Press Release

Itepekimab met the primary endpoint in one of two COPD
phase 3 studies
• AERIFY-1 study met its primary endpoint of a statistically significant reduction in
moderate or severe exacerbations in former smokers regardless of eosinophilic
phenotype and provided a clinically meaningful benefit
• AERIFY-2 study, a second Phase 3 study, did not meet the primary endpoint despite
a benefit seen earlier in the study
• Itepekimab was generally well tolerated in both AERIFY-1 and AERIFY-2
• Sanofi and Regeneron are assessing the data and will discuss with regulatory
authorities to evaluate next steps

Paris and Tarrytown, NY, May 30, 2025. The AERIFY-1 phase 3 study evaluating
itepekimab in former smokers with inadequately controlled chronic obstructive pulmonary
disease (COPD) met the primary endpoint of a statistically significant reduction in moderate
or severe acute exacerbations compared to placebo of 27% at week 52, a clinically
meaningful benefit. The AERIFY-2 phase 3 study did not meet the same primary endpoint,
although a benefit was seen earlier in the trial.

In the studies, patients were randomized to receive itepekimab every two weeks (AERIFY-1:
n=375; AERIFY-2: n=326), every four weeks (AERIFY-1: n=377; AERIFY-2: n=303), or
placebo (AERIFY-1: n=375; AERIFY-2: n=324), which was added to inhaled triple or double
standard-of-care therapy. The primary endpoint analysis for AERIFY-1 and AERIFY-2 was
the reduction in the annualized rate of acute moderate or severe COPD exacerbations with
itepekimab treatment.

The table below summarizes the reductions in moderate or severe exacerbations
(itepekimab compared to placebo) through weeks 24 and 52:

AERIFY-1 AERIFY-2
Week 24 Week 52 Week 24 Week 52
Itepekimab 30% 27%a 18% 2%
every two
weeks
Itepekimab 34% 21%a 21% 12%
every four
weeks
a
Formal significance testing was only performed at 52 weeks in the Phase 3 trials, with significance
achieved for both the every two-week arm and every four-week arm in AERIFY-1

The total number of exacerbations were lower than prospectively anticipated, decreasing
the power of both trials. Enrollment largely occurred during the time of the global COVID
pandemic, which could have contributed to the overall lower exacerbation rates.
Houman Ashrafian, MD, PhD
Executive Vice President, Head of Research and Development at Sanofi
“While we are encouraged by the results of AERIFY-1, the results of both studies merit further
exploration to have a full understanding of the data and the role that IL33 plays in this complex
disease. Certain people with COPD are in desperate need of new treatment options, especially those
who continue to experience exacerbations despite being on maximal therapy, and we remain
committed to discussing these data with regulatory agencies to evaluate our path forward.”

The safety profile of itepekimab was consistent across dosing regimens, and adverse events
(AEs) were generally comparable between treatment and placebo groups. In AERIFY-1, the
overall rates of AEs were 67% and 68% for itepekimab every two weeks and every four
weeks, respectively, compared to 68% for placebo. In AERIFY-2, the overall rates of AEs
were 64% and 71% for itepekimab every two weeks and every four weeks, respectively,
compared to 64% for placebo. In AERIFY-1, the rate of serious infections was 7% for each
itepekimab arm, compared to 10% for placebo. In AERIFY-2, the rate of serious infections
was 10% and 7% for itepekimab every two weeks and every four weeks, respectively,
compared to 7% for placebo. AEs leading to death were 1% for each itepekimab arm
compared to 2% for placebo in AERIFY-1, and 3% for each itepekimab arm compared to 2%
for placebo in AERIFY-2. Anti-drug antibodies were rare and had no apparent impact on
itepekimab drug levels.

Sanofi and Regeneron are reviewing the data and will discuss with regulatory authorities to
evaluate next steps.

Detailed results from these studies will be presented at a future medical meeting.
Itepekimab is currently being evaluated in other studies, including chronic rhinosinusitis
with nasal polyps (CRSwNP), chronic rhinosinusitis without nasal polyps (CRSsNP), and
bronchiectasis.


