Sanofi Pays Regeneron $1 Billion to Keep Dupixent’s Successors Inside a 23-Year Alliance
- Sanofi and Regeneron said on 1 October 2026 they will co-develop and co-commercialise four new long-acting, Regeneron-invented antibodies targeting IL-13, IL-4 and IL-4 receptor alpha, plus an IL-4xIL-13 bispecific. The IL-13 antibody REGN20423 is in a Phase 1 study in atopic dermatitis; the other three are expected to enter the clinic in 2027.
- Regeneron receives $1bn upfront and up to $7bn in milestones. The companies share costs and split profits 50:50 globally, with Regeneron leading R&D and Sanofi leading commercialisation. Dupixent’s existing profit share is unchanged, and Regeneron gets an option on Sanofi’s TSLP and IL-13 bispecific lunsekimig after its Phase 3 COPD studies.
- The alliance dates to 2003. A 2007 antibody pact produced Praluent, Dupixent and Kevzara, and after its 2009 renewal Sanofi funded up to $160m a year of Regeneron’s antibody research. Dupixent now treats more than 1.5 million people across nine indications.
- In November 2024 Regeneron sued Sanofi, alleging it refused access to Dupixent’s contracts with pharmacy benefit managers and suggesting they bundled Dupixent with Sanofi’s wholly owned drugs. The companies say that litigation is now settled. Sanofi chief executive Belén Garijo called the deal a deliberate first step in igniting Sanofi’s innovation engine.
Deal read
Sanofi is paying to keep the next generation of Dupixent inside the partnership, and the same agreement closes a lawsuit about whose interests Sanofi serves.
- Long-acting is the defence. The four antibodies target the same IL-4 and IL-13 biology as Dupixent, with longer dosing intervals. Bringing them into the alliance positions the partners against less frequently dosed challengers before Dupixent’s exclusivity ends, instead of leaving Regeneron free to partner them elsewhere.
- The settlement and the structure fit together. The 2024 suit centred on Sanofi contracting for partnered and wholly owned drugs at the same time. Sharing the next generation 50:50, and giving Regeneron an option on lunsekimig, aligns the companies’ incentives in exactly the area where they had diverged.
- $1bn buys one Phase 1 asset and three preclinical ones. The upfront is a clean 12.5% of the $8bn headline, clearer than most licences this month. With Regeneron running R&D on Sanofi’s money, it is the first major move under Sanofi’s new chief executive, and it is a bet on a partner’s science rather than Sanofi’s own.
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