Obe-cel in Refractory Progressive Forms of Multiple Sclerosis

This is a Phase 1 study to determine the safety, tolerability, and preliminary efficacy of obe-cel in participants with refractory progressive forms of multiple sclerosis. The study comprises 3 periods: Screening Period: From Day -30 to enrolment Treatment Period: From day of enrolment to End of Treatment (EOT) or Day 1 - Participants will be evaluated to confirm eligibility for lymphodepletion, and thereafter receive lymphodepletion to enhance treatment efficacy and cluster of differentiation (CD)19 chimeric antigen receptor (CAR) T cell survival. Obe-cel Administration: If the participant's eligibility for receiving obe-cel infusion is confirmed, the participant is to receive a single obe-cel infusion on Day 1. Post treatment Period: From Day 1 to End of Study all participants will be followed up for efficacy and safety evaluation.