George D. Yancopoulos, M.D., Ph.D.
Board co-Chair, President and Chief Scientific Officer at Regeneron
“COPD is a particularly complex disease, and novel approaches are needed to address the multiple
underlying biological disease driver. We are proud of our work in this challenging treatment
landscape, bringing Dupixent – the first-ever biologic medicine for COPD – to certain patients who
previously had very limited options remaining. We are encouraged by the initial results from
AERIFY-1 and are carefully reviewing the results from both itepekimab trials to inform next steps.
We remain committed to our broader itepekimab development program. The learnings will be
invaluable as we continue to advance itepekimab in respiratory diseases with unmet need.”


The safety and efficacy of itepekimab are currently under clinical investigation and have not
been fully evaluated by any regulatory authority.

About itepekimab
Itepekimab is a fully human monoclonal antibody that binds to and inhibits interleukin-33 (IL33), an initiator and
amplifier of broad inflammation in COPD. IL33 is thought to be involved in different types of inflammation and is
particularly elevated in the lungs of former smokers.

Itepekimab is being jointly developed by Sanofi and Regeneron under a global collaboration agreement and is
currently in clinical development programs for CRSwNP (phase 3), non-cystic fibrosis bronchiectasis (phase 2), and
CRSsNP (phase 2).

About the AERIFY clinical study program
AERIFY-1 and AERIFY-2 phase 3 studies were randomized, Phase 3, double-blind, placebo-controlled studies that
evaluated the efficacy and safety of itepekimab in 1,127 (AERIFY-1) and 953 (AERIFY-2) adults aged 40-85 years
who were former smokers with moderate-to-severe COPD. Former smokers were defined as those who have not
smoked for at least six months. Treatments were administered subcutaneously and added to double therapy
(inhaled corticosteroid [ICS] plus long-acting beta2-agonist [LABA] or long-acting muscarinic antagonist [LAMA]
plus LABA) or a maximal standard-of-care inhaled triple therapy (ICS, LABA and LAMA).

The primary endpoint for AERIFY-1 and AERIFY-2 was the annualized rate of acute moderate or severe COPD
exacerbations. Moderate exacerbations were defined as those requiring systemic steroids and/or antibiotics. Severe
exacerbations, also assessed separately as a pre-specified endpoint, were defined as those: requiring
hospitalization; more than 24 hours of observation in an emergency department or urgent care facility; or resulting
in death.

The AERIFY program includes two additional ongoing trials: AERIFY-3, a Phase 2 mechanistic study assessing the
impact of itepekimab on airway inflammation in patients with COPD, and AERIFY-4, a Phase 3 study assessing the
long-term safety of itepekimab in patients with COPD.

About Sanofi
Sanofi is an R&D driven, AI-powered biopharma company committed to improving people’s lives and creating
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.

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.

Sanofi Media Relations
Sandrine Guendoul | +33 6 25 09 14 25 | sandrine.guendoul@sanofi.com
Evan Berland | +1 215 432 0234 | evan.berland@sanofi.com
Léo Le Bourhis | +33 6 75 06 43 81 | leo.lebourhis@sanofi.com
Victor Rouault | +33 6 70 93 71 40 | victor.rouault@sanofi.com
Timothy Gilbert | +1 516 521 2929 | timothy.gilbert@sanofi.com
Léa Ubaldi | +33 6 30 19 66 46 | lea.ubaldi@sanofi.com

Sanofi Investor Relations
Thomas Kudsk Larsen |+44 7545 513 693 | thomas.larsen@sanofi.com
Alizé Kaisserian | +33 6 47 04 12 11 | alize.kaisserian@sanofi.com
Felix Lauscher | +1 908 612 7239 | felix.lauscher@sanofi.com
Keita Browne | +1 781 249 1766 | keita.browne@sanofi.com
Nathalie Pham | +33 7 85 93 30 17 | nathalie.pham@sanofi.com
Tarik Elgoutni | +1 617 710 3587 | tarik.elgoutni@sanofi.com
Thibaud Châtelet | +33 6 80 80 89 90 | thibaud.chatelet@sanofi.com
Yun Li | +33 6 84 00 90 72 | yun.li3@sanofi.com

