Effect of Ocrelizumab on Neuroinflammation in Multiple Sclerosis as Measured by 11C-PBR28 MR-PET Imaging of Microglia Activation
Effect of Ocrelizumab on Neuroinflammation in Multiple Sclerosis as Measured by 11C-PBR28 MR-PET Imaging of Microglia Activation
Using magnetic resonance-PET (MR-PET) imaging with [11C]PBR28, a second-generation 18kDa
 translocator protein (TSPO) radiotracer, we have previously demonstrated abnormally high TSPO
 expression, indicative of microglia activation, across different brain tissue compartments of
 multiple sclerosis (MS) patients1.

 In this study, we propose to study the efficacy of ocrelizumab, a humanized monoclonal
 antibody that has been shown to decrease neuroinflammation in relapsing-remitting multiple
 sclerosis (RRMS) and progressive multiple sclerosis (MS) patients.

 We will test these effects by studying a cohort of 24 MS patients (12 RRMS, 12 progressive
 MS). Participants will be studied before (within 3 months prior to initiating treatment) and
 after treatment with ocrelizumab (~12 month follow up), a therapeutic drug that will be part
 of their standard medical care. We will use [11C]PBR28 to help determine changes in
 neuroinflammation.

 The purpose of this study is to determine the effects of ocrelizumab treatment on
 neuroinflammation by analyzing the uptake and distribution of [11C]PBR28 in individuals with
 multiple sclerosis. The specific aims of the current study are:

 1. To assess whether treatment with ocrelizumab in subjects with either relapsing-remitting
 MS or progressive MS is associated with decreased [11C]PBR28 binding in the cortex and
 white matter (lesions and normal appearing white matter), suggesting reduced
 neuroinflammation.

 2. To assess whether changes in neuroinflammation under ocrelizumab treatment, as measured
 by [11C]PBR28 uptake at 12-month follow up relative to baseline, are associated with
 changes in structural MR metrics of brain tissue damage including white matter lesion
 load, cortical atrophy, and demyelination in the cortex and in the normal-appearing
 white matter as measured by magnetization transfer ratio (MTR).

 3. To explore whether changes in functional and structural imaging metrics under
 ocrelizumab are associated with changes in clinical outcome measures.
Inclusion Criteria:

 1. Signed informed consent

 2. RRMS and/or PMS subtype

 3. EDSS between 0 and 7.0

 4. Express at least one high-affinity (Ala147) allele of the TSPO receptor for PBR28

 5. Initiating Ocrelizumab treatment within the next 3 months

 Exclusion Criteria:

 1. Hypersensitivity to trial medications

 2. History of life-threatening reaction to Ocrelizumab

 3. Acute or uncontrolled chronic medical condition

 4. Impaired hearing

 5. Claustrophobia

 6. 300 lbs of greater (weight limit of MRI table)

 7. Pregnancy or breastfeeding

 8. Sensitivity to imaging agents

 9. Contraindications to MRI

 10. Use of benzodiazepines, topiramate, doxycycline, mynocicline