Sanofi, Regeneron broaden alliance to find their next Dupixent

An article from Sanofi, Regeneron broaden alliance to find their next Dupixent The deal carries a $1 billion upfront payment and tasks the two companies to develop long-acting antibody drugs that go after the same targets as their blockbuster anti-inflammation agent. Published Oct. 1, 2026 Jacob Bell Lead Reporter Share Copy link Email LinkedIn X/Twitter Facebook Print License Add us on Google Sanofi and Regeneron have expanded a longstanding alliance in the hopes of developing new immune system-regulating drugs in the vein of their megablockbuster product Dupixent.

Per terms of their revised alliance, the companies will co-develop and co-commercialize four long-acting, Regeneron-invented antibodies designed to interact with select members of a protein family known as interleukins, or “ILs” for short. Specifically, the antibodies will target either or both “IL-13” and “IL-4,” or they’ll go after a so-called subunit of IL-4 like Dupixent does. The most advanced of those four potential drugs, codenamed REGN20423, is currently in an early-stage clinical trial, where it’s being evaluated as a treatment for eczema.

The three others should enter human testing next year, according to the companies. “The Regeneron-Sanofi alliance has been one of the most productive in biopharma history,” Leonard Schleifer, Regeneron’s CEO, said in a statement. “This agreement builds on that foundation to bring the next generation of immunology medicines to patients even faster.” “By expanding our alliance, we are positioning promising new long-acting antibodies for the kind of rapid, global impact that our shared work on Dupixent has already achieved,” Schleifer added.

Dupixent was first cleared for market in 2017 as a treatment for eczema. It has since racked up approvals in asthma, COPD and a handful of chronic conditions affecting the skin, throat and nose. It has also become the top earner for both companies, reaching $10.9 billion in net product sales in the first half of this year.

Yet, key patents protecting Dupixent from biosimilar competition are set to expire over the next five years. While Sanofi and Regeneron contend that a patent thicket they’ve set up could protect the franchise until 2045, at least some investors remain concerned the drug’s outlook. In focusing on “next-generation” versions of Dupixent, the companies’ amended collaboration “may help quell” those patent concerns as well as “set the stage” for future collaborations, licensing agreements or immunology asset purchases, according to Brian Abrahams, an RBC Capital Markets analyst who covers Regeneron.

“We believe investors have wanted these types of scenarios to play out, and there had been considerable anticipation, so from an optics standpoint could be a positive given the perceived strength of the commercial [joint venture],” Abrahams wrote in a note to clients. In the expanded alliance, Regeneron has agreed to lead research and development activities while Sanofi will be in charge of global commercial efforts. The companies will share costs and future profits from these potential products evenly.

They also noted that their existing profit-sharing agreement regarding Dupixent will not change. Regeneron will receive $1 billion up front, and be eligible to receive as much as $7 billion in additional, milestone-based payments. The New York-based drugmaker also now has the option to include in the collaboration an experimental Sanofi medicine, lunsekimig, that’s exercisable once it completes certain late-stage studies.

Lunsekimig is being evaluated against a series of respiratory illnesses driven by chronic inflammation. Abrahams acknowledged that, while the amended joint venture is an overall positive for Regeneron, the drugs involved “are still very early” in development and “without any substantial data” to showcase they’re differentiated from other treatments. He also noted the “crowded” competitive landscape in eczema, where multiple biologics are being developed.

Pfizer’s “tilrekimig,” for example, just scored in a Phase 2 study and is now heading into more advanced testing across eczema, asthma and COPD. Recommended Reading Chasing Dupixent, a biotech aims to make better antibody drugs for eczema By Gwendolyn Wu • Aug. 11, 2026 Sanofi, Regeneron win FDA nod for Dupixent in chronic hives By Ben Fidler • April 18, 2025 Add us on Google Share Copy link Email LinkedIn X/Twitter Facebook Print License Filed Under: Pharma, Deals