Prospective Evaluation of Sequencing From antiCD-20 Therapies to Ozanimod

This study is following people with relapsing multiple sclerosis (MS) who are switching from a type of MS drug called an anti-CD20 therapy (which depletes immune cells) to a different drug called ozanimod (which works by a different mechanism). The goal is to understand how to safely transition between these treatments. **You may be eligible if...** - You have been diagnosed with relapsing MS - You have had MS symptoms for at least 3 years - You are 18 years or older - Your doctor has decided to switch you from an anti-CD20 therapy to ozanimod **You may NOT be eligible if...** - You have a form of MS that is not relapsing - You have fewer than 3 years of MS history - You have conditions that make ozanimod unsafe for you - You are currently pregnant or planning to become pregnant Talk to your doctor to see if this trial is right for you.