The primary purpose of the study is to evaluate the safety and tolerability of a single-ascending intravenous (IV) dose (Part 1), a single-ascending subcutaneous (SC) dose (Part 2), and multiple ascending SC doses (Part 3) of RO7121932 in participants with multiple sclerosis (MS).
Expanded Disability Status Scale (EDSS) score ≤7.0 at Screening
Participants with relapsing multiple sclerosis (RMS) or progressive multiple sclerosis (PMS) who fulfil international panel criteria for diagnosis (McDonald 2017 criteria)
Participants not treated with any approved MS treatment at Screening and not planning to start on any MS therapy during the study (including follow-up)
Female participants must practice abstinence or otherwise use contraception
Evidence of clinical disease activity as defined by any clinical relapse within 3 months prior to screening, or by >1 clinical relapse within 12 months prior to screening
Evidence of magnetic resonance imaging (MRI) activity as defined by the presence of ≥ 1 Gadolinium (Gd)-enhancing T1 lesion in the screening MRI scan or by ≥ 4 new or enlarging T2 lesions in the screening scan as compared to a reference scan
Participants who have active progressive multifocal leukoencephalopathy (PML), have had confirmed PML, or have a high degree of suspicion for PML
Known presence of other neurological disorders that may mimic MS including but not limited to: neuromyelitis optica spectrum disease, Lyme disease, untreated Vitamin B12 deficiency, neurosarcoidosis, cerebrovascular disorders, and untreated hypothyroidism