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

Key Points

• Regeneron and Sanofi expanded their collaboration with four Regeneron-originated antibody programs focused on type 2 inflammatory diseases. Sanofi will pay $1 billion upfront and up to $7 billion in milestones, while the companies will share costs and profits equally.
• The pipeline includes a long-acting IL-13 antibody for atopic dermatitis and three preclinical programs targeting IL-4 and IL-13 pathways. Registrational studies for the lead program could begin in late 2027 or early 2028, with dosing potentially required only every three to six months.
• The alliance will leverage the commercial infrastructure behind DUPIXENT, whose second-quarter 2026 sales reached €5.2 billion. Regeneron will control development decisions, Sanofi will retain commercial authority, and the revised agreement resolves litigation between the companies.

Regeneron Pharmaceuticals NASDAQ: REGN and Sanofi said they are expanding their long-running collaboration to develop and commercialize next-generation medicines for type 2 inflammatory diseases, adding four Regeneron-originated antibody programs and establishing a new equal-sharing economic framework for the assets.

Under the agreement, Sanofi will pay Regeneron $1 billion upfront and could pay up to $7 billion more upon specified development, regulatory and commercial milestones. The companies will share global development and commercialization costs equally and split global profits 50-50 for the new alliance medicines.

Sanofi will continue to record net sales under the companies’ existing reporting practice. François Roger, Sanofi’s executive vice president and chief financial officer, said the transaction is expected to be reflected in both companies’ fourth-quarter 2026 financial results.

Four Regeneron Antibodies Added to Alliance

Regeneron is contributing four fully human, long-acting antibody programs to the expanded alliance. The lead program is an IL-13 antibody currently in clinical development for atopic dermatitis. The other three programs are preclinical: an IL-4/IL-13 bispecific antibody, an IL-4 receptor alpha antibody and an IL-4 antibody.

George Yancopoulos, Regeneron’s co-founder, board co-chair, president and chief scientific officer, said the long-acting IL-13 antibody has demonstrated “remarkable long-lived pharmacokinetic properties” in the clinic. Registrational studies in atopic dermatitis are expected to begin in late 2027 or early 2028.

The IL-13 program is designed for a target dosing interval of at least every three to six months, according to Yancopoulos. He said the other three programs are expected to be ready for clinical development next year.

The expanded agreement also gives Regeneron an option to bring Sanofi’s lunsekimig, an IL-13/TSLP Nanobody, into the alliance depending on Phase II results in chronic obstructive pulmonary disease. Sanofi’s Manuela Buxo, executive vice president and head of specialty care, said the companies intend to assess COPD data before deciding whether to advance the molecule in other indications.

Building on DUPIXENT Platform

The companies said the new programs will use the global development and commercial infrastructure built around DUPIXENT. Leonard Schleifer, Regeneron’s co-founder, board co-chair, president and chief executive officer, said the existing platform serves more than 1.5 million DUPIXENT patients worldwide.

Schleifer said Sanofi recorded second-quarter 2026 global net sales of €5.2 billion for DUPIXENT, placing the treatment on an annualized run rate above €20 billion across nine indications. Yancopoulos said DUPIXENT is approved by the U.S. Food and Drug Administration for nine diseases affecting the skin, gut and respiratory system, for patients from six months of age through older adults.

Belén Garijo, Sanofi’s chief executive officer, said only about 20% of eligible U.S. patients currently receive 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. atopic dermatitis market could reach about $20 billion in sales by 2032.

Garijo said the companies see a need for longer dosing intervals without compromising efficacy or safety, and plan to use their established provider relationships, patient-support infrastructure, supply capabilities and market-access experience to support the new medicines if approved.

Governance and Intellectual Property Outlook

The companies also outlined a revised governance structure. Regeneron will have final decision-making authority for development, while Sanofi will retain final commercial decision rights, including pricing and access. Garijo said Regeneron will have increased participation in key payer engagements.

The prior agreement covering DUPIXENT remains unchanged, including its profit-sharing arrangement, Roger said. He said DUPIXENT’s U.S. loss of exclusivity is currently expected in March 2031, while Sanofi is working to extend protection by several years. He cautioned that there is no certainty that such an extension will be obtained.

Garijo said the agreement also resolves litigation between the companies. She described the expanded arrangement as providing clearer governance, greater transparency and a stronger framework for advancing new medicines.

“This strengthened alliance gives our next-generation programs the best opportunity to move rapidly through development,” Schleifer said, adding that the companies aim to extend their leadership in type 2 inflammatory diseases.

About Regeneron Pharmaceuticals (NASDAQ:REGN)

Regeneron Pharmaceuticals, Inc is a biotechnology company that discovers, develops and commercializes medicines for serious medical conditions. The company uses human genetics, antibody technology and other biological research platforms to develop treatments in areas including eye diseases, cancer, cardiovascular and metabolic disorders, inflammatory diseases, infectious diseases and rare conditions.

Regeneron's marketed products include EYLEA and EYLEA HD for certain retinal diseases; Dupixent, developed and commercialized with Sanofi, for multiple allergic and inflammatory conditions; Libtayo for certain cancers; Praluent for high cholesterol; Kevzara for rheumatoid arthritis and other inflammatory diseases; Evkeeza for homozygous familial hypercholesterolemia; and Veopoz for a rare immune-mediated disorder.

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