Press Release

Sanofi and Regeneron’s Dupixent approved as the first
targeted medicine in the EU in over a decade for chronic
spontaneous urticaria
• Approval based on phase 3 studies showing Dupixent significantly reduced itch and
hives at 24 weeks compared to placebo
• In the EU, there are approximately 270,000 adults and adolescents aged 12 years and
older living with CSU who remain symptomatic despite standard-of-care antihistamine
treatment
• Dupixent, which inhibits IL4 and IL13, two key and central drivers of type 2
inflammation, is now approved for patients across seven chronic, inflammatory
diseases in the EU

Paris and Tarrytown, NY, November 25, 2025. The European Commission has approved
Dupixent (dupilumab) for the treatment of moderate-to-severe chronic spontaneous urticaria
(CSU) in adult and adolescent patients 12 years and above with inadequate response to
histamine-1 antihistamines (H1AH) and who are naive to anti- immunoglobulin-E (IgE)
therapy for CSU. Eligible patients can use Dupixent as a first-line targeted treatment option.

“The unpredictable nature of chronic spontaneous urticaria leaves patients
guessing when they’ll have their next outbreak of disruptive, debilitating hives and
itch, which can make life challenging,” said Tonya Winders, President & CEO,
Global Allergy & Airways Patient Platform. “Dupixent is proven to reduce these
intense symptoms and has the potential to make a positive impact on people
struggling to control this disease.”

“Standard-of-care, first-line treatment options like antihistamines offer limited
relief for many people living with uncontrolled chronic spontaneous urticaria,
leaving them to face unrelenting cycles of itch and hives,” said Alyssa Johnsen,
MD, PhD, Global Therapeutic Area Head, Immunology Development at Sanofi.
“Dupixent significantly reduced these symptoms of CSU and led to more patients
experiencing well-controlled disease or a complete response compared to placebo
in two phase 3 studies. Now, eligible patients with CSU in the EU have a new
option that is proven to reduce itch and hives.”

The approval is based on data from two phase 3 clinical studies in the LIBERTY-CUPID program
(NCT04180488). Study A and Study C included 284 patients aged 12 years and older who
were symptomatic despite the use of antihistamines and who were naïve to anti-IgE therapy.
Both studies assessed Dupixent as an add-on therapy to standard-of-care antihistamines
compared to antihistamines alone and demonstrated Dupixent significantly reduced urticaria
activity (a composite of itch and hives), and individual measures of itch and hive severity
compared to placebo at 24 weeks. Dupixent also increased the percentage of patients with
well-controlled disease and complete response at 24 weeks compared to placebo. Study B
(n=108) provided additional safety data and evaluated Dupixent in patients aged 12 years
and older who were inadequate responders or intolerant to anti-IgE therapy and symptomatic
despite antihistamine use.
Safety results from Study A, Study B and Study C were generally consistent with the known
safety profile of Dupixent in its approved indications. The most common adverse reactions for
Dupixent overall are injection site reactions, conjunctivitis, conjunctivitis allergic, arthralgia,
oral herpes, and eosinophilia. Additional adverse reactions of injection site induration,
injection site dermatitis, and injection site hematoma were reported in the CSU adult and
adolescent studies. Adverse events more commonly observed with Dupixent (≥5%) than
placebo in patients with CSU were injection site reaction, COVID-19, hypertension, CSU, and
accidental overdose.

“The approval of Dupixent for certain adults and adolescents with chronic
spontaneous urticaria in the European Union represents the first innovation for
patients with this disease in over a decade,” said George D. Yancopoulos, MD,
PhD, Board co-Chair, President and Chief Scientific Officer at Regeneron.
“Physicians now have a new approach for CSU with Dupixent, as the only
treatment that inhibits IL4 and IL13, two key drivers of type 2 inflammation, and
can offer patients significant improvement in debilitating itch and hives. This
approval further demonstrates the ability of Dupixent to advance the treatment
landscape for yet another chronic type 2 inflammatory disease, with a well-
established safety profile across its indications.”

Beyond the EU, Dupixent is also approved for CSU in certain adults and adolescents in several
countries including the US and Japan.

About CSU
CSU is a chronic, inflammatory skin disease driven in part by type 2 inflammation, which
causes sudden and debilitating hives and recurring itch. CSU is typically treated with H1AH,
medicines that target H1 receptors on cells to control symptoms of itch and urticaria.
However, the disease remains uncontrolled despite H1AH treatment in many patients, some
of whom are left with limited alternative treatment options. These individuals continue to
experience symptoms that can be debilitating and significantly impact their quality of life.
More than 270,000 people in the EU aged 12 years and older suffer from CSU that is
inadequately controlled by antihistamines.

