Sanofi stops immune drug trial in latest research setback

An article from Dive Brief Sanofi stops immune drug trial in latest research setback The failure adds to a series of mixed or negative readouts and leaves in doubt the future of a therapy Sanofi has viewed as a potential blockbuster. Published June 10, 2026 By Kristin Jensen Share Copy link Email LinkedIn X/Twitter Facebook Print License Add us on Google Dive Brief: Sanofi on Wednesday announced the latest in a string of disappointments for its pipeline, stopping a late-stage study of an experimental anti-inflammatory medicine because an independent monitoring board deemed it unlikely to be successful. Researchers were testing the drug, riliprubart, in patients with chronic inflammatory demyelinating polyneuropathy, or CIDP. The rare neurological condition causes weakness and sensory impairments that can lead to long-term disability. The Phase 3 study, dubbed MOBILIZE, included patients who weren’t helped by standard-of-care medicines. The monitoring board didn’t see any safety concerns with the drug but concluded during an interim analysis that it was “unlikely to provide sufficient efficacy,” Sanofi said. Dive Insight: While Sanofi shares fell by only 1% in early U.S. trading Wednesday, the news had a more pronounced effect on smaller rival Dianthus Therapeutics, which is developing a similar medicine that acts on a target called C1 and is also testing it in CIDP. Concerns that Sanofi’s results might foreshadow problems for Dianthus sent its shares down 16%. “The news is obviously disappointing for the complement inhibitor class in CIDP,” especially after initially impressive Phase 2 results from riliprubart, William Blair analyst Myles Minter wrote in a note to clients. But it’s possible that the trial design could be at fault, he said. Dianthus and Argenx, the latter of which is developing a “C2” inhibitor, are using different study protocols to test their experimental treatments, he said. Investors in Argenx appeared less concerned about the Sanofi study implications; that company’s shares were little changed. Argenx also already sells a successful CIDP treatment called Vyvgart. In April, Sanofi executives highlighted the potential for riliprubart, expecting to be able to share the full CIDP data next year. Now, the company is evaluating the future for the drug — which was acquired in a buyout of Bioverativ in 2018 — and whether to continue another Phase 3 study known as VITALIZE. That trial is designed to compare the efficacy of riliprubart and IVIg. Sanofi is looking to regroup after a series of research and development setbacks. The company announced the hiring of a new CEO in February and in April posted an upbeat financial report for the first quarter. But investors are looking for more from their pipeline as competition looms for its best-selling Dupixent medicine. Add us on Google Share Copy link Email LinkedIn X/Twitter Facebook Print License Filed Under: Pharma