Sanofi Halts MOBILIZE Phase 3 Trial of Riliprubart in Refractory CIDP After Interim Analysis Shows Insufficient Efficacy
Key Insights
Sanofi announced the MOBILIZE phase 3 study of riliprubart in refractory CIDP will be stopped following an independent data monitoring committee interim analysis that found the trial unlikely to demonstrate sufficient efficacy.
No safety signals related to riliprubart were identified during the interim analysis, and the company will evaluate continuation of the VITALIZE phase 3 study in IVIg-treated CIDP patients.
Riliprubart is an IgG4 humanized monoclonal antibody targeting activated C1s (search) in the classical complement pathway, designed to inhibit inflammatory mechanisms driving demyelination in CIDP.
Sanofi announced on June 10, 2026, that the MOBILIZE phase 3 study (NCT06290128) of riliprubart in patients with chronic inflammatory demyelinating polyneuropathy (search) (CIDP) refractory to standard-of-care treatment will be stopped. The decision follows an interim analysis conducted by an independent data monitoring committee, which determined that the study is unlikely to provide sufficient efficacy.
No safety signals related to riliprubart were identified as part of this interim analysis. Sanofi stated it will work closely with investigators and site teams to ensure a wind-down of the MOBILIZE study, with appropriate transition of care for all enrolled patients.
"We are deeply grateful to the patients, caregivers, and investigators who participated in the MOBILIZE study," Sanofi said in its press release.
The company will conduct a thorough analysis of the MOBILIZE data to inform future research directions and contribute to the broader scientific understanding of CIDP. The termination of the study will not incur any significant financial cost, and there is no change to Sanofi's financial guidance for 2026.
VITALIZE study under evaluation
The continuation of other ongoing studies with riliprubart, including the VITALIZE phase 3 study (NCT06290141) in IVIg-treated patients with CIDP, will be evaluated accordingly. The VITALIZE study represents a distinct patient population — those receiving intravenous immunoglobulin (IVIg) as standard-of-care — and its fate will be determined following further assessment.
Mechanism of action and rationale
Riliprubart (SAR445088, BIVV020) is an IgG4 humanized monoclonal antibody that selectively inhibits activated C1s (search) in the classical complement pathway of the innate immune system. By blocking C1s, riliprubart was designed to inhibit key inflammatory mechanisms that drive demyelination and axonal damage in CIDP. The drug is currently under clinical investigation, and its safety and efficacy have not been evaluated by any regulatory authority.
The CIDP treatment landscape
CIDP is a rare neurological condition characterized by progressive weakness and sensory impairment in the arms and legs, caused by the immune system attacking the myelin sheaths around nerve cells in the peripheral nervous system. Timely diagnosis is essential to preventing long-term disability, yet despite available therapies, many individuals are left with residual symptoms including weakness, numbness, and fatigue that can lead to long-term morbidity and diminished quality of life.
According to Sanofi, approximately 30% of people with CIDP do not respond to standard therapies. Among those who do respond, about 70% of the response is considered incomplete. Furthermore, less than one-third of people with CIDP remain in remission without continued therapy, highlighting the significant unmet medical need that riliprubart sought to address in the refractory population.
The MOBILIZE study's failure to demonstrate sufficient efficacy in this difficult-to-treat population represents a setback for complement-targeted approaches in CIDP, though the full analysis of the trial data may yet yield insights that inform future therapeutic strategies in this challenging neurological disorder.