Sanofi, Regeneron Expand Immunology Partnership in Up to $8 Billion Deal

01:27 AM EDT, 10/01/2026 (MT Newswires) -- Sanofi (SAN.PA) and Regeneron Pharmaceuticals (RGO.F) agreed to expand their existing license and collaboration agreement to include multiple long-acting immunology antibodies. Under the expanded global partnership, the drugmakers will jointly develop and commercialize four new Regeneron-invented antibodies targeting interleukin-13, IL-4xIL-13 bispecific, interleukin-4, and interleukin-4 receptor alpha, according to a Thursday release. REGN20423, an IL-13 antibody, is in a phase 1 clinical study for atopic dermatitis, while the other three antibodies are expected to enter clinical trials in 2027. Regeneron will also have the option to add Sanofi's lunsekimig, an investigational therapy targeting TSLP and IL-13, to the collaboration following the completion of its phase 3 studies in chronic obstructive pulmonary disease. Sanofi will pay Regeneron $1 billion upfront, with Regeneron eligible to receive up to an additional $7 billion in development, regulatory and commercial milestone payments. The companies will share development and commercialization costs for the new programs and split future profits from potential products equally worldwide. Regeneron will lead research and development activities, while Sanofi will oversee global commercialization.