Lawsuit Claims Dupixent Cancer Diagnosis Occurred After Only 8 Months of Use

Lawsuit alleges manufacturer knew FDA was investigating cancer claims while plaintiff was taking Dupixent, yet failed to warn him or his doctors.

A Tennessee man has filed a Dupixent lawsuit alleging the drug’s manufacturers failed to warn that the eczema treatment increases the risk of developing a rare form of lymphoma, resulting in his cancer diagnosis.

William Douglas brought the complaint (PDF) on June 11, originally in New Jersey Superior Court. However, the defendants, Sanofi-Aventis U.S. LLC and Regeneron Pharmaceuticals Inc., removed the case to the U.S. District Court for the District of New Jersey on the same day.

The lawsuit accuses the manufacturers of misrepresenting the safety and effectiveness of the drug, placing patients at risk of cancer for the sake of profits.

Dupixent Cancer Risks

Dupixent (dupilumab) was originally approved for the treatment of atopic dermatitis, commonly known as eczema. However, the U.S. Food and Drug Administration (FDA) agreed to increase its approved uses over the years to include a number of inflammatory conditions affecting the skin and respiratory system, including asthma, chronic obstructive pulmonary disease, or COPD, and other conditions involving overactive immune responses.

The drug targets immune system pathways linked to inflammation, but growing evidence has linked Dupixent side effects to an increased risk of causing, or accelerating, rare forms of T-cell lymphoma. The primary cancer linked to the eczema drug is known as cutaneous T-cell lymphoma (CTCL), which is a kind of non-Hodgkin’s lymphoma that primarily affects the skin.

Because the symptoms of CTCL may resemble eczema or other inflammatory skin conditions, which the drug is often used to treat, it can be difficult to detect if doctors are not told what to look for. Some complaints claim individuals continued receiving Dupixent while their CTCL progressed because doctors and patients were not adequately warned to monitor for signs that the medication may be worsening or revealing an underlying malignancy.

These revelations have led to a growing number of Dupixent cancer lawsuits being filed, each alleging that the manufacturers failed to give the medical community or patients adequate warnings about the cancer risks and failed to instruct healthcare providers to provide the necessary medical monitoring to detect any early signs of cancer development.

Dupixent Cancer Diagnosis Allegations

In the complaint, Douglas indicates he first began receiving Dupixent injections in January 2025 and continued to receive the shots until September 2025. The same month he began taking the drug, the FDA launched an investigation into reports of Dupixent CTCL diagnoses.

Douglas was diagnosed with a subtype of CTCL known as mycosis fungoides in September 2025, eight months after beginning Dupixent treatment. Since then, he has received treatments including phototherapy and Targretin. Healthcare providers have already advised Douglas that he will probably need ongoing medical treatment and medical monitoring for the rest of his life.

The lawsuit notes that federal regulators issued a report in March 2025, warning of serious risks that linked Dupixent to a rising rate of cancer reports being submitted through the FDA Adverse Event Reporting System (FAERS). However, the lawsuit indicates the manufacturers still refuse to correct the medication’s label warnings.

“As of the filing of this complaint, Defendants have still failed to implement appropriate labeling revisions to add necessary information regarding the risk of CTCL development or exacerbation with Dupixent use or appropriate mitigation strategies to reduce or eliminate the risk of Dupixent-induced and Dupixent-exacerbated CTCL.”

– William Douglas v. Sanofi-Aventis U.S. LLC et al.

Douglas presents claims of failure to warn, design defect, negligence, negligent misrepresentation, breach of warranty and violations of the Consumer Fraud Act. He seeks both compensatory and punitive damages.

Dupixent Cancer Lawsuits

The complaint will be consolidated with similar Dupixent cancer lawsuits in the District of New Jersey as part of a multidistrict litigation (MDL) created earlier this month. U.S. District Judge Zahid N. Quraishi will oversee coordinated discovery and pretrial proceedings.

Currently, the litigation is restricted to CTCL diagnoses. However, other cancers may be considered if cases are filed involving separate forms of T-cell lymphoma, according to a ruling by the U.S. Judicial Panel on Multidistrict Litigation (JPML)

As the litigation progresses, Judge Quraishi is expected to direct the parties to prepare several cases representative of the litigation as a whole to serve as bellwether trials. These early test trials would give the parties a chance to see how juries interpret the evidence and testimony that would likely be repeated throughout most other Dupixent cancer lawsuits.

While the results of these trials are not binding on other Dupixent claims, the outcomes will be closely watched to serve as a potential basis for a Dupixent cancer lawsuit settlement agreement.

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