Sanofi halts phase 3 autoimmune trial early over insufficient efficacy as pipeline woes continue

Sanofi has halted the Phase 3 MOBILIZE study of riliprubart in patients with chronic inflammatory demyelinating polyneuropathy (CIDP) who are refractory to standard of care, after an interim analysis found the drug was "unlikely to provide sufficient efficacy".

The decision follows an interim review by an independent data monitoring committee and means Sanofi will not pursue regulatory registration based on this trial.

No new safety signals were identified, and the company says the discontinuation will not significantly impact its 2026 financial guidance.

The MOBILIZE trial was comparing riliprubart to placebo in about 140 patients who had failed prior treatment with immunoglobulin or corticosteroids; riliprubart is a complement inhibitor intended to block inflammatory mechanisms driving the rare autoimmune neuropathy.

Sanofi is assessing whether to continue other Phase 3 riliprubart trials, most notably the VITALIZE study in CIDP patients receiving intravenous immunoglobulin (IVIg) as maintenance therapy.

The setback is the latest in a series of late‑stage pipeline disappointments for the company, including past failures of the multiple sclerosis drug tolebrutinib in primary progressive MS and the discontinuation of several other Phase 2/3 programs.