Dupixent (dupilumab), a widely prescribed biologic medication used to treat several inflammatory skin and respiratory conditions, has recently come under scrutiny due to serious health concerns.
Concerns are emerging that patients were not properly warned about the potential risk of developing T-cell lymphoma, a serious cancer that affects the immune system. At least one lawsuit has been filed, and additional claims may follow.
Chaffin Luhana defective product attorneys are currently investigating cases in which patients took Dupixent and later developed lymphoma or other serious health complications. If you or a loved one has been affected by the potentially serious side effects of this drug, we’d be happy to discuss your case with you.
What Is Dupixent?
Dupixent (dupilumab) is a prescription injectable medication used to treat different types of inflammatory conditions, including moderate-to-severe eczema (atopic dermatitis), asthma, certain types of chronic obstructive pulmonary disease (COPD), and more.
The drug is manufactured jointly by Regeneron Pharmaceuticals, Inc. and Sanofi-Aventis LLC.
The U.S. Food and Drug Administration (FDA) first approved Dupixent in March 2017 to treat adults with moderate to severe atopic dermatitis, a chronic skin condition commonly known as eczema. At the time, it was the first and only biologic medicine approved for treatment of this condition in adults whose disease was not adequately controlled with topical prescription therapies. (A biologic medication is a class of drugs derived from living organisms like bacteria, viruses, or human cells and designed to target specific parts of the immune system.)
Since then, the drug’s approved uses have expanded several times, first to treat atopic dermatitis in pediatric patients; and later to treat asthma, chronic rhinosinusitis with nasal polyps (CRSwNP), and eosinophilic esophagitis (EoE) in adult and pediatric patients; and to treat Prurigo nodularis (PN) and COPD in adults.
Today, Dupixent is a top-selling blockbuster drug and a flagship product of both Sanofi-Aventis and Regeneron. In 2024, sales of the drug totaled $14.1 billion. In 2025, sales of the drug were at or above $4 billion per quarter for the first two quarters.
How Does Dupixent Work?
Dupixent works by blocking a key source of inflammation in the body. It’s a protein man-made in the laboratory that blocks the signaling of two key Type-2 cytokines—interleukin-4 (IL-4) and interleukin-13 (IL-13).
Cytokines usually signal molecules to coordinate and regulate certain immune responses, like inflammation. When you suffer an injury, such as a dog bite, these cytokines go to work to try to eradicate any potential infection. That’s why the wounded area swells up and turns red with inflammation.
When someone has a condition like eczema, however, the immune system malfunctions and causes inflammation where it shouldn’t. Dupixent blocks the signaling of these cytokines, helping to reduce the type-2 inflammation that drives eczema, as well as other conditions like asthma that Dupixent is approved to treat.
The drug has proven effective at reducing symptoms in many patients, but researchers are now learning that it can also have unintended consequences. It turns out that the very process that makes Dupixent effective at treating inflammatory conditions may also interfere with the body’s natural ability to keep abnormal cells in check, potentially allowing cancer cells to develop and grow.
Dupixent Connected to Certain Types of Cancer
Shortly after Dupixent was released on the market, doctors started publishing case reports linking the medication with T-cell lymphoma, a type of cancer that affects the immune system, particularly the T-cells.
There are many types of T-cell lymphoma. The two that Dupixent has been connected with include the following.
Cutaneous T-cell Lymphoma (CTCL)
This cancer starts in the skin. It typically shows up as patches, plaques, or tumors. Patches are flat areas that may be scaly and can look like a rash. Plaques are thick, raised areas that are often itchy and can be mistaken for eczema, psoriasis, or regular dermatitis. Tumors are raised bumps that may or may not develop sores. Patients can have one or more of these skin changes at the same time.
Another form of CTCL is Sézary syndrome, which is less common but more serious, as it affects both the skin and the blood. Most cases occur in people over 60 years old. The main symptoms include swollen lymph nodes and a red, intensely itchy rash that covers large areas of the body. When examined under a microscope, the skin shows abnormal T-cells, called Sézary cells, in both the skin and blood samples.
