This clinical trial is focused on studying a condition known as Primary Progressive Multiple Sclerosis (PPMS). This is a type of multiple sclerosis where symptoms gradually worsen over time without any periods of improvement. The study is evaluating a treatment called Ocrelizumab, which is given as an infusion, meaning it is administered directly into the bloodstream through a vein. The trial aims to determine if a higher dose of Ocrelizumab is more effective than the currently approved dose in slowing down the progression of disability in people with PPMS.

Participants in the study will receive either the higher dose of Ocrelizumab, the approved dose, or a placebo. The study will monitor the participants over a period to see how the treatment affects their condition. The main goal is to see if the higher dose can better reduce the risk of disability progression, which is a measure of how the disease affects a person’s ability to perform daily activities. The study will also look at other factors, such as changes in brain volume and levels of certain proteins in the blood that are related to nerve damage.

In addition to Ocrelizumab, some participants may receive other medications like Paracetamol, Methylprednisolone, and Diphenhydramine Hydrochloride to manage symptoms or side effects. The study is designed to be double-blind, meaning neither the participants nor the researchers know who is receiving which treatment, to ensure unbiased results. The trial will continue until the researchers have enough information to determine the effectiveness and safety of the higher dose of Ocrelizumab for treating PPMS.