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Three questions decide most Dupixent cases
You do not need to know the medicine or the law to find out whether you have a claim. You need three facts, and we can help you assemble the records that prove them.
Fact one: documented use
A prescription and/or pharmacy or injection record showing you actually received Dupixent, and roughly when you started and stopped.
Fact two: a confirmed diagnosis
A pathology report, oncology record or any treatment record confirming cutaneous T-cell lymphoma, mycosis fungoides, Sezary syndrome, or another T-cell lymphoma.
Fact three: the skin timeline
When the underlying skin disease which Dupixent was prescribed for actually began, and what it was called before the lymphoma was found. This is the fact the defense will press hardest, and the one that is easiest to lose if records go missing.
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Why these lawsuits are being filed
Dupixent is a biologic that blocks the interleukin-4 receptor alpha subunit, interrupting part of the immune signaling that drives inflammation. Its initial U.S. approval was in 2017 for moderate to severe atopic dermatitis, and it now carries nine approved indications, including asthma, chronic rhinosinusitis with nasal polyps, eosinophilic esophagitis, prurigo nodularis, COPD, chronic spontaneous urticaria, bullous pemphigoid, and allergic fungal rhinosinusitis.
Cutaneous T-cell lymphoma is a group of non-Hodgkin lymphoma in which malignant T-cells reside in the skin. It is often loosely called a skin cancer, but that is not precise: skin cancers such as melanoma and basal cell carcinoma arise from different cells entirely. Most CTCL is indolent, meaning chronic and treatable but not curable. There are also aggressive subtypes and cases that can progress over time.
One of the problems at the center of this litigation is recognition. In Mycosis Fungoides-the most common form, the rash can look like ordinary eczema or psoriasis and may be present for years or even decades before it is correctly diagnosed.
Lawsuits filed against Regeneron Pharmaceuticals, Sanofi-Aventis U.S., and Genzyme allege that the companies failed to warn patients and physicians that Dupixent may cause, accelerate, or mask cutaneous T-cell lymphoma, and failed to tell doctors to biopsy and monitor patients whose skin disease did not behave as expected. The companies deny these allegations. No court has decided the merits.
The label
The FDA-approved prescribing information for Dupixent, most recently revised in April 2026, lists ten Warnings and Precautions. None of them warns or concerns lymphoma, malignancy, or cutaneous T-cell lymphoma, and neither does the postmarketing experience section. The prescribing information also states that animal studies have not been conducted to evaluate the carcinogenic potential of dupilumab. Plaintiffs point to that gap, a safety signal the FDA has publicly flagged without a corresponding warning on the label, as the core of the failure to warn claim.
What the published research reports
| Source | What was reported |
|---|---|
| U.S. Food and Drug Administration, FAERS potential signals list, quarter covering October to December 2024 | The FDA listed "Dupixent (dupilumab) injection" against the potential signal "cutaneous T-cell lymphoma" and stated that it is evaluating the need for regulatory action. The entry remains on the agency’s published list. |
| Dermatologic Therapy, Mandel et al., 2024 retrospective cohort | Among 19,612 atopic dermatitis patients treated with dupilumab, researchers reported a relative risk of CTCL of 4.59 compared with patients never treated with the drug (95% confidence interval 2.459 to 8.567). Of those diagnosed after dupilumab use, 62% were diagnosed within the first year, and 81% of the CTCL cases were mycosis fungoides. |
| European Respiratory Journal, Ma et al., 2025 population-based cohort | Among asthma patients, dupilumab was associated with a higher risk of lymphoma than inhaled corticosteroid plus long-acting beta-agonist therapy (hazard ratio 1.79), with a stronger association for T-cell and natural killer cell lymphomas (hazard ratio 4.58). The same study found no increased risk of other malignancies and reported lower all-cause mortality among dupilumab patients. |
| Journal of Allergy and Clinical Immunology, 2024 to 2025 | Combined FDA adverse event data with gene expression analysis and reported a strong disproportionate reporting signal for CTCL, along with a proposed biological mechanism for unmasking or progression. |
| Pharmacovigilance analyses of FAERS, 2025 | It was reported that CTCL was disproportionately reported for dupilumab compared with other biologics, while reporting rates for other lymphomas were not similarly elevated. |
Caption under the table: Research is summarized in plain language for patients. An association reported in published studies is not proof of causation in any individual case. Some researchers have argued that the observed increase reflects unmasking of lymphoma that was already present and misdiagnosed rather than new disease caused by the drug. Causation is contested in this litigation, and no court has ruled on it.
Where the litigation stands right now
By transfer order dated June 4, 2026, the U.S. Judicial Panel on Multidistrict Litigation centralized the federal Dupixent cases as In re: Dupixent (Dupilumab) Products Liability Litigation, MDL No. 3180, in the U.S. District Court for the District of New Jersey before Judge Zahid N. Quraishi. An MDL is not a class action. Each person keeps an individual case and seeks individual damages while pretrial work such as document discovery and expert science is coordinated before one judge.
The Panel chose New Jersey because Sanofi’s principal place of business is there and Regeneron, headquartered nearby in Tarrytown, New York, has corporate offices in the district. The plaintiffs who sought centralization motion had asked for the Northern District of Georgia; the manufacturers had asked for the Southern District of New York.
| MDL 3180 | D.N.J. | June 2026 | 28 actions |
|---|---|---|---|
| In re: Dupixent(Dupilumab) ProductsLiability Litigation | Judge Zahid N. Quraishi | Centralized from 15cases across 12 districts | Pending per the JPMLreport dated August 3,2026 |
The docket is growing. Filing early in an MDL generally means your records are gathered while they still exist and your case is positioned before the science and the bellwether structure are set.
