official list of medications with potentially serious risks based on the adverse event data, signaling regulatory concern about the CTCL connection.
• Mechanism of Action Concerns: Dupixent works by blocking IL-4 and IL-13 signaling pathways involved in type 2 inflammation. Researchers are investigating whether this immune modulation may alter T-cell behavior in ways that promote or fail to suppress malignant T-cell transformation.
• Diagnostic Confusion: Medical literature has documented cases where CTCL in Dupixent patients was initially misdiagnosed as persistent or worsening eczema, because the two conditions present with similar skin manifestations (red, scaly patches and plaques).
• Post-Market Case Reports: Individual case reports in dermatology and oncology journals have documented CTCL diagnoses in patients receiving Dupixent, with some cases occurring within months of starting treatment.

The strength of the FDA's adverse event signal — a 30-fold elevation — is considered significant in pharmaceutical litigation. For context on how scientific evidence is used in mass tort cases, see our guide on how mass tort lawsuits work.

What Is Dupixent?

Dupixent (dupilumab) is a monoclonal antibody that targets and blocks interleukin-4 (IL-4) and interleukin-13 (IL-13), two key proteins involved in type 2 inflammation. It is administered as a subcutaneous injection and is approved for multiple conditions:

• Atopic Dermatitis (Eczema): FDA-approved March 2017 for adults, later expanded to children as young as 6 months
• Asthma: FDA-approved October 2018 as add-on maintenance therapy
• Chronic Rhinosinusitis with Nasal Polyps: FDA-approved June 2019
• Eosinophilic Esophagitis: FDA-approved May 2022
• Prurigo Nodularis: FDA-approved September 2022
• COPD: FDA-approved September 2024

Dupixent is one of the best-selling drugs in the world, with global revenue exceeding $13 billion in 2024. It is marketed jointly by Sanofi and Regeneron. Despite its commercial success, the emerging CTCL safety signal raises serious questions about whether the drug's risk profile was adequately communicated to patients.

Other pharmaceutical lawsuits involving drugs with post-approval safety discoveries include the Ozempic stomach paralysis lawsuit and the Depo-Provera brain tumor lawsuit.