Research for multiple sclerosis (MS) received a set back this week when two trials studying a promising new treatment for MS were halted. Patients in the trials were experiencing two different types of adverse events--some patients were experiencing a worsening of MS symptoms while others were experiencing hypersensitivity reactions.

The decision to halt the trials is a setback for MS research and the specific therapy involved. However, the trial was not a complete loss. Scientist did learn additional information about the disease that will enable them to design and target future research efforts.

Results of the trials, one organized by the National Institutes of Health and the other by Stanford University, were reported in the October issue of the journal Nature Medicine.

Relapsing remitting multiple sclerosis, a form of the disease marked by periodic increased in brain inflammation, followed by periods of recovery, was the subject of both studies. This and the progressive form of MS are thought to be caused by an autoimmune reaction in which the body attacks its own myelin, the protective coating on the nerves in the central nervous system.

The studies sought to alter the body's immune reaction by using a changed version of the protein in myelin, called an altered peptide ligand.

Introducing the new version was designed to cause the body to react to normal myelin in a protective way, instead of attacking it.

Dr. Roland Martin of NIH's National Institute of Neurological Disorders and Stroke said that while the results of these tests were disappointing, the myelin protein remains a promising target in the study of multiple sclerosis.

Eight patients received the altered protein in the NIH tests. The trial was stopped after three patients showed a worsening of their disease and others experienced hypersensitivity, fever and cluster-type headaches.

The Stanford trial involved 144 patients at 14 clinics in the United States and Europe. It was halted after 53 had completed therapy.

The researchers said that in this trial, brain inflammation was reduced in some patients, but 9 percent developed hypersensitivity to the drug, with symptoms such as itching, nausea and abdominal pain.