The purpose of this study is to assess early phase safety and tolerability of transitioning patients from approved oral and injectable RMS DMTs to siponimod. The results of this study will guide clinically relevant decisions related to the transition from frequently used RMS DMTs to siponimod and provide clinically relevant data on safety and tolerability for healthcare providers who are considering transitioning patients from currently approved RMS DMT to siponimod. The primary objective is to evaluate overall safety and tolerability profile of siponimod in advancing RMS patients (including a broader population that had not been previously studied with siponimod who are converting from currently approved oral or injectable RMS DMT).