Peripheral T-cell Lymphoma (PTCL)
This cancer is found in the lymph nodes, other organs, and the blood. It’s also classified as a type of non-Hodgkin lymphoma, and it specifically affects T-cells that have developed and started growing abnormally.
These lymphomas are considered “peripheral” because they affect mature T-cells that have left the thymus, an organ where T-cells develop. PTCL can occur in lymph nodes or in areas outside the lymphatic system, such as the gastrointestinal tract, liver, nasal cavity, or skin.
Can These Cancers Be Treated?
Treatment of T-cell lymphoma typically involves chemotherapy, radiation therapy, or both. In some cases, doctors may recommend targeted therapy or immunotherapy, as well as topical medications or light therapy. The prognosis varies widely and depends on the specific type of lymphoma, how advanced it is, and how well it responds to treatment.
What Causes T-Cell Lymphoma?
Researchers still don’t know exactly what causes T-cell lymphoma, but they have identified several risk factors and potential contributing factors.
Known risk factors include the following:
- A family history of lymphoma
- A weakened immune system or an autoimmune condition.
- Some infections, particularly Epstein-Barr virus and human T-cell lymphotropic virus Type 1 (HTLV-1).
Some of the conditions treated by Dupixent may also be associated with a slightly increased risk of lymphoma. Severe atopic dermatitis, for example, has been linked to an increased risk of lymphoma in some studies.
Meanwhile, the research on Dupixent suggests that the drug may add to this baseline risk, potentially unmasking hidden lymphomas, accelerating their development, or even directly contributing to their formation.
The concern is that because Dupixent blocks IL-4 and IL-13 signaling, it may interfere with the immune system’s normal job of identifying and eliminating abnormal cells before they become cancerous.
In essence, the drug may be removing important guardrails that usually keep cells from becoming cancerous or prevent existing cancer cells from growing.
Case Studies Link Patients’ Use of Dupixent with T-Cell Lymphoma
Shortly after Dupixent came onto the market, doctors started reporting cases of patients developing cancer.
In 2020, for instance, doctors reported on three patients treated with dupilumab for eczema, and all three developed T-cell lymphoma (CTCL). The doctors believed that the medication had exacerbated a pre-existing CTCL and suggested the need for further investigation.
That same year, another group of doctors reported on a patient treated with the drug who developed Sézary syndrome, which is a form of CTCL. “Although dupilumab provides promise for the treatment of atopic and allergic conditions,” the doctors wrote, “clinicians should take into account its novelty and the potential for unexpected adverse events.”
Many more case reports followed, yet the Dupixent manufacturers took no action to warn doctors or patients of the potential connection.
In 2023, researchers published a systematic review of 12 studies including 27 total patients, and found that dupilumab-associated CTCL was diagnosed on average 7.8 months following the start of treatment. The researchers suggested doctors take biopsies of the skin three to four months after patients start Dupixent in order to recognize CTCL in those patients who fail to improve while taking the drug.
Studies Mount Linking Dupixent to T-Cell Lymphoma
In 2024, researchers investigated the risk of CTCL after dupilumab use in patients with atopic dermatitis (AD). They found that patients with AD who were prescribed the drug had a four-fold higher risk of developing CTCL.
Another study that same year examined data from a large database including over one million patients with AD. Of these, over 19,000 were treated with dupilumab. These patients were found to have an almost five-fold increased relative risk of developing CTCL compared to those who were never treated with the drug.
The researchers added that the risk was highest in the first year of therapy in adult patients, and that about half of the CTCL cases occurred in patients over the age of 60.
Is Dupixent Only “Unmasking” CTCL?
It’s true that patients with a history of AD have an increased risk of CTCL, particularly those with severe AD. In some cases, CTCL can look like AD at first, and may only be revealed as cancer as it progresses.
This has led doctors and scientists to wonder: Could it be that Dupixent is only “unmasking” the presence of CTCL, rather than causing it?
Much of the research is finding an increased risk of cancer within the first year or two of Dupixent use. That may add weight to the idea that Dupixent is either unmasking lymphomas that were already there but hadn’t been detected yet, or accelerating the development of these pre-existing cancers.
