The Sanofi Regeneron Alliance Expansion, announced on October 1, 2026 from Paris and Tarrytown, NY, brings multiple next-generation, long-acting immunology antibodies into the partnership that built Dupixent® (dupilumab). Sanofi and Regeneron Pharmaceuticals, Inc. said the agreement builds on a collaboration of more than 20 years. According to the companies, 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.
Sanofi Chief Executive Officer Belén Garijo called the deal a “deliberate first step in igniting Sanofi’s innovation engine.” She said the longstanding collaboration has transformed treatment for patients with diseases driven by type 2 inflammation and created one of the world’s leading immunology businesses. Garijo added that deepening the relationship should speed progress toward the next generation of therapies for immune-mediated diseases while contributing to Sanofi’s long-term future.
Regeneron’s Leonard S. Schleifer, MD, PhD, Board co-Chair, President and Chief Executive Officer, described the alliance as “one of the most productive in biopharma history.” He said the agreement is meant to bring the next generation of immunology medicines to patients faster. Under the Sanofi Regeneron Alliance Expansion, Regeneron is positioning its promising new long-acting antibodies for the kind of rapid, global impact that the shared work on Dupixent has already achieved.
Sanofi Regeneron Alliance Expansion Financial Terms: $1 Billion Upfront and Up to $7 Billion in Milestones
Regeneron will receive an upfront payment of $1 billion from Sanofi. The companies also outlined the potential for development, regulatory and commercial milestone payments of up to an additional $7 billion. Those milestone payments are described as potential. The release does not disclose milestone triggers, individual payment amounts or timing, so any payment beyond the upfront amount depends on future events that have not been specified publicly.
The companies will share development and commercialization costs for the new programs and will split future profits from these potential products 50:50 on a global basis. Regeneron will lead research and development activities, while Sanofi will lead global commercial efforts. The release states that the existing profit-sharing agreement regarding Dupixent will not change, so the new terms apply to the newly added programs under the Sanofi Regeneron Alliance Expansion.
The companies also said they have settled their prior collaboration-related litigation. The press release provides no further detail on the terms of that settlement, so any financial effect is not disclosed. Readers tracking the Sanofi Regeneron Alliance Expansion should treat the $1 billion upfront payment and the $7 billion potential milestone figure as the only disclosed headline economics.
Sanofi Regeneron Alliance Expansion Pipeline: REGN20423 and Three Other Long-Acting Antibodies
Four new Regeneron-invented, long-acting antibodies will be co-developed and co-commercialized under the expanded license and collaboration agreement. They target interleukin-13 (IL-13), an IL-4xIL-13 bispecific, interleukin-4 (IL-4) and interleukin-4 receptor alpha (IL-4Rα). Regeneron invented all four, and Regeneron will lead research and development.
REGN20423, the IL-13 antibody, is currently in a phase 1 clinical study for atopic dermatitis. The other three antibodies are expected to enter clinical studies in 2027. The release includes no efficacy or safety data for these programs. The timelines are forward-looking statements, subject to the risks the companies describe, including research and development uncertainty and regulatory decisions.
Regeneron will also have the option to include Sanofi’s lunsekimig in the collaboration. Lunsekimig is an investigational bispecific Nanobody® VHH therapy targeting TSLP and IL-13. The option is exercisable upon completion of its phase 3 studies for chronic obstructive pulmonary disease. The Sanofi Regeneron Alliance Expansion therefore runs in both directions, with Regeneron contributing four antibodies and holding an option on a Sanofi asset.
Sanofi Regeneron Alliance Expansion Builds on Dupixent, the Alliance’s Flagship Antibody
Dupixent was invented using Regeneron’s proprietary VelocImmune® technology. It is a fully human monoclonal antibody that inhibits signaling of the IL-4 and IL-13 pathways and, as the companies note, is not an immunosuppressant. The companies say the Dupixent development program has shown significant clinical benefit and a decrease in type 2 inflammation in phase 3 studies. They say this establishes IL-4 and IL-13 as key and central drivers of type 2 inflammation.
Dupixent has received regulatory approvals in more than 60 countries in one or more indications. These include certain patients with atopic dermatitis, asthma, chronic rhinosinusitis with nasal polyps, eosinophilic esophagitis, prurigo nodularis, chronic spontaneous urticaria, chronic obstructive pulmonary disease, bullous pemphigoid and allergic fungal rhinosinusitis, across different age populations. This approval record is the commercial and scientific base on which the Sanofi Regeneron Alliance Expansion rests.
George D. Yancopoulos, MD, PhD, Regeneron’s Board co-Chair, President and Chief Scientific Officer and a principal inventor of Dupixent, noted that the clinical and commercial alliance dates to 2003. He said it has produced multiple approved medicines and that Dupixent has over 1.5 million active patients worldwide. Yancopoulos said the companies hope to combine Regeneron’s antibody discovery and development expertise with Sanofi’s global capabilities and reach to deliver the next wave of immunology innovation.
Sanofi Regeneron Alliance Expansion Next Steps: Investor Call, Ongoing Dupixent Studies and What to Watch
Sanofi and Regeneron scheduled a conference call for investors and analysts on October 1, 2026, at 14:00 CET / 8:00 a.m. ET. A presentation was to be available for download from the investor relations sections of sanofi.com and regeneron.com when the call started. The webcast was accessible through the Upcoming Events page of Sanofi’s website and the Events and Presentations page of Regeneron’s investor site, and telephone participation required advance registration.
Beyond approved uses, Sanofi and Regeneron are studying dupilumab in a broad range of diseases driven by type 2 inflammation or other allergic processes in phase 3 studies, including chronic pruritus of unknown origin. The companies emphasize that these potential uses remain under clinical investigation and that no regulatory authority has fully evaluated their safety and efficacy. The Dupixent pipeline therefore continues alongside the new Sanofi Regeneron Alliance Expansion programs.
Regeneron (NASDAQ: REGN) describes itself as a biotechnology company that invents, develops and commercializes medicines for serious diseases, using proprietary technologies such as VelociSuite®. Sanofi describes itself as an R&D-driven, AI-powered biopharma company listed on EURONEXT: SAN and NASDAQ: SNY. Both companies note that the press release contains forward-looking statements, and actual results may differ materially from those expressed or implied.
This report draws exclusively from the joint Sanofi press release dated October 1, 2026. Items to follow, all forward-looking, include the first clinical studies for the three programs expected to start in 2027. They also include progress of REGN20423 in its phase 1 atopic dermatitis study and any decision on the lunsekimig option after phase 3 COPD results.
Sanofi Regeneron Alliance Expansion Deal Terms
| Term | Detail |
|---|---|
| Announcement date | October 1, 2026 |
| Locations | Paris, France and Tarrytown, NY |
| Parties | Sanofi; Regeneron Pharmaceuticals, Inc. |
| Upfront payment | $1 billion, paid by Sanofi to Regeneron |
| Potential milestones | Up to an additional $7 billion (development, regulatory, commercial) |
| Cost sharing (new programs) | Development and commercialization costs shared |
| Profit split (new programs) | 50:50, global |
| R&D lead | Regeneron |
| Global commercial lead | Sanofi |
| Existing Dupixent profit-sharing | Unchanged |
| Prior litigation | Settled (terms not disclosed) |
| Milestone triggers and timing | Not disclosed |
