Sanofi pays Regeneron $1B upfront to continue search for Dupixent successor

News Business Sanofi pays Regeneron $1B upfront to continue search for Dupixent successor October 1, 2026 | 3 min read | Tristan Manalac Twitter LinkedIn Facebook Email Print Sanofi and Regeneron have had a long and “sometimes contentious” partnership, BMO Capital Markets noted, as the companies contend with the looming loss of exclusivity of their blockbuster drug Dupixent. As key patent expiries loom over immunology juggernaut Dupixent, Sanofi and Regeneron have renewed their long-term partnership, with the French pharma fronting $1 billion to advance four long-acting, next-generation antibodies for immune-mediated conditions.Sanofi is offering Regeneron up to $7 billion more in development, regulatory and commercial milestones, according to a Thursday morning announcement. The French pharma will co-develop and co-commercialize four Regeneron-discovered antibodies.“Today’s agreement extends a productive (but at some points contentious) partnership,” BMO Capital Markets wrote on Thursday morning.

Just last year, Regeneron sued Sanofi, alleging that the French pharma didn’t provide “full access to material information” about Dupixent’s sales. Sanofi has also resisted efforts by Regeneron to audit records related to the blockbuster drug.The companies have settled this dispute, according to their Thursday announcement. The slate of experimental therapies in the renewed partnership is led by the IL-13-targeting REGN20423, which is currently in Phase 1 development for atopic dermatitis.

The three other assets are preclinical and include an IL-4xIL-13 bispecific, an anti-IL-4 therapy and a molecule designed to target IL-4R-alpha. All three are expected to enter human studies next year, according to the companies. Legal Regeneron Sues Sanofi, Alleging Stonewalling in Dupixent Pact According to the lawsuit, Sanofi has failed to provide partner Regeneron adequate information regarding the sales of Dupixent—including agreements with payers and pharmacy benefit managers that determine pricing and rebates for the drug.

February 7, 2025 · 2 min read · Tristan Manalac Read more The deal could expand beyond these four therapies, as well. Regeneron has the option to include Sanofi’s TSLPxIL-13 bispecific lunsekimig into the alliance—a right that Regeneron can choose to exercise once the molecule clears Phase 3 testing for chronic obstructive pulmonary disease (COPD). Profits for these assets, if they reach the market, will be split 50-50.Lunsekimig is in a pair of Phase 3 trials for COPD, both of which are expected to have initial readouts in 2029.

Sanofi is also developing lunsekimig for asthma and chronic rhinosinusitis with nasal polyps, for which it cleared respective mid-stage studies in April. Lunsekimig was also being studied in atopic dermatitis but missed the primary endpoint of improving disease severity in the exploratory Phase 2b VELVET trial.The renewed deal positions “both companies for continued leadership in the development of the next generation of therapeutics for type 2 inflammation-driven disease,” BMO added.Sanofi and Regeneron are expanding their decades-long alliance amid exclusivity concerns for Dupixent. The drug surged 26% last year to bring in $17.8 billion worldwide.

But a key U.S. patent is set to expire in 2031, which could open the blockbuster up to biosimilar challenge and, in turn, erode revenue. Sanofi general counsel Roy Papatheodorou explained during the company’s first quarter call in April that Dupixent has a web of patents extending as far as 2045.

Still, the pharma has been working diligently to find a successor. Earnings Sanofi defends Dupixent patents, but execs insist it has nothing to do with CEO change Sanofi’s interim leadership sought on a Thursday earnings call to quell concerns that its sudden defense of Dupixent’s patents had anything to do with the departure of CEO Paul Hudson. April 23, 2026 · 3 min read · Annalee Armstrong Read more Sanofi had pinned a lot of hopes on the autoimmune asset amlitelimab, which came from the $1.4 billion acquisition of Kymab and had been under development for atopic dermatitis and celiac disease.

Sanofi in July ended the asset’s development in atopic dermatitis, noting that “the totality of efficacy and safety evidence generated to date does not support further development” in this indication. Similarly being set up as a potential heir to Dupixent was the investigational IL-33 inhibitor itepekimab. Sanofi decided to axe the asset in July following mixed data in a late-stage study for COPD.

Amlitelimab and itepekimab no longer appear on the pharma’s pipeline page.Sanofi and Regeneron split Dupixent’s U.S. earnings 50-50, while international profits are divvied up based on a pre-determined sliding scale that gives a slight edge to Sanofi, according to a 2007 agreement between the companies. Thursday’s agreement will not affect the current profit-sharing arrangement for Dupixent, the partners said.

Twitter LinkedIn Facebook Email Print Immunology and inflammation Pipeline Sanofi Regeneron Pharmaceuticals, Inc. Tristan Manalac Tristan is BioSpace‘s senior staff writer. Based in Metro Manila, Tristan has more than eight years of experience writing about medicine, biotech and science.

He can be reached at tristan.manalac@biospace.com, tristan@tristanmanalac.com or on LinkedIn.