LAUSR

Chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) is an acquired immune‐mediated polyneuropathy characterized by relapsing or steadily progressive clinical course. A major feature of the syndrome is that it encompasses several pathogeneses, and it is actually assumed that both cellular and humoral immunity can be involved with superiority depending on the particular subtype. Although cellular immunity typified by macrophage‐derived demyelination can play an essential role in classical CIDP, other pathogeneses that involve humoral immunity, such as autoantibodies targeting node of Ranvier proteins (neurofascin155: NF155; contactin1: CNTN1; contactin‐associated protein1: Caspr1; and neurofascin186/140: NF186/140), can bring about functional demyelination and have been discovered in approximately 5–15% of CIDP patients. Interestingly, such antibodies commonly belong to the immunoglobulin G4 (IgG4) subclass, and thus lack complement‐binding sites and compete with other IgG subclasses for the antigens. Patients with these IgG4 autoantibodies share clinical presentations to a certain extent, and anti‐NF155 and anti‐CNTN1 antibodies are representative examples. Patients with these IgG4 subclass antibodies fulfill the conservative diagnostic criteria for CIDP: distal‐dominant weakness, tremor and sensory ataxia. These patients also show poor responses to conventional first‐line therapeutics, and are non‐responders to intravenous immunoglobulins in particular. Therefore, novel treatment strategies other than first‐line therapies are awaited, and to date, small retrospective studies and several case reports have suggested the efficacy of rituximab. Accordingly, the Efficacy and Safety of Rituximab in Refractory CIDP Patients with IgG4 Autoantibodies trial, a prospective trial investigating the efficacy and safety of rituximab, is currently in progress.