Dupixent CTCL Lawsuit Filed Over Diagnosis of Both Mycosis Fungoides and Sezary Syndrome

Doctors should have been warned to monitor Dupixent patients for evidence of developing T-cell lymphoma before prescribing the drug, lawsuit claims.

After receiving Dupixent injections for a year to treat his eczema, a Louisiana man claims he developed a rare form of blood cancer that could have been avoided if the manufacturers had properly tested the drug and warned the medical community about its potential risks.

The complaint (PDF) was brought by Michael Phillips in the U.S. District Court  for the District of New Jersey on December 4, naming Regeneron Pharmaceuticals Inc. and Sanofi-Aventis U.S. LLC as defendants. 

The U.S. Food and Drug Administration (FDA) granted approval of Dupixent (dupilumab) in 2017 as a treatment for atopic dermatitis, also known as atopic eczema, as well as asthma, chronic obstructive pulmonary disease (COPD) and other inflammatory diseases affecting the skin and respiratory tract. Patients are given injections of the drug every two to four weeks.

While it has been marketed as a safe and effective treatment, concerns emerged soon after the drug’s release about a possible link between Dupixent and T-cell lymphoma, a rare cancer affecting white blood cells. Reports have associated the drug with increased risks of cutaneous T-cell lymphoma (CTCL) and peripheral T-cell lymphoma (PTCL).

Phillips’ claim is the second Dupixent lawsuit filed in recent weeks indicating the drug makers knew or should have known of the CTCL and PTCL cancer risks. In early October, Chandra Richardson of Tennessee filed a wrongful death lawsuit against Dupixent manufacturers, alleging her mother, Cynthia Hyde, died of PTCL caused by Dupixent in October 2024.

Phillips indicates he was first prescribed Dupixent in December 2023 after being diagnosed with adult-onset eczema. As a result, he received injections of the medication every two weeks.

Not only does Phillips report that there was no improvement of his condition, but this April he was also diagnosed with mycosis fungoides and sezary syndrome, which are the two most common subtypes of CTCL.

Mycosis fungoides is a form of non-Hodgkin’s lymphoma that begins in the skin, causing red, scaly patches and tumors that can both itch and cause pain. It can spread to lymph nodes, blood and organs. Sezary syndrome is another type of skin-related T-cell lymphoma, which includes red, itchy rashes, scaling, patches and thickening of skin.

According to the lawsuit, Phillips had to undergo total body skin radiation as well as pain medication. However, despite the treatments, doctors have informed Phillips that his Sezary syndrome is metastatic, meaning it has spread to other parts of the body and is in its advanced stages.

“Defendants should have warned patients and prescribers, including Plaintiff and Plaintiff’s treating physicians, that use of Dupixent may result in the development or exacerbation of T-cell lymphoma, which can lead to accelerated disease progression and death. Defendants were on notice of these risks from the peer-reviewed literature, reports of adverse events, presentations at professional conferences, and their own studies.”

– Michael Phillips v. Regeneron Pharmaceuticals Inc. et al

Phillips argues that the manufacturers should have instructed doctors to closely monitor Dupixent patients after treatment begins, regardless of whether they initially respond to the medication. The lawsuit claims those warnings should have alerted physicians to watch for nonresponders and to recognize early signs and symptoms of T-cell lymphoma in patients using the drug.

In addition, the lawsuit indicates the manufacturers should have warned physicians and patients that Dupixent should not be prescribed to individuals with confirmed or suspected T-cell lymphoma, including CTCL. It also argues that all patients should be tested for the cancer through skin biopsy, T-cell receptor gene arrangement testing, and appropriate blood tests before Dupixent treatment begins.

Phillips presents claims of failure to warn, negligence and breach of express warranty.

Dupixent Lawsuits

The complaint is one of what is expected to be many Dupixent lawsuits filed nationwide, as additional former users and families learn of the drug’s link to the development, or acceleration of T-cell lymphoma.

The management of Phillips’ and other early cases could set the pace for how the litigation and similar claims move forward. The two lawsuits filed to date both raise allegations that the drug makers put a desire for profits before the health and safety of users by withholding warnings from consumers and the medical community.

Law firms are now investigating complaints like Phillips’ for individuals who were prescribed the drug for any of its approved uses and later diagnosed with CTCL, PTCL or another T-cell lymphoma subtype. To receive a free consultation to determine if you or a loved one may be eligible to file a lawsuit, submit information for review by a Dupixent lawyer.