A Study of C-CAR168 in Participants With Progressive Multiple Sclerosis

Key Inclusion Criteria: * Able to sign and date the informed consent form. * Male or female, 18-55 years of age, body weight \>=40 kg. * Diagnosis of MS according to the 2024 McDonald criteria with cohort-specific progressive MS requirements. * Cohort 1: active SPMS; Cohort 2: PPMS or non-active SPMS. * Inadequate response to at least one prior high-efficacy disease-modifying therapy administered for at least 6 months. * Documented disability progression over the prior 24 months. * EDSS 3.0 to 6.5, inclusive. * Meets protocol-defined disease-duration, CSF, organ-function, cardiac/pulmonary, pregnancy testing, contraception, vaccination, and cellular-therapy follow-up requirements. Key Exclusion Criteria * RRMS, clinically isolated syndrome, radiologically isolated syndrome, or another diagnosis better explaining the neurologic course. * Alternative inflammatory demyelinating disorders, including AQP4-antibody-positive NMOSD and MOG-antibody-associated disease. * Active or chronic infection requiring antibiotics, or protocol-specified positive infectious disease testing. * Inadequate washout from prior MS therapy or specified recent immunomodulatory treatments. * Prior CAR T-cell therapy, other genetically modified immune cell therapy, or gene therapy. * Pregnant or breastfeeding, or planning pregnancy during the protocol-defined follow-up period. * Specified major cardiovascular, neurologic, transplant, malignancy, bleeding/thromboembolic, allergy, or protocol-compliance exclusions.