Cyclophosphamide in exacerbations of multiple sclerosis. Therapeutic trial and a strategy for pilot drug studies.

Cyclophosphamide (CY) has been shown to reverse the signs of experimental allergic encephalomyelitis (EAE) even after the onset of neurological deficits. Because of the analogy of EAE to exacerbations of multiple sclerosis (MS) a clinical trial of CY in acute MS exacerbations was undertaken. A 'sequential criterion' method was used to minimize the size of sample needed for this pilot study. CY failed to alter significantly the course of acute exacerbations of MS. Possible reasons for this failure, and the value of the sequential criterion method in pilot studies, are discussed.