Regeneron Pharmaceuticals, Inc. (NASDAQ:?REGN) and Sanofi today announced positive pivotal Phase 3 results from a trial evaluating Dupixent^??(dupilumab) in adults with uncontrolled prurigo nodularis, a chronic type 2 inflammatory skin disease that causes extreme itch and skin lesions. The trial met its primary and all key secondary endpoints, showing that Dupixent significantly reduced itch and skin lesions compared to placebo in this investigational setting. The impact of uncontrolled prurigo nodularis on quality of life is one of the highest among inflammatory skin diseases with intense, chronic itch. "Prurigo nodularis is an underdiagnosed disease with immense physical and emotional burden for the 74,000 people in the U.S. who are unable to control their disease with topical steroids and otherwise do not have an approved treatment option," said?George D. Yancopoulos, M.D., Ph.D., President and Chief Scientific Officer at Regeneron. "These patients are left to cope with severe itching and painful nodules that, in turn, significantly impair one's quality of life with many resorting to immunosuppressants and some to antidepressants. These results show ? for the first time in a Phase 3 prurigo nodularis trial ? that a systemic medicine was able to address the most debilitating symptoms such as itch without broadly suppressing the immune system, building on the promise of Dupixent in a broad range of serious dermatologic, respiratory and gastrointestinal diseases." People with prurigo nodularis experience intense, persistent itch, with thick skin lesions (called nodules) that can cover most of the body. It is often described as painful with burning, stinging and tingling of the skin. The debilitating signs and symptoms of prurigo nodularis can negatively impact health-related quality of life, including mental health, activities of daily living and social interactions. There are no approved systemic treatments for prurigo nodularis. High-potency topical steroids are commonly used, which are associated with safety risks if used long-term. "We are encouraged that patients in this trial experienced a significant reduction in itch and skin lesions, especially given that prior to enrollment nearly all patients had severe itch and nearly 40% had 100 or more nodules covering their body," said?John Reed, M.D., Ph.D., Global Head of Research and Development at Sanofi. "These data are an important step forward in furthering our knowledge of the role that targeting IL-4 and IL-13 can play in the treatment of skin diseases that cause extreme itch. We are committed to continuing to leverage the robust Dupixent clinical program to transform the understanding of the science behind a number of type 2 inflammatory diseases and look forward to presenting the full results at a future medical congress." In the Phase 3 PRIME2 trial, topline results comparing Dupixent (n=78) to placebo (n=82) showed:

• 37% of Dupixent patients experienced a clinically meaningful reduction in itch from baseline compared to 22% of placebo patients (p=0.0216) at week 12, the primary endpoint.
• At week 24, nearly three times as many Dupixent patients experienced a clinically meaningful reduction in itch from baseline: 58% of Dupixent patients compared to 20% of placebo patients (p<0.0001).
• At week 24, nearly three times as many Dupixent patients achieved clear or almost clear skin: 45% of Dupixent patients compared to 16% of placebo patients (p<0.0001).
• Dupixent patients experienced significantly greater improvements in measures of health-related quality of life, skin pain and symptoms of anxiety and depression.

