REGENERON AND SANOFI ANNOUNCE APPROVAL OF DUPIXENT® (DUPILUMAB) TO TREAT ADULT PATIENTS WITH MODERATE-TO-SEVERE ATOPIC DERMATITIS IN THE EUROPEAN UNION

 -- Regeneron Pharmaceuticals, Inc.(NASDAQ: REGN) and Sanofi today announced that the European Commission (EC) has granted marketing authorization for DUPIXENT^® (dupilumab), for use in adults with moderate-to-severe atopic dermatitis (AD) who are candidates for systemic therapy.

Atopic dermatitis, a form of eczema, is a chronic inflammatory disease with symptoms often appearing as a rash on the skin. Moderate-to-severe atopic dermatitis is characterized by rashes often covering much of the body, and can include intense, persistent itching and skin dryness, cracking, redness, crusting, and oozing. Itch is one of the most burdensome symptoms for patients and can be debilitating. In addition, people with moderate-to-severe atopic dermatitis experience impaired quality of life, including disrupted sleep, and increased anxiety and depression symptoms along with their disease.

"People with moderate-to-severe atopic dermatitis can experience unbearable symptoms that may significantly impact their quality of life. Many often struggle to control their disease with the treatment options currently available," said Christine Janus, Chief Executive Officer of the International Alliance of Dermatology Patient Organizations. "We support timely access to this important new medication for those with moderate-to-severe atopic dermatitis to help them control and provide relief for this life-altering, often severely debilitating, chronic 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 atopic dermatitis, and certain other allergic or atopic diseases. DUPIXENT will come in a pre-filled syringe and can be self-administered by a patient as a subcutaneous injection every other week after an initial loading dose. DUPIXENT can be used with or without topical corticosteroids.

"This approval of DUPIXENT in Europe demonstrates our approach of bringing innovative new therapies to those living with the highest unmet medical need and today's approval represents an important milestone for people living with moderate-to-severe atopic dermatitis in Europe," said Elias Zerhouni, M.D., President, Global R&D, Sanofi. "DUPIXENT targets an underlying cause of atopic dermatitis, helps clear the skin, manage the persistent debilitating itch, and improve overall quality of life. We are now focused on quickly making this important new treatment option available to people across Europe who live with this systemic disease."

Following the granting of this marketing authorization, Sanofi and Regeneron will work with relevant local authorities to make DUPIXENT available to patients in need in countries across Europe.

"DUPIXENT represents the culmination of decades of our scientific research into the biology of allergic diseases such as moderate-to-severe atopic dermatitis," said George D. Yancopoulos, M.D., Ph.D., President and Chief Scientific Officer, Regeneron. "We continue to evaluate the potential of dupilumab in the treatment of atopic dermatitis in children and adolescents as well as other allergic inflammatory diseases driven by the IL-4/IL-13 pathway."

DUPIXENT is approved in the U.S. for the treatment of adults 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.

LIBERTY AD Clinical Program and Results The approval of DUPIXENT was based on studies from the global LIBERTY AD clinical trial program which included nearly 3,000 patients. LIBERTY AD studies included SOLO 1, SOLO 2, CHRONOS, SOLO-CONTINUE and CAFÉ. The studies examined the use of DUPIXENT either alone (SOLO 1, SOLO 2 and SOLO-CONTINUE) or with topical corticosteroids (CHRONOS or CAFÉ) in moderate-to-severe AD patients who were inadequately controlled with topical prescription therapies or immunosuppresants such as cyclosporine, or for whom those therapies were not advisable. In all these studies, DUPIXENT alone or with topical corticosteroids met the primary and key secondary endpoints. The most common adverse events that occurred at a higher rate than placebo in the DUPIXENT group ( > one percent) included injection site reactions, eye and eye lid inflammation including redness, swelling, and itching, and cold sores in the mouth or on the lips.

Dupilumab Program OverviewDupilumab 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). These potential uses are investigational and the safety and efficacy have not been fully evaluated nor confirmed by any regulatory authority.

Dupilumab is also being studied in other inflammatory diseases that are believed to be driven by the IL-4/IL-13 pathway, including uncontrolled persistent asthma (Phase 3), nasal polyposis (Phase 3) and eosinophilic esophagitis (Phase 2). These potential uses are investigational and the safety and efficacy have not been fully evaluated by any regulatory authority. Dupilumab was discovered using Regeneron's proprietary VelocImmune^® technology that yields optimized fully-human antibodies, and is being jointly developed by Regeneron and Sanofi under a global collaboration agreement.

IMPORTANT SAFETY INFORMATION for U.S.

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
• have asthma
• 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.
• 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. 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 effects, including:

• Allergic reactions. Stop using Dupixent and go to the nearest hospital emergency room if you get any of the following symptoms: fever, general ill feeling, swollen lymph nodes, hives, itching, 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.

The most common side effects include injection site reactions, eye and eyelid inflammation, including redness, swelling and 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 1-800-FDA-1088.

Use Dupixent 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.