Inclusion Criteria:  Confirmed diagnosis of MS (according to the 2010 McDonald criteria). Age 25-70 years. Clinical diagnosis of non-active primary and secondary MS MRI imaging consistent with a diagnosis of MS at any time point. Score on the Expanded Disability Status Scale (EDSS) of 2.5-6.5  Adequate hematologic parameters without ongoing transfusion support:  Hemoglobin (Hb) ≥ 9 g/dL Platelets ≥ 100 x 109 cells/L  Creatinine ≤ 1.5 x the upper limit of normal (ULN), or calculated creatinine clearance  ≥ 60 mL/minute x 1.73 m2 per the Cockcroft-Gault formula  Total bilirubin ≤ 2 times the upper limit of normal (ULN) unless due to Gilbert's disease Alanine aminotransferase (ALT) and aspartate aminotransferase (AST) ≤ 2.5 times ULN, or < 5 times ULN for patients with liver metastases QT interval corrected for rate (QTcF) ≤ 470 msec for women and ≤ 450 msec for men on the ECG obtained at Screening Negative serum pregnancy test within 14 days prior to the first dose of study therapy for women of child-bearing potential (WCBP)  13. Ability to provide written informed consent.  Exclusion Criteria:  Corticosteroid use (oral or intravenous) within the last 30 days. Current use or use in the prior 6 months of MS immunotherapy, interferon, glatiramer acetate, fingolimod, siponimod, dimethyl fumarate or natalizumab or any other chronic immunosuppressive medication Inability to tolerate intranasally administered medications Nasal corticosteroids, nasal antihistamines, nasal flu dosing within the past 30 days. Chronic rhinitis, deviated septum, nasal polyps, history of sinusitis treated within the past 12 months. Active COVID-19 disease; according to FDA guidelines Female patient who is pregnant, lactating, breastfeeding, or planning on becoming pregnant during study. Female patients of childbearing age will undergo a pregnancy test and be excluded from the study if positive. Active malignancy within 5 years. Inflammatory bowel disease, rheumatoid arthritis, systemic lupus erythematosus, asthma, or type 1 diabetes Neutropenia (<500 neutrophils/mL) or other severe immunosuppression Unable or unwilling to comply with protocol requirements. Patients with a history of gadolinium allergy. Screening labs outside of the normal range; EBV IgM positive subjects with clinical signs will not receive study drug. Serious cardiac condition within the last 6 months, such as uncontrolled arrhythmia, myocardial infarction, unstable angina or heart disease defined by the New York Heart Association (NYHA) Class III or Class IV (See Appendix B) or hereditary long QT syndrome Concomitant medication(s) that may cause QTc prolongation or induce Torsades de Pointes, except for antimicrobials that are used as standard of care to prevent or treat infections and other such drugs that are considered by the Investigator to be essential for patient care Known positive for human immunodeficiency virus (HIV), hepatitis B virus surface antigen (HBsAg) or hepatitis C virus (HCV) Any other medical intervention or other condition which, in the opinion of the Principal Investigator, could compromise adherence to study requirements or confound the interpretation of study results