Regeneron and Sanofi expand antibody collaboration to four new assets

Regeneron Pharmaceuticals and Sanofi (through Sanofi Biotechnology SAS and Sanofi Parent) signed the Sixth Amendment to their Amended and Restated License and Collaboration Agreement on October 1, 2026, originally dated November 10, 2009. Under the amendment, the parties agreed to co-develop and co-commercialize four new long-acting, Regeneron-invented antibodies: one targeting interleukin-13, one targeting interleukin-4, one targeting IL-4 receptor alpha, and a bispecific antibody targeting IL-4xIL-13.¹

Regeneron also has the option, after completion of certain ongoing clinical trials, to add Sanofi's Phase 2/3 asset lunsekimig, an investigational bispecific Nanobody VHH therapy targeting TSLP and IL-13, as well as another Sanofi early-development product, with Regeneron reimbursing Sanofi for related development costs if it exercises that option.¹

Financially, Sanofi will make an upfront payment to Regeneron of $1.0 billion, and Regeneron is entitled to up to an additional $7.0 billion in development, regulatory, and commercial milestone payments for the New Licensed Products.¹ Global profits from sales of the new products will be split equally between the two companies.¹

On development responsibilities, the parties have agreed on an initial global development plan for the IL-13 asset and plan to agree on plans for the others, with development costs shared equally, though costs above a budget cap for the new products fall to Regeneron, subject to recoupment rights.¹ Regeneron will lead development and regulatory matters before marketing approval filings and will remain lead regulatory party in the United States, while Sanofi will lead regulatory matters outside the U.S. and lead commercialization of the new products.¹

Separately, Regeneron and Sanofi entered a settlement agreement under which Regeneron agreed to dismiss its lawsuit concerning Sanofi's obligation to share information on Dupixent (dupilumab) and other collaboration products, along with Regeneron's audit rights under the agreement.¹

On financial impact, Regeneron expects a roughly $22 million pre-tax acquired in-process R&D charge in the third quarter of 2026, reducing GAAP and non-GAAP earnings per diluted share by about $0.18.¹ The company cautioned that its third-quarter results are preliminary and unaudited.¹