B-cells have an important role in the pathogenesis of multiple sclerosis (MS). Ocrelizumab, a medication that targets B-cells have been found to be highly effective in stopping the disease activity in relapsing-remitting MS.

The efficacy of ocrelizumab might be related to the specific pattern of B-cell tolerance defect in patients with MS and the potential of its normalization with treatment with ocrelizumab. By analyzing the reactivity of recombinant antibodies expressed from single B-cells, the investigators' collaborators have demonstrated that the pattern of B-cell tolerance defect is different in people with MS who only display an impaired removal of developing autoreactive B-cells in the periphery while central B-cell tolerance in the bone marrow is functional in most patients. In contrast, patients with rheumatoid arthritis (RA), type-1 diabetes (T1D) or Sjögren's syndrome (SS) show defective central and peripheral B-cell tolerance checkpoints. As a consequence, while anti-B-cell therapy does not correct defective early B-cell tolerance checkpoints in T1D and only temporarily slows down autoimmune processes before newly generated autoreactive B-cells likely induce patient relapse, the investigators postulate that the efficacy of ocrelizumab in MS may be linked to normal central B-cell tolerance and the production of a normal B-cell and T-cell compartment after ocrelizumab therapy.

In an open-label study, 10 patients with relapsing MS will be treated with two courses of ocrelizumab and will be followed clinically and radiologically for at least two and a half years. Assessment of T and B-cell phenotypes and function at baseline and 18-24 months post-B-cell depletion will be the primary outcome of the study.

Inclusion Criteria:

• Diagnosis of relapsing remitting multiple sclerosis (RRMS) based on revised McDonald criteria
• At least one Gd-enhancing lesions on the brain or spinal cord MRI done in the prior three months OR at least one new T2/FLAIR lesion on the brain or spinal cord MRI done in the prior three months (compared to a prior MRI performed within 18 months of the most recent MRI)
• Naïve to Disease modifying therapy (DMT) or at least off these DMTs (natalizumab, fingolimod, DMF) for three months or on an injectable DMT (interferons or glatiramer acetate)
• Expanded Disability Status Scale (EDSS) score at the time of screening =<3
• Negative urine or serum pregnancy test must be available for premenopausal women and for women <12 months after the onset of menopause unless these women have undergone surgical sterilization
• Women of childbearing potential must agree to remain abstinent (refrain from heterosexual intercourse) or use one method of contraception with a failure rate of <1% per year or a barrier method supplemented with spermicide. Contraception must continue for the duration of study treatment and for at least 24 weeks after the last dose of study treatment

Exclusion Criteria:

• Contraindication to treatment with an anti- cluster of differentiation antigen 20 (CD20) antibodies, including being seropositive for HBsAg
• Active hepatitis B virus infection
• Ever received B-cell depleting antibodies (rituximab, ocrelizumab, ofatumumab), alemtuzumab, daclizumab, mitoxantrone or hematopoietic stem-cell transplant
• Pregnant or lactating women
• Hypersensitivity to ocrelizumab
• Treatment with steroids in the past 30 days

Participants received two courses of treatment with ocrelizumab six months apart. Adverse event data were collected up to 24 months after the second (last) ocrelizumab infusion.

The primary outcome measure was based on lab results; however, none of the antibodies from the immune cells were able to cloned for analysis, none of the lab samples from any participants could be analyzed, and consequently, no data for the primary outcome were generated. The study was considered completed as all participant data collection was conducted per the protocol. The failure of lab analysis affected only the primary outcome, the overall completion status is complete.