Press Release: Sanofi and Regeneron expand global Alliance with multiple next-generation, long-acting immunology antibodies

Press Release

Sanofi and Regeneron expand global Alliance with multiple next-generation, long-acting immunology antibodies

• REGN20423, a clinical-stage long-acting IL-13 monoclonal antibody invented and developed by Regeneron, is added to the Alliance, along with a long-acting IL-4xIL￾13 bispecific and two other long-acting pre-clinical antibodies from Regeneron
• Regeneron to receive $1 billion upfront, with potential for up to an additional $7 billion in future milestone payments; companies to equally share development and commercialization costs, as well as any future profits
• Sanofi and Regeneron to host a conference call for investors and analysts today at 14:00 CET/8:00am ET

Paris and Tarrytown, NY, October 1, 2026. Sanofi and Regeneron Pharmaceuticals, Inc. today announce an expansion of their longstanding antibody collaboration, adding multiple next-generation, long-acting antibodies to the Alliance that has jointly established Dupixent® (dupilumab) as the world-leading treatment for diseases driven by type 2 inflammation. The agreement builds on the companies' more than 20-year collaboration, through which more than 1.5 million people are currently receiving Dupixent across nine indications, making it one of the most widely used antibody medicines in the world.

“This is a deliberate first step in igniting Sanofi’s innovation engine. Our longstanding Alliance with Regeneron has transformed the treatment landscape for millions of patients living with diseases driven by type 2 inflammation and created one of the world's leading immunology businesses,” said Belén Garijo, Chief Executive Officer of Sanofi. “By deepening our collaboration, we will make rapid progress in creating the next generation of meaningful therapies for patients with immune-mediated diseases, while contributing to Sanofi’s long-term future.”

Under the expanded license and collaboration agreement, the companies will co-develop and co-commercialize four new long-acting, Regeneron-invented antibodies targeting interleukin￾13 (IL-13), IL-4xIL-13 bispecific, interleukin-4 (IL-4) and interleukin-4 receptor alpha (IL￾4Rα). IL-13 antibody REGN20423 is currently in a phase 1 clinical study for atopic dermatitis, and the other three antibodies are expected to enter clinical studies in 2027. Regeneron will also have the option to include in the collaboration Sanofi’s lunsekimig, an investigational bispecific Nanobody® VHH therapy targeting TSLP and IL-13, exercisable upon completion of its phase 3 studies for chronic obstructive pulmonary disease.

“The Regeneron-Sanofi Alliance has been one of the most productive in biopharma history. This agreement builds on that foundation to bring the next generation of immunology medicines to patients even faster,” said Leonard S. Schleifer, MD, PhD, Board co-Chair, President and Chief Executive Officer of Regeneron. “By expanding our Alliance, we are positioning promising new long-acting antibodies for the kind of rapid, global impact that our shared work on Dupixent has already achieved.”

Under the terms of the agreement, Regeneron will receive an upfront payment of $1 billion from Sanofi, with the potential for development, regulatory and commercial milestone payments of up to an additional $7 billion. The companies will share development and commercialization costs for the new programs and will split future profits from these potential products 50:50 on a global basis. Regeneron will lead research and development activities, and Sanofi will lead global commercial efforts. The existing profit-sharing agreement regarding Dupixent will not change.

“The companies’ clinical and commercial Alliance dates to 2003 and has resulted in multiple approved medicines to date, including Dupixent, which has redefined the standard of care for people with type 2 inflammatory diseases and is now one of the most widely used antibodies for any disease, with over 1.5 million active patients worldwide,” said George D. Yancopoulos, MD, PhD, Board co-Chair, President and Chief Scientific Officer at Regeneron, and a principal inventor of Dupixent. “By combining Regeneron’s world-class scientific discovery and antibody development expertise with Sanofi’s global capabilities and reach, we hope to once again deliver the next wave of innovation in immunology.”

The companies have settled their prior collaboration-related litigation.

Conference call for investors and analysts

Sanofi and Regeneron will host a conference call for investors and analysts today at 14:00 CET/8:00am ET. A presentation will be available for download from the Investor Relations section of sanofi.com and regeneron.com when the conference call starts.

Participants may access the conference call via webcast on the ‘Upcoming Events’ page of Sanofi’s website at https://www.sanofi.com/en/investors/news-events/upcoming-events, tab ‘Presentations' and on the 'Investors and Media' page of Regeneron's website at https://investor.regeneron.com/events-and-presentations. To participate via telephone, please register in advance at this link.

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. The Dupixent development program has shown significant clinical benefit and a decrease in type 2 inflammation in phase 3 studies, establishing that IL-4 and IL-13 are two of the key and central drivers of the type 2 inflammation that plays a major role in multiple related and often co-morbid diseases.

Dupixent has received regulatory approvals in more than 60 countries in one or more indications including certain patients with atopic dermatitis, asthma, chronic rhinosinusitis with nasal polyps, eosinophilic esophagitis, prurigo nodularis, chronic spontaneous urticaria, chronic obstructive pulmonary disease, bullous pemphigoid, and allergic fungal rhinosinusitis in different age populations. In addition to the currently approved indications, Sanofi and Regeneron are studying dupilumab in a broad range of diseases driven by type 2 inflammation or other allergic processes in phase 3 studies, including chronic pruritus of unknown origin. 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.

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 theRegeneron 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.

About Sanofi

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

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 | +1 617 356 4751 | 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
Laura Romby | +33 6 74 16 74 29 | laura.romby@sanofi.com
Ekaterina Pesheva | +1 410 926 6780 | ekaterina.pesheva@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
Keita Browne | +1 781 249 1766 | keita.browne@sanofi.com
Nathalie Pham | +33 7 85 93 30 17 | nathalie.pham@sanofi.com
Nina Goworek | +1 908 569 7086 | nina.goworek@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

Christina Chan | +1 914-383-6374 | christina.chan@regeneron.com
Alexandra Bowie | +1 914-346-0588 | alexandra.bowie@regeneron.com

Regeneron Investor Relations

Ryan Crowe | +1 914-847-8790 | ryan.crowe@regeneron.com
Mark Hudson | +1 914-847-3482 | mark.hudson@regeneron.com

Sanofi forward-looking statements

This press release contains forward-looking statements within the meaning of applicable securities laws, including 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