S1PR1 and myeloid sarcoma: Till now, there have been four S1PR modulators (distinct receptor subtypes targeted) approved for treatment of MS [fingolimod (S1PR1,3,4,5), siponimod (S1PR1,5), ozanimod (S1PR1,5), and ponesimod (S1PR1)], and several therapeutic candidates currently in clinical development [e.g., etrasimod (S1PR1,4,5), ceralifimod (S1PR1,5), and amiselimod (S1PR1,4,5)] [76, 81].