In separate clinical trials, a drug called ocrelizumab has been shown to reduce new attacks in patients with relapsing remitting multiple sclerosis (MS), and new symptom progression in primary progressive MS.
Three studies conducted by an international team of researchers, which included Amit Bar-Or and Douglas Arnold from the Montreal Neurological Institute and Hospital of McGill University, have discovered that ocrelizumab can significantly reduce new attacks in patients with relapsing MS, as well as slow the progression of symptoms caused by primary progressive MS.
In one study, 732 patients with primary progressive MS were randomized on a 2:1 ratio to receive either ocrelizumab, a humanized monoclonal antibody that depletes CD20+ B cells, or a placebo.
The proportion of patients with 12-week confirmed disability progression was 39.3 per cent with the placebo versus 32.9 per cent with ocrelizumab. After 24 weeks, the proportion with confirmed disability progression was 35.7 per cent with placebo versus 29.6 per cent with ocrelizumab. By week 120, timed 25-foot walk worsened by 55.1 per cent for placebo versus 38.9 per cent for ocrelizumab. Patients given ocrelizumab were also found to have fewer new brain lesions and less brain volume loss than those given the placebo.
Researchers also tested ocrelizumab in two separate studies of patients with relapsing remitting MS, one a group of 821 and the other 835. In both studies, patients were randomized on a 1:1 ratio to receive either ocrelizumab or an already established treatment for relapsing MS: subcutaneous interferon-beta, injected three times weekly. Compared to the placebo, relapse rates in patients given ocrelizumab were 46-per-cent lower in one study and 47-per-cent lower in the other. Ocrelizumab was found to reduce the risk of disability progression after 12 weeks and 24 weeks, and reduced the number of new brain lesions.
The study noted that infusion-related reactions occurred in 34.3 per cent of ocrelizumab-treated patients. Serious infections were not more frequent with ocrelizumab compared to the interferon (1.3 versus 2.9 per cent respectively). Malignancies occurred in four ocrelizumab-treated patients and in two interferon-treated patients. Further observation is required to determine the long-term safety of ocrelizumab.
“The results in patients with relapsing remitting MS not only demonstrate very high efficacy against relapses, but also underscore the important emerging role of B cells of the immune system in the development of relapses,” says Bar-Or. “While the results in patients with primary progressive MS are more modest, they nonetheless represent the very first successful trial in such patients, a breakthrough as primary progressive MS now transitions from a previously untreatable condition to one that can be impacted by therapy. It is an important step forward in the field.”