The safety results of the trial were generally consistent with the known safety profile of Dupixent in its approved indications. The occurrences of treatment-emergent adverse events were generally similar between Dupixent and placebo groups (57% [44/77] Dupixent, 51% [42/82] placebo). Rates of conjunctivitis (6% [5/77] Dupixent, 0% [0/82] placebo) and herpes viral infections (6% [5/77] Dupixent, 0% [0/82] placebo) were similar to what was previously observed in atopic dermatitis trials, and there was a numerically lower rate of skin infections observed with Dupixent (5% [4/77] Dupixent, 9% [7/82] placebo). Additionally, 3% (2/77) of Dupixent patients and 30% (25/82) of placebo patients discontinued prior to week 24. An additional trial in the LIBERTY-PN PRIME clinical program, PRIME, is fully enrolled. PRIME has a similar trial design and is expected to read out in in the first half of 2022. Regeneron and Sanofi plan to begin regulatory submissions in 2022. The potential use of Dupixent in prurigo nodularis is currently under clinical development, and the safety and efficacy have not been fully evaluated by any regulatory authority. About the Trial PRIME2, part of the LIBERTY-PN PRIME clinical program, is a randomized, Phase 3, double-blind, placebo-controlled trial that evaluated the efficacy and safety of Dupixent in 160 adults with prurigo nodularis inadequately controlled with topical prescription therapies or with whom those therapies were not advisable. During the 24-week treatment period, patients received Dupixent or placebo every two weeks with or without topical treatments (low- or medium-dose topical corticosteroids or topical calcineurin inhibitors were continued if patients were using these treatments at randomization). The primary endpoint evaluated the proportion of patients with clinically meaningful improvement in itch at week 12 (measured by a =4-point reduction in Worst-Itch Numeric Rating Scale [WI-NRS] of 0-10). Key secondary endpoints included the proportion of patients with clinically meaningful improvement in itch at week 24 and the proportion of patients with clear or almost clear skin at week 24 (measured by a score of 0 or 1 on the Investigator's Global Assessment PN-Stage [IGA PN-S] 0-4 scale). Additional secondary endpoints included health-related quality of life (measured by change in baseline according to the 0-30 point Dermatology Life Quality Index), skin pain (measured by change in baseline on a 0-10 scale), and symptoms of anxiety and depression (measured by change in baseline according to a 0-42 Hospital Anxiety and Depression scale). The average age in the trial was 49 years and 64% were female. Approximately 33% of patients were Asian, 13% were Latino/Hispanic and 5% were Black/African American. In the trial, 46% of patients had at least one coexisting type 2 inflammatory disease. About 24% of patients enrolled had prior history with systemic (non-steroidal) immunosuppressants and 11% had been treated with antidepressants. About Dupixent Dupixent, which was invented using Regeneron's proprietary?VelocImmune^??technology, is a fully human monoclonal antibody that inhibits the signaling of the interleukin-4 (IL-4) and interleukin-13 (IL-13) pathways and is not an immunosuppressant. IL-4 and IL-13 are key and central drivers of the type 2 inflammation that plays a major role in atopic dermatitis, asthma and chronic rhinosinusitis with nasal polyposis (CRSwNP). Dupixent is currently approved in the U.S.,?Europe,?Japan?and other countries around the world for use in specific patients with moderate-to-severe atopic dermatitis, as well as certain patients with asthma or CRSwNP in different age populations. Dupixent is also approved in one or more of these indications in more than 60 countries around the world and more than 300,000 patients have been treated globally. About Regeneron's VelocImmune Technology Regeneron's?VelocImmune?technology utilizes a proprietary genetically engineered mouse platform endowed with a genetically humanized immune system to produce optimized fully human antibodies. When Regeneron's President and Chief Scientific Officer?George D. Yancopoulos?was a graduate student with his mentor?Frederick W. Alt?in 1985, they were the first to?envision?making such a genetically humanized mouse, and Regeneron has spent decades inventing and developing?VelocImmune?and related?VelociSuite^??technologies. Dr. Yancopoulos and his team have used?VelocImmune?technology to create approximately a quarter of all original, FDA-approved or authorized fully human monoclonal antibodies currently available. This includes Dupixent, REGEN-COV^??(casirivimab and imdevimab), Libtayo^??(cemiplimab-rwlc), Praluent^??(alirocumab), Kevzara^??(sarilumab), Evkeeza^??(evinacumab-dgnb) and Inmazeb^??(atoltivimab, maftivimab, and odesivimab-ebgn). Dupilumab Development Program To date, dupilumab has been studied across 60 clinical trials involving more than 10,000 patients with various chronic diseases driven in part by type 2 inflammation. Regeneron and Sanofi are studying dupilumab in a broad range of diseases driven by type 2 inflammation or other allergic processes, chronic obstructive pulmonary disease with evidence of type 2 inflammation (Phase 3), pediatric atopic dermatitis (6 months to 5 years of age, Phase 3), eosinophilic esophagitis (Phase 3), bullous pemphigoid (Phase 3), prurigo nodularis (Phase 3), chronic spontaneous urticaria (Phase 3), chronic inducible urticaria-cold (Phase 3), chronic rhinosinusitis without nasal polyposis (Phase 3), allergic fungal rhinosinusitis (Phase 3), allergic bronchopulmonary aspergillosis (Phase 3) and peanut allergy (Phase 2). 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. Dupilumab is being jointly developed by Regeneron and Sanofi under a global collaboration agreement. U.S. Indications DUPIXENT is a prescription medicine used:

