Thursday, October 1, 2026

Sanofi and Regeneron expand immunology alliance

Sanofi and Regeneron have expanded their long-running antibody collaboration with four Regeneron-discovered, long-acting immunology programs. The companies said the additions are intended to extend their joint work in diseases linked to type 2 inflammation.

The most advanced asset is REGN20423, a monoclonal antibody targeting interleukin-13. It is currently being evaluated in a phase 1 study in atopic dermatitis. The agreement also covers a long-acting IL-4xIL-13 bispecific antibody and two preclinical antibodies directed at IL-4 and IL-4Rα. Those three programs are expected to enter clinical development in 2027.

Deal terms

Sanofi will pay Regeneron $1 billion upfront. Regeneron may also receive up to $7 billion in development, regulatory and commercial milestone payments.

The partners will share development and commercialization costs for the new programs. Any future profits from the potential products will be split equally worldwide. Regeneron will lead research and development, while Sanofi will take responsibility for global commercial activities. The current profit-sharing arrangement for Dupixent is not being changed.

Building on Dupixent partnership

The Sanofi-Regeneron alliance dates back to 2003 and has produced several approved medicines. Its key product is Dupixent, which inhibits signaling through the IL-4 and IL-13 pathways and is used in diseases associated with type 2 inflammation.

According to the companies, more than 1.5 million people worldwide are currently receiving Dupixent across nine indications. The medicine has approvals in more than 60 countries in one or more indications, including 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.

Option linked to Sanofi asset

The amended agreement also gives Regeneron the option to add Sanofi’s lunsekimig to the collaboration. Lunsekimig is an investigational bispecific Nanobody VHH therapy targeting TSLP and IL-13. The option can be exercised after completion of its phase 3 studies in chronic obstructive pulmonary disease.

Sanofi and Regeneron also said they have settled previous litigation related to their collaboration. The companies scheduled a conference call for investors and analysts on October 1, 2026.