The Ministry of Health, Labour and Welfare (MHLW) in Japan has granted orphan drug designation to riliprubart, a monoclonal antibody that selectively inhibits activated C1s in the classical complement pathway for people with chronic inflammatory demyelinating polyneuropathy (CIDP). Despite available therapies, many CIDP patients are left with residual symptoms, including weakness, numbness, and fatigue that can lead to long-term morbidity and diminished quality of life.