Regeneron Media Relations
Hannah Kwagh | +1 914-847-6314| hannah.kwagh@regeneron.com

Regeneron Investor Relations
Mark Hudson | +1 914-847-3482 | mark.hudson@regeneron.com

Sanofi forward-looking statements
This press release contains forward-looking statements as defined in the Private Securities Litigation Reform Act of 1995, as
amended. Forward-looking statements are statements that are not historical facts. These statements include projections and
estimates regarding the marketing and other potential of the product, or regarding potential future revenues from the product.
Forward-looking statements are generally identified by the words “expects”, “anticipates”, “believes”, “intends”, “estimates”,
“plans”, and similar expressions. Although Sanofi’s management believes that the expectations reflected in such forward-looking
statements are reasonable, investors are cautioned that forward-looking information and statements are subject to various risks
and uncertainties, many of which are difficult to predict and generally beyond the control of Sanofi, that could cause actual results
and developments to differ materially from those expressed in, or implied or projected by, the forward-looking information and
statements. These risks and uncertainties include among other things, unexpected regulatory actions or delays, or government
regulation generally, that could affect the availability or commercial potential of the product, the fact that product may not be
commercially successful, the uncertainties inherent in research and development, including future clinical data and analysis of
existing clinical data relating to the product, including post marketing, unexpected safety, quality or manufacturing issues,
competition in general, risks associated with intellectual property and any related future litigation and the ultimate outcome of such
litigation, and volatile economic and market conditions, and the impact that global crises may have on us, our customers, suppliers,
vendors, and other business partners, and the financial condition of any one of them, as well as on our employees and on the global
economy as a whole. The risks and uncertainties also include the uncertainties discussed or identified in the public filings with the
SEC and the AMF made by Sanofi, including those listed under “Risk Factors” and “Cautionary Statement Regarding Forward-
Looking Statements” in Sanofi’s annual report on Form 20-F for the year ended December 31, 2024. Other than as required by
applicable law, Sanofi does not undertake any obligation to update or revise any forward-looking information or statements.

All trademarks mentioned in this press release are the property of the Sanofi group except for VelociSuite and Regeneron Genetics
Center.

