Lawsuit Indicates Dupixent Lymphoma Diagnosis Resulted in Multiple Rounds of Chemotherapy

Patient alleges Dupixent use caused mycosis fungoides CTCL diagnosis and sézary syndrome, two forms of skin cancer that will require life-long medical treatment and monitoring.

A Louisiana woman’s product liability lawsuit claims she developed a rare form of t-cell lymphoma due to the side effects of using the eczema treatment Dupixent.

The complaint (PDF) was filed by Alicia Johnson in the U.S. District Court for the District of New Jersey on April 28. It names Regeneron Pharmaceuticals Inc., Sanofi-Aventis U.S. LLC, and Genzyme Corporation as defendants, alleging they developed, manufactured and sold a defective drug capable of causing users to develop cancer.

Dupixent Risks

Dupixent (dupilumab) was first approved in 2017 for the treatment of atopic dermatitis, a form of eczema. Its label was later expanded, allowing the manufacturers to market the drug for the treatment of asthma, chronic obstructive pulmonary disease (COPD) and other inflammation-based respiratory tract and skin conditions.

The drug was marketed as safe and effective, becoming a blockbuster treatment in the U.S. However, Dupixent side effects have recently been linked to T-cell lymphoma, a rare form of cancer that impacts the body’s white blood cells, which are a key part of the immune system. These concerns have raised warnings that the medication may increase the risk of cutaneous T-cell lymphoma (CTCL) and peripheral T-cell lymphoma (PTCL).

Johnson’s claim joins a growing number of similar Dupixent lawsuits from other consumers. These filings all raise allegations that the manufacturers knew, or should have known, Dupixent was linked to the development of CTCL and PTCL, yet failed to adequately warn patients or the medical community about the potential life-long, devastating and sometimes fatal risks.

Dupixent CTCL Lawsuit

According to her lawsuit, Johnson began using Dupixent in October 2022 for the treatment of atopic dermatitis. She continued to use the medication until May 2024.

In May 2025, doctors diagnosed Johnson with mycosis fungoides, the most common form of CTCL. Mycosis fungoides causes red scaly and itchy patches on the skin, often leading it to be confused for the skin problems that Dupixent is prescribed to treat. This may lead to a delayed diagnosis, making proper label warnings particularly important.

The cancer generally progresses slowly, and it rarely causes death when diagnosed early. However, the malignancy is incurable. If not caught until later stages, it can become far more dangerous by spreading to lymph nodes and other organs. At this point, the five-year survival rate plummets.

Since her mycosis fungoides diagnosis, Johnson has also been diagnosed with sézary syndrome, which is an aggressive leukemic form of CTCL. The lawsuit blames Johnson’s use of Dupixent for both CTCL diagnoses.

The filing also notes doctors have advised Johnson that she will require medical treatment and monitoring for CTCL “indefinitely.”

“As a result of Plaintiff’s CTCL diagnosis, she has required extensive treatments and the use of medications including topical medications, oral medications, and injected/infused medications. Additionally, Plaintiff, Alicia Johnson, is undergoing multiple rounds of chemotherapy.”

– Alicia Johnson v. Regeneron Pharmaceuticals Inc. et al

Johnson presents claims of failure to warn, negligence, fraudulent misrepresentation, negligent misrepresentation and breach of warranty. She seeks both compensatory and punitive damages.

Dupixent Cancer Lawsuits

In February, a group of plaintiffs filed a petition for the creation of a Dupixent CTCL lawsuit multidistrict litigation (MDL) in the Northern District of Georgia before one judge for coordinated discovery and pretrial proceedings.

On April 16, the U.S. Judicial Panel on Multidistrict Litigation (JPML) announced it will hear oral arguments on the potential consolidation at a hearing scheduled for May 28. If the panel decides to consolidate the claims, it would appoint a judge to oversee all federal Dupixent lawsuits. That judge is likely to order the parties to prepare a small group of representative cases to serve as potential bellwether trials.

These early test cases are designed to give the parties a chance to see how evidence, testimony and arguments affect actual jury decisions. While these outcomes are not binding on other cases, they are closely watched in expectation that similar juries will arrive at similar conclusions, often making bellwether trials a lynchpin in settlement negotiations.

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