A research study is underway to determine if LOU064/remibrutinib is safe and beneficial for people with relapsing multiple sclerosis (RMS). The primary purpose of this study is to determine if patients treated with remibrutinib experience fewer MS relapses (also called clinical attacks, flare-ups, or exacerbations) than patients treated with teriflunomide (also known as Aubagio®). Teriflunomide is an approved medication for the treatment of relapsing MS. Remibrutinib (LOU064) is a medication that has not been approved by any health authority (INVIMA) for the treatment of people with relapsing MS. Currently, remibrutinib is not available for purchase or prescription in any country as a medication for treating RMS. Remibrutinib selectively and highly effectively inhibits Bruton's tyrosine kinase (BTK), an enzyme responsible for the function of B lymphocytes. B lymphocytes are a type of white blood cell implicated in the development of multiple sclerosis (MS). Remibrutinib is expected to have beneficial clinical effects in a variety of chronic autoimmune inflammatory diseases, including relapsing-remitting MS. In this study, teriflunomide is used to determine whether remibrutinib is better than teriflunomide as a treatment for relapsing MS. Since we do not know which drug is better, we must compare them.