• to treat people aged 6 years and older with moderate-to-severe atopic dermatitis (eczema) that is not well controlled with prescription therapies used on the skin (topical), or who cannot use topical therapies. DUPIXENT can be used with or without topical corticosteroids. It is not known if DUPIXENT is safe and effective in children with atopic dermatitis under 6 years of age.
• with other asthma medicines for the maintenance treatment of moderate-to-severe eosinophilic or oral steroid dependent asthma in people aged 6 years and older whose asthma is not controlled with their current asthma medicines. DUPIXENT helps prevent severe asthma attacks (exacerbations) and can improve your breathing. DUPIXENT may also help reduce the amount of oral corticosteroids you need while preventing severe asthma attacks and improving your breathing. DUPIXENT is not used to treat sudden breathing problems. It is not known if DUPIXENT is safe and effective in children with asthma under 6 years of age.
• with other medicines for the maintenance treatment of chronic rhinosinusitis with nasal polyposis (CRSwNP) in adults whose disease is not controlled. It is not known if DUPIXENT is safe and effective in children with chronic rhinosinusitis with nasal polyposis under 18 years of age.

IMPORTANT SAFETY INFORMATION FOR U.S. PATIENTS Do not use?if you are allergic to dupilumab or to any of the ingredients in DUPIXENT^?. Before using DUPIXENT, tell your healthcare provider about all your medical conditions, including if you:

• have eye problems
• have a parasitic (helminth) infection
• are scheduled to receive any vaccinations. You should not receive a "live vaccine" if you are treated with DUPIXENT.
• are pregnant or plan to become pregnant. It is not known whether DUPIXENT will harm your unborn baby.
  • A pregnancy registry for women who take DUPIXENT during pregnancy collects information about the health of you and your baby. To enroll or get more information call 1-877-311-8972 or go to?https://mothertobaby.org/ongoing-study/dupixent/
• are breastfeeding or plan to breastfeed. It is not known whether DUPIXENT passes into your breast milk.

Tell your healthcare provider about all the medicines you take, including prescription and over-the-counter medicines, vitamins and herbal supplements. Especially tell your healthcare provider if you are taking oral, topical, or inhaled corticosteroid medicines; have asthma and use an asthma medicine; or have atopic dermatitis or CRSwNP, and also have asthma.?Do not?change or stop your corticosteroid medicine or other asthma medicine without talking to your healthcare provider. This may cause other symptoms that were controlled by the corticosteroid medicine or other asthma medicine to come back. DUPIXENT can cause serious side effects, including:

• Allergic reactions (hypersensitivity), including a severe reaction known as anaphylaxis.?Stop using DUPIXENT and tell your healthcare provider or get emergency help right away if you get any of the following symptoms: breathing problems, fever, general ill feeling, swollen lymph nodes, swelling of the face, mouth and tongue, hives, itching, fainting, dizziness, feeling lightheaded (low blood pressure), joint pain, or skin rash.
• Eye problems. Tell your healthcare provider if you have any new or worsening eye problems, including eye pain or changes in vision.
• Inflammation of your blood vessels. Rarely, this can happen in people with asthma who receive DUPIXENT. This may happen in people who also take a steroid medicine by mouth that is being stopped or the dose is being lowered. It is not known whether this is caused by DUPIXENT. Tell your healthcare provider right away if you have: rash, shortness of breath, persistent fever, chest pain, or a feeling of pins and needles or numbness of your arms or legs.

The most common side effects by indication are as follows:

• Atopic dermatitis:?injection site reactions, eye and eyelid inflammation, including redness, swelling, and itching, and cold sores in your mouth or on your lips.
• Asthma:?injection site reactions, pain in the throat (oropharyngeal pain), high count of a certain white blood cell (eosinophilia), and parasitic (helminth) infections.
• Chronic rhinosinusitis with nasal polyposis:?injection site reactions, eye and eyelid inflammation, including redness, swelling, and itching, high count of a certain white blood cell (eosinophilia), trouble sleeping (insomnia), toothache, gastritis, and joint pain (arthralgia).

