Sanofi and Regeneron Announce FDA Approval of Dupixent (dupilumab), the First Targeted Biologic Therapy for Adults with Moderate-to-Severe Atopic Dermatitis - Dupixent will be available later this week to U

Sanofi and Regeneron Announce FDA Approval of

(dupilumab), the First Targeted Biologic Therapy for Adults with

Moderate-to-Severe Atopic Dermatitis

- Dupixent will be available later this week to U.S. patients suffering from this chronic and debilitating form of eczema -

Paris, France and Tarrytown, New York - March 28, 2017 Sanofi and Regeneron Pharmaceuticals, Inc. announced

today that the U.S. Food and Drug Administration (FDA) approved Dupixent (dupilumab) Injection, the first and only biologic medicine

approved for the treatment of adults with moderate-to-severe atopic dermatitis (AD) whose disease is not adequately controlled with topical prescription therapies, or

when those therapies are not advisable.

moderate-to-severe atopic dermatitis cope with intense, sometimes unbearable symptoms that can impact them for most of their lives, said Julie Block, President

and Chief Executive Officer, National Eczema Association. To date, there have been few options available to treat people with moderate-to-severe atopic

dermatitis who have uncontrolled disease. That s why today s approval of Dupixent is so important for our community. Now we have a treatment that is expected to help address patients suffering from this devastating disease.

Dupixent is a human monoclonal antibody that is designed to specifically inhibit overactive signaling of two key proteins,

IL-4 and IL-13, which are believed to be major drivers of the persistent underlying inflammation in AD. Dupixent comes in a

pre-filled syringe and can be self-administered as a subcutaneous injection every other week after an initial loading dose. Dupixent can be used with or without topical corticosteroids. It should not be used

in patients who are allergic to dupilumab or any of the ingredients in Dupixent.

AD, the most common form of eczema, is a chronic inflammatory disease

with symptoms often appearing as a rash on the skin. Moderate-to-severe AD is characterized by rashes often covering much of the body, and can include intense,

persistent itching and skin dryness, cracking, redness, crusting, and oozing.i Itch is one of the most burdensome symptoms for patients and can be debilitating.ii Of the adults with uncontrolled moderate-to-severe AD in the United States, it is estimated

that 300,000 are most in need of new treatment options.iii

Dupixent is the result of years

of tireless research by our scientists into the underlying causes of allergic and atopic diseases. In atopic dermatitis, Dupixent was shown to help clear the skin and manage the intense itch caused by the disease, said George D.

Yancopoulos, M.D., Ph.D., Founding Scientist, President, and Chief Scientific Officer, Regeneron. Today s approval would not be possible without the dedication of the clinical investigators and the participation of the patients who

took part in the global LIBERTY AD clinical program.

Dupixent was evaluated by the FDA with Priority Review, which is reserved for

medicines that represent potentially significant improvements in safety or efficacy in treating serious conditions.

This followed the FDA s 2014 Breakthrough Therapy designation for Dupixent for inadequately controlled

moderate-to-severe AD. Breakthrough Therapy designation was created by the FDA to expedite the development and review of drugs developed for serious or life-threatening

conditions/ Dupixent represents the first time this designation was granted for a dermatological disease, other than in dermatologic cancers.iv

We strive to transform scientific innovation into therapeutic solutions that make a meaningful difference to people s lives, said

Olivier Brandicourt, M.D., Chief Executive Officer, Sanofi. The approval of Dupixent offers new hope for adults with moderate-to-severe AD in the United States,

and we look forward to working with regulatory authorities around the world to bring this important new medicine to patients globally.

Genzyme, the specialty care global business unit of Sanofi, and Regeneron will market Dupixent in the United States. Dupixent is expected to be available to patients and providers in the U.S. later this week.

Sanofi and Regeneron recognize that Dupixent can only help those uncontrolled

moderate-to-severe AD patients that were prescribed the medicine if they can both access the medicine and use it properly. Therefore, the companies have launched

Dupixent MyWayTM, a comprehensive and specialized program that provides support and services to patients throughout every step of the treatment process.

Dupixent MyWayTM will help eligible patients who are uninsured, lack coverage, or need

assistance with their out-of-pocket costs. Additionally, Dupixent MyWayTM offers personalized

support from registered nurses and other specialists who are available 24/7 to speak with patients and help them navigate the complex insurance process. For more information, please call 1-844-Dupixent (1-844-387-4936) or visit www.Dupixent.com

The Wholesale Acquisition Cost (WAC) of Dupixent in the United States is $37,000 annually. Actual costs to patients, payers and health systems are anticipated

to be lower as WAC pricing does not reflect discounts, rebates or patient assistance programs.