Regeneron forward-looking statements and use of digital media
This press release includes forward-looking statements that involve risks and uncertainties relating to future events and the future
performance of Regeneron Pharmaceuticals, Inc. (“Regeneron” or the “Company”), and actual events or results may differ
materially from these forward-looking statements. Words such as “anticipate,” “expect,” “intend,” “plan,” “believe,” “seek,”
“estimate,” variations of such words, and similar expressions are intended to identify such forward-looking statements, although not
all forward-looking statements contain these identifying words. These statements concern, and these risks and uncertainties
include, among others, the nature, timing, and possible success and therapeutic applications of products marketed or otherwise
commercialized by Regeneron and/or its collaborators or licensees (collectively, “Regeneron’s Products”) and product candidates
being developed by Regeneron and/or its collaborators or licensees (collectively, “Regeneron’s Product Candidates”) and research
and clinical programs now underway or planned, including without limitation itepekimab in adults who were former smokers with
inadequately controlled chronic obstructive pulmonary disease (“COPD”) and other potential indications; the likelihood, timing, and
scope of possible regulatory approval and commercial launch of Regeneron’s Product Candidates and new indications for
Regeneron’s Products, such as itepekimab for the treatment of COPD as discussed in this press release as well as itepekimab for the
treatment of chronic rhinosinusitis with nasal polyps, non-cystic fibrosis bronchiectasis, and chronic rhinosinusitis without nasal
polyps; any feedback that may be provided by regulatory authorities on the results from the AERIFY-1 and AERIFY-2 trials
discussed in this press release, including the impact of any such feedback on any potential regulatory approval of itepekimab;
uncertainty of the utilization, market acceptance, and commercial success of Regeneron’s Products and Regeneron’s Product
Candidates and the impact of studies (whether conducted by Regeneron or others and whether mandated or voluntary), including
the studies discussed or referenced in this press release, on any of the foregoing or any potential regulatory approval of
Regeneron’s Products and Regeneron’s Product Candidates (such as itepekimab); the ability of Regeneron’s collaborators, licensees,
suppliers, or other third parties (as applicable) to perform manufacturing, filling, finishing, packaging, labeling, distribution, and
other steps related to Regeneron’s Products and Regeneron’s Product Candidates; the ability of Regeneron to manage supply chains
for multiple products and product candidates and risks associated with tariffs and other trade restrictions; safety issues resulting
from the administration of Regeneron’s Products and Regeneron’s Product Candidates (such as itepekimab) in patients, including
serious complications or side effects in connection with the use of Regeneron’s Products and Regeneron’s Product Candidates in
clinical trials; determinations by regulatory and administrative governmental authorities which may delay or restrict Regeneron’s
ability to continue to develop or commercialize Regeneron’s Products and Regeneron’s Product Candidates; ongoing regulatory
obligations and oversight impacting Regeneron’s Products, research and clinical programs, and business, including those relating to
patient privacy; the availability and extent of reimbursement or copay assistance for Regeneron’s Products from third-party payors
and other third parties, including private payor healthcare and insurance programs, health maintenance organizations, pharmacy
benefit management companies, and government programs such as Medicare and Medicaid; coverage and reimbursement
determinations by such payors and other third parties and new policies and procedures adopted by such payors and other third
parties; changes in laws, regulations, and policies affecting the healthcare industry; competing drugs and product candidates that
may be superior to, or more cost effective than, Regeneron’s Products and Regeneron’s Product Candidates (including biosimilar
versions of Regeneron’s Products); the extent to which the results from the research and development programs conducted by
Regeneron and/or its collaborators or licensees may be replicated in other studies and/or lead to advancement of product
candidates to clinical trials, therapeutic applications, or regulatory approval; unanticipated expenses; the costs of developing,
producing, and selling products; the ability of Regeneron to meet any of its financial projections or guidance and changes to the
assumptions underlying those projections or guidance; the potential for any license, collaboration, or supply agreement, including
Regeneron’s agreements with Sanofi and Bayer (or their respective affiliated companies, as applicable), to be cancelled or
terminated; the impact of public health outbreaks, epidemics, or pandemics on Regeneron's business; and risks associated with
litigation and other proceedings and government investigations relating to the Company and/or its operations (including the pending
civil proceedings initiated or joined by the U.S. Department of Justice and the U.S. Attorney's Office for the District of
Massachusetts), risks associated with intellectual property of other parties and pending or future litigation relating thereto (including
without limitation the patent litigation and other related proceedings relating to EYLEA® (aflibercept) Injection), the ultimate
outcome of any such proceedings and investigations, and the impact any of the foregoing may have on Regeneron’s business,
prospects, operating results, and financial condition. A more complete description of these and other material risks can be found in
Regeneron’s filings with the U.S. Securities and Exchange Commission, including its Form 10-K for the year ended December 31,
2024 and its Form 10-Q for the quarterly period ended March 31, 2025. Any forward-looking statements are made based on
management’s current beliefs and judgment, and the reader is cautioned not to rely on any forward-looking statements made by
Regeneron. Regeneron does not undertake any obligation to update (publicly or otherwise) any forward-looking statement,
including without limitation any financial projection or guidance, whether as a result of new information, future events, or otherwise.
Regeneron uses its media and investor relations website and social media outlets to publish important information about the
Company, including information that may be deemed material to investors. Financial and other information about Regeneron is
routinely posted and is accessible on Regeneron's media and investor relations website (https://investor.regeneron.com) and its
LinkedIn page (https://www.linkedin.com/company/regeneron-pharmaceuticals).