Sanofi pays $1B upfront to expand Regeneron alliance beyond Dupixent
Sanofi will pay Regeneron Pharmaceuticals $1 billion upfront (€0.9 billion) to expand the alliance that led to the blockbuster Dupixent with four antibody candidates designed to work longer between doses.
Why it matters: The companies are building on the inflammatory pathways behind one of biopharma’s biggest commercial successes. Longer-acting treatments could reduce the injection burden for patients, although the new candidates remain early in development.
The backstory: Sanofi and Regeneron’s clinical and commercial alliance dates to 2003. Its flagship product, Dupixent (dupilumab), first won US approval in 2017 for adults with moderate-to-severe atopic dermatitis.
- Dupixent has since expanded into diseases including asthma, chronic obstructive pulmonary disease and eosinophilic esophagitis. The companies say more than 1.5 million patients currently receive it across nine indications.
- Sanofi reported €15.7 billion in Dupixent sales in 2025, showing the scale of the business the partners now want to build on.
How it works: Dupixent blocks IL-4 receptor alpha, inhibiting signaling from IL-4 and IL-13, two proteins that drive type 2 inflammation. The expanded alliance explores several ways to target the same biology with longer-acting antibodies.
The four Regeneron-developed candidates are:
- REGN20423: An IL-13 antibody in a Phase 1 trial for atopic dermatitis.
- An IL-4/IL-13 bispecific antibody: Designed to target both proteins.
- An IL-4 antibody and an IL-4 receptor alpha antibody: Two additional preclinical programs.
The three preclinical candidates are expected to enter clinical studies in 2027.
The deal: Regeneron could receive another $7 billion (€6.2 billion) in development, regulatory and commercial milestones. The companies will share development and commercialization costs equally and split future profits 50:50 globally.
- Regeneron will lead research and development, while Sanofi will lead global commercialization. The companies also said they have settled their previous collaboration-related litigation, without disclosing settlement terms.
Also notable: Regeneron gains an option to bring Sanofi’s lunsekimig into the alliance after completion of its Phase 3 studies in chronic obstructive pulmonary disease. The investigational bispecific therapy targets TSLP and IL-13, adding a different combination of inflammatory targets to the potential portfolio.
Yes, but: The announcement provides no clinical results or intended dosing intervals for the new long-acting antibodies. Whether they can maintain disease control with fewer injections, or improve on Dupixent’s efficacy and safety, still needs to be established.
What’s next: REGN20423’s Phase 1 program and the planned clinical starts in 2027 will provide the first tests of the expanded portfolio’s promise.
What they’re saying: The expanded alliance marks the first major pipeline deal under Belén Garijo, who became Sanofi’s CEO in May. She called it “a deliberate first step in igniting Sanofi’s innovation engine.”
