The primary purpose of this phase 3b study is to assess the efficacy of a modified regimen of ublituximab in participants with relapsing multiple sclerosis (RMS) as measured by T1 Gadolinium (Gd)-enhancing lesions in Part A; PK in Part B along with efficacy of ublituximab as measured by T1 Gd-enhancing lesions in participants who had a suboptimal experience on prior anti-CD20 therapy in Part C. The study consists of 3 parts: Part A is single-armed and open-label, Part B is randomized, double-blind, placebo-controlled, and Part C is single-armed and open-label.
Diagnosis of RMS (2017 Revised McDonald criteria).
Participants naïve to treatment.
Participants previously treated with a disease modifying therapy (DMT) who have discontinued treatment prior to consent and meet the washout requirements.
Expanded Disability Status Scale (EDSS) score ≤ 5.5 at screening.
History of any serious 3 Infusion Related Reaction (IRR) on prior anti-CD20 therapy.
Primary-progressive multiple sclerosis (PPMS) or inactive Secondary Progressive MS (SPMS).
Active chronic (or stable but treated with immune therapy) disease of the immune system other than MS (e.g., rheumatoid arthritis, scleroderma, Sjögren's syndrome, Crohn's disease, ulcerative colitis, etc.) or immunodeficiency syndrome (hereditary immune deficiency, drug-induced immune deficiency, etc.).
Current evidence or known history of clinically significant infection, including: chronic, recurrent, or ongoing active viral, bacterial, or fungal infectious disease requiring long term systemic treatment such as, but not limited to chronic urinary tract infection, chronic pulmonary infection with bronchiectasis, tuberculosis, or active hepatitis C virus (HCV).