The primary objective of this expanded access program is to provide ocrelizumab as treatment for eligible participants with primary progressive multiple sclerosis (PPMS) before it is commercially available in the United States (U.S.) for the indication of PPMS.

Inclusion Criteria:

• Age 18 to 55 years (inclusive)
• Diagnosis of PPMS in accordance with the revised 2010 McDonald criteria and the presence or documented history of cerebrospinal fluid oligoclonal bands by isoelectric focusing or elevated immunoglobulin G (IgG) index
• Expanded Disability Status Score (EDSS) of 2.0 to 6.5 points at screening
• For women of childbearing potential: agreement to remain abstinent (refrain from heterosexual intercourse) or use contraceptive methods that result in a failure rate of less than (<)1 percent (%) per year during the treatment period and for at least 24 weeks after the last dose of study treatment or until their B-cells have repleted, whichever is longer

Exclusion Criteria:

• History of relapsing-remitting multiple sclerosis (RRMS), progressive relapsing multiple sclerosis (PRMS) or secondary progressive multiple sclerosis (SPMS) at screening
• History of severe allergic or anaphylactic reactions to humanized or murine monoclonal antibodies
• History or known presence of recurrent or chronic infection
• History of recurrent aspiration pneumonia requiring antibiotic therapy
• History of cancer, including solid tumors and hematological malignancies (except basal cell, in situ squamous cell carcinomas of the skin, and in situ carcinoma of the cervix of the uterus that have been excised and resolved with documented clean margins on pathology)
• History of or currently active primary or secondary immunodeficiency
• History of coagulation disorders because ocrelizumab is administered via infusion
• Known presence or history of other neurologic disorders
• Significant, uncontrolled disease, such as cardiovascular (including cardiac arrhythmia), pulmonary (including chronic obstructive pulmonary disease), renal, hepatic, endocrine, gastrointestinal, or any other significant disease
• Congestive heart failure
• Known active bacterial, viral, fungal, mycobacterial infection, or other infection
• Any concomitant disease that may require chronic treatment with systemic corticosteroids or immunosuppressants during the course of the expanded access program (EAP)
• Contraindications for or intolerance to oral or IV corticosteroids, including IV methylprednisolone
• Treatment with therapies approved for relapsing forms of Multiple Sclerosis (MS), including: Beta interferons, glatiramer acetate, fingolimod (Gilenya®), teriflunomide (Aubagio®), dimethyl fumarate (Tecfidera®), IV immunoglobulin, plasmapheresis, or other immunomodulatory therapies within 12 weeks prior to enrollment (Participants should not be excluded from the EAP due to previous treatment with rituximab)
• Participants who have received fingolimod (Gilenya®) or dimethyl fumarate (Tecfidera®) if their lymphocyte count is not within normal values
• Previous treatment with natalizumab (Tysabri®) within 6 months of screening (Participants are not eligible for the EAP if they have been treated with natalizumab (Tysabri) for more than 1 year)
• Any previous treatment with alemtuzumab (Lemtrada®)
• Any previous or current treatment with any experimental procedure for MS