Sanofi and Regeneron Pharmaceuticals announced on October 1, 2026, an expansion of their longstanding antibody collaboration, adding multiple next-generation, long-acting antibodies to the Alliance that jointly established Dupixent (dupilumab) as the world-leading treatment for diseases driven by type 2 inflammation. The announcement, made from Paris and Tarrytown, NY, builds on a collaboration that dates to 2003 and spans more than 20 years.

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), an IL-4xIL-13 bispecific, interleukin-4 (IL-4), and interleukin-4 receptor alpha (IL-4Rα). One of these, the IL-13 antibody REGN20423, is currently in a phase 1 clinical study for atopic dermatitis, while the other three antibodies are expected to enter clinical studies in 2027.

Financial terms of the deal

Regeneron will receive an upfront payment of USD 1 billion from Sanofi, with the potential for development, regulatory, and commercial milestone payments of up to an additional USD 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 have also settled their prior collaboration-related litigation.

Leadership commentary

Belén Garijo, Chief Executive Officer of Sanofi, described the agreement as "a deliberate first step in igniting Sanofi's innovation engine."

She said the 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, adding that deepening the collaboration will enable rapid progress in creating the next generation of meaningful therapies for patients with immune-mediated diseases while contributing to Sanofi's long-term future.

Leonard S. Schleifer, MD, PhD, Board co-Chair, President and Chief Executive Officer of Regeneron, called the Regeneron-Sanofi Alliance one of the most productive in biopharma history.

He said the agreement builds on that foundation to bring the next generation of immunology medicines to patients even faster and that expanding the Alliance positions promising new long-acting antibodies for the kind of rapid, global impact that the companies' shared work on Dupixent has already achieved.

George D. Yancopoulos, MD, PhD, Board co-Chair, President and Chief Scientific Officer at Regeneron and a principal inventor of Dupixent, noted that 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.

He said that by combining Regeneron's scientific discovery and antibody development expertise with Sanofi's global capabilities and reach, the companies hope to once again deliver the next wave of innovation in immunology.

A pipeline option on lunsekimig

In addition to the four antibodies, Regeneron will have the option to include in the collaboration Sanofi's lunsekimig, an investigational bispecific Nanobody VHH therapy targeting TSLP and IL-13. That option is exercisable upon completion of lunsekimig's phase 3 studies for chronic obstructive pulmonary disease.

The Dupixent foundation

Dupixent, 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.

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. Dupixent has received regulatory approvals in more than 60 countries in one or more indications.

Investor call

Sanofi and Regeneron hosted a conference call for investors and analysts on the day of the announcement at 14:00 CET/8:00am ET. When the conference call started, the Investor Relations section made the presentation available for download.

Participants could access the call via webcast through Sanofi's website and Regeneron's investor events page or participate via telephone with advance registration.

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