Study to Assess the Efficacy of Mayzent on Microglia in Secondary Progressive Multiple Sclerosis

Inclusion Criteria: * Patients diagnosed with active SPMS according to the Lublin 2014 criteria. Activity is determined by MRI activity (contrast-enhancing lesions; new and unequivocally enlarging T2 lesions) and/or clinical relapses in the 24 months prior to the study baseline. If the clinical MRI is not available to determine the activity (contrast-enhancing lesions; new and unequivocally enlarging T2 lesions), then a screening MRI will be offered to the subjects to determine inclusion/exclusion criteria eligibility. * Age between 18 and 60 years * Have EDSS scores between 3.0 and 6.5 * Treatment naïve to both Mayzent and to Ocrevus * Not being on S1P modulators or B-cell therapies for the last 9 months * Subjects starting treatment as part of their clinical routine * Be willing and able to comply with the study procedures for the duration of the trial * Have given written informed consent and signed Health Insurance Portability and Accountability Act (HIPAA) authorization before any study-related activities are carried out * Normal kidney functioning (creatinine clearance \>59) * No known hypersensitivity reactions to contrast agents * None of the exclusion criteria Exclusion Criteria: * Have received treatment within 30 days prior to enrollment with steroids or any other concomitant immunomodulatory therapies * Have received an investigational drug or experimental procedure within the past 30 days * Low affinity (LAB) for the DNA single nucleotide polymorphism (SNP) of…