High-dose Cyclophosphamide for Moderate to Severe Refractory Chronic Inflammatory Demyelinating Polyneuropathy

• The primary endpoint of this study is to evaluate the response rate of CIDP patients as determined by functional score, change in Summated compound motor action potential and strength, after high-dose cyclophosphamide therapy.
  

• The secondary endpoint of this study is to determine remission duration.
  

Chronic inflammatory demyelinating polyneuropathy (CIDP) is a common and under-recognized peripheral neuropathy that is thought to be immune-mediated. Randomized, placebo controlled clinical trials in CIDP demonstrate benefit from treatment with corticosteroids, plasmapheresis, and IV Ig. However, not all patients respond to these therapies. IV cyclophosphamide, cyclosporine, interferons, total lymphoid irradiation, and mycophenolate mofetil have been proposed as appropriate therapies for refractory patients.

Patients with CIDP often respond to immune-modulating treatment. However, the high rate of relapse and treatment-related side effects result in poor long-term outcomes for many patients. CIDP is assumed to be an autoimmune disease, but the pathogenesis is poorly understood. T cell infiltrates are predominantly CD8, suggesting a T cell mediated process. There is not, however, restricted T cell receptor Vbeta utilization seen in sural nerve biopsies. Immunoglobulin and complement deposits noted on the myelin sheaths support an antibody-mediated process. Antibodies to the P0 myelin protein are seen in a minority of patients. High-dose cyclophosphamide is believed to eradicate both B and T lymphocytes. This therapy does not damage hematopoietic stem cells, which allows for rapid white cell recovery without stem cell rescue.