Inclusion Criteria:
* Participants have been diagnosed with relapsing forms of MS and have had multiple sclerosis related symptoms at least 3 years prior to baseline visit
* Male or female participants \> or = to 18 years of age at the time of initiation of de-escalation
* Participants do not have evidence of new inflammatory disease activity (no new T2/contrast enhancing lesions, absence of relapses) for a minimum of two years prior to de-escalation
* Participant is taking an anti-CD20 therapy as a DMT continuously for a minimum of two years (e.g., has received at least 3 courses of rituximab, ocrelizumab, ublituximab; 24 months of treatment with ofatumumab; or a combination of treatments whereby the patient has been deemed to be B-cell depleted for 2 years) prior to initiation of de-escalation
* Participants received their last anti-CD20 infusion, including ocrelizumab subcutaneous injection, within 6-12 months or received their last ofatumumab injection within 30 -180 days from Day 1
* Participants must provide written informed consent and be able to comply with the visit schedule and study related assessments
* Participants must be able to undergo a brain MRI without anesthesia
* Woman of Childbearing Potential must agree to practice a highly effective method of contraception throughout the study until completion and willing to follow pregnancy precautions.
Exclusion Criteria:
* Any progression of neurological disability in the year prior to the screening visit that would be consistent with progressive MS
* Participant has an EDSS \>6.5
* Participant has a history of other chronic neurological illnesses that might mimic MS with chronic or intermittent symptoms (i.e. ALS, myasthenia gravis, chronic neuropathy, etc.)
* Participant is considering pregnancy in the short term, is pregnant, lactating or has a positive serum beta human chorionic gonadotropin (B-hCG) measured during screening.
* Participant has any other significant medical or psychiatric illness, if uncontrolled, that could jeopardize a subject's health or put them at significant safety risk during the course of the study in the opinion of treating investigator. Examples: uncontrolled hypertension, uncontrolled diabetes, uncontrolled asthma, uncontrolled depression
* Participant has a history of cancer within the last 5 years, including solid tumors and hematological malignancies (except basal cell and in situ squamous cell carcinomas of the skin or cervical dysplasia/cancer that has been excised and resolved)
* Participant has a history in the last 6 months of myocardial infarction, unstable angina, stroke, transient ischemic attack, decompensated heart failure requiring hospitalization, or Class III or IV heart failure
* Participant has Mobitz type II second-degree or third degree atrioventricular (AV) block, sick sinus syndrome, or sino-atrial block, unless the patient has a functioning pacemaker
* Participant has severe untreated sleep apnea
* Participant has a history of diabetes mellitus type 1, or uncontrolled diabetes mellitus type 2 with hemoglobin A1c (HbA1c) \> 9%, or is a diabetic subject with significant comorbid conditions such as retinopathy or nephropathy, or a history of uveitis
* Participant has a history or known presence of recurrent or chronic infection (e.g., hepatitis B virus (HBV), hepatitis C virus (HCV), human immunodeficiency virus (HIV); recurrent urinary tract infections are allowed.
* Any known or suspected active infection (excluding onychomycosis) at screening, including but not limited to a confirmed or suspected progressive multifocal leukoencephalopathy (PML). Known currently active tuberculosis (TB). History of incompletely treated Mycobacterium tuberculosis (TB) infection, as indicated by: Subject's medical records documenting incomplete treatment for Mycobacterium TB; Subject's self-reported history of incomplete treatment for Mycobacterium TB; Subjects with a history of TB who have undergone treatment accepted by the local health authorities (within 1 year from screening) may be eligible for study entry.
Exclusions related to Medications:
* Concomitant use of a monoamine oxidase inhibitor
* Use of systemic corticosteroids in the last 2 years, except for the use as a premedication for B-cell depleting treatment (Note: Use of inhaled or topical steroids; use of oral steroids for no greater than 14 days given for a non-MS condition are allowed)
* Prior use of alemtuzumab, mitoxantrone, cyclophosphamide, methotrexate, cyclosporine, or any experimental MS treatment within 5 half-lives
* Prior allergy to ozanimod
Exclusions related to Laboratory results:
* Participant has IgG levels \<400 mg/dL
* Participant has neutrophils \< 1500/μL (1.5 GI/L)
* Participant has an absolute white blood cell (WBC) count \< 3500/μL (3.5 GI/L)
* Participant has an absolute lymphocyte count (ALC) \< 800 cells/μL (0.80 GI/L).
* Participant has liver function impairment or persisting elevations of aspartate aminotransferase (AST) or alanine aminotransferase (ALT) results \> 3 x the upper limit of normal (ULN)
