Inclusion Criteria:

• - Written informed consent must be obtained prior to any assessment being performed.

• - Patients diagnosed with relapsing remitting multiple sclerosis and a disease duration of < 15 years.

• - Male or female patients aged 18-55 years (inclusive) - Use of appropriate contraception during period of trial (women).

• - Post-menopausal for at least 1 year OR.

• - Surgically sterile (have had a hysterectomy or bilateral oophorectomy, tubal ligation, male partner vasectomy or otherwise incapable of pregnancy) OR.

• - Practicing a highly effective method of birth control if sexually active, including hormonal prescription oral contraceptives, contraceptive injections, contraceptive patch, intrauterine device, double barrier method (e.g., condoms, diaphragm or cervical cap with spermicidal foam, cream or gel), or male partner sterilization consistent with local regulations regarding use of birth control methods for patients participating in clinical trials, for the duration of their participation in the study OR.

• - Not heterosexually active (patients who are not heterosexually active at screening must agree to utilize a highly effective method of birth control if they become heterosexually active during their participation in the study) OR.

• - Practicing true abstinence (when this is in line with the preferred and usual lifestyle of the subject) Period abstinence (e.g., calendar, ovulation, symptothermal, post ovulation methods) is not an acceptable method.

Exclusion Criteria:

• - Radiologic identification of marked brain atrophy relative to patients age based on recent MRI and interpretation of expert neuroradiologist or PI.

• - New lesion in most recent MRI (within 3 months) - Hypersensitivity to clemastine or other arylalkylamine antihistamines, or any of the excipients.

• - Treatment with corticosteroids within 30 days prior to screening.

• - Expanded Disability Status Scale (EDSS) ≥ 4.5.

• - History of significant cardiac conduction block.

• - History of cancer.

• - Suicidal ideation or behavior in 6 months prior to baseline.

• - Pregnancy, breastfeeding or planning to become pregnant.

• - Involved with other study protocols simultaneously without prior approval.

• - Concomitant use of any other putative remyelinating therapy as determined by the investigator.

• - Prior treatment with total lymphoid irradiation, T cell or T cell receptor vaccination.

• - Prior treatment with alemtuzumab, mitoxantrone, or cyclophosphamide.

• - Serum creatinine > 1.5 mg/dL; aspartate transaminase (AST), alanine transaminase (ALT), or alkaline phosphatase > 2 times the upper limit of normal.

• - History of drug or alcohol abuse within the past year.

• - Untreated B12 deficiency (as determined by B12 serological assessments and metabolites including methylmalonic acid [MMA] and homocysteine) or untreated hypothyroidism.

• - Clinically significant cardiac, metabolic, hematologic, hepatic, immunologic, urologic, endocrinologic, neurologic, pulmonary, psychiatric, dermatologic, allergic, renal, or other major diseases that in the PI's judgment may affect the interpretation of study results or patient safety.

• - History of or presence of clinically significant medical illness or laboratory abnormality that, in the opinion of the investigator would preclude participation in the study.

• - Inability to participate in MRI, including extreme claustrophobia.

• - Any dental braces or permanent or undetachable metals in the jaw or face.

Treatments capable of remyelination are a major unmet need for multiple sclerosis and other diseases that involve myelin damage, loss, or dysfunction in the central nervous system (CNS). Chronic demyelination of axons is believed to be injurious to neurons and serves as a major contributor to irreversible cell loss that underlies permanent disability. Available MS treatments are primarily immunosuppressing, without directly addressing or fully preventing axonal degeneration and disability. Clemastine fumarate was identified along with a series of other antimuscarinic medications as a potential remyelinating agent using the micropillar screen (BIMA) developed at UCSF. The screen demonstrated that clemastine promoted the differentiation of the endogenous oligodendrocyte precursor cells (OPCs) into mature myelinating oligodendrocytes. Following in vivo validation, an FDA investigational new drug (IND) exemption was granted to investigate clemastine for the treatment of multiple sclerosis in the context of chronic optic neuropathy. That pilot study was recently completed and is the first randomized control trial documenting efficacy for a putative remyelinating agent for the treatment of MS. The preselected primary efficacy endpoint (visual evoked potential) was met and a strong trend to benefit was seen for the principal secondary endpoint assessing function (low contrast visual acuity). That trial number was 13-11577. This clinical trial is intended to assess magnetic resonance imaging evidence of remyelination using Clemastine Fumarate in patients with chronic demyelinated lesions. Specifically speaking, the primary objective will assess various multi-parametric MRI sequences on the corpus callosum region, a region that animal models studies identified as a promising candidate for assessing remyelination. The aim was to help define the potential for MRI in measuring remyelination in MS, determine the optimal sequences and location for measuring myelin recovery, and help guide trial design for future remyelinating trials. Finally, the study is designed to assess tolerability and clinical efficacy of Clemastine using outcomes intended to assess for (a) adverse events and (b) recovery of myelin.

Arms

Interventions