Finally, other S1P metabolism modulators such as siponimod (functional antagonist of S1P1 and S1P5), ozanimod (a potent agonist of S1P1 and S1P5), ponesimod (functional antagonist of S1P1), ceralifimod (selective S1P1 and S1P5 modulator), GSK2018682 (selective S1P1 and S1P5 modulator) and amiselimod (MT-1303) (selective S1P1 modulator), deserve to be explored in cancer, especially in PC [148]. The gene discussed is S1PR5; the disease is pachyonychia congenita.