As with all clinical trials, the ocrelizumab trial in primary progressive MS limited the characteristics of people who could participate. The trial only included people who were aged 18 to 55, who had an EDSS (Expanded Disability Status Scale – a scale to assess neurological functioning used in clinical trials) score of up to (meaning they were able to walk with the help of a walker or bilateral crutches or other devices on both sides), and who had evidence of immune proteins in a test of their spinal fluid (“oligoclonal bands”). It is not possible to predict how a specific individual will respond to treatment. The use of ocrelizumab in clinical practice will help determine who is likely to benefit.
When the symptoms of the attack subside, an individual with MS is said to be in remission. However, MRI data have shown that this is somewhat misleading because MS lesions continue to appear during these remission periods. Patients do not experience symptoms during remission because the inflammation may not be severe or it may occur in areas of the brain that do not produce obvious symptoms. Research suggests that only about 1 out of every 10 MS lesions is perceived by a person with MS. Therefore, MRI examination plays a very important role in establishing an MS diagnosis, deciding when the disease should be treated, and determining whether treatments work effectively or not. It also has been a valuable tool to test whether an experimental new therapy is effective at reducing exacerbations.