[Clinical practice and research of chronic inflammatory demyelinating polyneuropathy: current status and future]

Chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) is the most common chronic immune-mediated neuropathy. Japanese national survey conducted in 2021 showed that the estimated number of CIDP patients is 4,180. Whereas CIDP is a rare disease, immunological therapy is highly effective, and therefore appropriate diagnosis and treatment have a substantial clinical impact. In international (2021) and Japanese (2024) clinical practice guidelines, CIDP is not considered a single disease entity but is categorized into typical CIDP and CIDP variant; typical CIDP constitutes the major phenotype, and several distinct variants such as multifocal, distal, and pure motor/sensory CIDP, referred to as CIDP variants. In this review article, we describe current insights into the pathophysiology of CIDP, focusing on typical CIDP, based on findings in electrophysiology, pathology, neuroimaging, and immunology. Current evidence suggests that typical CIDP is antibody-mediated, whereas multifocal CIDP is largely driven by cellular immunity. Previous clinical trials have mainly targeted typical CIDP, and first-line treatments include corticosteroids and immunoglobulin therapy. More recently, the efficacy of the neonatal Fc receptor blocker with a single mechanism of reducing serum IgG levels, supports the concept that typical CIDP is an antibody-mediated disorder. Whereas detailed data on the long-term prognosis of CIDP remain limited, a patient survey conducted by the CIDP Support Group in 2024 has shown that 33% of patients were receiving oral corticosteroid therapy and 57% were undergoing maintenance immunoglobulin therapy. The survey also reported that 69% of patients had to retire or change occupations because of CIDP, suggesting that the impact of treatment on quality of life remains insufficient. A CIDP registry launched in 2022 in Japan has enrolled over 330 patients to date, and real-world investigations of clinical practice are underway. This article provides an overview of the current status, future directions, and remaining challenges in CIDP management and research.