An open trial of OKT3 in patients with multiple sclerosis.

We report our experience with treatment with Muromonab-CD3 (Orthoclone OKT3) of 16 patients with multiple sclerosis (MS) who were in a progressive phase of their disease (n = 13) or in an acute severe attack lasting longer than 1 month without recovery (n = 3). We induced acute severe T-cytopenia with OKT3. Fifteen patients completed treatment for 10 days. Side effects were common and severe and included hypotension, nausea and vomiting, diarrhea, fever, and myalgia. In two of two patients tested, there was a transient though major rise in the levels of interferon gamma and tumor necrosis factor in the first 12 hours of treatment. Nonetheless, we did not detect new clinical or MRI activity of MS during the period of treatment, although many patients deteriorated transiently in disability scores. At the conclusion of follow-up, only four patients had deteriorated by 1.0 or more points on the Expanded Disability Status Scale of Kurtzke (EDSS) (73% stabilization rate). Of those patients who deteriorated, two died of complications of MS (EDSS 10). Only two patients had clinical improvement at 1 year follow-up. The attendant toxicity of OKT3 makes it unlikely that it will play a major role in the treatment of MS.