About the Dupixent CSU phase 3 study program
The LIBERTY-CUPID phase 3 program evaluating Dupixent for CSU consists of Study A, Study
B, and Study C. These studies were randomized, double-blind, placebo-controlled clinical
studies that evaluated the efficacy and safety of Dupixent as an add-on therapy to standard-
of-care antihistamines compared to antihistamines alone. Studies A and C were replicate
studies that assessed patients aged 6 years and older who remained symptomatic despite the
use of antihistamines and were naïve to anti-IgE therapy. Study B was conducted in patients
aged 12 years and older who were symptomatic despite use of antihistamines and were
inadequate responders or intolerant to anti-IgE therapy. During the 24-week treatment period
in all three studies, all patients received an initial loading dose followed by either 300 mg
Dupixent every two weeks, or 200 mg every two weeks for adolescents weighing <60 kg.

The primary endpoint in all three studies assessed the change from baseline in itch and hives
(weekly urticaria activity score [UAS7], 0-42 scale). The key secondary endpoint (also
assessed at 24 weeks) was change from baseline in itch (measured by the weekly itch severity
score, 0-21 scale). Additional secondary endpoints assessed at 24 weeks evaluated:
• Change from baseline in hives (measured by the weekly hive severity score, 0-21
scale)
• Proportion of patients achieving well-controlled disease status (UAS7 ≤6)
• Proportion of patients with complete response (UAS7=0).
The results from Studies A and B were published in The Journal of Allergy and Clinical
Immunology.

About Dupixent
Dupixent (dupilumab) is an injection administered under the skin (subcutaneous injection) at
different injection sites. In adults with CSU who remain symptomatic despite H1AH treatment,
Dupixent 300 mg is administered every two weeks after an initial loading dose. In patients
aged 12 to 17 years with CSU who remain symptomatic despite H1AH treatment, Dupixent is
administered every two weeks based on weight (200 mg for adolescents ≥30 to <60 kg, 300
mg for adolescents ≥60 kg) after an initial loading dose. Dupixent is intended for use under
the guidance of a healthcare professional and can be given in a clinic or at home after training
by a healthcare professional. In adolescents aged 12 to 17 years, Dupixent should be
administered under the supervision of an adult.

Dupixent is a fully human monoclonal antibody that inhibits the signaling of the interleukin-4
(IL4) and interleukin-13 (IL13) pathways and is not an immunosuppressant. The Dupixent
development program has shown significant clinical benefit and a decrease in type 2
inflammation in phase 3 studies, establishing that IL4 and IL13 are two of the key and central
drivers of the type 2 inflammation that plays a major role in multiple related and often co-
morbid diseases.

Dupixent has received regulatory approvals in more than 60 countries in one or more
indications including certain patients with atopic dermatitis, asthma, chronic rhinosinusitis
with nasal polyps, eosinophilic esophagitis, prurigo nodularis, chronic spontaneous urticaria,
chronic obstructive pulmonary disease, and bullous pemphigoid in different age populations.
More than 1.3 million patients are being treated with Dupixent globally.

Dupilumab development program
Dupilumab is being jointly developed by Sanofi and Regeneron under a global collaboration
agreement. To date, dupilumab has been studied across more than 60 clinical studies
involving more than 10,000 patients with various chronic diseases driven in part by type 2
inflammation.

In addition to the currently approved indications, Sanofi and Regeneron are studying
dupilumab in a broad range of diseases driven by type 2 inflammation or other allergic
processes in phase 3 studies, including chronic pruritus of unknown origin, lichen simplex
chronicus, and allergic fungal rhinosinusitis. These potential uses of dupilumab are currently
under clinical investigation, and the safety and efficacy in these conditions have not been fully
evaluated by any regulatory authority.

About Regeneron
Regeneron (NASDAQ: REGN) is a leading biotechnology company that invents, develops and
commercializes life-transforming medicines for people with serious diseases. Founded and led
by physician-scientists, our unique ability to repeatedly and consistently translate science into
medicine has led to numerous approved treatments and product candidates in development,
most of which were homegrown in our laboratories. Our medicines and pipeline are designed
to help patients with eye diseases, allergic and inflammatory diseases, cancer, cardiovascular
and metabolic diseases, neurological diseases, hematologic conditions, infectious diseases,
and rare diseases.

Regeneron pushes the boundaries of scientific discovery and accelerates drug
development using our proprietary technologies, such as VelociSuite®, which produces
optimized fully human antibodies and new classes of bispecific antibodies. We are shaping the
next frontier of medicine with data-powered insights from the Regeneron Genetics
Center® and pioneering genetic medicine platforms, enabling us to identify innovative targets
and complementary approaches to potentially treat or cure diseases.

For more information, please visit www.Regeneron.com or follow Regeneron on LinkedIn,
Instagram, Facebook or X.

About Sanofi
Sanofi is an R&D driven, AI-powered biopharma company committed to improving people’s
lives and delivering compelling growth. We apply our deep understanding of the immune
system to invent medicines and vaccines that treat and protect millions of people around the
world, with an innovative pipeline that could benefit millions more. Our team is guided by one
purpose: we chase the miracles of science to improve people’s lives; this inspires us to drive
progress and deliver positive impact for our people and the communities we serve, by
addressing the most urgent healthcare, environmental, and societal challenges of our time.

Sanofi is listed on EURONEXT: SAN and NASDAQ: SNY.

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