Regeneron Pharmaceuticals and Sanofi have announced an expansion on their long-standing antibody collaboration, adding multiple next-generation, long-acting antibodies to the alliance that has jointly established Dupixent (dupilumab).

The expanded agreement builds on the companies' 20+ year collaboration, through which more than 1.5 million people are currently receiving Dupixent across nine indications, making it one of the most widely used antibody medicines in the world.¹

"The Regeneron-Sanofi alliance has been one of the most productive in biopharma history. This agreement builds on that foundation to bring the next generation of immunology medicines to patients even faster," said Leonard S. Schleifer, board co-chair, president and chief executive officer of Regeneron. "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."

What does the expanded agreement cover?

Under the expanded license and collaboration agreement, Regeneron and Sanofi will co-develop and co-commercialize four new long-acting, Regeneron-invented antibodies targeting interleukin-13 (IL-13), an IL-4xIL-13 bispecific, interleukin-4 (IL-4), and interleukin-4 receptor alpha (IL-4Rα).¹

The IL-13 antibody Regn20423 is currently in a Phase I clinical trial for atopic dermatitis, and the other three antibodies are expected to enter clinical studies in 2027.¹ As part of the collaboration, Regeneron will also have the option to include Sanofi's lunsekimig, an investigational bispecific Nanobody VHH therapy targeting TSLP and IL-13, in the collaboration, exercisable once lunsekimig completes its Phase III trials for chronic obstructive pulmonary disease.¹

Financially, Regeneron will receive an upfront payment of $1 billion from Sanofi, with the potential for additional development, regulatory, and commercial milestone payments of up to $7 billion.¹ The companies will also share development and commercialization costs for the new programs, along with splitting future profits from any resulting products 50:50 on a global basis.¹

Belén Garijo, chief executive officer of Sanofi, framed the expansion as part of a broader push to reinvigorate the company's pipeline. "This is a deliberate first step in igniting Sanofi's innovation engine. Our longstanding alliance with Regeneron has transformed the treatment landscape for millions of patients living with diseases driven by type 2 inflammation and created one of the world's leading immunology businesses," Garijo said. "By deepening our collaboration, we will make rapid progress in creating the next generation of meaningful therapies for patients with immune-mediated diseases, while contributing to Sanofi's long-term future."

Settling differences

As part of the new agreement, the companies also settled their prior collaboration-related litigation iusse.^1,2

Previously, Regeneron had filed a suit against Sanofi, in which Regeneron alleged that Sanofi breached provisions of their collaboration agreement by withholding full access to pharmacy benefit manager contracts and other records tied to Dupixent sales, and by blocking Regeneron's efforts to fully audit the books and records related to the drug.² Regeneron had sought declaratory judgment, injunctive relief, and damages in that dispute, while Sanofi maintained its stance that it was in full compliance with the collaboration agreement.²

Sources

1. Regeneron and Sanofi Expand Global Alliance with Multiple Next-Generation, Long-Acting Immunology Antibodies Regeneron October 1, 2026, https://www.globenewswire.com/news-release/2026/10/01/3372510/0/en/regeneron-and-sanofi-expand-global-alliance-with-multiple-next-generation-long-acting-immunology-antibodies.html
2. Regeneron Sues Sanofi, Alleging Stonewalling in Dupixent Pact BioSpace February 7, 2025, https://www.biospace.com/business/regeneron-sues-sanofi-alleging-stonewalling-in-dupixent-pact