Sanofi to Pay Regeneron $1bn Upfront in Expanded Dupixent Alliance
Sanofi will pay Regeneron $1bn upfront and up to $7bn more in milestones to add four long-acting immunology antibodies to their Dupixent alliance, and the two companies have settled earlier litigation.
Sanofi (EPA: SAN) has agreed to pay Regeneron Pharmaceuticals (NASDAQ: REGN), the US biotech behind the eye drug Eylea, $1bn upfront and up to $7bn more in milestones. Sanofi’s Paris-listed shares were up 1.06% at 10.55am UK time, while Regeneron’s US shares have yet to trade.
Wall Street opens at 2.30pm UK time, so there is no US reaction yet. Regeneron closed yesterday at $758.27, about 12% below its intraday high of $859.34 on the 3rd of September. Sanofi traded at €73.41 by 10.55am against a previous close of €72.64; the timing is consistent with the deal but does not prove it caused the move.
The companies announced the expansion of their Dupixent alliance at 6am today. Four Regeneron-invented, long-acting antibodies, designed to work with fewer injections, join it. Regeneron also has an option to add Sanofi’s lunsekimig once its Phase 3 studies in chronic obstructive pulmonary disease are complete.
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REGN20423 targets IL-13, an immune-system protein that drives allergic inflammation, and is in Phase 1, the first small safety study in humans, for atopic dermatitis. An IL-4xIL-13 bispecific (an antibody blocking two targets), an IL-4 antibody and an IL-4Rα antibody are expected to enter clinical studies in 2027.
Only the $1bn is guaranteed. Adding the two figures gives up to $8bn, but the $7bn depends on development, regulatory and commercial milestones for antibodies that are mostly not yet in patients. Costs and profits are split 50:50 globally, with Regeneron leading research and Sanofi leading global commercial work. The existing Dupixent profit-share is unchanged.
Regeneron shares gained roughly 20% over the three months to 30 September 2026 while Sanofi ADRs fell about 5% (rebased to 100 at 29 June).
More than 1.5 million people are receiving Dupixent across nine indications, according to the companies. The pair also settled prior collaboration-related litigation, with no terms disclosed.
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Sanofi chief executive Belén Garijo said in the release:
This is a deliberate first step in igniting Sanofi’s innovation engine.
Belén Garijo, Sanofi
A joint investor and analyst call is scheduled for 1pm UK time today, ahead of the US open at 2.30pm.
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