Itepekimab

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 benefitAERIFY-2 study, a second Phase 3 study, did not meet the primary endpoint despite a benefit seen earlier in the studyItepekimab was generally well tolerated in both AERIFY-1 and AERIFY-2Sanofi 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 every two weeks 30% 27%a 18% 2% Itepekimab every four weeks 34% 21%a 21% 12% 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, PhDExecutive 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 itepekimabItepekimab 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 programAERIFY-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 RegeneronRegeneron (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 RelationsSandrine Guendoul | +33 6 25 09 14 25 | sandrine.guendoul@sanofi.com Evan Berland | +1 215 432 0234 | evan.berland@sanofi.comLéo Le Bourhis | +33 6 75 06 43 81 | leo.lebourhis@sanofi.comVictor Rouault | +33 6 70 93 71 40 | victor.rouault@sanofi.comTimothy Gilbert | +1 516 521 2929 | timothy.gilbert@sanofi.comLéa Ubaldi | +33 6 30 19 66 46 | lea.ubaldi@sanofi.com Sanofi Investor RelationsThomas Kudsk Larsen |+44 7545 513 693 | thomas.larsen@sanofi.comAlizé Kaisserian | +33 6 47 04 12 11 | alize.kaisserian@sanofi.comFelix Lauscher | +1 908 612 7239 | felix.lauscher@sanofi.comKeita Browne | +1 781 249 1766 | keita.browne@sanofi.comNathalie Pham | +33 7 85 93 30 17 | nathalie.pham@sanofi.comTarik Elgoutni | +1 617 710 3587 | tarik.elgoutni@sanofi.comThibaud Châtelet | +33 6 80 80 89 90 | thibaud.chatelet@sanofi.comYun Li | +33 6 84 00 90 72 | yun.li3@sanofi.com Regeneron Media RelationsHannah Kwagh | +1 914-847-6314| hannah.kwagh@regeneron.com Regeneron Investor RelationsMark Hudson | +1 914-847-3482 | mark.hudson@regeneron.com Sanofi forward-looking statementsThis 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). Attachment Press Release

Sanofi and Regeneron Pharmaceuticals on Friday reported a mixed bag of results from a pair of pivotal Phase III trials evaluating their IL-33 monoclonal antibody itepekimab (earlier REGN3500) to manage chronic obstructive pulmonary disease (COPD) in ex-smokers. While AERIFY-1 met its main efficacy goal, AERIFY-2 fell short on the primary outcome despite early treatment benefits, sending the respective companies’ shares tumbling by over 6% and 11% in premarket trading.AERIFY-1 and AERIFY-2, respectively randomised 1127 and 953 former smokers aged 40-85 years with inadequately managed moderate-to-severe COPD to receive either subcutaneous itepekimab every two weeks, four weeks, or placebo on top of inhaled triple or double standard-of-care therapy.Results showed that in AERIFY-1, both itepekimab regimens achieved statistical significance, with the every-two-week schedule reducing moderate or severe exacerbations by 27% and the every-four-week regimen by 21% compared with placebo. However, in AERIFY-2, the respective itepekimab regimens had non-significant impact on exacerbations at 52 weeks versus placebo — only 2% and 12% reductions, despite early signals of benefit — 18% and 21% reductions at 24 weeks, respectively.On the safety front, itepekimab maintained a consistent safety profile in the two studies, with adverse event (AE) rates comparable between treatment and placebo groups in the range of 64% to 71%. Moreover, rates of serious infection remained low in both studies, ranging from 7% to 10% across treatment arms. "The results of both studies merit further exploration to have a full understanding of the…role that IL-33 plays in this complex disease,” said Houman Ashrafian, R&D head at Sanofi. The partners noted they will engage with the regulatory authorities upon analysis of the complete dataset to evaluate potential pathways forward.Following favourable Phase II data reported at the European Respiratory Society (ERS) meeting last year, a key opinion leader interviewed by FirstWord said they were “cautiously optimistic” that itepekimab would succeed in Phase III, giving it a more than 50% chance.The broader AERIFY programme also includes two ongoing trials —  the Phase II AERIFY-3 study evaluating itepekimab’s effect on airway inflammation in COPD, and the Phase III AERIFY-4 examining its long-term safety in the same population. Besides COPD, the IL-33 inhibitor is also undergoing a bunch of studies in chronic rhinosinusitis and bronchiectasis.