Brain Imaging and Immune Changes During Remibrutinib Treatment in Multiple Sclerosis.

Multiple sclerosis (MS) is associated with ongoing inflammation within the central nervous system that may contribute to disease progression even when relapses are controlled. Remibrutinib, a Bruton tyrosine kinase (BTK) inhibitor, may affect immune cells involved in this process, but its effects on inflammation within the brain and spinal cord are not fully understood. [REDEFINE_p...2026_clean | Word] This study will evaluate changes in neuroinflammation and immune activity in participants with relapsing MS by combining advanced imaging and biomarker assessments. Measurements of microglial activity using positron emission tomography (PET), cerebrospinal fluid (CSF) analyses, blood-based biomarkers, and magnetic resonance imaging (MRI) will be used to assess changes associated with remibrutinib treatment. [REDEFINE_p...2026_clean | Word] The study will examine whether changes in imaging and fluid biomarkers are associated with measures of disease severity and whether these biomarkers may help predict longer-term clinical outcomes. Results may improve understanding of the biological effects of BTK inhibition in MS and help identify biomarkers that can be used to monitor treatment response and disease progression.

Inclusion criteria

• Capable of providing written informed consent for volunteering to undergo research procedures.
• Male or female, any race
• Age between 40 and 70 years of age, inclusive
• Diagnosis of RMS according to revised 2017 McDonald criteria at screening 15
• EDSS score of 0 to 6.5 (inclusive) at screening
• Treated with ocrelizumab according to routine clinical practice and at standard dose for at least 18 months. The last administration of ocrelizumab must have occurred within 5 to 9 months prior to randomization.
• Neurologically stable within 30 days prior to screening, including no MS relapse during this period.
• Suitable to be switched to remibrutinib based on physician judgement or patient preference.

Exclusion criteria

The exclusion criteria of the parent study are adapted and inherited under this section (See parent study protocol section 5.2). In addition, the following exclusion criteria apply:

• Hypersensitivity to [11C]-DPA-713 or any of its excipients
• Contraindications to PET or MRI (e.g. certain incompatible electronic medical devices, inability to lie still for extended periods) that make it potentially unsafe for the individual to participate
• Presence of a low affinity binding TSPO polymorphism.
• Any condition that, in the opinion of the Principal Investigator or his designee, could increase the risk to the participant or limits their ability to participate (e.g., liver or kidney disease, advanced cancer)
• Current or recent (within 12 months prior to screening) participation in research studies involving radioactive agents such that the total research-related radiation dose to the participant in any given year would exceed the limits set forth in the U.S. Code of Federal Regulations (CFR) Title 21 Section 361.1. https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/CFRSearch.cfm?FR=361.1.