Yet we can’t be certain of that yet. In a 2025 cohort study from the Memorial Sloan Kettering Cancer Center, researchers identified 30 patients treated with dupilumab for eczema who developed CTCL. Yet similar patients treated with other biologic treatments did not develop the cancer, which seemed to indicate it was the drug, not the disease, causing the increased risk of cancer.
Either way, the manufacturers are not doing enough to protect the public.
If it’s true that Dupixent increases the risk of CTCL only in those who are susceptible to it, that should still be revealed on the label and in advertisements. At the very least, doctors should be warned to carefully watch those who may be at risk for CTCL while treating with Dupixent.
When considering the typical user of the drug, this becomes even more critical, as most people who are treated with Dupixent already have moderate-to-severe, inadequately controlled Type-2 inflammatory diseases, which may put them at risk of lymphoma from the start. Doctors should be warned of this potential connection, and instructed to screen their patients to increase the odds that they will be able to use the drug safely.
Evidence Connecting Dupixent to CTCL Continues to Pile Up
There were several published analyses of the FDA Adverse Event Reporting System (FAERS) database of events reported between 2017 and 2023 that found a strong concern for CTCL with dupilumab.
One published in May 2025 found over 180,000 reports of dupilumab-related adverse events, with the drug having 30 times the proportional reporting ratio for CTCL compared to all other medications in the database.
“These data suggest that dupilumab might be causing an unmasking or progression of CTCL via the same mechanism through which it improves AD,” the researchers wrote.
Yet to date, the manufacturers have still failed to take any action to warn doctors and patients of this dangerous risk, or to suggest that doctors carefully monitor patients in the first year of treatment. Instead, they have continued to heavily market the drug in television advertisements, on social media and the internet, and in print brochures, describing only the positive aspects of the medication.
Types of Personal Injuries Possible with Dupixent
In addition to T-cell lymphoma, patients using Dupixent have reported various other adverse effects, some of which were known and warned about, while others have emerged through post-market surveillance.
- Eye problems, including eye inflammation
- Injection site reactions
- Allergic reactions
- Blood abnormalities, including eosinophilia, which means having too many eosinophils (a type of white blood cell) in the blood
- Increased infection risk
- T-cell lymphoma
Lawsuits Against Dupixent Manufacturers
As more people become aware of the connection between Dupixent and T-cell lymphoma, some have begun filing lawsuits against manufacturers Regeneron Pharmaceuticals and Sanofi-Aventis. These lawsuits typically claim that the makers of the drug failed to adequately warn doctors and patients about the risk of developing lymphoma while taking the drug.
In one notable case filed in Tennessee, a plaintiff alleged that Dupixent caused or significantly contributed to the development and progression of a deceased woman’s T-cell lymphoma. The plaintiff claimed that despite mounting evidence of the lymphoma risk, the manufacturers failed to update the drug’s warning label to adequately inform healthcare providers and patients.
Other patients and their families affected by Dupixent-related cancer are likely to soon seek compensation for the serious harm they suffered, including medical expenses for cancer treatments, lost wages, pain and suffering, and in cases where the patient died from lymphoma, wrongful death damages.
Chaffin Luhana Investigates Dupixent T-Cell Lymphoma Cases
The attorneys at Chaffin Luhana are currently investigating cases involving patients who developed T-cell lymphoma and other serious complications after using Dupixent. The firm is examining the scientific evidence, analyzing the drug manufacturers’ conduct, and working to hold Regeneron and Sanofi accountable for the harm their product may have caused.
As more patients learn about this issue, we expect the number of lawsuits to increase. The evidence continues to mount, with new studies published regularly documenting the association and exploring the mechanisms that may explain it.
If you or a loved one was diagnosed with T-cell lymphoma, CTCL, PTCL, mycosis fungoides, Sézary syndrome, or another form of lymphoma after using Dupixent, contactone of our personal injury lawyers today. We are passionate advocates for people who were harmed by drugs that were supposed to help them. We stand ready to assist you in pursuing fair compensation for your injuries to the fullest extent allowed under the law.
Call us today at 888-480-1123 to learn more about your legal options.