Sanofi, Regeneron Expand DUPIXENT Alliance in Deal Worth Up to €8 Billion

Key Points

• Sanofi will pay Regeneron €1 billion upfront and up to €7 billion in development, regulatory and commercial milestones to expand their alliance around four next-generation antibodies targeting IL-4 and IL-13 pathways. The companies will share development costs and global profits equally.
• The lead program is a long-acting IL-13 antibody for atopic dermatitis, with potential dosing every three to six months and registrational studies expected to begin in late 2027 or early 2028. Sanofi may also add its lunsekimig asset depending on results from a Phase II COPD study.
• The expanded partnership builds on DUPIXENT, which generated €5.2 billion in second-quarter 2026 global sales, and resolves litigation between the companies. Regeneron will control final development decisions, while Sanofi retains commercial authority over pricing and market access.

Regeneron and Sanofi NASDAQ: SNY announced an expanded collaboration focused on developing next-generation medicines for type 2 inflammatory diseases, extending an alliance that has produced the blockbuster therapy DUPIXENT.

Under the agreement, Regeneron will contribute four long-acting, fully human antibody programs targeting the IL-4 and IL-13 pathways. Sanofi will make a EUR 1 billion upfront payment to Regeneron and could pay up to EUR 7 billion more upon development, regulatory and commercial milestones. The companies will split development costs and global profits equally for the new alliance medicines.

The prior agreement governing DUPIXENT, including its profit-sharing arrangement, remains unchanged. Sanofi will continue to record net sales under the companies’ existing reporting practice, according to François-Xavier Roger, Sanofi’s executive vice president and chief financial officer.

Next-generation antibody portfolio

The lead asset added to the alliance is a long-acting IL-13 antibody currently in clinical testing for atopic dermatitis. Regeneron said the program has shown long-lived pharmacokinetic properties and is targeting a dosing interval of at least every three to six months. Registrational studies are planned to begin in late 2027 or early 2028.

The other three Regeneron programs are preclinical and are expected to be clinic-ready next year:

• A long-acting IL-4/IL-13 bispecific antibody designed to block both cytokines;
• A long-acting antibody targeting the IL-4 receptor alpha, the same target addressed by DUPIXENT; and
• An antibody targeting IL-4.

George Yancopoulos, Regeneron’s co-founder, board co-chair, president and chief scientific officer, said the companies intend to use the portfolio to select different approaches for different diseases, depending on whether blocking IL-13 alone or both IL-4 and IL-13 is considered appropriate.

Sanofi is also providing Regeneron an option to add lunsekimig, Sanofi’s IL-13/TSLP Nanobody, to the alliance. The option is contingent on data from a Phase II chronic obstructive pulmonary disease study. Sanofi’s Paulo Fontoura, executive vice president and head of research and development, said the company intends to use the COPD data to determine future plans for the asset.

Built on DUPIXENT commercial platform

Leonard Schleifer, Regeneron’s co-founder, board co-chair, president and chief executive officer, said the companies plan to use their established global development and commercial infrastructure to support potential launches of the new medicines. The platform currently serves more than 1.5 million DUPIXENT patients globally, he said.

DUPIXENT recorded EUR 5.2 billion in global net sales in the second quarter of 2026, as reported by Sanofi, and was annualizing at more than EUR 20 billion across nine indications, Schleifer said. Yancopoulos said the therapy is FDA-approved across diseases involving the skin, gut and respiratory system, including use in patients from 6 months of age through older adults.

Belén Garijo, Sanofi’s chief executive officer, said only about 20% of eligible U.S. patients are currently treated with advanced therapies and that the market could nearly double over the next five years. She cited more than 2.5 million U.S. patients with moderate-to-severe atopic dermatitis and said Sanofi projects the U.S. market could reach approximately EUR 20 billion in sales by 2032.

Garijo said the expanded alliance assigns Regeneron final development decision-making authority, while Sanofi retains final commercial decision rights, including those related to pricing and market access. Regeneron will have increased participation in key payer discussions.

Agreement also resolves litigation

Garijo said the transaction provides a stronger framework for the partnership, including clearer governance, greater transparency and the resolution of litigation between the companies.

During the question-and-answer session, Roger said DUPIXENT’s U.S. loss of exclusivity is currently expected in March 2031. He added that Sanofi is pursuing an extension of that period, though he said there is no certainty that an extension will be obtained.

Regeneron said the first EUR 1 billion milestone payment beyond the upfront consideration would be linked to the start of a Phase III program. Both companies said they aim to advance the new programs as quickly as possible, using their experience with clinical trial design, regulatory engagement and patient recruitment in type 2 inflammatory diseases.

About Sanofi (NASDAQ:SNY)

Sanofi is a France-based global healthcare company that develops, manufactures and markets prescription medicines, vaccines and consumer healthcare products. Its portfolio focuses on areas including immunology, rare diseases, vaccines, diabetes and other chronic conditions, as well as specialized treatments for selected neurological and inflammatory disorders.

The company is known for products such as Dupixent, a biologic used to treat several inflammatory conditions, and a broad range of vaccines marketed through its Sanofi Pasteur business.

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