Sanofi, Regeneron Expand Antibody Collaboration With $8B Deal

Sanofi and Regeneron Pharmaceuticals are expanding their long-running antibody collaboration to develop four next-generation, long-acting treatments for immune-mediated diseases.

The expanded agreement builds on more than 20 years of work between the companies, which includes the development of Dupixent (dupilumab). More than 1.5 million people worldwide are currently receiving Dupixent across nine approved uses, according to the companies.

Under the new agreement, Sanofi and Regeneron will jointly develop and commercialize four antibodies invented by Regeneron. The programs target key proteins involved in type 2 inflammation, including interleukin-13 (IL-13), interleukin-4 (IL-4), IL-4 receptor alpha (IL-4Rα), and the IL-4/IL-13 pathway.

One of the programs, REGN20423, is already being studied in a Phase 1 clinical trial for atopic dermatitis. The other three antibody programs are expected to enter clinical trials in 2027.

The companies will also explore the potential addition of Sanofi’s investigational therapy lunsekimig to the collaboration. Lunsekimig is a bispecific Nanobody therapy designed to target thymic stromal lymphopoietin (TSLP) and IL-13. Regeneron will have an option to include the program after completion of its Phase 3 studies in chronic obstructive pulmonary disease (COPD).

Under the financial terms, Regeneron will receive an upfront payment of $1 billion from Sanofi. It could receive up to another $7 billion in development, regulatory and commercial milestone payments.

Sanofi and Regeneron will share development and commercialization costs for the new programs and split future profits from the potential medicines equally on a global basis.

Regeneron will lead research and development activities, while Sanofi will be responsible for global commercial operations. The existing profit-sharing arrangement for Dupixent will remain unchanged.

The companies said the expanded partnership is aimed at developing longer-acting antibody medicines that could provide new treatment options for people with immune-mediated diseases.

“This is a deliberate first step in igniting Sanofi’s innovation engine,” said Belén Garijo, CEO of Sanofi. She said the expanded collaboration could support the development of new therapies while building on the companies’ existing immunology business.

Regeneron CEO Leonard S. Schleifer said the agreement would build on the companies’ previous work and support the development of the next generation of immunology medicines.

The collaboration between Sanofi and Regeneron began in 2003 and has resulted in several approved medicines, including Dupixent. The companies said they have also settled their previous litigation related to their collaboration.

The expanded agreement gives both companies a broader pipeline of long-acting antibody programs as they continue to develop treatments targeting pathways involved in inflammatory and immune-mediated diseases.