Regeneron lands $1 billion upfront from Sanofi in new antibody pact, drops Dupixent info lawsuit

Regeneron and Sanofi are expanding their partnership and ending a legal fight. Under a new amendment to their long-running antibody collaboration, Sanofi will pay Regeneron $1.0 billion upfront, with up to $7.0 billion more tied to development, regulatory and commercial milestones, Regeneron said in a regulatory filing Tuesday.

The deal, signed Oct. 1, covers four new long-acting antibodies invented by Regeneron: ones targeting IL-13, IL-4 and the IL-4 receptor alpha, plus a bispecific aimed at both IL-4 and IL-13. The companies will split global profits on those products equally and share development costs 50-50, though Regeneron is on the hook for costs above a budget cap, with some rights to recoup them later.

Regeneron will lead development and U.S. regulatory filings and keep the U.S. lead after approval. Sanofi will lead commercialization and regulatory work outside the United States.

Regeneron also gets an option, after certain ongoing trials, to bring Sanofi's Phase 2/3 drug lunsekimig, a bispecific Nanobody therapy targeting TSLP and IL-13, and another early-stage Sanofi product into the collaboration. If it does, it would reimburse Sanofi for certain development costs.

Alongside the amendment, Regeneron agreed to dismiss its lawsuit over Sanofi's obligation to give it full access to information on the commercialization of Dupixent and other partnered products, and over Regeneron's audit rights.

Regeneron also flagged a third-quarter charge. It expects an acquired in-process research and development charge of about $22 million pre-tax, cutting both GAAP and non-GAAP earnings per diluted share by about $0.18. The company said its quarterly results are not yet final.

By the numbers

• Upfront payment from Sanofi: $1.0 billion
• Potential milestones: up to $7.0 billion
• New antibodies in the pact: 4
• Profit and development cost split: 50/50
• Q3 acquired IPR&D charge: about $22 million pre-tax, about $0.18 a share

Sources

1. Regeneron Pharmaceuticals, Inc. Form 8-K (Items 1.01, 2.02 and 8.01), filed Oct. 6, 2026, accession 0001104659-26-113895

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