This clinical trial is focused on studying Relapsing Multiple Sclerosis, a condition where the immune system mistakenly attacks the protective covering of nerves, causing communication problems between the brain and the rest of the body. The study will use a treatment called YTB323, which involves a type of cell therapy. This therapy uses a patient’s own T cells, a type of white blood cell, that are modified to better recognize and attack certain cells in the body. The main goal of the study is to assess the safety of different doses of YTB323 in patients who have experienced disease activity despite previous treatments.

Participants in the study will receive YTB323 through an intravenous infusion, which means the treatment is delivered directly into the bloodstream. In addition to YTB323, some participants may also receive other medications such as Tocilizumab, Cyclophosphamide, and Fludarabine Phosphate, which are commonly used in medical treatments to manage immune responses and support the main therapy. The study will monitor the participants over time to observe any changes in their condition and to ensure the treatment is safe.

The trial will also involve regular check-ups, including tests like MRI scans, to track the progress of the disease and the effects of the treatment. The study aims to gather information on how the treatment affects the body and how well it works in managing the symptoms of Relapsing Multiple Sclerosis. This information will help in understanding the potential benefits and risks of using YTB323 for this condition.