Sanofi is terminating a Phase III chronic inflammatory demyelinating polyneuropathy (CIDP) trial of riliprubart after analysis showed the drug is unlikely to show efficacy.

The Phase III MOBILIZE study (NCT06290128) investigated the IgG4 humanised monoclonal antibody (mAb) in patients with CIDP refractory to standard-of-care (SoC). SoC includes corticosteroids.

This decision follows an interim analysis by an independent data monitoring committee (IDMC), which found the study is unlikely to provide sufficient efficacy. No safety signals related to riliprubart were identified as part of this interim analysis.

While MOBILZE has been stopped, other studies with riliprubart, including the VITALIZE phase III study (NCT06290141) in IVIg-treated patients with CIDP, will continue. The company added that these other ongoing studies will be “evaluated accordingly.”

Sanofi said 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. Sanofi will conduct a thorough analysis of the MOBILIZE data to inform future research directions and contribute to the broader scientific understanding of CIDP. 

Riliprubart selectively inhibits activated C1s, protease proteins, in the classical complement pathway of the innate immune system. CIDP is a rare neurological condition that causes progressive weakness and sensory impairment in the arms and legs. CIDP occurs when the body’s immune system attacks the myelin sheaths around nerve cells in the peripheral nervous system.

Approximately 30% of people with CIDP do not respond to standard therapies. In people with CIDP who do respond, about 70% of the response is considered incomplete. Less than one-third of people with CIDP remain in remission without continued therapy.

In a Phase II trial, riliprubart offered disease-controlling benefits, with improving or stable disease, including those who failed or had an inadequate response to SOC treatment, as well as those with residual disability on SOC. It also offered disease-controlling benefits in all cohorts.

Among the SoC-treated, SoC-refractory, and SoC-naïve subjects, 87%, 89%, and 92%, respectively, showed improvement or were stable when switching from SOC treatment to riliprubart after 24 weeks.

Sanofi acquired the rights to riliprubart as part of a $11.6bn acquisition of Bioverativ in March 2018.