Ublituximab for Acute Neuromyelitis Optica (NMO) Relapses

Inclusion Criteria: 1. Able and willing to provide written informed consent. 2. 18-100 years of age. 3. New acute optic neuritis and/or transverse myelitis. A clinical event is defined as an episode of inflammation in the spinal cord and/or optic nerve leading to neurologic deficits on physical exam not attributable to another disease process. 4. Confirmed or highly suspected diagnosis of NMO according to the 2006 revisions of the Wingerchuk diagnostic criteria for NMO (Wingerchuk, 2006), or AQP4 positive NMOSD. 5. The B cell count must be normal (5-20% of total lymphocytes) in subjects who have not received another B cell depleting therapy in the past year. For those on B cell depleting therapy within the past year, a B cell count of at least 0.5% is necessary. 6. A female subject is eligible to enter the trial if she is: * Not pregnant or nursing; * Of non-childbearing potential OR of child-bearing potential 7. Subject has a negative serum pregnancy test at screening and agrees to one of the following: * Complete abstinence from intercourse for the period from consent into the trial until 6 months after the last dose of investigational product; or, * Consistent and correct use of one of the following acceptable methods of birth control for the period from consent into the trial until 6 months after the last dose of investigational product: * Oral contraceptives * Injectable progesterone * Levonorgestrel implants * Estrogenic vaginal ring * Percutaneous contraceptive patches * Intrauterine device (IUD) or intrauterine system (IUS) * Male partner sterilization * Double barrier method Exclusion Criteria: 1. Current evidence or known history of clinically significant infection including: * Chronic or ongoing active infectious disease * Previous serious opportunistic or atypical infections. * Hepatitis B * Tuberculosis (TB) * HIV 2. History of clinically significant central nervous system (CNS) trauma (e.g. spinal cord compression). 3. Past or current history of medically significant adverse effects from: * Corticosteroids * Diphenhydramine * Murine or mouse/human chimeric antibodies 4. Past or current malignancy, except for * Cervical carcinoma Stage 1B or less * Non-invasive basal cell and squamous cell skin carcinoma * Cancer diagnoses with a duration of complete response (remission) \>5 years A history of hematologic malignancy excludes a subject from participation, regardless of response. 5. Significant concurrent, uncontrolled medical condition including, but not limited to, cardiac, renal, hepatic, hematological, gastrointestinal, endocrine, immunodeficiency syndrome, pulmonary, cerebral, psychiatric, or neurological disease which could affect the subject's safety, impair the subject's reliable participation in the trial, impair the evaluation of endpoints, or necessitate the use of medication not allowed by the protocol, as determined by the PI of the trial. 6. Use of an investigational drug or other experimental therapy for a condition other than NMO within 4 weeks, 5 pharmacokinetic half lives or duration of biological effect (whichever is longer) prior to screening. 7. Current participation in any other interventional clinical trial. Participation in non-interventional trial requires approval of the protocol by investigator. 8. Subjects who are concurrently receiving any other investigational agents, or have participated in an interventional clinical trial within the last 21 days, or subjects who have been vaccinated with a live vaccine \< 2 months prior to trial inclusion. 9. Because there is an unknown but potential risk for adverse events in nursing infants secondary to treatment of the mother with ublituximab breastfeeding should be discontinued if the mother is treated with ublituximab.