On other T-cell lymphomas
The manufacturers asked the Panel to limit the MDL to CTCL claims. The Panel declined to decide that question, noting that none of the plaintiffs before it alleged a T-cell lymphoma other than CTCL or one of its subtypes, and said it can address expansion later through the conditional transfer process. Plaintiffs’ counsel argued the literature also links dupilumab to non-cutaneous T-cell lymphomas, including peripheral T-cell lymphoma and anaplastic large cell lymphoma. All sides agreed that the MDL should not include B-cell lymphoma or Hodgkin lymphoma.
Not sure whether your diagnosis counts?
Bring to us the diagnosing pathology report and we will tell you whether we think there is a case or not. We can also request the pathology report on your behalf if you retain and authorize us to do so.
Warning signs patients describe
- A rash that improved at first on Dupixent, then returned worse
- Patches spreading to skin normally covered by clothing
- Swollen lymph nodes, night sweats, or unexplained weight loss
- Repeated biopsies described as inconclusive or atypical
- A cancer diagnosis within months of starting the drug
What to gather now
Records and chronology of events are the case. Start collecting before pharmacies purge data and before practices change systems.
- Pharmacy dispenses, printout or injection records showing Dupixent dispensing dates
- Dermatology progress notes or charts going back to the first appearance of the skin condition
- Every relevant biopsy and pathology report, including inconclusive ones
- Oncology and hematology records, staging, and treatment history
- Photographs of the skin over time, dated if possible
- Insurance explanations of benefits and out of pocket payment receipts
- For a wrongful death claim, the death certificate and estate paperwork such as Will(s)/Trust(s)
Compensation a claim may seek
Every case is different and no outcome can be promised. Depending on the specific facts and the governing state law, a valid and proved Dupixent claim may seek:
- Past and future medical costs, such as chemotherapy, phototherapy, radiation, and transplant care
- Lost wages and lost earning capacity
- Pain, suffering, disfigurement, and loss of enjoyment of life
- Care and travel costs shouldered by the family
- Loss of consortium for a spouse
- Wrongful death and survival damages
- Punitive damages where state law allows them
Why Brown, LLC
Pharmaceutical mass torts from filing to resolution
Jason T. Brown was the first attorney in the country to commence a battery of cases against a major pharmaceutical company over undisclosed risks, litigation that produced a $100 million settlement fund. The firm’s aggregate recoveries exceeded a billion dollars.
Built by a former FBI Special Agent
The firm is led by a former FBI Special Agent and Legal Advisor and includes Department of Justice alumni. Failure to warn cases are won on what a company knew and when, which is an evidence problem before it is a legal one.
Contingency fee, nationwide
No fee unless we recover. We handle claims across the United States, working with trusted local counsel where required, and we are selective about the cases we accept.
Frequently Asked Questions
Who qualifies for a Dupixent lawsuit?
Generally, someone who was prescribed and used Dupixent was later diagnosed with cutaneous T-cell lymphoma, including mycosis fungoides or Sezary syndrome, or another form of T-cell lymphoma. Family members may bring a claim where a loved one has died. The strength of a case depends on the pharmacy history of Dupixent usage, when the underlying skin disease actually began, and the pathology.
Is this a class action?
No. Federal cases are consolidated in MDL No. 3180 in the District of New Jersey. In a multidistrict litigation each plaintiff files an individual case reflecting individual damage, and pretrial proceedings are coordinated before one judge for efficiency. That is different from a class action, where one outcome binds an entire class.
Does Dupixent cause cutaneous T-cell lymphoma?
That is the contested question at the center of the litigation. Published studies have reported higher rates of CTCL among Dupixent (dupilumab) users, and the FDA has listed dupilumab and CTCL as a potential safety signal while it evaluates the need for regulatory action. Plaintiffs allege the drug can cause the cancer, accelerate it, or suppress the symptoms that would otherwise have prompted an earlier biopsy. The manufacturers dispute this. No court has ruled on the merits.
How long do I have to file?
Each state sets its own statute of limitations, and the clock often starts at diagnosis or at the point when the injury reasonably should have been linked to the drug. These deadlines are strict and vary widely. If you think you may have a claim, have the dates reviewed promptly rather than waiting for the litigation to develop further.
How much does it cost?
Nothing up front. Brown, LLC handles these cases on a contingency fee, which means there is no attorney fee unless we obtain a recovery for you. The initial case review is free and confidential
Should I stop using Dupixent?
That decision belongs to you and your treating physician, and nothing on this page is medical advice. Many patients rely on this medication. If you have concerning skin changes or symptoms, ask your dermatologist directly about a biopsy.
My loved one died. Can our family still bring a claim?
Often yes. Depending on state law, a spouse, child, parent, or the representative of the estate may bring a wrongful death or survival action. Preserve the medical records, the pharmacy history, pathology reports, and the death certificate, and speak with a lawyer about the deadlines that apply where the death occurred.
Will I have to go to New Jersey or testify in court?
Most plaintiffs in an MDL never appear in court unless selected as a bellwether case. Your participation typically involves providing medical records, completing a plaintiff fact sheet, and possibly sitting for a deposition, which can often be arranged near where you live.
Talk to a lawyer, not a call center
If you or someone you love used Dupixent (dupilumab) and was diagnosed with cutaneous T-cell lymphoma, mycosis fungoides, Sezary syndrome, or another T-cell lymphoma, contact Brown, LLC for a free and confidential review. If it’s not right, we’ll fight.