Sanofi has stopped a Phase 3 trial of riliprubart in chronic inflammatory demyelinating polyneuropathy (CIDP) after an independent monitoring board concluded the therapy was unlikely to achieve sufficient efficacy. The MOBILIZE study was testing the anti-inflammatory medicine in patients who were not helped by standard of care. The decision came without new safety concerns. The halt adds to a string of late-stage disappointments for Sanofi and sets up new strategic questions for riliprubart, which was acquired from Bioverativ in 2018. Sanofi said it is evaluating whether to continue another Phase 3 study, VITALIZE, designed to compare riliprubart and IVIg. Analysts framed the update as particularly notable for complement-inhibitor competitors in CIDP, including Dianthus Therapeutics, which is developing a similar approach targeting C1. Investors appeared to weigh the possibility that study design—not only biology—may be the deciding factor for efficacy outcomes in this class.