Dupixent Cancer Lawsuit Claims Eczema Drug Caused Woman’s CTCL Diagnosis

Lawsuit alleges Dupixent manufacturers promoted the eczema drug as a breakthrough treatment while failing to warn it may trigger or worsen cutaneous T-cell lymphoma in certain patients.

A Delaware woman has filed a Dupixent lawsuit alleging the widely prescribed eczema drug caused her to develop cutaneous T-cell lymphoma (CTCL), a rare form of non-Hodgkin’s lymphoma that she claims can be triggered or accelerated by the biologic medication.

The complaint (PDF) was brought by Joyce Filppi in the U.S. District Court for the District of Delaware on May 20, naming Regeneron Pharmaceuticals Inc. and Sanofi-Aventis U.S. LLC as defendants. 

Filppi claims the manufacturers failed to adequately warn patients and the medical community that Dupixent may trigger, worsen or accelerate CTCL in patients being treated for eczema and other inflammatory skin conditions.

Dupixent Cancer Risks

Dupixent (dupilumab) was first approved by the FDA in 2017 for the treatment of moderate-to-severe atopic dermatitis, commonly known as eczema. Since then, the injectable biologic has gained additional approvals for asthma, chronic sinus inflammation, eosinophilic esophagitis and other conditions, becoming one of the world’s best-selling prescription drugs.

Marketed as a safe and effective treatment, Dupixent rapidly became one of the most commonly prescribed and commercially successful therapies in the United States. However, mounting reports have associated Dupixent side effects with rare T-cell lymphomas like CTCL and peripheral T-cell lymphoma (PTCL), which are both cancers that involve immune system white blood cells.

Filppi’s complaint joins a growing wave of Dupixent cancer lawsuits now being pursued nationwide. Many of the complaints allege that the drug makers knew or should have known about the potential lymphoma risks but failed to adequately warn doctors and patients about the possibility of serious, permanent or potentially fatal injuries.

Dupixent CTCL Allegations

In the lawsuit, Filppi claims the defendants knew or should have known that eczema symptoms may overlap with early manifestations of CTCL, and that treatment with Dupixent could delay accurate diagnosis or worsen the disease course in affected patients.

The complaint cites published case reports, retrospective analyses and adverse event reports dating back to 2018. These reports often identified CTCL diagnoses emerging after Dupixent treatment, even as the manufacturers continued aggressively marketing the drug as a breakthrough therapy.

Researchers referenced in the lawsuit include physicians from Memorial Sloan Kettering Cancer Center, Tulane University and several international dermatology centers. In one analysis published in 2024, researchers found patients previously treated with Dupixent faced a significantly higher risk of advanced-stage CTCL at diagnosis.

Other studies cited in the complaint found that some patients who failed to respond adequately to Dupixent treatment were later diagnosed with mycosis fungoides, the most common form of CTCL, after undergoing additional testing and biopsies.

The lawsuit also references reports involving patients who allegedly experienced rapid disease progression after beginning Dupixent treatment, including some who later died from advanced CTCL complications.

According to the complaint, the manufacturers received multiple postmarketing adverse event reports involving CTCL shortly after Dupixent entered the market, including reports submitted by physicians and healthcare professionals in the United States and Europe. Several allegedly identified Dupixent as the “primary suspect product” associated with the CTCL reactions.

Despite the mounting evidence, the lawsuit claims the manufacturers failed to update Dupixent warnings, recommend additional screening measures or advise physicians to conduct more extensive testing before prescribing the drug to patients with atypical or treatment-resistant dermatitis symptoms.

“As a direct and proximate result of the dangerous and defective nature of Dupixent as described herein, Plaintiff suffered severe bodily injury, and resulting pain and suffering, disability, disfigurement, mental anguish, loss of capacity for the enjoyment of life, and expense of hospitalization and treatment.”

— Joyce Filppi v. Regeneron Pharmaceuticals Inc. et al.

The lawsuit raises allegations of strict liability—failure to warn, negligence, fraudulent misrepresentation and negligent misrepresentation. It seeks general, special, exemplary and punitive damages.

Dupixent Cancer Lawsuits

Due to the steady number of claims being filed, several plaintiffs asked the U.S. Judicial Panel on Multidistrict Litigation (JPML) to consolidate all federal Dupixent CTCL lawsuits before one judge in the Northern District of Georgia for coordinated discovery and pretrial proceedings in a multidistrict litigation, or MDL.

The JPML announced on April 16 that it will hear oral arguments on the consolidation request during a hearing scheduled for May 28. If the panel agrees to centralize the litigation, one federal judge would likely oversee the coordinated proceedings and organize a series of early bellwether trials involving representative cases.

Those bellwether trials are designed to help the parties evaluate how juries may respond to evidence and legal arguments expected to be repeated throughout the litigation. While the outcomes would not directly affect other plaintiffs’ claims, the results often shape the course of settlement negotiations and broader case resolutions.

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