LIBERTY AD Clinical Program and Results

The approval of Dupixent was based on data from the global LIBERTY AD clinical program, which included three randomized Phase 3 pivotal trials known as SOLO 1,

SOLO 2 and CHRONOS (enrolled 2,119 total adult patients). The studies examined the use of Dupixent either alone (SOLO 1 or SOLO 2, 1,379 adult patients enrolled) or with topical corticosteroids (CHRONOS, 740 adult patients enrolled) in patients with

inadequately controlled moderate-to-severe AD. In all these studies, Dupixent alone or with topical corticosteroids met the primary and key secondary endpoints,

The most common adverse events that were noted to be greater than or

equal to one percent with Dupixent treatment included injection site reactions, eye and eye lid inflammation including redness, swelling, and itching, and cold sores in the mouth or on the lips.

In December 2016, the European Medicines Agency accepted for review Sanofi s and Regeneron s marketing authorization application (MAA) for Dupixent

for adults with uncontrolled moderate-to-severe AD.

Dupilumab is currently being evaluated in a comprehensive development program for AD that includes studies in children with severe AD (6

months to 11 years of age) and adolescents with moderate-to-severe AD (12 to 17 years of age). In October 2016, the FDA granted dupilumab Breakthrough Therapy

designation for both populations. These potential uses are investigational and the safety and efficacy have not been evaluated nor confirmed by any regulatory authority.

Dupilumab is also being studied in other inflammatory diseases that are believed to be driven by IL-4 and IL-13 cytokines, including persistent uncontrolled asthma (Phase 3, results expected later this year), nasal polyposis (Phase 3) and eosinophilic esophagitis (Phase 2). These potential uses are investigational and

the safety and efficacy have not been evaluated by any regulatory authority. For more information on dupilumab clinical trials please visit www.clinicaltrials.gov.

IMPORTANT SAFETY INFORMATION

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:

your healthcare provider about all the medicines you take, including prescription and over-the-counter medicines, vitamins and herbal supplements. If you have asthma and

are taking asthma medicines, do not change or stop your asthma medicine without talking to your healthcare provider.

Dupixent can cause serious side

The most common side effects include injection site reactions, eye and eyelid inflammation, including redness, swelling, itching, and cold sores in

your mouth or on your lips.

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 may report side effects to FDA at

exactly as prescribed. 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.

Please click here for the full Prescribing Information. The patient

information is available here.

Dupixent is used to treat adult patients 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.

global healthcare leader, discovers, develops and distributes therapeutic solutions focused on patients needs. Sanofi is organized into five global business units: Diabetes and Cardiovascular, General Medicines and Emerging Markets, Sanofi

Genzyme, Sanofi Pasteur and Consumer Healthcare. Sanofi is listed in Paris (EURONEXT: SAN) and in New York (NYSE: SNY).

focuses on developing specialty treatments for debilitating diseases that are often difficult to diagnose and treat, providing hope to patients and their families.

About Regeneron Pharmaceuticals, Inc.

REGN) is a leading science-based biopharmaceutical company that discovers, invents, develops, manufactures and commercializes medicines for the treatment of serious medical conditions. Regeneron commercializes medicines for eye diseases, high LDL-cholesterol, atopic dermatitis and a rare inflammatory condition and has product candidates in development in other areas of high unmet medical need, including rheumatoid arthritis, asthma, pain, cancer and

infectious diseases. For additional information about the company, please visit www.regeneron.com or follow @Regeneron on Twitter.

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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

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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 absence

of guarantee that the product will 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 conditions, as well as those

risks 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, 2016. Other than as required by applicable law, Sanofi does not undertake any obligation to update or revise any forward-looking information or

Regeneron Forward-Looking Statements

This news 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 Regeneron s products, product candidates, and research and clinical

programs now underway or planned, including without limitation Dupixent (dupilumab) Injection; the likelihood, timing, and scope of possible regulatory approval and commercial launch of

Regeneron s late-stage product candidates and new indications for marketed products, such as Dupixent for the treatment of uncontrolled moderate-to-severe atopic

dermatitis in jurisdictions outside the United States and other potential indications; unforeseen safety issues and possible liability resulting from the administration of products and product candidates in patients, including without limitation

Dupixent; serious complications or side effects in connection with the use of Regeneron s products and product candidates (such as Dupixent) in clinical trials; coverage and reimbursement determinations by third-party payers, including

Medicare, Medicaid, and pharmacy benefit management companies; ongoing regulatory obligations and oversight impacting Regeneron s marketed products, research and clinical programs, and business, including those relating to the enrollment,

completion, and meeting of the relevant endpoints of post-approval studies; 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 product candidates, such as Dupixent; competing drugs and product candidates that may be superior to Regeneron s products and product candidates; uncertainty of market acceptance and commercial success of

Regeneron s products and product candidates and the impact of studies (whether conducted by Regeneron or others and whether mandated or voluntary) on the commercial success of Regeneron s products and product candidates; the ability of