Tell your healthcare provider if you have any side effect that bothers you or that does not go away. These are not all the possible side effects of DUPIXENT. Call your doctor for medical advice about side effects. You are encouraged to report negative side effects of prescription drugs to the FDA. Visit?www.fda.gov/medwatch, or call 1-800-FDA-1088. Use DUPIXENT exactly as prescribed. Your healthcare provider will tell you how much DUPIXENT to inject and how often to inject it. DUPIXENT is an injection given under the skin (subcutaneous injection). If your healthcare provider decides that you or a caregiver can give DUPIXENT injections, you or your caregiver should receive training on the right way to prepare and inject DUPIXENT.?Do not?try to inject DUPIXENT until you have been shown the right way by your healthcare provider. In children 12 years of age and older, it is recommended that DUPIXENT be administered by or under supervision of an adult. In children younger than 12 years of age, DUPIXENT should be given by a caregiver. Please see accompanying full?Prescribing Information?including Patient Information. About Regeneron Regeneron (NASDAQ:?REGN) is a leading biotechnology company that invents life-transforming medicines for people with serious diseases. Founded and led for over 30 years by physician-scientists, our unique ability to repeatedly and consistently translate science into medicine has led to nine FDA-approved treatments and numerous product candidates in development, almost all 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, pain, hematologic conditions, infectious diseases and rare diseases. Regeneron is accelerating and improving the traditional drug development process through our proprietary?VelociSuite?technologies, such as?VelocImmune, which uses unique genetically humanized mice to produce optimized fully human antibodies and bispecific antibodies, and through ambitious research initiatives such as the Regeneron Genetics Center, which is conducting one of the largest genetics sequencing efforts in the world. For additional information about the company, please visit?www.regeneron.com?or follow @Regeneron on Twitter. About Sanofi Sanofi is dedicated to supporting people through their health challenges. We are a global biopharmaceutical company focused on human health. We prevent illness with vaccines, provide innovative treatments to fight pain and ease suffering. We stand by the few who suffer from rare diseases and the millions with long-term chronic conditions. With more than 100,000 people in 100 countries, Sanofi is transforming scientific innovation into healthcare solutions around the globe. 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 impact of SARS-CoV-2 (the virus that has caused the COVID-19 pandemic) on Regeneron's business and its employees, collaborators, and suppliers and other third parties on which Regeneron relies, Regeneron's and its collaborators' ability to continue to conduct research and clinical programs, Regeneron's ability to manage its supply chain, net product sales of products marketed or otherwise commercialized by Regeneron and/or its collaborators (collectively, "Regeneron's Products"), and the global economy; the nature, timing, and possible success and therapeutic applications of Regeneron's Products and product candidates being developed by Regeneron and/or its collaborators (collectively, "Regeneron's Product Candidates") and research and clinical programs now underway or planned, including without limitation Dupixent^??(dupilumab); 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?Dupixent for the treatment of prurigo nodularis, chronic obstructive pulmonary disease with evidence of type 2 inflammation, pediatric atopic dermatitis, eosinophilic esophagitis, bullous pemphigoid, prurigo nodularis, chronic spontaneous urticaria, chronic inducible urticaria-cold, chronic rhinosinusitis without nasal polyposis, allergic fungal rhinosinusitis, allergic bronchopulmonary aspergillosis, peanut allergy, and other potential indications;?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 study discussed in this press release, on any of the foregoing or any potential regulatory approval of Regeneron's Products (such as Dupixent) and Regeneron's Product Candidates; the ability of Regeneron's collaborators, 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; safety issues resulting from the administration of Regeneron's Products (such as Dupixent) and Regeneron's Product Candidates 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, including without limitation Dupixent; 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 of Regeneron's Products from third-party payers, including private payer 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 payers and new policies and procedures adopted by such payers; competing drugs and product candidates that may be superior to, or more cost effective than, Regeneron's Products and Regeneron's Product Candidates; the extent to which the results from the research and development programs conducted by Regeneron and/or its collaborators 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, Bayer, and Teva Pharmaceutical Industries Ltd. (or their respective affiliated companies, as applicable), to be cancelled or terminated; and 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, Dupixent, Praluent^??(alirocumab), and REGEN-COV^TM?(casirivimab and imdevimab)), other litigation and other proceedings and government investigations relating to the Company and/or its operations, 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, 2020?and its Form 10-Q for the quarterly period ended?June 30, 2021. 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 (http://newsroom.regeneron.com) and its Twitter feed (http://twitter.com/regeneron). 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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 COVID-19 will 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. Any material effect of COVID-19 on any of the foregoing could also adversely impact us. This situation is changing rapidly and additional impacts may arise of which we are not currently aware and may exacerbate other previously identified risks. 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, 2020. Other than as required by applicable law, Sanofi does not undertake any obligation to update or revise any forward-looking information or statements.