The Japanese Ministry of Health, Labour and Welfare (MHLW) has granted orphan drug designation to riliprubart, an investigational monoclonal antibody developed by Sanofi, for the treatment of chronic inflammatory demyelinating polyneuropathy (CIDP). CIDP is a rare autoimmune disorder that affects the peripheral nerves, leading to symptoms such as weakness, numbness, and fatigue. Approximately 4,000 people in Japan are diagnosed with the condition.
Riliprubart works by selectively inhibiting activated C1s in the classical complement pathway, a mechanism that plays a role in inflammation and immune response. While therapies for CIDP are available, an estimated 30% of patients do not respond to current standard treatments, highlighting the need for new options.
“The orphan drug designation of riliprubart for people living with CIDP in Japan underscores our commitment to applying our deep understanding of the immune system to address rare neurological disorders with significant unmet medical needs,” said Erik Wallstroem, MD, PhD, Global Head of Neurology Development at Sanofi. “Our ongoing development of riliprubart reflects our dedication to challenging the status quo in neurology with the goal of improving people’s lives.”
Sanofi recently presented 76-week efficacy and safety data from a phase 2 trial of riliprubart at the Peripheral Nerve Society meeting in Edinburgh, UK, in May 2025. The findings suggest potential long-term benefits across a broad spectrum of CIDP patients. The antibody is now being evaluated in two phase 3 trials: the MOBILIZE study for patients unresponsive to standard care (NCT06290128), and the VITALIZE study for patients currently receiving intravenous immunoglobulin (IVIg) therapy (NCT06290141).
Orphan drug designation in Japan is awarded to treatments targeting conditions that affect fewer than 50,000 patients and address high unmet medical needs.