S1PR1 and immune system disorder: Other S1PR modulators such as siponimod (S1PR1 and S1PR5 agonist), ponesimod (S1PR1 agonist), etrasimod (S1PR1, S1PR4, and S1PR5 agonist), and amiselimod (S1PR1 antagonist) for immune diseases are in clinical trials [54].