[Primary Progressive Multiple Sclerosis]

Primary progressive multiple sclerosis (PPMS) is a chronic inflammatory disease of the central nervous system that leads to demyelination and neurodegeneration. PPMS is characterized by a gradual accumulation of disabilities that may occur from the initial disease onset. The pathological processes underlying PPMS are complex and include a variety of different mechanisms and pathways, including inflammation, axonal degeneration, microglial activation/oxidation byproducts, mitochondrial injury, and glutamate excitotoxicity. There is currently no disease-modifying drug approved for PPMS in Japan. However, ocrelizumab, a humanized anti-CD20 monoclonal antibody, has been approved for PPMS by the Food and Drug Administration. In addition, some disease-modifying drugs have demonstrated significant efficacy in the treatment of PPMS in clinical trials.