S1PR1 and myeloid sarcoma: Recent studies show that the prevalence of MS is rising, with about 2.8 million people living with MS worldwide as of 2020 [1]. At the same time, disease-modifying therapies (DMTs) for MS have been evolving, with current drug options including interferons, glatiramer acetate, sphingosine 1-phosphate receptor modulators, cladribine, fumarates, teriflunomide, and monoclonal antibodies [2].