Immunomodulatory treatment other than corticosteroids, immunoglobulin and plasma exchange for chronic inflammatory demyelinating polyradiculoneuropathy

Chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) is an uncommon disease that causes weakness and numbness of the arms and legs, which can be progressive or have a relapsing and remitting course. It is due to inflammation which damages the insulating sheaths (myelin) around individual nerve fibres. In severe cases the actual nerve fibres themselves are affected. The underlying cause is thought to be an autoimmune response in which immune cells are misdirected against the myelin. Cochrane reviews have presented evidence that other treatments do help. These are corticosteroids, plasma exchange (in which the abnormal plasma portion of the blood is replaced with a substitute) and intravenous infusions of human immunoglobulin (antibodies). However, benefit from these treatments is often absent, inadequate, or short-lived, lasting only a few weeks. Other treatment options include immunomodulatory or cytotoxic drugs, which kill the harmful immune cells, and drugs that regulate the immune system, such as interferons. There have only been four randomised trials. One was a parallel group open trial of the cytotoxic drug azathioprine for nine months involving 27 participants. The second was a double-blind crossover trial of the immune regulating drug interferon beta-1a involving 10 participants, with each treatment period lasting 12 weeks. Neither trial showed a significant result but neither was large enough to detect even moderate benefit. The third trial was a double-blind dose-ranging trial of interferon beta-1a; 67 participants were randomised and it lasted 32 weeks. The fourth was a double-blind placebo controlled trial of methotrexate involving 60 participants for 40 weeks. These two recent trials, although larger, did not show significant benefit from methotrexate or interferon beta-1a and were still not large enough to detect or rule out minor or moderate benefit. Observational studies of these and other drugs, including the cytotoxic drugs cyclophosphamide, ciclosporin A, and mycophenolate, and the immune regulating drug interferon alfa, have been performed but are insufficient to determine whether any of them are beneficial.