A Study to Evaluate the Safety, Tolerability, Cellular Kinetics, and Pharmacodynamics of P-CD19CD20-ALLO1 in Participants With Multiple Sclerosis

This study is testing a new CAR-T cell therapy called P-CD19CD20-ALLO1 for people with multiple sclerosis (MS). CAR-T therapy reprograms immune cells to eliminate certain B-cells that are thought to drive MS. This is an early-phase safety study in both progressive and relapsing forms of MS. **You may be eligible if...** - You are between 18 and 60 years old - You have progressive MS with a disability score between 3 and 6, and have shown disability worsening without relapses for the past 2 years - OR you have relapsing MS with active relapses and MRI changes in the past 2 years while on treatment, with a disability score between 0 and 6 **You may NOT be eligible if...** - You are pregnant or breastfeeding - You have or are suspected to have a rare brain infection called PML - You have a known or suspected history of hemophagocytic lymphohistiocytosis (HLH) or neurotoxicity from prior therapies - You have another neurological condition that could mimic MS - You have a history of immune deficiency, serious infections, or prior CAR-T therapy Talk to your doctor to see if this trial is right for you.