Sanofi stops development of Nurix-partnered immune drug

An article from Dive Brief Sanofi stops development of Nurix-partnered immune drug The decision sparked a sell-off in Nurix shares as well as analyst debate about the prospects of drugs designed to degrade a tough-to-reach protein called STAT6. Published Nov. 4, 2026 Delilah Alvarado Reporter Share Copy link Email LinkedIn X/Twitter Facebook Print License Add us on Google Dive Brief: Sanofi has stopped development of an experimental protein-degrading immune disease drug licensed from biotechnology company Nurix.

Nurix on Tuesday revealed Sanofi’s decision to scrap “SAR448272,” an oral medicine designed to eliminate STAT6, a protein involved in many inflammatory conditions. Nurix didn’t specify the reason for the decision, but Sanofi separately told analyst firm Leerink Partners “emerging nonclinical findings ... didn’t warrant further development” in eczema, according to a note to investors.

Nurix received a $10 million payment from Sanofi in August when a Phase 1 study began and would’ve been eligible for additional payouts if the treatment moved forward in testing. Company shares plummeted more than 40% in early trading Wednesday. Dive Insight: Many proteins still remain beyond the reach of traditional drugmaking methods.

Protein degraders — therapeutics built to destroy a protein, rather than block its activity — are one way around that problem. STAT6 is one example. The protein plays an important role in a misdirected immune response known as “Type 2 inflammation.” It’s also in the same molecular pathway as IL-4 and IL-13, the targets of Sanofi and Regeneron’s blockbuster anti-inflammatory drug Dupixent.

Still, drugmakers have had a tough time designing small molecules that can stifle STAT6, making it a ripe opportunity for protein degradation specialists to capitalize on. Sanofi began collaborating with Nurix in 2020, betting $55 million up front and possibly $2.5 billion overall in a broad partnership centered around protein degraders. And just last year, that deal advanced, with Sanofi exercising an option to a STAT6 degrader Nurix had discovered.

Since then, STAT6 degraders have gained momentum. Kymera Therapeutics, another company working on protein degraders, posted positive early data for a similar drug last year. Kymera’s share price skyrocketed afterwards, setting the stage for an anticipated readout from a mid-stage trial later this year.

Kymera’s progress had made analysts optimistic about the potential for Nurix’s drug. Sanofi’s sudden decision to end development, then, caught some of them off guard. The move is “disappointing,” wrote RBC Capital Markets analyst Brian Abrahams.

“We thought initial preclinical properties looked reasonably similar to [Kymera’s drug].” Sanofi told analysts at the firm Leerink Partners that the company still believes STAT6 is “an important pathway in immunology” but that this “particular molecule will not be able to move forward.” It has another program partnered with privately held Recludix Pharma in development. “We thus do not view this termination as a negative read-through to the broader STAT6 class,” wrote Leerink’s David Risinger in a note to clients Wednesday. The setback also doesn’t affect Nurix’s “core value driver,” a Roche-partnered medicine called bexobrutideg, wrote Jefferies analyst Roger Song.

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