A Study to Evaluate the Pharmacokinetics, Pharmacodynamics, Safety, Radiological and Clinical Effects of Subcutaneous Ublituximab in Participants With Relapsing Multiple Sclerosis (RMS)

The purpose of this study is to assess the pharmacokinetics of ublituximab when administered subcutaneously (SC) compared to intravenous (IV) administration in participants with RMS.

Inclusion Criteria: 1. Diagnosis of RMS (2017 Revised McDonald criteria). 2. Expanded Disability Status Scale (EDSS) score ≤ 5.5 at screening. 3. Neurologically stable for \> 30 days prior to Screening and Day 1. 4. Female participants of childbearing potential must consent to use a highly effective method of contraception from consent and for 6 months after the last dose of ublituximab. Exclusion Criteria: 1. Primary-progressive Multiple Sclerosis (PPMS) or inactive Secondary Progressive Multiple Sclerosis (SPMS). 2. Active chronic disease of the immune system other than MS or immunodeficiency syndrome. 3. Participants with significantly impaired bone marrow function or significant leukopenia or thrombocytopenia. 4. Participants who previously received anti-CD20 therapy at any time; any approved therapy to treat MS within 5 half-lives of the medication prior to screening. Note: Other Inclusion/Exclusion criteria may apply.