Sanofi's Dupixent Faces Emerging Threat as Regeneron Deal Raises Financial Eyebrows

Sanofi enlists Karl-Anthony Towns to promote Nuvaxovid in the U.S. as Pfizer's atopic dermatitis data and a €17.3 billion patent cliff weigh on the stock.

Sanofi has rolled out a high-profile marketing push for its COVID-19 vaccine in the United States, enlisting NBA champion Karl-Anthony Towns as a paid spokesperson. The partnership, announced Tuesday, will see Towns use digital and social media platforms to promote vaccination and raise awareness about Nuvaxovid, with a particular focus on at-risk populations and encouraging conversations with healthcare providers.

The shot holds a distinctive position in the U.S. market: it is the only protein-based, non-mRNA COVID-19 vaccine approved by the Food and Drug Administration. Its clearance covers adults aged 65 and older, as well as adolescents and younger individuals aged 12 and up who have underlying conditions putting them at elevated risk of severe illness. Sanofi holds regulatory approvals in the U.S., the European Union, and the United Kingdom.

Pfizer's Pipeline Progress Puts Dupixent in the Crosshairs

While Sanofi works to build momentum on the vaccine front, pressure is quietly building on the company's most lucrative franchise. Rival Pfizer recently unveiled Phase II data for its antibody candidate Tilrekimig in atopic dermatitis and is laying groundwork for Phase III trials that will include a head-to-head comparison against Dupilumab. That development brings a potential challenger to Sanofi's blockbuster Dupixent one step closer to market, a prospect that has market participants scrutinizing every clinical milestone from would-be competitors.

The looming competitive threat arrives during a delicate transitional period for the French drugmaker. Beyond new entrants, the company faces the prospect of patent expirations toward the end of the decade, gaps it will need to fill through its own pipeline of novel drug candidates. The stakes for clinical development success are correspondingly high.

JPMorgan Flags €17.3 Billion Patent Cliff

Just how steep those revenue losses could become was underscored by JPMorgan, which estimates that patent expirations between 2030 and 2035 could cost Sanofi as much as EUR 17.3 billion.

To shore up its pipeline, the company struck an expanded partnership with Regeneron to jointly research new antibodies — a move that Barclays noted comes with the caveat that the assets remain at a very early stage of development.

Regeneron Alliance: $1 Billion Upfront, $7 Billion in Milestones

The deepened collaboration covers four long-acting antibody programs for immunology developed by Regeneron. Under the terms, Sanofi is making an immediate upfront payment of $1 billion, with success-based milestone payments of up to $7 billion also agreed. Development and worldwide commercialization costs will be split evenly between the two partners, as will potential profits from future products. Sanofi, however, will take full global leadership of all commercialization activities.

The arrangement follows earlier efforts by Sanofi to streamline its pharmaceutical portfolio, but the fresh financial commitments for externally sourced assets have stirred concerns among investors about the company's financial flexibility.

Market Skepticism Weighs on the Stock

Sentiment on the stock has shifted noticeably. What initially drew attention as a pipeline-strengthening move has given way to a more sober assessment of the deal's financial terms. While management frames the deepened alliance as a boost to its development pipeline, market observers are questioning the heavy capital commitment. Concerns about portfolio balance and growth prospects outside immunology have kept institutional investors cautious.

The combination of rising competition for Sanofi's flagship product and the lengthy development timelines for new hopefuls weighed on investor mood. Sanofi shares closed Friday's session down 3.5% at EUR 70.65, narrowing the gap to their 52-week low of EUR 70.35 to just 0.4%.

Whether the steps taken can restore market confidence may become clearer when Sanofi reports third-quarter 2026 results, scheduled for October 30, 2026. Management will field investor questions on its strategic direction during a web conference that day.